The collet-held collet holder

[justgary]

All -

With nothing much to chat about on the forum lately, I have been out in the shop tinkering. I decided that if I'm going to switch to a router for my (main) high-speed spindle, then it probably should have the ability to hold small tooling like the Proxxon does.

I bought the Dremel collet and nut kit and proceeded to make an adapter that has a 1/2" shaft so I can easily put it in either the router or a TTS collet. I specifically chose Dremel because:

1. The tooling I have does not fit the Proxxon collets very well at all, probably because they are metric;

2. I can't just go get a Proxxon collet; and,

3. I can buy new Dremel collets and nuts nearly anywhere, anytime. I probably have a few of them stuck to the bottom of my flip-flops.

You'll ask how I did it, so I'll save your fingertips. Here's how you can make one:

1. Chuck a 2.5" piece of 1/2" drill rod in a TTS collet.

2. Clamp a lathe tool in your vise (I have an aluminum block that holds 3/8" triangle insert holders).

3. You could write a program, but I just typed the G-Code line by line into the Mach DRO. Anyway, turn the bottom 0.8" or so of the rod down to 0.275" diameter.

4. Take the TTS collet (with the rod still in it) out of the spindle and grab the collet shank in your vise with the rod pointing up. The TTS ring will get it pretty darned plumb.

5. Find the center of the rod using your favorite method.

6. Drill the center of the rod about 0.9" deep using a drill just a little larger than the Dremel collet shank (from memory, I think I used 0.180").

7. Whip out that threadmill that you made about a month ago and thread the outside of the rod to 0.275-40. You *did* make a threadmill, didn't you? Get the threads good and sloppy so they will allow the collet to do the centering.

8. Put the TTS collet and rod back in the main spindle, and clamp your Dremel or Proxxon or whatever into your vise so that its spindle is inclined 60 degrees. Chuck a small, straight grinder into it (I used the "diamond" cylinder-shaped grinder from my chinese "diamond" 1/8" set). Sure they are diamonds. They seem more like blobs of chrome plating. Anyway, they stayed on long enough for this job...

9. Center the mill spindle by eye over the tip of the grinder and slowly lower the spindle (uhhh, with both spindles running) until you have cut a nice 60 degree taper inside the rod. The dremel collet should now fit the inside your adapter, the collet should mate with the taper, and the nut should thread on outside.

Right after I made it I put a fairly long 3/32" burr (not the one in the photos) in it and measured 0.0003" TIR about .375" from the end of the small collet. I moved the holder to the router and measured 0.0005" TIR. No adjustment, no careful setup, just put it in and tightened it. That's probably on the outside of good enough for very small cutters, but it probably won't break them. I can regrind it in the router once I get the mount made for that if I need better alignment.

Enjoy!

- Just Gary

[zephyr9900]

Neat accessory and great writeup, Just Gary.

Almost makes me wish I had a router just to try making one myself...

The biggest surprise to me is that the Dremel collets themselves allow that kind of accuracy. I wouldn't have expected it of them.

Obviously your meticulous setup and machining processes make up for any shortcomings of the collets.

Randy

[justgary]

Randy -

I think it may be as much blind luck as meticulous setup. Honest, if I can make one of these, anyone can. I just trusted the TTS holder to plumb itself in the vise, so nothing special there. I did measure the center twice, though, before I started the threadmill.

The only thing that really needs to be truly on center is the collet taper, provided that the threads are sloppy enough to allow the nut to wander a bit.

I had wondered about the Dremel collets' ability to hold center, but I have used them for at least 25 years and not ever had any problems with them. After all, they are double-angle, and should work. Maybe I just got really lucky!

I got the router at Sears for about $90, by the way. I went looking for the Porter-Cable $150 job, but decided to cheap out and get this one. The spindle is rated 12,000 to 25,000 RPM. As you know, I'll have a gap in the ranges of the main and second spindles, but I still have the Proxxon.

Regards,

- Just Gary

[zephyr9900]

Originally Posted by justgary I just trusted the TTS holder to plumb itself in the vise,

Maybe squarer than depending on a vee-notch in the vise (which my vise doesn't have anyway).

If things go well there may be a move in my near future (plus money is getting tighter) so I'm holding off on buying any new tools for now. It's a good excuse for me to work on finishing some of the many projects I've started and left hanging...

Originally Posted by justgary I had wondered about the Dremel collets' ability to hold center, but I have used them for at least 25 years and not ever had any problems with them.

I do have a couple of Dremel nuts and a handful of their collets, but no actual tool (since I burned out my last one) so I will keep your tip in mind. I never used my Dremels in any other but handheld mode--for which the Proxxon is excellent (Dremel on steroids!)

Randy

[justgary]

Randy -

In fact, I was about to set it up in the vee-notch in the little vise and then put that in the big vise, but decided that too many fixtures would only add to the error.

Having only made one of them, I have no idea if it was luck, but I suspect that it is as repeatable as the ability to measure the center of the rod.

Workholding is always the big challenge for me. I like puzzles, so I make it fun. What kills me is taking the time to set up a fixture for a one-off part.

Regards,

- Just Gary

P.S. I'd hate to think of moving my mill. Lifting it and resetting on the stand it would go OK, but crating it for a van ride would stink. Good luck!

[justgary]

(And to you folks who just arrived, this is a reply to a sidebar discussion that began over in the "How many are out there?" thread; I moved here to avoid a complete hijack)

Randy -

Thanks for the feedback. I'll continue to draw the bracket with the router height setting gear and cam lock. I just hope it turns out worth the effort.

I planned to use the height adjustment as a convenience for setting both tool clearance and Z touch off, but what I really meant by that is per installation of the bracket/router or maybe per job, but not necessarily each tool change.

In other words, you pretty much have to measure the X, Y, and Z offsets to the second spindle each time you mount it (the main spindle housing is not keyed to allow repeatable positioning), so that's when I would use the cam lock to make sure that the primary spindle would clear all of the clamps, etc.

After that (as long as I leave the cam lock alone and don't remove the Dremel collet adapter), I can index off of the Dremel collet like we have discussed before (distance rings, chicken feet, etc).

As for the tool side load on the bearings, I'm assuming that the router was made to turn tools up to about 1.5" at least 1" from the collet. Even a 1/4" endmill is probably OK at about 2" past the router collet, but the only thing I'd use that for (at router speeds) is wood, and that's what it was made for. I think it will work just fine. If it doesn't last forever, the router only cost me about $90 in the first place.

I'll keep you posted on my progress.

Regards,

- Just Gary

[zephyr9900]

Originally Posted by justgary In other words, you pretty much have to measure the X, Y, and Z offsets to the second spindle each time you mount it

[sigh] I've pretty much come to that conclusion about my Proxxon mount, Just Gary, even though it is one piece with both bores machined in the same setup with a brand new endmill. Not to in turn hijack this thread, I'm beginning to think that the single-nose-bearing Proxxon is not quite up to snuff for the work I'm doing (thus the less-than-optimum surface finish). I'm beginning to daydream about taking the three extra hybrid-ceramic bearings I bought from Australia and making a "proper" nose section for it--the motor seems just fine.

And I'm sure your router will indeed do just fine. I'll be interested to see how you integrate the height adjustment. Looks like a fun design and fabrication job.

Randy

[justgary]

Randy -

Try as you might, you can't hijack my threads. My mind blows around like the down on a Dandelion, so I doubt you could think of anything off-topic! Have at it.

You could, of course, sell me one of your three ceramic bearings for my Proxxon, use the other two for your hatchet job on your Proxxon (and you'd still have the one that's in it now), then go out and find yourself a cheap router to use as your second spindle.

Regards,

- Just Gary

[zephyr9900]

Ah, so you are aware of my hatchet skills, Just Gary. Be afraid. Be very afraid. (Think Ed Ames on Johnny Carson...) I've sent you an email about the bearing.

And I don't think you get down on a dandelion--you get down on a duck. [rimshot]

Randy

[justgary]

Right now I'm getting down on my bad self, LMAO.

- Just Gary

[zephyr9900]

Just Gary, I stand corrected. The panel of judges have determined that dandelion seeds are indeed sometimes called down. So we have credited your score with the $1200, and deducted the same from Randy's score. (Have I been watching too much Jeopardy or what?)

When you get to replacing the Proxxon nose bearing, the instructions say you need a long-nosed snapring pliers, since the bearing and snapring are way down in the nose. I tried making extension pins for my pliers using hex keys (the most heat-treated things I have) but they still bent--and one snapped.

I remembered I had a very skinny needle-nose (snipe nose? mosquito nose? swallowtail butterfly proboscis nose?) pliers in the bottom of my "pinchy tools" drawer, which I attacked with the corner of my bench grinder wheel. The closeup photo flatters not my grinding "skill", but they were just the right combination of heft and reach to do the job. If you don't have a similar pair, you're welcome to borrow mine. On second thought, you probably have the proper tool in the first place...

There's a nice PDF copy of the Proxxon manual (from which you can print out a usable-size exploded drawing) at Proxxon World's website.

Randy

[justgary]

Just Gary, I stand corrected. The panel of judges have determined that dandelion seeds are indeed sometimes called down. So we have credited your score with the $1200, and deducted the same from Randy's score. (Have I been watching too much Jeopardy or what?)

Wow, and I thought that it was only the $400 question. I'll take "Seeds" for $600, Alex.

Anyway, down to business. Call it a parallel universe, or maybe we're brothers of another mother, or something, but here's a photo of my "similar pair" of the "proper tool." I don't know of a decent substitute for that tool, because a regular snap-ring plier doesn't come close.

Thanks for the link to the manual.

Regards,

- Just Gary