TAL-1M motor gearbox woes

[sloz1664]

Hi All,

Have checked the Final Cog and can confim with Andy the OD is 13.5mm, 32 teeth and a bore of 4mm. The shaft is always knurled to "key" the cog when it is pressed home. What you see inside the bore of the cog is the staked markings from the shaft.

I would be happy to use HPC ref: GO.4-32 cog it is thicker than the existing Tal cog and therefore more robust. I have my doubts on the current cog, in my opinion it's too thin, it's drive cog is chamfered and because of this does not mate fully across the width of the teeth of the final cog. As a precaution, just in case the tooth profiles are diffrent with both the Tal & HPC cogs, I will send one of my damaged cogs to HPC, later today.

NB: I have sent an email to motor - semz regarding the Tal motors.

Steve

[AndyH]

Alistair - A fair and understandable rant ! The number of small to medium sized companies out there, that have NO interest in small jobs, is very dissapointing. There may be members on SGL that have the kit and skills that could help with small machining jobs. You couldn't go wrong by starting a thread regarding something like that? At the very least, someone could read it and recommend someone?

Steve - We await any further info, with extreme interest !!

Cheers,

Andy.

[AndyH]

Any updates?

Cheers,

Andy.

[Penguin]

Any updates?

Cheers,

Andy.

Graham has offered to have a look at my gearbox and I have packed it up. I have yet to send it off to him though!

Any news from TAL or the motor/gearbox manufacturers?

--- Alistair.

[sloz1664]

I have had a reply from HPC Gears Ltd. The part number GO.4-32-SO4 Spur Gear (includes boring to 4mm) would replace the damaged drive cog. Price £12.18 + vat & delivery.

I have had one reply from Yuri, although he has sent two emails. I have sent three further emails, including western union funds for two motors - cost £45.50 (includes shipping) sent 21st Jan and, as yet, had no replies. Nor has Yuri collected the Western Union deposit. I will let you know on the proceedings.

cheers

Steve

[AndyH]

Excellent on the HPC front !

The delay in the W.U. collection happened to me once too. I shouldn't think there's anything to worry about.

Thanks for the update, Steve.

Andy.

[Penguin]

I have had a reply from HPC Gears Ltd. The part number GO.4-32-SO4 Spur Gear (includes boring to 4mm) would replace the damaged drive cog. Price £12.18 + vat & delivery.

I have had one reply from Yuri, although he has sent two emails. I have sent three further emails, including western union funds for two motors - cost £45.50 (includes shipping) sent 21st Jan and, as yet, had no replies. Nor has Yuri collected the Western Union deposit. I will let you know on the proceedings.

cheers

Steve

Is that 2 motor/gearbox combos for £45.50 including delivery? If I'd known you were placing that order, I'd have given you the funds for a 3rd!

Is anyone else thinking of ordering one?

--- Alistair.

[sloz1664]

Sorry about that Alistair. I had ordered from Yuri before and it was a simple "repeat order".

You are probably wondering why I seem to go through so many motors. I had previously ordered two motors. On fitting the first motor I only just "nipped" the screws on the motor bracket, prior to any final adjustment. Set the axis for a timed one hour, to check if the clutches were correctly set, came back 15 mins later to hear an unpleasent clicking sound. The bracket had moved jamming the gears and resulted in the dreaded damaged final cog.

The second motor I damaged unaware that hand-controlling the mount while having the motor running DOES damage the final cog.

Best if you purchase two motors, you will then have a spare. Don't think, due to my misfortunes they are flimsy little things. They are Russian made. Built to last. Unless you're name is Steve.

If you require any details on how to obtain the motors, let me know.

Regards the HPC front. I will contact them to obtain total cost of the Cog. If reasonable I will order one, but I am a little uncertain on how to clamp the unit back together. Will have to think on that one.....

Cheers

Steve

[EssexMigrant]

Hi all,

I've only just picded up this thread, and to be honest I've only just skimmed through it, so if what I'm about to say has already been said, ignore me.

Re the cog spinning on the shaft, surely that's a simple fix; drill a hole into the edge of the cog and into the shaft, then insert a steel pin of the right diameter (a broken drill?). A small amount of either resin, or super glue could ensure it doesn't come out. If there's a reason that this isn't a good idea, and I've missed it also, again ignore me.

Cheers

Max

[EssexMigrant]

They'd need to be machined up out of a 4mm diameter piece of steel or brass. Overall length 15mm, with about 2mm either end machined down to 3mm, to let the pass through the sideplates.

A friendly machinist could easily bang these out.

Andy.

Hi Andy!

Nah, anybody could do this with a secured hand drill if they were careful, using a small file to turn down the ends. Agreed, they'd be simple to make on a lathe, and would be improved if instead of 'pressing' were drilled and tapped to take a securing screw. Obviously if you were using brass, it would be easier to do using the drill method.

I've got some some small brass pillars to make soon for my C8 dec drive housing, so I could possibly make one or two sets of gearbox 'pins' while I'm at it.

Cheers

Max

[sloz1664]

Just a had a bit of a shock. Went to place an order for two Spur Gears from HPC Gears..... Total cost £37.21. That's nearly the price of two full motors from Yuri. Considering you have to split the gearbox & fix it back together, which, as Max points out, could require three new pillars it's not viable. At present with Yuri's help motors are still available, if this dries up then HPC Gears would be an option.

As yet no reply from motor - semz regarding the Tal motors.

Steve

Edited January 30, 2012 by sloz1664

[Penguin]

Ouch, Yuri definitely seems to be the way to go then. One day I might get my **** in gear to email him. If I do, would anyone else be interested in adding to my order?

--- Alistair.

[AndyH]

I second that 'Ouch'.

That's a lot of dosh for two small gears.

I wonder how the delrin gears in the same spec would cope. Could be drilled out to 4mm by the user. I have seen one or two Tal gearboxes that use plastic/delrin gearing.

Using nylon spacers(3.2x6x15 - ground or cut down to 12mm) and M3 x 20 c/sunk setscrews & nuts, should hold the gearbox together? After checking the web, I reckon £5 would be enough for about 6 sets.

Andy.

**edit

Edited January 30, 2012 by AndyH

[AndyH]

Hi Andy!

Nah, anybody could do this with a secured hand drill if they were careful, using a small file to turn down the ends. Agreed, they'd be simple to make on a lathe, and would be improved if instead of 'pressing' were drilled and tapped to take a securing screw. Obviously if you were using brass, it would be easier to do using the drill method.

I've got some some small brass pillars to make soon for my C8 dec drive housing, so I could possibly make one or two sets of gearbox 'pins' while I'm at it.

Cheers

Max

Good info, Max

[Penguin]

I finally sent the gearbox off to Graham and he had it for a few weeks. He ended up replacing all the plastic spindle mounts with brass, fixed that final cog and sent it back with no charge. A top man he most certainly is!

It seems much better now (actually works!). I set the hour circle on zero and one hour later it was on 1 so seems pretty good to me. I think I need to play with the clutches though. Once I got the scope on there and pointed it skywards it seemed a little intermittent. I'm sure its the clutches slipping now though rather than the gearbox but I am nervous of doing them too tight.

--- Alistair.

[AndyH]

Hi Alistair.

Great news on the fixed gearbox !

Yeah, you have to have the mount loaded up with the scope to really know if you have the clutches set up correctly.

You won't do any harm to the motor gearbox by having the RA clutch too tight. It'll just make moving it in that axis hard to impossible by hand.

The most important thing to do first is to get the motor clutch adjusted correctly. You want it just tight enough so it moves the scope without it slipping. Too tight and the RA handwheels won't turn by hand.

With the scope balanced on the axis as well as you can, have the scope/DEC axis horizontal to the ground on the RA axis.

Try fully tightening the 3 RA clutch screws, then do the 1 hour test. Actually if you sit by the mount for a few minutes, keep an eye on the RA hand wheels. If they move intermittently, then the motor clutch needs to be slightly tightened. If all seems well, leave it running and come back in an hour. Again, if it's not moved the full hour, try another slight tweek to the motor clutch.

Once you have that sorted, you can loosen the RA clutch screws a touch, each and try the above test on that clutch.

The motor clutch is the most important clutch to get right. Once done you may not need to touch it again. The RA clutch may need a tweek now and again in a session if you've been swinging the scope around the skies. I've found it can sometimes loosen off, especially if the mounts carrying a heavy load, so I always have a screwdriver to hand.

Just get in the habit when you go to move the RA handwheels, to click the power switch off on the mount. Better safe than sorry!

Hope that helps a bit.

Cheers,

Andy.

Edited May 6, 2012 by AndyH

[steelfixer]

Glad to here it is working ok Alistair.

If anyone else wants to sort their's out this is what I did to penguins.

I first stripped the gearbox down.

I removed the stripped gear cog and spindle, cleaned them up and soldered them together.

I then removed all the plastic bearings and replaced them with with Brass bearings.

Then it was just a case of rebuilding the gearbox and trimming back the bush that encroached on the main drive shaft hole.

Job done.

See the photo.

[AndyH]

Sorry, just had to use this

Nice fix for the bearings. On one of my 'in bits', gearboxes, the final gear shafts bearing is pretty chewed and wide. I had been scratching my head over how I would go about repairing it, should I get round to getting some replacement gears.

Andy.

[AndyH]

Oh........

If you don't mind me asking, how do you 'fix' the brass bearings in place?

Cheers,

Andy.

[steelfixer]

Hi Andy they are a machined interference fit with the plate secured with a metal glue.

[AndyH]

Ta for that.

Andy.

[steelfixer]

No probs Andy - have fun with yours.

[Davey-T]

Lots of mags for this sort of thing, miniature engineering ,model trains etc must be someone advertising custom made parts . These guys probably have forums on Yahoo so I'd try there as well.Bet it's suprising how many amature engineers are lurking about with lathes in their sheds just waiting to show how clever they are at making stuff.

You don't want to be making gears as a first project.

Davey-T

[Penguin]

Hi Alistair.

Just get in the habit when you go to move the RA handwheels, to click the power switch off on the mount. Better safe than sorry!

Hope that helps a bit.

Cheers,

Andy.

Thanks for the advice. I think I will have to get much more practice with setting it up before I try putting a camera on it.

--- Alistair.

[Mark Hardaker]

I know that this thread is a decade old now, but I wonder if anyone here has a spare TAL-2 drive assembly available, or know where I can get one?

I have recently acquired a(nother) TAL-2 6-inch Newt serial number 0004!  It's in good working order, apart from the drive motor isn't working.  To be more accurate, the motor is turned but the gearbox isn't turning the final output drive.  I can see that the last cog has been turned in to moulding and has broken.  I will try to repair it if possible but I suspect it's getting a bit brittle and long in the tooth.

Does anyone has one spare or know where I could get one?

Cheer

Mark