I have an 8" chiwanese jointer, and one of the knife gibs' threads seems to have stripped out. There are 5 gib screws on the piece, and the stripped one is on the outboard end. Naturally, I'd prefer not to run the machine without all the keepers properly in place. Any and all ideas would be very appreciated. Tom
"tom" wrote
First thing I'd try is to ream it with the same size tap in the hopes that may fix it ... sometimes worth a shot. Next would be to find a size larger gib screw and tap if for that.
Strangely enough, I'm waiting, as we speak, for a hardware store to open to try and find a 1/4", 20 threads to the inch, gib screw to fix a similar problem, although not on a jointer.
Good luck ...
As an addition to that, I've occasionally found that reaming it out with the same size tap and then running some loctite #2 into the threads (semi permanent loctite) will restore enough thread grab to hold for use.
Good suggestions but also consider a couple of other alternatives. Heli-coil inserts, and or Mold-in insert. The last is/was a product made by Permatex. You would clean out the damaged thread area of debris, put in an epoxy type material in the hole with the intended bolt inserted into the mixture. The bolt being used would be coated with an anti-seize compound so that it would not adhere to the mixture. After the mixture hardened/ cured you would screw out the bolt and use as you normally would.
"Upscale" wrote
Excellent point/suggestion ... Duh!, even have a couple of tubes, of different types, hiding somewhere in the shop. :)
Thanks!
Thanks, guys. Looking at the threads with a jeweler's loupe shows total thread loss where the screw grabs. I wonder how much the cutterhead's balance would be affected by going up a size or two. Maybe the amount I remove in tapping will offset the extra mass in the new screw, or do I worry too much? A neighbor friend has a stick welder, and I'll be talking with him later today about another possible fix.
Hmm, Permatex mold-in. Along the lines of J-B weld would you say, or have there been improvements in epoxy technology? I'm stopping at the hardware store during today's bike ride to check out that option. Thanks very much. Tom
That Permatex product has been around a long time. There very well could be several other similar products however a good hardware store should have one of the versions.
Well, the stick welding option was too heavy-handed to work, but my neighbor also has an oxy-acetylene torch, and was able to apply a judicious amount of material to the stripped threads. Oddly enough, the threads are 1/4x28, not metric as I would have thought. Anyway, the gib screw is holding tension, and I'm back on line for now. It seems that rust may have been the culprit. I'd rescued the jointer from a friend's backyard, where it had sat for a couple of years. Could be more trouble on the way in this regard. I guess I'll make a bowl for my neighbor for his effort. Thanks again to all who replied with solutions. Tom
I think HeliCoils work pretty good. I have used them in the past. Give em a look:
Otherwise, braze the original hold and drill and re-tap..
Philski
Helicoils make sense even in new machining. You're essentially installing hardened steel threads into the softer tapped metal.
I wonder if it's common practice in any industry.
That's (brazing) what worked. Thanks! Tom
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