Jump to content

Banner.jpg.b89429c566825f6ab32bcafbada449c9.jpg

DIY Moon Phase Dial


Gina

Recommended Posts

Plenty of better items here http://www.rdgtools.co.uk/acatalog/Rotary_Tables_with_chucks.html

Far more useful - they have a worm drive which means you can mill circular stuff, as opposed to just indexing (and from what I can see that Proxxon thing doesn't even index, you have to go by the division scale, and doing that would get old real fast!)

ChrisH

  • Like 1
Link to comment
Share on other sites

Rather too big for my mill though.  OTOH could be useful for use with pillar drill.  Maybe something to look at next month :)

Link to comment
Share on other sites

That looks a good one - I like the worm drive, I would probably be able to add a stepper motor to that though quite usable as it is I think :)  I'll have to see how my finances work out and see if I can possibly afford it this month.  The price looks more affordable than others I've seen.  One thought is that I can use a dividing table with my lathe for larger parts.

Link to comment
Share on other sites

Very nice unit but expensive :)   I have a NEMA17 with 100:1 gearbox that I originally bought for a 3D printer but now just sitting around.  That could have a platform directly attached to the output shaft.  Half-stepping gives 40,000 steps per 360° a resolution of 0.009° - that's adequate :D

Directly driving that 3" chuck rotary table with 36:1 worm drive, with a non-geared NEMA17 gives 0.025° resolution half-stepping.  Well adequate and faster getting to any position, so that would be good.

All this is with a view to clock making.  The micro mill and small rotary table for the smaller parts and lathe with a larger rotary table for larger gears etc.  Cutters with involute gear profile are available or rotary table and mill are two options for gear making.  Stepper driving both mill and rotary table would make for unattended gear production :)

Edited by Gina
Link to comment
Share on other sites

I'll be sorting the lathe out shortly but meantime I've been looking into using the micro mill to make holes for the pins forming the pinion.  I already have 3mm flat ended milling cutters.  Practicing first on the reject hub, I mounted it in the Proxxon micro vice and made the first hole.  X = 5.2mm and Y = 0.  I have drawn a diagram in sketchUp with the five holes marked with their centres from which I've measured off the XY co-ordinates.  ATM I'm limited to cartesian co-ordinates for milling - once I get a rotary table I shall have polar co-ordinates too - much easier for this type of job.  ie. r=5.2mm  ϴ=0, 72, 144, etc.

Seconds Pinion Holes Diagram 01.JPGSeconds Wheel Hub Milling 01.jpgSeconds Wheel Hub Milling 02.jpg

  • Like 1
Link to comment
Share on other sites

Five holes made but I don't think it went perfectly - I don't think the cutter was really "happy" even though I took it very slowly.  I wonder if a 3mm twist drill bit would be better than a milling cutter.  Maybe I should get a book on milling since I haven't done it before.  Adjusting the co-ordinates by hand, counting the millimetres and then turning the knobs for the fractions was a little bit tricky.

Seconds Wheel Hub Milling 03.jpg

Edited by Gina
Link to comment
Share on other sites

For anyone who already has many of the parts the cost can be minimal and that's how he did it for a fiver :D 

I have a few stepper motors from defunct projects and Nanos that I bought cheaply in bulk.  Touch screen TFT displays can be obtaind from China/HK for a couple of quid and I bought a couple a little while back.  I also have a SainSmart LCD display with integral menu system driven by a few buttons that I used on an astro project that was replaced by something better.  I see no problem in adding stepper motors to my micro mill and a worm drive rotary table when I get one.

I have plans for reusing most of the stuff I bought for the Giant 3D Printer but some of the bits I could use twice over :D  I am also making good use of the space I had allocated for that printer for more bench and cupboard space in my workshop.  I wonder if anyone would be interested in my workshop project :D 

Link to comment
Share on other sites

1 hour ago, Gina said:

Five holes made but I don't think it went perfectly - I don't think the cutter was really "happy" even though I took it very slowly.  I wonder if a 3mm twist drill bit would be better than a milling cutter.  Maybe I should get a book on milling since I haven't done it before.  Adjusting the co-ordinates by hand, counting the millimetres and then turning the knobs for the fractions was a little bit tricky.

 

Yes, plunge-cutting with a milling cutter can be tricky also - you need a stiff machine and the workpiece needs to be very firmly held (round objects held in a vice - even with a V-groove - is asking for trouble). The cutter will tend to grab the work otherwise! I note you have a roughing cutter in the chuck - not the ideal tool either, a simple slot-drill would be a better choice. Drilling with a 2 or 2.5mm drill first then following with the milling cutter would be safer under your conditions. Use cutting lubricant too - for alloy then WD40 will do.

ChrisH

  • Like 1
Link to comment
Share on other sites

Yes, the vice was not ideal for holding the cylindrical workpiece - really wants a chuck.  Collets supplied are 1.0mm, 1.5mm, 2.0mm, 2.4mm, 3.0mm and 3.2mm so I could use a 2mm drill - I don't think a 2.5mm drill will fit in a 2.4mm collet but I could try :D  Or I could check my Imperial drills for their metric sizes.  It doesn't matter what shape the bottom of the hole is but it does need to be an accurate size and these holes have come out oversize.  I used 3-in-1 oil for lubrication but as I recall, paraffin is best for aluminium.  Should have a can of WD40 too.

I think I'll get some more practice with drilling holes with the mill and see if I can get a better fit for 3mm rod.

Link to comment
Share on other sites

Been practising a bit with the mill.  Found a 2mm conical cutter was good for starting the holes and a 3mm twist drill bit good for finishing - obtained a good fit for 3mm rod.

To get the holes right for the pinion, I think I shall need to a make a jig.  The problem is setting the mill tool exactly at the centre of rotation of the hub.  One way I've thought of is to clamp a block of aluminium to the bed and cut a 3mm hole.  That will be  the reference.  I can turn a stepped shaft in the lathe with 3mm and 5mm sections with the 3mm going in the milled hole and the 5mm in the hub.  The hub could be marked out with lines at 72 degree intervals or something clamped on to enable it to be turned a fifth of a revolution at a time.

This is getting complicated - maybe a rethink is required :D

Link to comment
Share on other sites

Use a simple probe (a broken 3mm bit shaft will do) using a pin (5 say) and the led on the Nano.  Place the shaft in the chuck and connect to the probe using a croc clip and ground to the work piece (you may have to insulate the shaft of the probe) Place the probe in the hole and slowly wind the x axis until the LED comes on.  Set to zero and then slowly wind back until you make contact with the other side of the hole.  Divide the distance by half and set the x axis to that value.  Then to the same for the Y axis and then you will have set center of the hole to a fairly accurate position

--

Mark

  • Like 1
Link to comment
Share on other sites

Been thinking about turning the seconds wheel hub...  I think two things contributed to the bad job.  The chuck is not accurate in centring the workpiece and the drill didn't accurately follow the axis.  I should have a suitable centre drill somewhere to start the hole and I need to increase the size in stages.  The lathe needs a service and more care needed to prevent digging in, resulting in the workpiece moving in the chuck.  All work needs doing with the workpiece continuously fixed in the chuck without moving an iota to counteract the inaccurate chuck.

Link to comment
Share on other sites

Hmm sounds like a flat ended milling bit. They will skip around when they bite if you're attempting to drill.

I have a drill press that has the same issue as the chuck with the shaft narrows and the check fits onto the narrowing. Annoying but once it's centred .. it works.

  • Like 1
Link to comment
Share on other sites

Yesterday morning I spent a couple of hours working on the little UP Plus 2 3D printer and got it working much better.  Tightened a few loose screws, cleaned connectors etc. and removed pleny of debris.  Found a broken plastic spring which will need sorting out and spent a lot of the time manually levelling the bed and setting nozzle height as the automatic method is now impossible due to the add-on probes not working.  Testing has shown that the fault must be in the circuit board but I haven't been able to find it.  There's also an intermittent fault with the extruder fan circuit, again traced to the PCB but I can get the fan working by wiggling the DC power input plug.  The printer now produces properly vertical prints and if I hold the RHS of the platform mounting so that the running wheel contacts the track, I can get decent prints.

I've also been looking into producing better fitting involute gears on 3D printers.  3D printers (with eg. 0.4mm nozzles), produce slightly oversize prints due to the filament deposited being 0.4mm diameter with the dimensions used in the STL data being the centre of this resulting in an extra 0.2mm on the outside of the print.

I have been allowing for this by reducing the size of the gears in the involute gear process which reduces the overall size but the main result of oversize printing is in the width of the teeth.  So rather than reducing the overall size, the outline of the gear teeth wants reducing by 0.2mm all over.  SketchUp has the "Offset" tool that will do this :)  From now on then I shall use the Offset tool rather than reducing the gear size overall.  Using an offset slightly larger than half the nozzle diameter will correct the oversize printing and provide a bit of clearance. 

Edited by Gina
Link to comment
Share on other sites

Printed a new seconds wheel with a hub to fit a 10mm x 26mm x 8mm ball bearing.  The teeth were reduced by 0.4mm to allow for oversize printing and give a nice bit of clearance for free running.

Seconds Wheel & Bearings 01.jpgSeconds Wheel & Bearings 02.jpgSeconds Wheel & Bearings 03.jpg

Link to comment
Share on other sites

Here is the intermediate gear between seconds and minutes just as printed and still on the perf board cooling down.

Intermediate Gear SM & Bearing 01.jpg

Same intermediate gear cleaned up, with pinion glued on and bearing fitted.
Intermediate Gear SM & Bearing 02.jpgIntermediate Gear SM & Bearing 03.jpg

  • Like 1
Link to comment
Share on other sites

Checking the meshing between the seconds pinion and the intermediate large gear I found it doesn't work too well.  The pinion teeth tend to catch on the top of the large gear teeth.  I think this may have been the problem all along - I need to look into this further.  A 10:1 gear ratio doesn't seem to work well with printed plastic involute gears - maybe this was one reason old clocks used cage pinions and I think this could work better.  So it looks like I may go back to a turned hub and SS pins for the pinion or look into other gear train arrangements.  More research needed...

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.