Beaver VBRP MKII Mill missing spindle seal

[Peter_HParticipant @peter_h]

Hi everyone.

I'm a newbie here, but have had a lifetime in engineering, now retired. I converted a home VBRP MKII to single phase, using one variable speed inverter for the spindle motor and a fixed 50Hz inverter for the table and carriage feed motors. I replaced the old belt varidrive with HTD pulleys and belt. I rigged a shaft encoder and backgear detection switch to a frequency display so it displays spindle RPM correctly in either gear. I was lucky enough to happen on several matched pairs of the correct Fafnir ultra precision spindle bearings on Ebay, just as I was stripping the head

My instruction manual for the mill has an exploded view entitled "Mk.2 Head – Bottom Section" on page 26. The key on page 27 shows item 64 as part number S972 decribed as "Felt Soaking Pad". It is basically a felt seal at the bottom of the spindle/housing which soaks up any excess lubricant to stop it escaping, and lubricates the shaft.

When I received my mill, many years ago, that seal had hardened, broken up, and was mostly missing. I've ran it like that ever since and suffered a lubricant line across my shirt and in a ring round the workshop every time I lubricate it!. Hence the obvious question – does anybody know where I might get a replacement, or better still, have taken note of the dimensions during a rebuild so I can make one?

Also, could any kind person share the full parts/maintenance manuals that I saw talked about in the VBRP rebuild thread please?.

Many thanks,

Peter

[Peter_HParticipant @peter_h]

[Peter_HParticipant @peter_h]

re Beaver VBRP MKII spindle seal

I know it has been a long time, but has anybody happened upon the information I need by any chance?. I am thinking of a doing a head strip soon so I have to tackle that problem somehow. Assuming there is an obvious groove and running surface, any ideas on type of felt, amount of compression or otherwise, or if I should try to simply replace it with a standard oilseal?. Also, I have never managed to find a cross sectional view of the spindle assembly, so if anybody knows the whereabouts of better. Many thanks.

To record some spindle info, there are three angular contact bearings in the spindle bearings on the Mk2. The bottom two are a matched pair of "back to back" bearings (DB config) and the more distant top bearing forms a back to back set with the lower pair (ie it's open/filling side is uppermost).

 

Bottom Bearing types :

• Matched pair of angular contact, P4/ABEC-7 precision or better.
• Nominally 25 degree, but 15 degree are much easier to source
• Size is 35x72x17mm.
• Recognised base bearing size is 7207
• Originals – Hoffman 135ACDEP
• Replacement – Fafnir 2MMV207 WI DUL
• Replacement – SKF 7207 ACD/HCP4A
• Separated by a pair of precision preload spacers. Heights differ by only a tenth of a thou or so.

Top Bearing type :

• Angular contact bearing of similar precision
• Nominally 25 degree, but 15 degree are much easier to source
• Size is 30x62x16mm.
• Recognised base bearing size is 7206
• Original – Hoffman 135ACD
• Replacement – SKF 7206 ACD/HCP4A

Don't be tempted to "clean up" the lower bearing spacers. The tiny difference in height determines the preload between the bearings. This is probably of the order of 10um or so, some pairs can need as low as 3um. Consider that 1 micron is about 0.00004 inches!

As an aside, the origin of VBRP are the initials of the two top guys at Balding Engineering who designed and made machine tools under the Beaver brand name. Their names were Vic Balding and Richard (Dick) Payne.

Regards,

Peter

 

Edited By Peter_H on 27/10/2017 13:01:31

[David George 1Participant @davidgeorge1]

Beware using an ordinary rubber oil seal as friction at higher speeds can cause a temperature rise and bearing failure as happened to me on a large CNC spindle. If you contact a specialist bearing and seal supplier they should find the correct felt seal as long as you give them the basic dimensions etc.

David

[Peter_HParticipant @peter_h]

Thanks, yes, it can be a problem with larger seal, although it's rare to go over 1200 rpm on this machine, and it is well heatsunk, but it is a big seal. I've been looking at PTFE seals recently, I'll see if they are available that size (when I know the size!). Not knowing the size is the sticking point to contacting a seal company about felt seals. Some spare part suppliers (you know who you are) stock many old Beaver parts, new and old, but the prices are astronomical. This is why I asked if anbody had any section drawings or had maybe made a note of the various dimensions. I'll happily do a CAD drawing/model of the spindle assembly if anyone has the dimensions, or maybe is in the middle of a strip down and can get their calipers out.

**LINK**

**LINK**

Peter

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