How To Secure Cutterhead Bearings in Older Parks Planer?

[Mark R Webster]

I am nearing the end of a renovation of an older Parks/Sears 12 inch thickness planer and I am replacing the cutterhead on the planer. The new sealed bearings that came with the cutterhead fit into the babbit recesses ok, but the original gasket/shim material that was under the bearing caps is gone. What kind of material should I use here, brass shim stock, cork gasket material, something else? How tight should I tighten the bolts. It seems that the spaces need shimming about 0.040 to hold the bearing in place While I see the space is approximately 0.040, I am struggling to find the exact shim thickness that keeps the bearing/cutterhead from rising but doesn’t allow the bolts to squeeze down on the bearings too hard causing a little drag. Any suggestions on how to decide the right tightness and what kind of shim material to use. Should I stop tightening before I detect any drag on the shaft or is a little drag appropriate? I am a woodworker and not a machinist so this is new territory for me. I have posted this question to the OWWM forum but haven't received a response so I thought I would ask here as well. Thanks!

[David Kumm]

So you are converting a babbit machine to ball bearing by using new head with a smaller shaft and fitting the bearings into the babbit cavity? I hope the owwm guys have an answer because I've not heard of that. Outer bearing housings are usually machined to pretty close tolerances to a press fit, and the bearing clearance ( fit of the balls to the inner and outer ) is adjusted ( CN, C3, C4 etc ) depending on the speed of the shaft vs the rating of the bearing. Any pressure on the bearing that is uneven will deform the bearing very slightly but enough to create a tight spot and either run hot, or if too loose, allow runout on the shaft. Is there any way the two babbit journals can be removed, screwed together and machined, or is the bottom one cast into the machine? Dave

[M Toupin]

The classic 12" Parks model 97/95 uses ball barrings (3204 if IRC) on the shaft which is then seated in a babbit mount. The trick is to get the caps shimmed to just hold the bearings in place, not too loose so they spin, not too tight so they are compressed or deform the babbit and throw off the cutter head alignment. It's a trial and error process and heavy paper or thin solid gasket material works fine for shims. I would not try and re-engineer the system as it's an effective system used in thousands, if not 10's of thousands of Parks over the years.

OWWM will be your best source of info, there's many many threads on rebuilding Parks with a ton of hands on knowledge. Check the wiki on vintagemachinery.org also, there's a good how-to on rebuilding a parks there too. I had a parks for many years and sold it a couple years back. To be honest I really wished I hadn't they are a very nice little planner once you get it dialed in.

Mike

[Mark R Webster]

Thanks guys I appreciate the info. Mike I have basically done what you said while I was waiting for a reply and I think I have it dialed in. It gives me a bit more confidence knowing I was approaching in an appropriate manner.
Mark

[David Kumm]

Thanks from me too, Mike. Was not familiar enough with Parks and thought a modification was being made. Makes sense now. Dave