Not sure if the spring collets are fully hardened or if there is enough annular material, but maybe drill/tap a hole with recessed grub screw to just kiss the flat on male arbor? Even if it slides down when un-sprung during spindle removal, it cant drop because of the milled notch.
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Not sure if the spring collets are fully hardened or if there is enough annular material, but maybe drill/tap a hole with recessed grub screw to just kiss the flat on male arbor? Even if it slides down when un-sprung during spindle removal, it cant drop because of the milled notch.
Maybe shrink-fit or loc-tite a sleeve on the Heimer's shank to bring it to 9/16", and dremel a little divot in the sleeve to line up with the Weldon set screw. The Heimers are adjustable for runout, so once it's in there and indexed by the screw you should be able to true it up.
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Alan H.
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Thanks for all the links and insights Mark, good stuff to consider.
You hit the nail on the head, I use R8's in my PM935. As you point out, the 12MM R8 holding the Haimer is prone to fumbles and like you, I dislike that. Therefore my quest to semi-permanently install the Haimer in a R8 holder of some sort. The shorter the overall length, the better for getting it in and out of the spindle of course. Therein lies the incentive to think about securing it to the R8 collet somehow. I imagine that most R8 adapters are quite hard and not easily machined.
This morning I pondered buying a cheap R8 drill chuck adapter and attempting to making an adapter by boring it for the Haimer. But I am betting that would be an unpleasant and likely unsuccessful endeavor due to the hardness. Maybe cheap means not so hard in this case. Does this idea have any merit at all?
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Alan H.
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Peter, I like that concept. As you alluded, the trick is the drilling and tapping and I am betting the 12 mm Crawford R8 I have is quite hard. I likely wouldn't want to modify my Crawford R8 anyway since they are hard to come by now. I would buy a cheap collet for such a trial.
This alternative maintains the shortest overall height of a mount which makes it easier to get the Haimer in and out of the mill.
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Hi Alan,
If you look at the different ER-25 collet holders, something like the Metaltech collet chuck is 1.7" in length from the spindle to the end of the ER nut. This is probably as short as you can get, and also gives you something to hold onto. The GMT R8-ER25 collet chuck looks to be similar, I have their ER-32 collet chuck and it has unmeasurable runout. An end mill holder would most likely extended further beyond the spindle.
https://www.ebay.com/itm/Metaltech-...-ER25-R8-43-mm-Standard-472-7920/181895990118
The hardening process is often a surface treatment, not sure on the collets, but they should be able to be drilled and tapped. You would only want a set screw to prevent the shaft from falling out, not pressing against it. There should be is enough material on a 12mm collet that it should be ok, but somewhat awkward if you are switching the Haimer between a collet and chucks. You could use a Nylon tipped Allen screw that would offer just enough resistance to allow the haimer to be pushed into the collet and not fall out. I would not be happy if the set screw backed out and you mounted the R-8 collet in your spindle. If the Haimer was dedicated to the 12mm R-8 collet, I guess you could use a small amount of blue Loctite to marry the two together, but then you would need another Haimer
for use with a standard chuck.
If you look at the different ER-25 collet holders, something like the Metaltech collet chuck is 1.7" in length from the spindle to the end of the ER nut. This is probably as short as you can get, and also gives you something to hold onto. The GMT R8-ER25 collet chuck looks to be similar, I have their ER-32 collet chuck and it has unmeasurable runout. An end mill holder would most likely extended further beyond the spindle.
https://www.ebay.com/itm/Metaltech-...-ER25-R8-43-mm-Standard-472-7920/181895990118
The hardening process is often a surface treatment, not sure on the collets, but they should be able to be drilled and tapped. You would only want a set screw to prevent the shaft from falling out, not pressing against it. There should be is enough material on a 12mm collet that it should be ok, but somewhat awkward if you are switching the Haimer between a collet and chucks. You could use a Nylon tipped Allen screw that would offer just enough resistance to allow the haimer to be pushed into the collet and not fall out. I would not be happy if the set screw backed out and you mounted the R-8 collet in your spindle. If the Haimer was dedicated to the 12mm R-8 collet, I guess you could use a small amount of blue Loctite to marry the two together, but then you would need another Haimer
for use with a standard chuck.If you want a machinable R8 collet, buy a blank (emergency collet) for $10
http://www.shars.com/r8-emergency-collet
Set up a 7/16" drill in the mill vise vertically, center the spindle over it and drill it out with the quill or Z axis. Use a boring bar oriented the same way to bore it to 12mm if you don't have a reamer. It'll be concentric. And much easier to machine for the set screw.
http://www.shars.com/r8-emergency-collet
Set up a 7/16" drill in the mill vise vertically, center the spindle over it and drill it out with the quill or Z axis. Use a boring bar oriented the same way to bore it to 12mm if you don't have a reamer. It'll be concentric. And much easier to machine for the set screw.
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Alan H.
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Thanks, good tip - this has a lot of merit. Going to do a little measuring on the Haimer shank length and collets today and likely get something on order for a trial.
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Alan H.
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Took a deeper look at the emergency collet idea. Unfortunately the Haimer I have doesn't have a Weldon flat on it. This eliminates a setscrew in an R8 spring collet.
So I don't think you want any kind of set screw marring up that surface.
Some considerations of gluing it into an expandable collet is it would have to be set that way with the collet tightened, not loose. But (especially longer R8) now you have kind of a long unwieldy assembly with collet + indicator. That might be a PITA raising the head high in order to swivel out of the way. The other issue is removal. If the LT is strong enough so the expensive unit wont drop out, you don't want to be torqueing on it or applying heat. Then when you get it off, risk of glue remnants on your stem. On a cheapo tool not a biggy, but that is a high end $$ unit.
I have a similar issue with heavier tools wanting to drop out, especially sharp ones you don't want to hold without a glove or rag. Maybe its just easier to spin the drawbar nut off & cradle the unit with your other hand (reverse of installing it).
Some considerations of gluing it into an expandable collet is it would have to be set that way with the collet tightened, not loose. But (especially longer R8) now you have kind of a long unwieldy assembly with collet + indicator. That might be a PITA raising the head high in order to swivel out of the way. The other issue is removal. If the LT is strong enough so the expensive unit wont drop out, you don't want to be torqueing on it or applying heat. Then when you get it off, risk of glue remnants on your stem. On a cheapo tool not a biggy, but that is a high end $$ unit.
I have a similar issue with heavier tools wanting to drop out, especially sharp ones you don't want to hold without a glove or rag. Maybe its just easier to spin the drawbar nut off & cradle the unit with your other hand (reverse of installing it).