Vacuum Bearings for TMP-50

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Gustavo Cervantes
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Vacuum Bearings for TMP-50

Post by Gustavo Cervantes » Wed Apr 28, 2021 9:44 pm

Has anyone here replaced the bearings of a Leybold TMP-50?
I have purchased one of these pumps for very cheap along its controller, but the bearings are shut, the pump spins up but they made a terrible noise.
The pump uses a ceramic version of the 625 bearings, but not sure exactly what would be a suitable replacement.
I'm in Mexico so it's kinda hard to get speacialty parts here, other that international shipping so I'm looking for options.

John Futter
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Re: Vacuum Bearings for TMP-50

Post by John Futter » Sat May 01, 2021 5:04 am

The original bearings are made by Barden - i think ihave spelled that right.
They are a little strange being wider than most at this size
I was looking at Boca bearings to do the job but when I said what I wanted then for they clammed up -- maybe they didn't like that fact that the TMP50 goes over max bearing speed for a bearing of that size

Gustavo Cervantes
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Real name: Gustavo
Location: Guadalajara, Mexico

Re: Vacuum Bearings for TMP-50

Post by Gustavo Cervantes » Mon May 03, 2021 4:22 am

Yeah I, got a word that the ones used are 34-5H Barden i found this specs, the page mentions the same dimentions as the 625 but with a speed rating of 183krpm which seems a lot.
Looking around i found thesebearing from skf which is just rated at 50krpm, i swear to god last week i saw another bearing with higher speed rating, but seems that they retired it or is not in production at the moment.
I also asked Acer racing for a spec sheet for its 625 ceramic bearing, they havent replied yet (I'm not too sure what to expect from a cheap bearing anyways).
Will keep looking for areplacement, next week I'll try to dissasemble the whole rotor assembly to do the bearing swap.

Peter Schmelcher
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Re: Vacuum Bearings for TMP-50

Post by Peter Schmelcher » Mon May 03, 2021 7:24 pm

Glasslinger is a fringe YouTube channel about repairing old radios and making vacuum tubes, the guy has got skill and talent.
https://www.youtube.com/watch?v=jL0fXUZ4wFQ is a video about repairing a turbo and using ceramic ball bearings, also some bent blades are left out during the reassembly. Pumped down fine during testing.

Repairing a turbo is honestly a risk reward issue. If the turbo was had for free then $40 of ball bearings seems mighty reasonable. If you spent $2000+ on a turbo system and the bearings are finally starting to make some noise then a pair of bearings for $500 also seems reasonable.

Gustavo Cervantes
Posts: 22
Joined: Thu Apr 05, 2018 1:17 am
Real name: Gustavo
Location: Guadalajara, Mexico

Re: Vacuum Bearings for TMP-50

Post by Gustavo Cervantes » Mon May 03, 2021 7:38 pm

I saw that video, the guy's amazing, i got my pump, for around 15 USD, but being honest I don't want to damage the pump.
These are kinda hard to get, more so down here in Mexico, the guy who sold it to me thought it was a fan, so I got lucky on that.
I will try the quality SKF bearings, and maybe the Chinese ceramic ones.

Peter Schmelcher
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Real name: Peter Schmelcher

Re: Vacuum Bearings for TMP-50

Post by Peter Schmelcher » Tue May 04, 2021 12:49 am

Personally I would go with ceramic balls and then the choices get a bit more convoluted. Choose a better ABEC tolerance like 5 or 7 with a riveted ball cage or even better would be a fiber phenolic resin ball cage. Ceramic balls are stiffer and stronger than metal and will not weld to the metal races or the ball cage reducing the chance of RUD (rapid unscheduled disassembly). Expect to spend $20
to $100 for a few ounces of high speed bearing grease, and you will absolutely need to clean and repack the ball bearings.

This is another fringe YouTube machining channel video that you should watch before you start.
https://www.youtube.com/watch?v=grUdsTTRGl4 TIPS ON PRECISION SPINDLE REBUILD

Gustavo Cervantes
Posts: 22
Joined: Thu Apr 05, 2018 1:17 am
Real name: Gustavo
Location: Guadalajara, Mexico

Re: Vacuum Bearings for TMP-50

Post by Gustavo Cervantes » Wed May 05, 2021 3:58 am

Thanks for the advice Peter, the video was really informative.
Today i spent the afternoon with a machinist friend puting together a simple wrench to remove the rotor nuts, will post photos of the process soon maybe next week ill buy the bearings.

John Futter
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Re: Vacuum Bearings for TMP-50

Post by John Futter » Wed May 05, 2021 7:48 pm

Yes the barden bearing uses a phenolic cage

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