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micro drill adapter for mill


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I was looking at a very smooth operating drill at my local Jewellery tool supplier, it was nice but outside my budget. What I liked was the positive lock and vibration free running of this tool. Evidently the local wood carvers really like this tool. I have never really liked my dremel flex shaft for hand work it just doesn't suit my way of working. so not wanting to give up the manager/owner of the store said to me "I Have and older version take it home and try it" What I like is it takes the 3/32 shaft drill bits and burs. and runs up to 30,000rpm. also it has a decent amount of torque. 

 

I wanted to be able to hold it securely in a fixture added to the mill drill.

First picture shows the basic block to hold the fixture and the method to stop it from rotating, I did not want to do any machining on the mill drill but just wanted to use what was already there for attaching to. the tab sticking off the side of the quill was for the original drill stop I squared up a bit of 1" square brass bar on the lathe and turned down a bit of 1/2 inch bar to locate within the slot where the #3 morse taper fits in it is helt in place with a threaded rod through the quill normally . This arrangement ensured that the 1 inch bar cannot rotate but is easy to fit or remove.

 

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Next the holder for the mini drill was made from some 1 1/4" diameter brass round and sme 5/8" brass square bar.

 

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this was attached to the 1" carrier bar with a couple of allen head cap screws

 

The 2 sections of round that the tool slips into were made independently so that they were a snug fit in the locations that were chosen Both of them were held together and flattened on one side to accept the 5/8 bar the 2 parts were slipped onto the tool then the bar was glued to them with ACC as a temporary measure in order to drill and tap the permanent fixing screws.

 

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The tool slipped in and a 1/4 x 28 locking screw was all that was needed to secure it in place. Now I have the full scope of the mill table and up and down movement of the quill for precision milling at high speed which was not available before. 

so to test this i used a taper dovetail type cutter and cut a slot in some Castelo.  

 

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Next I switched cutters for a micro slitting cutter

 

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and so I can use it for drilling with the proper speed for the very fine drills and for micro milling on larger Items.

 

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I am going to test it out on a few tasks and then decide whether to keep it. It uses a foot control pedal to turn it on and off.

 

Michael

   

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Yes you might be right there Druxey.

Hi Geoffs, the small diameter cutters require a much higher speed than My big mill is capable of, and I am not yet familiar enough with the data to give you a meaningful answer. perhaps those with more knowledge of the very small burs and cutter will be able to give you a better answer. I will know better soon though.

 

Michael 

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There some reasonably price micro-motors now on the market from the usual Chinese sources. Know some colleagues who have one and they seem to be happy with it for carving etc. I have been thinking of adapting one to my micro-mill, but for the moment I was happy with the top speed of 5000 rpm of the current arrangement for Plexiglas and brass. Wood may need indeed higher speeds.

 

Nice adapatation by the way. Does the big mill have a light enough 'feel' on the handwheels for such delicate work ?

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Higher the speed, the smoother surface, a router bit acts the same as a milling cutter. Same idea with my wood planer; 2 speeds: the higher for finishing.

  

At the opposite if you go too low, the knives will not cut  as well;  they will  want to tear in  the wood, especially at the edges

Proxxon has a small mill that runs 20,000 rpm which is  perfectly fine.

 

Some model maker prefers to use a mill for wood at 5000 rpm... the only good reason I can see is because of the many accessories of other brands.

 

When I can, I prefer to use aluminium where the cutters plunge like in butter. 

When strength is not a factor, I prefer to use high density plastic, very easy to turn and high degrees of accuracy can be reach.

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Thanks Carl.

Eberhard, thanks the wheels on the bib mill are pretty good in that respect, plus I have added the dials to give very accurate feed to the X , Y and Z axis and I have the gib strips set such that the table moves smoothly without too much effort without slop, even though it is old it has not been pushed hard.

Gaetan, thanks for the info regarding speeds.

Michael

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