Dumore toolpost grinder spindle endplay

[jakes_66]

I purchased a used Dumore 8171 Series 44 toolpost grinder a while ago, and after purchasing a new drive belt I set it up to use for the first time. I don't have experience using these, but something doesn't seem right with the spindle bearings. There seems to be some endplay when I 'push' on the end where the grinder stone mounts, but it seems to be (lightly) spring-loaded. It seems to move about 40 thousandths (approx.), and has noticeable radial play as well. When I release my 'push', the spring returns the spindle to its normal position and takes up all the axial and radial play.

I'm not sure what to do, disassembling the spindle looks like it will require making some kind of spanner tool. Does anyone have experience with these spindles? Is this normal, or do I need to repair? Perhaps I just need to tighten something up?

 

[benmychree]

Use extreme caution in messing with it, best not to if it functions normally.

 

[f350ca]

Don't know how the Dunmore spindle is built but I've seam high speed spindles that use a spring or springs to set the preload on angular contact bearings. Angular contact bearings need preload to centre themselves. This can be done with ground to fit hard stops or in this case spring load. The spring setup easily compensates for thermal expansion as the spindle warms up. BUT can't carry any axial load, which a tool post grinder shouldn't exert.

Greg

 

[machPete99]

Its been I while since I rebuilt my grinder, but I put in new NSK 7203 bearings, which differed a bit from originals, and has to add additional shims.
I have some notes on the process. There is an adjuster that is used to take up the play and add some preload.

 

[jakes_66]

I've looked around for information on resetting the adjuster, but haven't located anything. I'll try using it but I'm not confident it will work.

Any advice on resetting the bearing preload? I'd love to get some feedback from someone who's done it.

 

[machPete99]

Very little preload is needed. You want to tighten until there is no discernible play in the spindle and maybe a pinch more.
If you can feel a drag on the spindle using your fingers you've probably gone too far.
You can also monitor temperature while running, should not get overly hot (warm is ok).
You also want to feed this thing lots of spindle oil, the manual says 25-50 drops, I use Mobil Velocite #6, some say to use #3, its probably not overly critical.

 

[pontiac428]

According to the user-level manuals at http://vintagemachinery.org/mfgIndex/detail.aspx?id=2020&tab=3 the spring is supposed to be the factory-set preload adjustment... however, there is no indication of what that setting should look like when properly set. Dumore is still in business, they might just entertain a call about that setting, or at the very least send you a tech manual for the model 44 if you asked for it. I have a tiny little 1/15th horse Dumore that has more traditional friction cup preload setting minus the spring, so I'm of little help otherwise.