Mini Lathe and Accessory Advice Please.

[Ajohn]

I don't know if it will handle the size of work you want but Siege C3's are popular and going on the errors some one has just found on a new one for what they cost it isn't bad at all. Arceuro sell them. A company that does try hard like Harrry??? on ebay. I feel it's a bit small for you though. People also spend time sorting them out. Arceuro have a nice detailed leaflet on that here

http://www.arceurotrade.co.uk/projects/prepguides/C3%20Mini-Lathe%20Preparation%20Guide.pdf

This doesn't include such things as lapping the tailstock casting if it happens to be out and you need it to be precise.

For 4in diameter work I feel you should be looking for a lathe that comes with a 5in 3 jaw. The 4 jaw is likely to be bigger. I feel that the makers give a better idea of the real capacity of the lathe this way than quoted centre heights etc but this doesn't mean you will be able to take huge cuts at that diameter. Do make sure that the work you will want to do will pass over the cross slide.

One problem is that lathes like this are likely to weigh circa 100kg, probably more. As do Myford's actually but buying used Myfords can be a very disappointing experience. It's a mine field. Used lathes generally can be. People get round the weight problem by dismantling them. People also use files and emery cloth or what ever to get round accuracy problems.

A lathe with a 4in 3 jaw might come with a 5in 4 jaw. That will hold 4in dia work firmly and if aluminium it cuts pretty easily compared with steels.

Screw cutting anything other than rather fine threads when lathes can only go down to 100 rpm isn't much fun but if people stick to what is basically an imperial lathe and it has a screw cutting indicator it helps.  It can also help cutting metric threads when the lathe has to be reversed at the end of each cut. If some one is making something for themselves it doesn't really matter if imperil threads are used. It's pretty common for metric lathes to have no screw cutting indicator. Some do but they tend to have 2 gears which can be fitted to mesh with the leadscrew and unevenly spaced divisions.

One of the reasons I mentioned the C3 is that it has a sane looking headstock. Sounds silly but imagine when the holes for the bearings are made and there is say 0.001in error. If the head is 4in thick that's how much taper it will turn on work over 4in. If say it's 10in thick the distance goes up. Bearing errors will add to this as well. Looks like the 920 mentioned also has a decent depth of head but it's hard to be sure without physically looking at one. All real lathes have long heads for this very reason. The bigdog link on the 920 page mentions how low the run out of the bore of the spindle is - this only means anything when work is being turned between centres. The axial alignment of the head is the important thing and never mentioned. He also seems to be showing metric dials and imperial screw cutting ????  but it does have a screw cutting indicator. It will also go to a lower speed than the C3. Mention of 3in chucks too.

One problem with bigger lathes is what happens to the price. This one will be about under other names

http://www.warco.co.uk/metal-lathes-metalworking-lathe-machine/17-wm-250-variable-speed-lathe.html

Weight and price  goes up but it does come with the bits people are likely to need 3 jaw, 4 jaw, fixed steady and a face plate which can have it's uses at times.

Some lathes have T slotted cross slides. They can come in useful on hobby machines. I'd guess they are thin on the ground because they restrict the swing over the cross slide a bit and cost more money to make. The heads get thinner to increase the distance between centres. Sometimes the tailstock is too short to allow work be turned up right to the end when there is a centre in it - same reason.

 Sorry if this doesn't help your choice much but at least it might give you an idea what to look for. Apart from a Hobbymatt, a Unimat and a Peatol / Taig I have stuck to used machines. The head on the Peatol bent a bit eventually, it was very precise when it came, swarf also gets on the rack. Hobbymatts aren't too bad but need checking over carefully and if the original tool holder is over tightened the casting will crack. The unimatt is a different sort of machine. I did have a fair sized chinese lathe at one point - hopeless in respect to alignment but they may well have improved since then. It was the lathe with a sort of miller bolted to the top of the head - bad idea. I sold it to some one with a garage that just wanted to shorten bolts.

I'd guess you need to step back from 4in dia really. It's not a bad idea to have a small lathe about that doesn't take up much space even when you have a larger one. Making bits for the bigger one for instance. I have had my Boxford spindle on a Peatol. Sold but if the same sort of problem crops up I have another small lathe now. Do try and get one with all of the needed bits though. Costs shoot up when bought separately.

Sorry I haven't read Gina's thread so can't comment.

John

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[RLWP]

http://www.ebay.co.uk/itm/Amadeal-Mini-Lathe-Brand-New-7x14-Machine-with-DRO-4-Chuck-Metal-Gears-/261740534866?pt=LH_DefaultDomain_3&hash=item3cf0f39c52

Not this one! There's far too much in there for the money - and so it's going to be cheap and nasty. This is confirmed by the diecast scale on the topslide. Horrible

How about an old Unimat? http://www.ebay.co.uk/itm/Emco-Unimat-SL1000-Lathe-With-Tools-Original-Box-Stunning-For-Age-/331593114061?pt=LH_DefaultDomain_3&hash=item4d347d61cd

There are a great many accessories, including riser blocks for larger turning. From memory, there were a lot of articles in the Model Engineer magazine about the Unimat. I was always amazed at what folk could achieve with it

Richard

[Bizibilder]

The old Unimat SL (the one linked to above) is really only suitable for very small scale model making - and for turning small wooden and brass parts - many model boat and R/C plane makers use them for tiny stuff.  There is a modern Unimat (Unimat 4) which unfortunately is no longer available in the UK (the price had become astronomical!).  Now we can only get a very poor Chinese copy of a good Austrian machine and by poor I mean awful!  Not recommended at all, sorry.

Just to return to the larger lathes for a moment - the Colchester and Harrisons - apart from the sheer weight and size of them one has to be careful over the pricing.  A lathe of that size costing under £800 is likely to be an ex industrial machine that has been thoroughly worn out.  These are OK for folks who are prepared to do a total rebuild and can hunt around for spares and attachments to get the lathes serviceable again - the rebuild costs can run into a few hundred or even a few thousand pounds depending on how much work is contracted out for things like bed regrinds etc.  These are also likely to be the much older models where spares are getting rare.

From £1000 to £4500 you will get a more modern version but again the lathe is likely to be well worn and in need of some TLC.  Many ex college and university lathes fall into this price range.  Going up from that price point you are into the realms of "one careful owner from new and hardly used" - lovely if you can find them as most dealers snap them up and have a list of customers waiting for them so they don't actually appear on the open market that often.

Additionally all these lathes are likely to be three phase and cannot therefore be run directly from the household mains - you would need at least an inverter and connections/switchgear and possibly a new motor which will soon add several hundred pounds to the price and to your electricity bill when running the beast!.

Maybe that is why companies like Myford, Boxford and now the Chinese are making lathes in the 3" to 5" centre height range and selling them by the thousands.  Amateur engineers are turning 6" - 10" diameter cast iron locomotive wheels on them and steel wheels of 4" to 5" diameter for their riding cars and passenger wagons.  They will do the job - but just a little slower than their industrial cousins.  I have a 3.5" lathe and used it to turn and bore an adapter to attach my EQ6 to my pier.  This was from a 6" diameter by 1.5" thick billet of aluminium and the job was machined all over  in about an hour.

[Chris]

I don't know if it will handle the size of work you want but Siege C3's are popular and going on the errors some one has just found on a new one for what they cost it isn't bad at all. Arceuro sell them. A company that does try hard like Harrry??? on ebay. I feel it's a bit small for you though. People also spend time sorting them out. Arceuro have a nice detailed leaflet on that here

http://www.arceurotrade.co.uk/projects/prepguides/C3%20Mini-Lathe%20Preparation%20Guide.pdf

This doesn't include such things as lapping the tailstock casting if it happens to be out and you need it to be precise.

For 4in diameter work I feel you should be looking for a lathe that comes with a 5in 3 jaw. The 4 jaw is likely to be bigger. I feel that the makers give a better idea of the real capacity of the lathe this way than quoted centre heights etc but this doesn't mean you will be able to take huge cuts at that diameter. Do make sure that the work you will want to do will pass over the cross slide.

One problem is that lathes like this are likely to weigh circa 100kg, probably more. As do Myford's actually but buying used Myfords can be a very disappointing experience. It's a mine field. Used lathes generally can be. People get round the weight problem by dismantling them. People also use files and emery cloth or what ever to get round accuracy problems.

A lathe with a 4in 3 jaw might come with a 5in 4 jaw. That will hold 4in dia work firmly and if aluminium it cuts pretty easily compared with steels.

Screw cutting anything other than rather fine threads when lathes can only go down to 100 rpm isn't much fun but if people stick to what is basically an imperial lathe and it has a screw cutting indicator it helps.  It can also help cutting metric threads when the lathe has to be reversed at the end of each cut. If some one is making something for themselves it doesn't really matter if imperil threads are used. It's pretty common for metric lathes to have no screw cutting indicator. Some do but they tend to have 2 gears which can be fitted to mesh with the leadscrew and unevenly spaced divisions.

One of the reasons I mentioned the C3 is that it has a sane looking headstock. Sounds silly but imagine when the holes for the bearings are made and there is say 0.001in error. If the head is 4in thick that's how much taper it will turn on work over 4in. If say it's 10in thick the distance goes up. Bearing errors will add to this as well. Looks like the 920 mentioned also has a decent depth of head but it's hard to be sure without physically looking at one. All real lathes have long heads for this very reason. The bigdog link on the 920 page mentions how low the run out of the bore of the spindle is - this only means anything when work is being turned between centres. The axial alignment of the head is the important thing and never mentioned. He also seems to be showing metric dials and imperial screw cutting ????  but it does have a screw cutting indicator. It will also go to a lower speed than the C3. Mention of 3in chucks too.

One problem with bigger lathes is what happens to the price. This one will be about under other names

http://www.warco.co.uk/metal-lathes-metalworking-lathe-machine/17-wm-250-variable-speed-lathe.html

Weight and price  goes up but it does come with the bits people are likely to need 3 jaw, 4 jaw, fixed steady and a face plate which can have it's uses at times.

Some lathes have T slotted cross slides. They can come in useful on hobby machines. I'd guess they are thin on the ground because they restrict the swing over the cross slide a bit and cost more money to make. The heads get thinner to increase the distance between centres. Sometimes the tailstock is too short to allow work be turned up right to the end when there is a centre in it - same reason.

 Sorry if this doesn't help your choice much but at least it might give you an idea what to look for. Apart from a Hobbymatt, a Unimat and a Peatol / Taig I have stuck to used machines. The head on the Peatol bent a bit eventually, it was very precise when it came, swarf also gets on the rack. Hobbymatts aren't too bad but need checking over carefully and if the original tool holder is over tightened the casting will crack. The unimatt is a different sort of machine. I did have a fair sized chinese lathe at one point - hopeless in respect to alignment but they may well have improved since then. It was the lathe with a sort of miller bolted to the top of the head - bad idea. I sold it to some one with a garage that just wanted to shorten bolts.

I'd guess you need to step back from 4in dia really. It's not a bad idea to have a small lathe about that doesn't take up much space even when you have a larger one. Making bits for the bigger one for instance. I have had my Boxford spindle on a Peatol. Sold but if the same sort of problem crops up I have another small lathe now. Do try and get one with all of the needed bits though. Costs shoot up when bought separately.

Sorry I haven't read Gina's thread so can't comment.

John

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Hi John, thanks for your post. Yes, I have decided to stand back from 4" diameter, I wish I could edit my initial post really because I kind of meant 4" would be the very most I would wan't to try, there was one specific thing which is a flange for fitting a better focuser in my C100ED, ok maybe 2 things as I would also like to turn a counter cell for a 4" objective, but there are many many smaller things I would love to make myself also.

I think my wording has 'turned' the conversation towards larger lathes which a) I need to get my wife used to a small mini lathe first I can't lift and carry, and c) I can't fit in the space allotted.

Yes, the Sieg super C3 was Gina's compromise recommendation at the end of her thread. I have also seen some impressive Youtube vids of it ploughing huge cuts of swarf off a ali bar without even dropping revs, it seems very good for the size. I believe it has brushless motors and a direct belt drive which Gina could have done with on hers at one point as she stripped the plastic gearing and had to strip the head stock and upgrade the parts gearing.

One reason I'm reluctant to go second hand is because I'm clueless and would probably miss something bad staring me in the face. I have had some experience with CNC a long time ago where I used to write a programs in Gcode based on a drawing, run the simulation on screen, set all the tooling up with datum points so the computer knew where stuff was, then I would run hundreds of parts off whilst I checked tollerances and made offset adjustments (Literally this is all I can remember apart from a vending machine full of tungsten carbide tips).

Thanks your post has been helpful because the C3 is back on the table, it's a two horse race. 

[RLWP]

Between the Seig C3 and the Warco WM180, I think I'd have the Warco

Richard

[Chris]

Not this one! There's far too much in there for the money - and so it's going to be cheap and nasty. This is confirmed by the diecast scale on the topslide. Horrible

How about an old Unimat? http://www.ebay.co.uk/itm/Emco-Unimat-SL1000-Lathe-With-Tools-Original-Box-Stunning-For-Age-/331593114061?pt=LH_DefaultDomain_3&hash=item4d347d61cd

There are a great many accessories, including riser blocks for larger turning. From memory, there were a lot of articles in the Model Engineer magazine about the Unimat. I was always amazed at what folk could achieve with it

Richard

Yeah there does seem to be a lot for the money which is a bit suspicous. Bizibilder said it was cheap because it's probably got little in the way of aftercare support. I'm guessing it might need setting up and cleaning with paraffin more than some of the others. Having said this, I think this is the one Spaceboy has and seems very happy with, I think he mentioned abusing it for 12 years so far  

Thanks for the link to the Unimat, I was going to look into it but see that it might be better for very small parts. Looks cool still!

[Chris]

Between the Seig C3 and the Warco WM180, I think I'd have the Warco

Richard

I found this link to a guy with a WM 180 and it sounds fairly decent. I got the jist that things like screw cutting and changing from low to high ratio were hard with it though. I need to really get my head round how screw cutting works on a manual lathe? It was just a few lines of code and the correct tooling with CNC.

http://andysmachines.weebly.com/introduction.html

[RLWP]

Check out some of the modified Unimat SL lathes on the Internet. You'll find them doing some amazing things

It would still be a second hand lathe though.

If it helps, I never, ever have to strip and clean my lathe with paraffin. A brush down and then some slide way oil is all it ever needs. Cleaning the way you suggest would imply a lathe that swallows lumps of swarf, or generates pieces of debris internally. Walk away from any lathe that does that

Richard

[Chris]

Check out some of the modified Unimat SL lathes on the Internet. You'll find them doing some amazing things

It would still be a second hand lathe though.

If it helps, I never, ever have to strip and clean my lathe with paraffin. A brush down and then some slide way oil is all it ever needs. Cleaning the way you suggest would imply a lathe that swallows lumps of swarf, or generates pieces of debris internally. Walk away from any lathe that does that

Richard

I read that this is how you should clean a budget new lathe when it arrives, to clean all the protective thick sludge oil off it. I can't remember where I read it though?

Edit: found it, it was on this review of the Ebay 7x14 lathe:

http://www.mini-lathe.com/Mini_lathe/Reviews/Big_dog/bigdog2.htm

Ups, it wasn't paraffin, it was kerosene or liquid WD40.

[RLWP]

I need to be careful here. Yes, cleaning down a new machine is necessary. On the other hand, it should only be the protective materials you are removing.

A personal thing. I do tend to treat some of these imports as a kit of parts that happen to be assembled when I get them. So I would expect to dismantle, clean, measure and modify them. Not everyone wants to do this

I have had a look at that Warco website, are you sure you wouldn't prefer a nice, old second hand lathe with back gear, tumbler reverse and an assortment of tooling?

Richard

[Gina]

After much fettling of my lathe it's resaonable   I can't say more than that.  It certainly still has limitations but all my work on it made an enormous difference.  ArcEuroTrade are good for parts for the Seig C3 and all it's badged variants.  There is a lot of flexibility in it and I've found I have to hold the tools to stop vibratilon and jumping/gouging.  The largest metal I have turned was 80mm aluminium stock and I have succeeded in cutting threads for astro parts.  The two speed feature was useful for this as the low speed will go down to 20RPM - saves turning by hand.  You need plenty of patience if you are to avoid rejects (of which I managed a fair few). 

The largest item I have turned was a 6" pulley in acetal plastic for my observatory roof chain drive.  That started as a 150mm diameter x 20mm thick blank.  I drilled a 12mm hole drill in it with my pillar drill and mounted it on a turned aluminium mandrel which I held in the standard 80mm 3 chuck.  It took some careful manoevering of the tool post and tools but I succeeded in cutting an adequate square groove in to to take standard bicycle chain.  This job did not need great accuracy and acetal (aka Delrin and various other trade names) is very easy to turn - quite a joy in fact

As has been said, sharp tools make a big difference.  HSS tool steel is what I use and I have a twin stone bench grinder.  You also need decent personal protection - the last thing you want is a metal (or even plastic) sharp edged chip in your eye   These machines are noisy too and ear defenders not only protect your ears but make the working more pleasurable.

[Gina]

After much fettling of my lathe it's resaonable   I can't say more than that.  It certainly still has limitations but all my work on it made an enormous difference.  ArcEuroTrade are good for parts for the Seig C3 and all it's badged variants.  There is a lot of flexibility in it and I've found I have to hold the tools to stop vibratilon and jumping/gouging.  The largest metal I have turned was 80mm aluminium stock and I have succeeded in cutting threads for astro parts.  The two speed feature was useful for this as the low speed will go down to 20RPM - saves turning by hand.  You need plenty of patience if you are to avoid rejects (of which I managed a fair few). 

The largest item I have turned was a 6" pulley in acetal plastic for my observatory roof chain drive.  That started as a 150mm diameter x 20mm thick blank.  I drilled a 12mm hole drill in it with my pillar drill and mounted it on a turned aluminium mandrel which I held in the standard 80mm 3 chuck.  It took some careful manoevering of the tool post and tools but I succeeded in cutting an adequate square groove in to to take standard bicycle chain.  This job did not need great accuracy and acetal (aka Delrin and various other trade names) is very easy to turn - quite a joy in fact

As has been said, sharp tools make a big difference.  HSS tool steel is what I use and I have a twin stone bench grinder.  You also need decent personal protection - the last thing you want is a metal (or even plastic) sharp edged chip in your eye   These machines are noisy too and ear defenders not only protect your ears but make the working more pleasurable.

[Ajohn]

One thing that should be noticed on Arceuro's sieg c3 is the upgrade section but on the other hand the chester DB7VS comes with the bits most people need and goes to a lower speed. None of the lathes mentioned have a screw cutting indicator which is a bit of a pain. This seems to be because they tend to use lead screws with a pitch of about  16 tpi rather than 8. Looking at the DB7 there is another common silly. Swing over the bed quoted at 180mm were as the cross slide limits facing to 150mm, less in practice.

Some one mention distance between centres and drilling. True.  An old idea of a useful min distance between centres is 18in, bit short of 500mm. This is why they reduce the head size on the next larger size - to get it in and still keep the lathe small. The other old rule was for 1in bar to pass through the spindle. Not really possible to obtain but believe it or not the odd Eastern lathe did crop up with that and then disappeared.  Only in the USA  though.

One old lathe that might interest you is the Myford ML10 or better still Speed 10. In some ways it's Myfords usual design disaster from a purists point of view but they are likely to be a lot less troublesome than the 7's. You will be able to pick one of those up but it will be a bit of a struggle. It will be a lot less of a problem with tailstock, head and motor removed. They are around 3ft long. You will get the usual lathe facilities with one of these including a back gear and there are plenty of spares around for them. One nice thing is that the bearings can be changed more easily than other Myfords but there may be a need to find some one with a bearing press. They use taper roller bearings. Some of them wont have had too hard a life as they are mostly a model engineer lathe. That isn't the case with the older smaller ML's. They might have even been used as a capstan day in and day out at some point in their lives. Curiously the metric version of 10's does have a screw cutting indicator that can be used on some pitches. Change wheels are available for cutting metric on imperial lathes as well but the lathe will have to be reversed at the end of each cut - as it will on some metric pitches on a metric lathe. Myfords are budget real lathes really and looked at that way the 10's are a clever design to keep costs down. Current prices for new 7's are basically stupid, no one in their right mind would spend that much on one but no doubt a few might.

As I see it astro bits are likely to need screw cutting - adapters and things like that but most other screw cutting is done with taps and dies. As I see it if you want to do the lot it would be best to go for a lathe that includes a screw cutting indicator so maybe it would be best to re arrange your shed a bit. One thing I feel is very important when buying a lathe is don't rush. The other thing to remember is that buying bits an pieces for lathes is a money pit so it's best to buy with at least the basics are included or to at least look and realise what adding them will cost. The essentials as I see it are 3 jaw, 4 jaw, change wheels if needed and a fixed steady plus probably a face plate. Then there is a drill chuck and revolving centre and in the end for most a quick change tool post with a few holders.

Actually as a 1st lathe I suspect that a decent ML10 would suite you rather well but personally I wouldn't touch one unless it came with it's change wheels as buying them individually would push the price up even as cheap as they are on Ebay but having to buy a couple isn't too bad. They do crop up on ebay from time to time. Maybe a wanted add on homeworkshop.org might turn one up. I'd guess that a new fixed steady would be a bit of an arm and a leg price and it might be hard to find one. One possible problem.  They are used when doing things like boring long tubes or doing things to the end of long work even just facing and centring. As stupid as it might sound for light work one could be made out of a mix of MDF and metal for the fingers, brass would do. It's also possible to route aluminium with normal carbide tipped woodworking cutters if light cuts are taken. The router cutters aluminium window frame people used might still be about too.  The Peatol / Taig lathe uses a very simple design that works. There vertical slide is excellent too even though it's a bit small. It can be adapted to fit most things by adding a plate.

One problem with wanted adds is the crooks. Beware of super shiny freshly painted stuff. Lathes tarnish. Another place where used lathes can be found is lathes.co.uk. There are also a number of dealers around but generally they sell the lathe without bits and pieces as they make more money that way. Might be worth looking at homeworkshop.org.uk too. Gumtree, Preloved, local ones etc.

Failing that I suspect a re arranged shed and the bigger chester is the best bet. It doesn't look like a 918 to me, nothing like it. Those are from the days when most of the lathes the East did looked to be pretty sensible all round. Maybe one of those plastic thingies to keep the lawn mover in etc would help. A used one of those might be about. I have no idea just how good these lathes are. I went Chinese once and never again currently but I understand that with a bit of titivating they are a lot better now.

When I bought my Boxford I asked the person selling it to turn 6in of bar with no centre in and measure the taper. He reckonned it was 0.002in. A photo of the finish wouldn't have been a bad idea The taper turned out to be less than that, the bearings needed adjusting which would also spoil the finish and bars bend a bit when turned like that. It was on ebay with a reserve. At the time no one would pay more than about £500 for a Boxford. This one had lots of bits with it so I valued it on that basis. The bidding stopped  at around £500 or so and I placed a bid of £1000 a few seconds before the end of the auction and got it for £700 which was his reserve price. A bargain really especially for me as it was rear drive and I have to have a bench lathe. Often when well equipped lathes turn up people wont pay what they are worth. I had a brief interest in a Cowell's recently and one with all of it's bits and pieces turned up. It would cost well over 2k to buy new and it went for £800 - I went to look at it and it was in excellent order. Biggest problem really is that the lathe new sells at what is really a silly price for what it is so I bought something else instead but waited for the right machine to turn up. It would sell on Ebay for a lot more than I paid for it.

Over all message really is don't rush, that's easy to do if the money is about and also to think carefully. There are always several options in areas like this.

 Just hope that if you or anyone else does buy an ML or Speed 10 it does turn out to be a decent one. On the other hand if resold little if any money will be lost and it is also worth spending more on lathes like these to fix them up if needed.  The other problem with mentioning things like this on the web is that it often pushes prices up. Been there and done that so now keep ultra quiet if I'm buying something.

John

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[Chris]

Thanks for all the advice Gina and John

I've just sold my C8 Edge HD plus accessories so funds are in place. I think you're right about not rushing, I will take a bit of time over this purchase and look at possibly cutting through the pier of the scope room in the obs to allow a bigger lathe to go in there. I'll also start to scope out ebay a bit more although I can't travel far due to family commitments.

I really need to get my head around screw cutting on a manual lathe, I don't know why imperial would be better than metric for this? If I was going to buy a new lathe I would instinctively choose metric because my brain works in metric, say an inch and I think 25.4mm.

I could do with a good book on hobby lathe turning perhaps, so I'll look into that also

[Stub Mandrel]

I have a 17 year old Clarke CL300M mini lathe, but if I were buying now I would go for the Arc Euro super C3, no question.

If you have a limited budget, it's probably the ideal machine for astronomical use, as the 350mm between centres/180mm swing is unlikely to be a limiting factor.

A selection of what I've done on mine can be seen here: http://www.model-engineer.co.uk/albums/member_albums.asp?c=45510

People moan at me for posting astronomical images on etthat forum, so i'l post an engineering one here. All done on a mini-lathe and an X2 mill:

If you want advice and support I suggest you visit: http://www.model-engineer.co.uk/ but I have to declare an interest (I'm one of the site admins )

[Ajohn]

Sounds to me like you might need to do some work on your slides Gina and also the headstock bearings.

It's best to set the gibs on the slides with the lead screws out and look for slight drag when pushed by hand. Might be worth checking for sharp corners fouling too. I've also lapped slides a little at times using a mix of CIF kitchen cream and oil. It wont cure errors of any significant size but it can make things run smoother. It's a case of keeping on adjusting the gibs and sliding back and forth by hand while thinking about keeping the "wear" even. It's well worth buying some Vactra slideway oil as well. It has been on Ebay in smaller quantities but there are also web sources.

I can't give specific instructions on setting the head stock bearings but have the problem on my Boxford. They give very specific instructions but it doesn't work out. The bearings need to be preloaded and the question is how much. Boxford state stick a face plate on fix some rope etc to it and pull with spring balance and set for so and so. Initial stiction messes it up but even accounting for that it leaves them too loose. The fact that the bearings are pre loaded means that there is friction. Friction means things warm up. What I do is run the lathe for 20min after an adjustment at a medium speed and feel the heat in the area under the rear bearing with a finger via the spindle bore. I expect it to be cosey warm. I never run my lathe flat out but if people do best check at that speed too. It will be hotter. The end result is that I can see a slight improvement in finish after the lathe has warmed up. Even grease and moderate warmth can still mean that the bearings are loose. One way of telling is to take a cut and wind back along the work at the same setting. If more is taken of the spindle is moving via the bearings or the bar has bent. It's best to make it a decent cut in say a 1 1/2 in of 1in OD mild steel. AFTER the slides have been set as on some lathes looseness there can cause similar problems especially if the saddle is not seated well.

The reason I mention this is that bits shouldn't fly off. The worst offender I had was an ML7 whose bearings were shot, all that kept the spindle in place was tension from the belt. It was also brilliant at chipping carbide tools. Things don't dig in if the lathe is set up correctly and most materials should produce nice strings of swarf to such an extent that it has to be pulled off with a swarf hook.

People often buy 6in grinders. Much to my amazement as much larger wheels are usually reckoned to produce better results Axminster sell some white aluminium wheels that make an excellent job of HSS. HSS tools really need polishing after grinding though as the finish on them will be transferred to the work. Arceuro sell some diamond lapping stick that could be used, best add a bit of oil such as 3in1. It also best to put the radius on the tool this way unless some one has high off hand grinding skills. A rad on the tool distorts the metal and promotes tearing and only needs to big in comparison with the feed that is being used. It's hard to achieve that on an off hand grinder. The other point is that the lapping sticks can be used to resharpen the tools periodically without even removing them from the lathe. When doing this and also polishing them it needs to be done in a way that wont radius the cutting edges. That just need a bit of thought - working up and down on the cutting edge might just do that for instance. Do this regularly and tools last "for ever" and only get ground once.

 As astronomers are rich or so people tell me it might be worth mentioning carbide especially disposable tips. I use one of these from time to time

The holder is out of one of those cheap sets off ebay. Wish I could get this one singly. The tips that come with them are so so and if bought make sure that they come with Torx screws as the hex keys soon wear out. The tip on it is an 1100xxxx series 11mm  from APT that was listed for finishing stainless. They also do them for aluminium. The stainless ones work well on most things but the aluminium ones will improve aluminium. APT also sell their own brand of holder for these, a turning and facing type but the smallest one might be too big for lathes like the C3. While opinions vary some including me reckon this type is as good as can be bought for small lathes even up to Boxford size. Like them I have tried a number of types at one time or the other.

Brazed tip carbide tools can also be sharpened - just buy a green grit wheel for the grinder. They can't have the sort of rake that is on the tips though and if clearance angles are pushed past some point they will chip. I used to grind up brazed tip paring off tools for screw cutting. I usually use HSS chasers now as I have them.

There is an interesting grinder about at the moment made by Ferm. Same as one by Record but a lot cheaper if bought off Amazon. It has one white wheel and is because of that wheel more suitable for converting to a lathe tool grinder IF PEOPLE ARE FULLY AWARE OF WHAT THEY ARE DOING. The sides of wheels can only be used for light touching up. Oddly 6in grinders run at the right sort of speed for 6in diamond wheels but frankly I feel that they are a bit of a waste of money for little gain really. They might be worth having if super fine grades were about to save polishing.

If a C3 goes down to 20 rpm or even 50 it would be the one I would buy because Arceuro really try hard. I buy all sorts of things off them and haven't been disappointed yet. Can't say the same about RGD. I also visited Chester once to help a friend choose a lathe. I suppose they are all the same really but after mentioning a couple of things they didn't have anything available that would suite me.  The friend ignored the advice mostly due to demo type web sites and weight of machines and regretted it. He went for the baby size though. There is a guy trying to make a C3 super accurate at the moment - read things on the web and wont even make a between centre test bar to help him be sure of what he is about to do. Or even turn up a few bits of bar to see what the lathe is actually doing. Good luck is all I can say.

Meant to also mention another useful item. A hammer headed diamond grinding wheel dresser Axminster sell. It makes dressing easy and so far has lasted well for me. The white wheels don't need it any where near as often as others though. They are friable enough to remain sharp.

John

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[Stub Mandrel]

John's advice is excellent for taper roller bearings in general, but there is some mini-lathe specific advice:

Setting headstock bearings on mini-lathes depends if they are deep groove, angular contact or roller bearing. For the first two, tighten up the adjuster c-nut at the end of the spindle until there is no play at all, give it another 1/4turn then back off very slightly. If the lathe has an overload trip, run at full speed and if it trips, back off a little more.

For roller bearing lathes, best results are with no or very , very slight preload. Adjust until there is no play.

Well adjusted bearings should run warm to the touch after a while, but not hot. Hot bearings will self-destruct rapidly.

If greasing the bearings only 1/4 - 1/3 fill them with grease.

This is a very brief summary of first-hand advice from Arc.

John - I think we both know to whom you are referring at the end ;-)

[sdkfz181]

My other hobby is model engineering, here is my experience for what it is worth.

I cannot recommend a Chinese lathe. I bought  a new 3 - in -1 a few years ago which I completely stripped down and rebuilt before use. I cleaned an egg cup of sand out off the headstock, I replaced all of the red grease, much of which had dried out. I had to hand finished all of the castings and machined parts before I dare reassemble and set it up. Even after all that, it just did not come up to a standard I could recommend. In the end I used it largely for roughing out, and later sold it.

I have had a Unimat  SL, 3, and 4. They are ok but only for very small work. Unless you are a complete novice (in which case they are excellent to learn on because you are less likely to injure yourself) their limitations will soon frustrate, and they can work out dearer than a larger machine by the time they are fully accessorized.

I still have several Austrian made Emco 5 machines, bought second hand, which are very good and easily work to "tool room" standards. I use them to make narrow gauge steam engines in "16mm" scale on 32mm gauge (SM32). However little steam engines don't require screw cutting, and like most small machines, it runs too fast for screw cutting. If necessary, I would hand turn by making a winding handle to fit on the rear of the spindle.

I regularly use a friends Myford Super 7, which is a superb "tool room" machine with low speeds for screw cutting. It is undoubtedly the most popular and versatile model engineering lathe but it comes at a price, expect to pay four times the price of an Emco 5. It is also twice the size.

A machine I have often admired, and were my Emco's ever to wear out (extremely unlikely), I would most likely buy a new Proxxon PD 400.

Do remember that the lathe is only part of the cost. You will also need a lot of  other bits and pieces, if you don't already have them.

[Stub Mandrel]

Just noticed this comment; "Unfortunately your going to need a good sized lathe to turn down a 4" billet as that will be beyond the capability of most mini lathes."

This lump was 7 1/2" across the diagonal...

[Ajohn]

I'm spending too much time on the web but suppose I could explain the metric thread problem.

Some one explained the maths to me a long time ago in a lecture but I don't have the notes. If some one does I'd appreciate it. From memory it uses radians / sec which cancel out.

The lead screw and the work are usually rotating at different rates and the lead screw has a thread on it. When screw cutting is engaged the saddle moves along and cuts a spiral at some pitch according to the relationships. So get to the end of where the thread has to be cut and disengage screw cutting. Wind the tool out and wind the saddle back to the start, re engage screw cutting again. The problem is that there is no guarantee that the tool will travel down the same spiral again. It will if the lathe is set up to cut the same pitch as the one on the lead screw. I have heard that there are others but suspect that is confusing something else.

A screw cutting indicator is a gear that meshes with the lead screw side on with a dial on top of it so the dial rotates as the lead screw rotates and also when the saddle is moved when screw cutting is dis engaged. So this time when a thread is being cut screw cutting is engaged according to the marks on the dial. That ensures that it will go straight in rather than riding on top of the thread on the lead screw but it doesn't something else as well. It's indicating the rotational angle of the lead screw. Get to the end of the thread and disengage and the dial will then start rotating again indicating the current rotational angle. Wind back to the start and as it's still meshed with the lead screw it will continue to indicate it. It remains in sync. Then when another cut is taken the tool will travel down exactly the same spiral as it did before if the same mark on the indicator is used. Actually there are some rules.  Some thread pitches could be engaged on any mark, some on every other one and some on just one. How far that goes depends on the design of the indicator. I suspect some knowledge in that area has been lost as I have cut threads on one lathe this way that wouldn't be possible on any other lathe I am aware of.

If there isn't an indicator or it can't cope a different technique can be used. The usual one is to wind out the tool and stop the machine at the same time at the end of the cut. Select reverse and run the saddle back to the start again. As screw cutting is never disengaged it will always be in sync.  It's not much fun screw cutting up to a shoulder. It's still possible to make good use of an indicator when threads are cut this way. Sounds hard but it isn't. At the end of the cut note where the indicator is, wind out, disengage the screw cutting and turn off the lathe. Select reverse and engage screw cutting when the indicator is back where it was when you disengaged. Much easier to work up to a shoulder this way. It works because the lead screw is highly unlikely to revolve enough times for it to loose sync when the lathe turns off. Actually it would be extremely unlikely to revolve too much to prevent this from working due to the relationship of pitches that need this and lead screw pitches.

Imperial threads are based on TPI as are lead screws. The important thing is threads per inch. This means that there can always be a sensible fractional ratio between leadscrews and commonly used pitches. This means that the usual thread cutting indicator with 8 marks on the dial can be used to cut all of them. This is how the pitches were chosen to make that so. There may be odd ball ones on pipes, gas fitting etc but little else. This comes about because the pitches used have a simple fractional basis. Try dividing common metric pitches with each other and you will see what I mean. They have more than one "base".  And when cut on an imperial lathe they have no common base at all. To be honest I have hardly ever seen a metric lathe with a screw cutting indicator. Where I have they tend to have more than one gear available to mesh with the lead screw. Myford came up with one gear that will do some useful pitches on the ML10. Colchester did an amazing one, more gears and then comes another problem - the time it takes for the indicating marks to come round on some pitches. This comes down to how often the pitch being cut divides exactly into a number of lead screw pitches. It has to do that for indicators to work.  The answer is probably never when metric is cut on an imperial machine via conversion gears or some number that is absolutely enormous before it gets insignificant - help with the screw cut indicator disengage method.

This probably comes about because our impoverished European neighbours lacked King Henry's thumb as a base measurement and probably were not keen on choosing teeth per cm as it isn't long enough to give enough numbers. Teeth per metre would be a bit weird. They picked pitches like topsy, same as out BA threads which are sort of metric and aimed at instrumentation work not engineering. An instructor once said to me after enquiring what metric fine was about said forget it as metric coarse is too fine really, what do you expect they are basically a bunch of watch makers. There is some truth in this. BSW/UNC into aluminium should be sadly missed if it disappears and other materials too. It was aimed at iron. BSF at steel. If any one finds a real list of what have been standard metric threads they would be gob smacked at the range - yet more pitches to get round the problems.

Seeing what has popped up since starting this post and doing one or two other things too I would still say investigate bearing heat what ever is fitted. The question is how much heat. Can't help there. To me there is little difference between angular contact and deep groove really as deep groove will wear to only running on one side just as angular contact will. I feel that the best option is to try and keep them adjusted but at some point they will have to be replaced. Grease - not much at all and it does cause problems with adjustment as it has to settle down and takes a lot of effort to displace. Turning is good at doing that - some decent hefty cuts as big as the lathe can take. Drilling max capacity holes in mild steel is good too. The nut on the end isn't so good. Cutting pressures will get the front bearings seated and loosen the rear which is at least a start. I found i had to set the ones on my Boxford several times. I suspect like the Boxford method and also feeling for drag that this will only work with new bearings as supplied are fitted and before they are greased. I started on the heat route because some one who should know told me that lathe bearings run at over 100C. These are big lathes and the front of the headstock on these does get rather warm. There is also sometimes an improvement in finish too. The spindle warms and expands where as the heat in the outer shells of the bearings remain cooler as heat is taken away by the head stock casting.  That's my theory anyway and is why I mentioned 20min. 10 will probably do really.

John

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[Ajohn]

LOL I have a feeling I know who Stub is now.

One more thing on adjusting bearings. From the arc details on sprucing up a C3 it looks like it has a common problem with bearing fit. The bearings and spindle have to be made to some suitable tolerance. An interference fit in this case that will vary. Trying to produce a light interference fit is a challenge but some lathes will have one. My boxford was super tight

I thought I would never get it out but did eventually.   Before putting it back I stuck it on a Peatol and got the lapping sticks and honing oil out

There's a need to use a mic with extreme care.

Perhaps the best way to adjust bearings due to this sort of thing is what I did before loosening the rear one a bit. Put the C spanner on and tap some tiny fraction of a turn with a hammer if a lot of effort is needed to turn it which I suspect is likely in many cases. This also means that once over tightened they might not release that easily so tighten very very slowly.

Just a tale on cuts. It can be surprising what even low powered lathes can do.

While sorting out a Raglan I dropped a cast iron pulley about 3 to 4in diameter onto concrete and broke a corner off it. I mounted it into a Peatol and turned that rim off completely and then made mild steel annulus to replace the missing side of the V groove. Wanting to make sure that it ran true I then fixed it to the pulley and mounted it on a turned mandrel to turn the replacement side of the V  Couldn't use the compound slide but just managed to get a angled form tool in. Poor old Peatol finished up taking 3/4in cuts with nice shiny curls of swarf coming off. Didn't do the lathe much good as it bent the head but it did it helped because the in feed was very slow so. Just goes to show that apart from that sort of problem what a tiny lathe can do if it's set up correctly and rigid in the right way. They are pretty good actually but the head will bend over time. They will work to well sub 0.0005in all round tolerance till that happens. Swarf also gets on the rack due to where it's positioned. Like Unimat's though size and other things are a real limitation.  They are great for getting nice square tidy ends on drain pipes with most of the length sticking out of the back door.

John

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[Stub Mandrel]

Rumbled!

Anyone who wants to cut metric threads on an imperial mini-lathe or vice versa can take a look here: http://www.arceurotrade.co.uk/reviews/MEW204-P31_P36-Thread-Cutting.pdf the technique uses a custom 63-tooth gear from Arc Euro. Extra (ordinary) change wheels may be needed for some pitches.

And doing that to a poor Peatol! What's next? Super Adept abuse?

[spaceboy]

Just noticed this comment; "Unfortunately your going to need a good sized lathe to turn down a 4" billet as that will be beyond the capability of most mini lathes."

This lump was 7 1/2" across the diagonal...

I can strap a 7 1/2" slab of iron to my lathe also but it doesn't mean I should!

[Ajohn]

Rumbled!

Anyone who wants to cut metric threads on an imperial mini-lathe or vice versa can take a look here: http://www.arceurotrade.co.uk/reviews/MEW204-P31_P36-Thread-Cutting.pdf the technique uses a custom 63-tooth gear from Arc Euro. Extra (ordinary) change wheels may be needed for some pitches.

And doing that to a poor Peatol! What's next? Super Adept abuse?

Pultra abuse if the same problem crops up again. I mean I have 40mm riser blocks for it giving a swing of 180mm plus and an incredibly high tool post.  Should be able to use 1in HSS in that. It mated with something else over night and 17/70 appeared so the blocks on that would give a 220mm swing and an even taller tool post.  They are both variants that don't appear on lathes co uk nor in the usual pultra manuals.

People need to realise on swing etc that the main thing is not to overload the motor or don't load it any more than they usually do. Bigger stuff needs lighter cuts and that's all. Get it correct and the load is no different to what it would be at smaller sizes. With big slabs like the one shown balance is also important as lack could shake the lathe to bits - as could smaller bits. In fact when certain types of things are made on a face plate weight has to be added to keep it all balanced.   It's a bit like balancing a telescope - but best arrange the spindle to be completely free some how. This area touches on why face plates are sometimes bigger than anything else that fits one the spindle - so that work can be done when it isn't all central to the axis. It's really a better option than a 4 jaw then as the work can be balanced.

John

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[Stub Mandrel]

> Bigger stuff needs lighter cuts and that's all.

Agreed. I often point out that the bearings on a mini lathe are bigger than those on many cars - and they are expected to do 200,000 miles of hard, dirty, shock-loaded work with minimal maintenance.

Neil