Building a precision mini drill press - any motor and spindle suggestions ?

[David Morrow]

I have a basic, larger size bench model drill press that goes up to about 3/8" drills. Now, I'd like to build a mini drill press. Something really accurate but smaller. I've looked at Jerry Howell's web site for some ideas and picked up a couple. I have most of the design sorted out in my mind but need to source a motor, variable speed control, and spindle. I have most of the rest of the material needed including a chuck.

Any thoughts ?

 

[Kermit]

Think Dremel.


It will need to be fairly powerful and much faster than most motors. By far the majority of motors that fit that bill will be DC motors. The ones without brushes are what you need, but they are more expensive than the ones with carbon brushes most times.

So, that has been perfectly useless! Still need to know where to get one, huh?

As for variable speed controls, it depends on what you think you need to spend. You can make a dirty cheap one with a high power pass transistor on a heat sink controlled with a small rheostat. Or you can get fancy and have digital this and pulse width that, you know! ;D If you only run it for a few hours in a week, the brute force, Cheap, and energy wasteful one will do just fine.

A Spindle can come from most anywhere, other members could better give opinions on that than I can.

Worthless, but always wordy,
kermit

 

[black85vette]

Heard of quite a few projects that used the motor and control system from tread mills. Might keep an eye out for a cheap used one.

 

[Blogwitch]

If you have air in your shop, you can do it a lot easier.

I am making a high speed drill for really small holes.

A cheap mini air grinder. The speed control is the silver knurled bit on the back end, 0 to 50K+ RPM.
See the first pic.

All you have to do then is make a stand. As I will only be drilling about 1/4" deep max, I found a cheap DTI stand on the net with a dovetail slide at the top. By taking out the limit screws I can get about 3/4" throw on the dovetail. The second pic shows the basic layout.

Cost up to now, about £35 ($45), the remaining bits to be made will be out of the junk box.

The rest is just a matter of a return spring, and a cam with a handle to give the push/pull to the dovetail.

I am also looking at a slightly larger air grinder (even cheaper) that will slot in place of the small one, but it will have a belt driven spindle, to get the chuck up to over 100K RPM for those really tiny holes.

Blogs

 

[jonesie]

blogwitch, i like your idea for the drill. you might look and getting a small pin chuck set that has a set of collets. i have one that has the outside o.d. at around 3/8. you can just turh the shank down to fit the grinder chuck.the smaller size would be better on you grinder bearing and the collet would give you a good range. i think i got the small pin chuck from enco or someone like that. i think i will make myself a set-up like that. thanks for the idea jonesie

 

[Blogwitch]

Jonesie,

That chuck looks larger than it really is. That is the smallest one that Jacob's make, and is only about 3/4" diameter. I have collets to fit the grinder, but I used the chuck for the flywheel effect if I have to drill holes a little larger, rather than relying on the torque of the air tool alone.

I don't think that the bearings in the unit are going to bother me, for the amount it will be used, they will definitely outlast me. Anyone who owns it after me, it then becomes their problem.

Blogs

 

[Tin Falcon]

I have been thinking of one off those little ar engravers to use as live tooling
I think i need these too
http://www.micromark.com/MINI-CHUCK-FOR-CORDLESS-SCREWDRIVER-1and4-HEX-SHANK,7852.html

 

[dwentz]

As far as a chuck goes, you need precision. Dremel collets, and their little chuck work good, up to 1/8 inch.

As far as motors go, brushless DC motors from electric RC planes are cars work well, are small, and have no runout that I can measure. You have to build a controller for them, but using a speed controller built for the motor, all you need is a little 555 timer circuit to simulate the signal from the RC receiver.

Dale

 

[Kermit]

This is the motor I would choose were this my project.

http://www.electromate.com/products/series.php?&series_id=105169


Hope this gives you some good ideas,
Kermit

 

[Tin Falcon]

As far as a chuck goes, you need precision. Dremel collets, and their little chuck work good, up to 1/8 inch.

I just picked up a couple of these . They are German made I believe by Bosch

Dremel
Model: 4486-03
1/32" Multi-Pro Tool Chuck

Lowes Item #: 107391 I actually got them at home depot

these use a dremel thread see here for more info
http://www.homemodelenginemachinist.com/index.php?topic=4957.msg50468;topicseen#msg50468

Tin

 

[Dunc]

The standard, I believe, for using very small drills was an Albrecht (uncertain if this is the correct spelling) chuck.

Edit: Delta ( and probably others) offered a high-speed bench-top drill press many years ago (thinking the 60's or 70's). Back then, this was part of their industrial tool catalog - not the home stuff. Expensive then but second hand today... who knows.

There is an article in Pop Mech, Dec 1941 with plans to build a small modelmaker's drill press powered by a sewing machine or vacuum power brush head motor.

Elektor magazine had a construction article - early 2001, I think - but I cant locate any more info.