Drill-mill fixure for central Dremel mounting

I want to mill printed circuits boards (PCB’s). The required small mills demand for a high speed. So a Dremel with 30000 tpm is an adequate tool. The cross table of my drill-mill is very useful when the copper traces are orthogonal or under 45 degrees.
I don’t have a CNC mill but a simple hand controlled drill-mill.
I started some years ago with a quill clamp which holds the Dremel besides the machine head (picture 1).
This design has a drawback: the quill has angular play which changes the position of the Dremel wrt the work piece.

So I decided to make a Dremel fixture where the Dremel is mounted centrally to the quill (picture 2). To limit the length of the fixture I directed the power cord through the spindle boring. To that end it was necessary the cut the power cord of the Dremel and provide it with a small (11 mm) plug and socket, small enough to allow passage through the boring (picture 3). The soldered connections are isolated with heat shrink and hot glue.
Attachment 34806Attachment 34807Attachment 34808Attachment 34809

The Dremel itself was screwed in a PLA nut, 3-D printed by a friend. The nut was pressed and hot fixed in a steel strip (picture 4). 3-D printing screw thread seems to be difficult for, in different trials, the threads where always to small. So I made a tap for this non standard thread (¾”, 12 tpi, 60 degrees) and widened the thread. (Alternatively an alu nut can be made with the same tap.)

The Dremel is supported by an enclosure made from 4 stacked layers of 8 mm compact laminate sheet (see pictures 2 and 6). It ensures a stiff mounting without side movement.

For clamping the fixture to the quill I used 32 mm plywood (pictures 2 and 5). Perhaps it is not the best material, but it was the only material of sufficient thickness I had in stock from a discarded kitchen top. The hole encloses the quill’s collar narrowly and is fixed by a pair of alumin(i)um cotter pins (British naming) (picture 5). The hole in the clamp for the cotter pins is provided by a copper tube in order to let the pins slide easily.
Attachment 34810Attachment 34811
My Dremel is an old model. I noticed some radial play in the Dremels spindle. Dismantling showed that it was not the bearing itself but the bearing house. I filled it with small pieces of 0.1 mm milar sheet. Now the spindle is without any play.

This design is giving a very stiff mounting thanks to the 4 vertical studs. The shorter two are made from 12 mm round rod, the longer ones are 10 mm threaded rod.

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Thanks Carnel! We've added your Rotary Tool Mounting Fixture to our Rotary Tools category,
as well as to your builder page: Carnel's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-rotary-tool-mounting-fixture"> <img src="/uploads/232969/homemade-rotary-tool-mounting-fixture.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-rotary-tool-mounting-fixture">Rotary Tool Mounting Fixture</a> <span> by <a href="https://www.homemadetools.net/builder/Carnel">Carnel</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/dremel'>Dremel</a>, <a href='https://www.homemadetools.net/tag/mount'>mount</a>, <a href='https://www.homemadetools.net/tag/fixture'>fixture</a> </div> </div> </div> </div>
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Really like this perfect for small cutters thanks for sharing.
The Home Engineer

Thank you, Home Engineer, for your interest. Specially for your small models it could be a good alternative. Also useful when your cross table is CNC controlled.

My first thought was "That is a serious little unit. I like it." Very creative too.

Bob
Manitoba, Canada

I needed to do some PCB work so I bought a Proxxon drill stand and a Proxxon XY table.

Attachment 35007 Attachment 35008

It worked well but I burned up two of the Proxxon motor's electronics in short order, so I'd had enough of lowest cost electronics. I also had a Foredom hand carver with a powerful motor and I decided to adapt it to the Proxxon hardware. The Foredom has 1" diameter handpieces so I bought a unitized rifle scope mount for 1" scopes and attached it to the Foredom stand and now I have a small, precise and powerful milling machine that's perfect for making holes in circuit boards or other small milling work.

Attachment 35009

For those of you that're interested in hand carvers, while the Fordom is a nice tool, I later found that the MasterCarver clone is just as good as the Foredom at about half the cost. The MasterCarver handpieces also take ¼" shank bits so are more versatile that the Foredom ones.

I have the Grizzly version of the Foredom, the motor is fine for what I do but the bearings in the handpiece were bad. They replaced and it still got hot, so I bought a real Foredom handpiece when I saw one for a reasonable price.

Take a look at the Master Carver handpiece. It seems equivalent to a Foredom except the ability to mount ¼" shank bits opens up a new world of uses. Small router bits are available in a broad spectrum of profiles and they work well in my experience.

I've also used a 3m sanding burr (hard carbide nuggets on a shaped core) in it to completely carve banjo necks in short order, but do it outside or you'll be cleaning up sawdust for months.

Nice set of photos. Many of the original Dremel tools have a strange front collar thread size of 3/4" by 12 TPI. The taps are available and I adapted my Dremel tools to some of my lathes for drilling and light grinding purposes.

Buying a tap and the associated tap drill can get expensive. My guess would be somewhere in the neighborhood of $50.

I've threaded adaption collars on the lathe and that works well but, for folks lacking a thread cutting lathe, consider buying the Dremel router attachment...

https://www.amazon.com/Dremel-565-Mu...s%2C212&sr=8-4

and repurposing the already threaded sleeve which is used to mount the Dremel tool.

It may also be possible to repurpose the less expensive easy twist nose cap...

https://www.amazon.com/dp/B009PBU0K0...s%2C200&sr=8-1

although I can't guarantee it.

Incidentally, people with metric equipment can thread an adapter M19 x 2 mm. This is very close to the inferial size: 3/4" = 19.05 mm and 12 TPI (.083" pitch) = 2.11 mm.

You guys break me up some days. You make a threaded threaded collar for the Dremel tool, one of you pisses away hours doing a single point thread on a lathe, the next goes on about the cost of the drill and tap, and I go buy a nut with the right thread and turn the flats off and weld or braze it in place. Might get really lazy, and not even turn off the flats.

Y'all forget the KISS principle in a heartbeat, makes me shake my head.

I've got a friend like that, every damn job requires it to done to show off his artistry, stroke his damn ego, and takes way too long to do. I don't ask him to do anything for me, he was doing a transmission rebuild for me and got pissed off when I walked over to my transmission, put a cupcake with a lit candle on it, and sang "Happy Birthday" to it! Told him in a year, he'd had more then enough time to git it done, time to get his thumb out of his ass and DO IT. Also told him be glad he's a friend; anyone else, I'd have taken a 2# mason's hammer and pounded the thumb in further, so he could feel up his tonsils!

It was done by week's end.

Murph

I doubt where the "low cost" of electronics is the cause of power electronics failure. Designers mostly use bare or tinned copper traces for high currents. But for a free conductor a current density of 10 A/mm2 is the maximum to tolerate. For a motor current of 10 A and a trace thickness of 35 micrometer you need a trace width of 30 cm! That's impractical. So, as a consequence, in practice you always should cover high current traces with copper wire or strip which can be soldered to the trace. I use 1,5 mm2 up to 10 A, 2,5 mm2 up to 16 amp. So, when you buy electronic boards for high current applications, check which traces draw these high currents and modify your PCB.

Quote:

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Originally Posted by Murph1090

You guys break me up some days. You make a threaded threaded collar for the Dremel tool, one of you pisses away hours doing a single point thread on a lathe, the next goes on about the cost of the drill and tap, and I go buy a nut with the right thread and turn the flats off and weld or braze it in place. Might get really lazy, and not even turn off the flats.

Y'all forget the KISS principle in a heartbeat, makes me shake my head.

I've got a friend like that, every damn job requires it to done to show off his artistry, stroke his damn ego, and takes way too long to do. I don't ask him to do anything for me, he was doing a transmission rebuild for me and got pissed off when I walked over to my transmission, put a cupcake with a lit candle on it, and sang "Happy Birthday" to it! Told him in a year, he'd had more then enough time to git it done, time to get his thumb out of his ass and DO IT. Also told him be glad he's a friend; anyone else, I'd have taken a 2# mason's hammer and pounded the thumb in further, so he could feel up his tonsils!

It was done by week's end.

Murph

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Hi Murph1090, I like your reaction very much! It confronts me with my motivation working in my shop.
A sidestep: the thread of the Dremel is not standard (3/4", 12 tpi, 60 deg) so the nut which you want to buy isn't available, I think, and when, you have to buy a full box of 100 or so.
But why spending such a lot of time? In fact this project was growing while working on it. When the opportunity of 3-D printing came up my friend an I were wondering whether one can 3-D print screw threads. And after producing some try outs whith too narrow threads the idea of a tap came up. So, the whole project was playing. And that gives me satisfaction. I do my projects out of hobby and production time is of no importance for me. Being 84 I can afford it. I am glad having enough power to do these stuff.
So, in my opinion, an important difference in motivation is whether production or playing is your motivation.
Thanx for you reply!

Counterbalancing small high speed spindles can add another dimension to the use of such tools. Here is a post that I made a while back. The linked video shows more detail.
https://www.homemadetools.net/forum/...ll-press-71947

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Thanks Crusty! We've added your PCB Drill to our Drilling and Drill Presses category,
as well as to your builder page: Crusty's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-pcb-drill-5"> <img src="/uploads/233658/homemade-pcb-drill-5.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-pcb-drill-5">PCB Drill</a> <span> by <a href="https://www.homemadetools.net/builder/Crusty">Crusty</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/pcb'>PCB</a>, <a href='https://www.homemadetools.net/tag/drill'>drill</a> </div> </div> </div> </div>
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Isn't cutting corners on traces being cheap?

Quote:

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Originally Posted by Carnel

I doubt where the "low cost" of electronics is the cause of power electronics failure. Designers mostly use bare or tinned copper traces for high currents. But for a free conductor a current density of 10 A/mm2 is the maximum to tolerate. For a motor current of 10 A and a trace thickness of 35 micrometer you need a trace width of 30 cm! That's impractical. So, as a consequence, in practice you always should cover high current traces with copper wire or strip which can be soldered to the trace. I use 1,5 mm2 up to 10 A, 2,5 mm2 up to 16 amp. So, when you buy electronic boards for high current applications, check which traces draw these high currents and modify your PCB.

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Carnel,

Very nice project and neatly executed also.
Thanks for posting this useful idea!

Nicely done, Carnel. I've been thinking of mounting my Unimat motor head, capable of high speed, to a 25 mm rod held in the mill collet chuck. This would mean that the Unimat spindle would not be coaxial with the mill spindle but I don't see that as a problem since the main reason for doing it would be to take advantage of the mill's X-Y table and the motor drive for the X axis.

Please be sure to disable the power to the mill when using the Dremel. It's too easy for one's motor memory to take over in a moment of distraction and make you turn on the mill with the Dremel mounted. DAMHIKT. On my mill I have two power switches mounted in series for just this reason. One is the switch I use most of the time. The other is in a hard-to-reach location that my motor memory doesn't remember. Turning the latter off is a great way to prevent me from turning the mill on while some only-power-off operation is under way.

EDIT: the 3-D printed nut had a short live. Little force did break it. Apparently it could not withstand a pulling force. The inner cohesion was too small. I turned a new alumin(i)um nut and press fitted in the steel strip.