A Rotary Chamfer Attachment Hack for a Dremel

[wbc]

While not even in the bush league compared to the standards of Yoda Master Renzetti, this hack was inspired by YMR.

The pictured Dremel chamfer attachment was within my limited abilities, was cheap, and works ok. Can use free-hand, or clamped down.



The Robrenz Inspiration: MAKING AN AIR TOOL CHAMFER ATTACHMENT

https://www.youtube.com/watch?v=gRioQ8Vq_tk

Took a little-used antique Dremel, some 1/8" piloted drywall Rotozip bits, a 1/8" id R2 bearing, and went from there.
The zip bits are flimsy and must have a pilot/bearing support, but work and last ok, seems like.
The YMR sliding jaws make use of a good portion of the zip bit's flutes and make simple work of chamfer depth setting.
Carbide zips do not appear to have a piloted tip, so their use would necessitate a smaller ID bearing, or some tip support scheme.

The great simplification here was to weld up the jaws from intact angle iron, then do the milling and guide-rod drilling/reaming,
leaving sawing of the jaws into two pieces for the very very last. Vibration will shake things loose, so the guide rod retaining
setscrews and a bearing retainer are vital. And a screw-driver gronk on the jaw-fixing thumbscrews is in order once you get the chamfer depth you like.
(The YMR jaw-retention scheme is a lot slicker and robust, i.e., more Yoda Master-like.)

The resulting chamfers are not YMR-smooth, but turn out better than a poke in the eye with a sharp stick.
Expect the bearing will beat itself to death, but haven't gotten there yet, and, they are cheap and expendable, as are the zipbits.

[JoeLee]

Clever idea, but easy to overloaded bearing from excessive force.

JL.....

[mattthemuppet]

that is real slick, I like it. Those chamfers look lovely to me. As my dad would say, a blind man would be glad to see them

[Bob Engelhardt]

Very nice! Both in the execution and the write-up. The captioned photos are especially good - they make everything very clear. I'm sure that a lot of effort went into them. The chamfers are as good as I'd want them.

You do yourself a great disservice by comparing your work to YMR's. His work is to be admired and inspired by, but matched by very few.

Do you ever use it just sitting on the bench top? One hand on the Dremel and only one holding the work doesn't seem like a good idea.

Even if the Rotozips are HSS, I'd not expect them to last long. Carbide burrs are a lot more expensive but would be more cost-effective. The best benefit would be not having to adjust the jaws as often.

[Doozer]

YMR ?
It is not fashionable to be that clever.
It's ok. Sometimes smart people have
the worst fashion sense.
I do like the outboard bearing idea however.

-D

[wbc]

Bob E: Did add foot, as it makes more stable on tabletop, and easier to clamp down. Un-clamped or freehand ok for a quick pass. As noted, zips and bearing are consumables. A Dremel is hardly a precision instrument.

[Tobias-B]

That Dremel cannot be an antique, as I still have mine from when I was- I mean, I am STILL a kid, dammit!

with the bearing, I can't see normal home shop work wearing much out, other than the bit.

t

[Noitoen]

My first Dremel had bushings, not bearings and it was the first serious tool I bought with holiday wages back in 1978. I still have it and 2 others almost 20 years old. Shame that the older model's accessories were not compatible with the later ones

[Paul Alciatore]

It appears that this very nice accessory uses a simple clamp to hold it on the Dremel nose, apparently on the crest of the thread.

I also have made some accessories for my Dremels and they incorporate a 3/4"-12 UN thread which is what most Dremels use. I do understand that some have used a 3/4" - 16 thread, but I have never seen one and suspect that is obsolete. Using the actual thread makes the attachment a lot more robust.

[DR]

I had a commercial version of that very same concept. It was designed to use a heavy duty pneumatic die grinder as a power source. Sold that one in favor a floor standing version that was much like router table, but far more solidly built of cast iron. The latter one was powered by a 1/2 hp motor driving a 1" diameter carbide multi tooth cutter. Depth of cut, angle of chamfer were all adjustable. It was heavy enough to be vibration free so parts to be chamfered could be stacked on the table. It was made by one of the older, big names in machine tools which I don't recall right now.

[wbc]

Paul A: What you may be thinking of as a clamp is actually a foot added to the AL body to make everything rest on a level plane.
The body is threaded to screw onto the nose.

This is an antique Dremel, and has a 3/4-16 threaded nose. And it has bushings, not bearings. The bushings are fairly tight, but
there was/is slop between the housing and the innards, which I addressed via an extra collar/bushing inside the plastic case to cause the nose
to bear down on the innards -- else it does little good to screw the AL body to the case when all inside is flopping around.

[Paul Alciatore]

My error, I apologize. The threads were not apparent in the photos and I just wanted people to know that the thread is a better way to attach something and that it is a standard thread with the 3/4" - 16 exception which you do have. I have looked at the photos closer and can see where it must be a thread, not a simple clamp.

I have two Dremel brand tools and both of them have the 3/4" - 12 thread and that appears to be on all the presently sold Dremel brand tools.

Paul A: What you may be thinking of as a clamp is actually a foot added to the AL body to make everything rest on a level plane.
The body is threaded to screw onto the nose.

This is an antique Dremel, and has a 3/4-16 threaded nose. And it has bushings, not bearings. The bushings are fairly tight, but
there was/is slop between the housing and the innards, which I addressed via an extra collar/bushing inside the plastic case to cause the nose
to bear down on the innards -- else it does little good to screw the AL body to the case when all inside is flopping around.