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Thread: Scratched spindle repair?
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13th Oct 2017, 10:42 PM #1Senior Member
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Scratched spindle repair?
I noticed a while back my collet holder had a scratch near the top, suggesting to me that I'd inserted it in the mill with a small chip on it without noticing. I was milling on my RF-45 yesterday and the collet holder spun in the spindle. The collet holder now has a scratch as indicated in the photo below, going all the way around. I stuck my finger in the spindle and was able to feel a scratch there. Can I repair the spindle and/or collet holder? If so, how?
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13th Oct 2017, 11:34 PM #2Senior Member
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Use a fine arkansas stone to flatten any raised burr on the tool holder.
Very carefully, with a small round diamond burr in a Dremel, reach up into the taper and grind away any felt burr or raised surface. Likely to be an unwieldy and unpleasant task.
Once you get rid of the raised burr on either side of the taper, the depressed area created by the stoning/grinding is inconsequential to the effectiveness of the taper. The burr area is just a tiny percentage of the overall contact area.
Be sure to take the Brylcreem approach to touching up the spindle. A little dab'll do ya.
Edit: I just had a real good look at the photo and just to be clear - if you can't physically feel a burr raised above the surface of either the tool holder or the spindle, you don't really need to worry about it. The mark on the tool holder posted looks like a burnish mark rather than an actual burr.
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13th Oct 2017, 11:49 PM #3
Just polish the 2 parts with some wet and dry. Use blueing liquid or a texta etc to check whether there is any interference from the damage. You only need to remove this interference.
Dean
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14th Oct 2017, 05:36 PM #4Banned
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Looks tapered, if so use a tapered reamer.
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14th Oct 2017, 09:03 PM #5Most Valued Member
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15th Oct 2017, 11:17 AM #6Golden Member
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It probably a piece of swarf stuck in the socket . This is how I would fix it . Glue a piece of emery cloth around the taper arbour right where the scratch is. Then oil it.
Clean the socket as well as possible with a rag and wooden dowel then push the arbour in gently and turn it around and around and polish the area , If it's a stuck piece of swarf it should come off eventually or grind away if a burr it will grind away . Do a lot of cleaning out and feeling as you go so you know when it's gone .
Then thoroughly swab out and clean the socket to get any grit out . Swab out the full length of the spindle . Get into the habit of wiping an arbour off and cleaning the socket each time you insert an arbour .The volume of a pizza of thickness 'a' and radius 'z' is given by pi z z a.
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15th Oct 2017, 05:58 PM #7Most Valued Member
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The probability is your spindle is hardened (to a greater or lesser extent), hence you most certainly don't start shoving reamers, dremels, or anything else similar in there! It's likely that when you inserted a tool you had a chip stuck on it and that chip both caused the tool to not seat correctly. That's caused the tool to spin and scratch both the tool and your spindle socket. You don't say what type of taper it is, but looking at it I'd guess its MT3.
The chances are the most appropriate action now is to kick yourself up the butt for not checking the tool/socket correctly before inserting it, and just use it as one of life's lessons. If it's just a scratch on both surfaces the only harm done is to your pride, and it won't affect performance. Even if there's a slight burr raised, it's quite likely it will peen itself back down in use, and somewhat self-heal.
Based on my own work making tapers, I don't think you'll have much luck trying to blue the surface and checking for fit, the marking medium is just much too thick. You can sometimes see by looking extremely carefully on the male taper how the fit is going, and any high spots will look slightly different (shinier) than the rest. Sorry that's hard to explain over the net, but if you have somebody show you, you'll know what to look for.
In this case you're not trying to check for fit, you're checking for potential damage affecting the security of the socket. I'd suggest inserting a few different tools hard, and checking to see how secure they are. If they seem secure, then just move on. If they're not secure or you can feel a definite raised burr even after all that, then you may need to remove the burr manually. It doesn't take much to remove a burr, and you definitely don't want to start shoving dremmels etc in there to do the job! The ideal is probably a round fine honing stick, you only want a fine one as it doesn't take much. For this type of work I've also used FINE wet and dry paper wrapped around a dowel. This is where the nanny-state "experts" who hang around forums just waiting to jump on people will have a fit, so all I can do is suggest what I've done, acknowledge there's some chance of danger with it, and just wait to be jumped on. With the spindle ON you hold the dowel or (preferably) honing stone gently against the inside of the taper. Be patient here and don't force anything. You will feel the burr hitting the dowel/stone each time. Move the dowel up and down the inside and just let the fine abrasive stone away the burr. It's essentially just the same process you use when stoning out any other burr on a grinder chuck, CI surface plate, etc etc. When done even semi intelligently the stone will remove the burr but will hardly touch the material below it. As soon as the burr(s) have been taken out then stop, clean it out, and you're done.
Shallow tapers can have what appear to be some rather horrible damage and they will still lock ok just as long as there's no raised burrs. No need to be concerned about your machine, and it's just one if those things that will eventually happen.
Good luck, take your time, and it will be 100% again.
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