small but precise mill
small but precise mill
(OP)
I need to drill two 0.050 inch holes in stainless steel. The part is effectively a 1/16 npt bolt, which has been hollowed out. The hex head end has a circular recess 1/4 inch in diameter, and in that recess I need to drill the two holes. They need to be placed accurately, within 0.001 inches. The thickness being drilled is about 0.10 inches. This is a small part, so I dont need a giant turning center. We will be doing a few hundred a month plus prototypes. I would like to find a mill that would give that capability. Initial efforts comes up with mini-mills which seem like just low cost bench top drill presses. Any suggestions?





RE: small but precise mill
Depending on the space you have available, you might consider the very versatile Bridgeport Series l turret-mill, there should be plenty about with vari-speed heads and digital readout for not too much money.
If this is too big and you want quality (I agree with your comments about mini-mills), then look for a small toolroom miller like the Deckel FP1 or 2, the Aciera F1 or F2, or one of the many small universal mills (Adcock Shipley, Elliot, Fritz Werner Etc) get one fitted with a self powered, quill-feed vertical head. Be wary of the the vertical milling attachment fitted to a lot of small horizontal mills as they are often driven off the main spindle and so are quite slow, also, you have to raise the saddle as the head is fixed, making them not ideally suited for drilling relatively small holes.
RE: small but precise mill
doug
RE: small but precise mill
RE: small but precise mill
RE: small but precise mill
Doug,
Thanks for the star! I don't know where you are located, but here in the UK there are several other small mills (Tom Senior, Centec, Boxford and Myford) that predate all the modern light weight offerings and it is worth taking a look at model engineering suppliers and magazines.
However, If you don't have other potential uses for this small mill and really only need to drill these two accurately positioned holes in a few hundred modified bolt heads, then have you considered getting a jig made up by a toolmaker that holds one or more at a time and has hardened bushes to locate and guide the drill. The job can then be repeatably and easily done by a relatively unskilled operator on a simple pillar drill. Bearing in mind that you stated the holes were to be at the bottom of a quarter inch diameter recess, which in itself makes the job more difficult, especially pre-spotting for the drills which is necessary for accurately positioning a drill of this size on a surface which might not be truly flat.
RE: small but precise mill
RE: small but precise mill
doug
RE: small but precise mill
http://w
RE: small but precise mill
http://www.najet.com/tooling/newDefault.htm
If you have use some other drilling head you should look at the reamer drill from Atom.
http://www.atomprecision.com/index.html
There are special drill bits that will get you pretty good flat bottom hole.
What material are you drilling? If possible a change in material could be very beneficial in your process.
RE: small but precise mill
SO:
1) jig
2) pre-drill with small drill
3) next size up
4) finish with reamer.
or find a neat-o drill or mill that will do the job.
RE: small but precise mill
http://www.lathes.co.uk/bca/index.html
Got one in my workshop and it's brilliant. One came up for sale recently.
RE: small but precise mill
Regarding "good old tools" from your side of the pond, I knew someone in London a few years ago, who had an American made Clausing 8230 tool mill that was pretty neat. Also the Hardinge TM was often fitted with the Bridgeport Type M self powered quill-head, and I believe Rockwell made small vertcal mills at one time, but like the Millrite from (I think) Burke they may be too large.
I'm still inclined to think that the jig is the best option, if for no other reason that you've got to effectively work blind in the bottom of a small recess, with tool changes for each hole and get each one right. With a well designed jig you only have to worry about the odd drill breakage.
RE: small but precise mill
It seems like the route with a jig is the most practical, and I shall proceed in that direction. A good source of mill bits which machine dead-flat at the bottom is on the shopping list. But, having said that, I think I shall be gunkholing in search of that perfect antique that will do the job, just for the enjoyment of "doing it right". Thanks again everyone.
doug
RE: small but precise mill
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There are several companies that make flat bottoms on SHCS for UT testing. We have had several hundred in use at times.
http://www.phtool.com/pages/fbh.asp
If you are going the jig route you might want to look at the AutoDrill products. Build your own.
http://www.autodrill.com/index.html
If you are still interested in small mill/drill machines look at these two sites.
http://www.smithy.com/products.php?cid=1
http:/
RE: small but precise mill
RE: small but precise mill
doug
RE: small but precise mill
http://www.heinrichco.com/drilljig.htm
ht
You also might want to look at the Blue Ridge Machinery Catalogue as they carry most of the small mill drill machines. They were good people to deal with. I bought 2 pieces of equipment from them and have gotten very good service
http://ww
RE: small but precise mill
RE: small but precise mill
I am new here and am looking for ways to use my new/used Deckel FP1 and FP2 Universal Milling/Boring Machines. The company where I received them from never used them other than a drill press and that was only with small drills. They are practally new, and are in excellent condition. Any comments of course will be greatly appreciated. Thanks!
Bob
RE: small but precise mill
A.R. "Andy" Nelson
Engineering Consultant
anelson@arnengineering.com
RE: small but precise mill
doug
RE: small but precise mill
RE: small but precise mill
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RE: small but precise mill
Thanks. I shall be back.
doug
RE: small but precise mill