care and feeding of the dumore TPG?

[yorgatron]

i have a dumore No.14 "Tom THumb" in need of some TLC.i checked the archives,but the best recommendation there was to contact dumore and buy (expensive) parts from them.screw that! the reason i have a lathe is to make one-off widgets.i figure i can make new pulleys myself,the diameters are shown on the motor tag.the belt i can get from hoover or kirby.the thing i need is bearings.they look to be .750 o.d .250 i.d. about 1/4" wide,maybe a little more.they aren't sealed,which is probably why they feel so rough.i pulled a wheel off my nephew's skateboard,damn the luck they are metric 22mm o.d 8mm i.d. i also think i'd like to adapt a 1/4" collet the end of the spindle so i could use die grinder bits.what do you guys think? -george


[This message has been edited by yorgatron (edited 12-13-2003).]

[JCHannum]

The bearing sounds like an R4 0.250 x 0.750 x 0.2812 thick. It should be a high precision.
Take it to a bearing house for positive ID. There are many variations. Mention what it is for, and the speed ranges you intend to run. They should be readily available and not break the bank.
When making spindles, turn on center to ensure they will be true when done, or you will get a poor finish.
Put whatever you want on them. A collet chuck is a good idea. The small stones are good for internal grinding. I would not recommend rotary files or burrs though. You will want to be able to accomodate something larger for OD grinding.
Put your nephew's skate board back together.

[SGW]

Nope. Skateboard bearings ain't gonna do it. A Dumore, properly set up, has NO discernable vibration. Zip. Nada. Nil. That's why Dumore parts cost so much. That's why you need good bearings. Otherwise you'll get chatter marks on the finished surface, and it doesn't take much vibration, at all, to get chatter marks.

That's also why you need balanced pulleys. If you do make 'em, if you drill a setscrew hole HERE, be sure to put one THERE, opposite, to maintain balance. Even that may not be good enough, but at least do that.

[Rich Carlstedt]

I don't believe that R-4's ( 4/16" bore !)come in super precision grades..
What you really want is a Barden R4 and that is the best you can get.
What is really important is the mounting of the bearings.
Any mis-alignment is a killer.
latest technolgy is to mount them on the shaft and use Loctite on the OD (loose bore).
That way, the bearing alligns itself to the shaft and the Loctite holds it in the housing WITHOUT any mounting deflections !

[Oso]

Does yours have an oil hole on top of the spindle housing and the felt oil wick?


If so, I have one like it. The spindle bearings are really sorta sloppy, but get pre-loaded by springs in the pulleys and run true.

There is a supplier in Cleveland who still had a few NOS bearings for those TPGs a while back. And a few other parts.

But I got new bearings at the local bearing house and they have been fine.

If you need measurements for pulleys etc, I can get them off mine.

The collet for the spindle is the same as later models and is still available. Only about $50, which for 20,000 rpm is probably best. it holds 1/8 shanks though. A heavier shank might whip the spindle right off if it sticks out too far.

If you call Dumore they will get you a photocopy of the manual. Check the motor for a model number, although the motor and spindle might not match as the same model. Mine don't, and Dumore got me manual copies for both.

[Paul Gauthier]

Don't forget that the Dumore pulleys are not flat but are crowned so the belt won't fly off.



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Paul G.