Drilling small holes

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Mr Ron
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Re: Drilling small holes

Post by Mr Ron »

pete wrote: Wed Sep 15, 2021 7:35 pm How easy or hard was that size of end mill to work with Bill? CNC might not be too bad, but on a manual mill I've always wondered if it would be possible or they would just break.

I have a set of solid carbide boring bars meant to be used in a boring head and could also be used on a lathe I suppose. The smallest is capable of starting in a .050" hole. The larger one's do work great, but so far I've not had the guts to use the two smallest one's. At $45 each they would make a fairly expensive sound if/when I break one. If money is no object PH Horn in Europe have some really small cutting tools.

Jerry Kieffer has made the taps and dies, heat treated and then produced working nuts & bolts on a lowly Shereline manual lathe to just under .010" in diameter with if I remember correctly over 300 tpi. His 1/30th scale Corliss stationary engine he used them on is mind boggling it could even be made and operate as well as it does. https://www.craftsmanshipmuseum.com/Kieffer.htm
Mr. Kieffer must use a microscope to see his work. I would be interested in knowing how he was able to use a Sherline machine and how he is able to hold material to be machined. I don't even know how a chuck can be used to hold work that small. The screw (.010") is smaller than a 0000-160 thread, the smallest tap made. I couldn't find a die smaller than an 0-80.
Mr.Ron from South Mississippi
Russ Hanscom
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Re: Drilling small holes

Post by Russ Hanscom »

Kieffer makes his own taps and dies, if I remember the article correctly. Special gearing to get the necessary TPIs. Only limit is patience.
pete
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Re: Drilling small holes

Post by pete »

Yep he does use a tool makers microscope for very small work on his Shereline lathe & mill. He wrote an article about how it was all done and it got published in the HSM magazine years ago. If my memory is correct and as Russ said, he had to make the proper gear cutters to match the apparently fairly uncommon Shereline gear tooth pitch. Then cut his own extra gears to use on Sherelines hand rotated threading accessory to get the ratios fine enough to cut 300+ tpi. Then precision lapped a 60 degree micro 100 braised carbide tip on a Glenndo Accu-Finish. Used that and the microscope to make the taps, heat treated those, then used them to make the dies and again heat treat. Jerry is the type where no step seems to be too far to go. He also provided side by side comparison pictures of more standard thread pitches (0-80 I think) against his much finer threads and they much better represented how the full size part should actually look when reduced in size.

I've done down to 0-80 in stainless and multiple xxxxxx-300+ tpi is something I can't even imagine. Sherline used to use a picture of one of his bolts in there magazine ads some years ago. I seem to recall he may even have made some with .005" on the major diameter. 0000-160 might be the smallest that are easier to find, and last I checked a tap or die in that thread pitch was over $100 each. Easy to see why he made his own as well as not being able to buy what he wanted anyway. I'm pretty sure there's what's known as a metric constant pitch series used now for fine instrument work that replaces the now almost discontinued imperial instrument series. And it goes smaller than the 0000-160 tpi. Very specialized and hard to find though. I think that pitch series might be mentioned somewhere in Machinery's Handbook.
RSG
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Re: Drilling small holes

Post by RSG »

Man....you're a wealth of knowledge Pete!
Vision is not seeing things as they are, but as they will be.
pete
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Re: Drilling small holes

Post by pete »

Lol thanks, but not really. More like a head full of trivia that's not of much use most times.
Mr Ron
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Re: Drilling small holes

Post by Mr Ron »

Harold_V wrote: Thu Sep 16, 2021 1:32 am
Not to make little of the accomplishment, it's not all that big of a deal.
Many years ago, when I operated my machines for gain, one of the tools I built for Litton Guidance & Control required six pieces of what I recall to be 5/8" diameter free machining brass with a .030" diameter extension 5/8" long. Sounds impossible, but they were quite easy to make (turned from bar stock) with my 12" Graziano, top spindle speed of only 2,000 rpm.

H
I would be interested in how you machined that piece. This is the kind of work I need to do in my model building.
Mr.Ron from South Mississippi
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Harold_V
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Re: Drilling small holes

Post by Harold_V »

The projection was machined in steps. I roughed the length considerably oversized, then started at the end, reducing it to the desired diameter in short lengths. I repeated until the 5/8" length was achieved.

Needless to say, there were minor steps in the length, but it was easy enough to spin polish the 1/32" diameter probe to blend them.

This works so long as the tolerance at one's disposal is reasonable. It would not work without considerable effort for high precision work.

Note that such a slender item is easily bent, so it is just as easily straightened while spinning. The probes were straight after machining.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
Mr Ron
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Re: Drilling small holes

Post by Mr Ron »

Harold_V wrote: Fri Oct 15, 2021 4:01 pm The projection was machined in steps. I roughed the length considerably oversized, then started at the end, reducing it to the desired diameter in short lengths. I repeated until the 5/8" length was achieved.

Needless to say, there were minor steps in the length, but it was easy enough to spin polish the 1/32" diameter probe to blend them.

This works so long as the tolerance at one's disposal is reasonable. It would not work without considerable effort for high precision work.

Note that such a slender item is easily bent, so it is just as easily straightened while spinning. The probes were straight after machining.

H
Thank you Harold. Yes it doesn't look all that hard to do following your steps.
Mr.Ron from South Mississippi
Rich_Carlstedt
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Re: Drilling small holes

Post by Rich_Carlstedt »

Jerry is one exceptional man and impressive model builder in miniature.
here is one of his articles showing you how to do it !
https://sherline.com/wp-content/uploads ... ip_047.pdf

Rich
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Harold_V
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Re: Drilling small holes

Post by Harold_V »

Thanks, Rich. I sure agree with his method.

There was a time when I could do such things without aids. I can still remember creating 80 pitch threads in tungsten, used as balance weights in gyroscopes in Litton's guidance systems. That would be impossible for me today.

I've pondered the reason why I enjoyed success with small work, which was my specialty. I suspect that a good portion of my success was the ability to see the work, something that I can no longer do the way I used to.

H
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Conrad_R_Hoffman
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Re: Drilling small holes

Post by Conrad_R_Hoffman »

I've done some very small threading on a Sherline and it's actually more suited to it than something like an HLV. I bought two threading attachments so I could make up compound gearing for the fine threads. I used an opposed carbide rest for stability and could do a couple inches of threaded rod with little trouble. Just recently I needed some small holes and bought some 0.0085" cobalt drill bits. They were far easier to use than I would have thought and I have little fear of going smaller, if necessary. No doubt I'd snap carbide instantly. The truth is I went with that size because there was a step change in price for anything smaller!
Conrad

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Harold_V
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Re: Drilling small holes

Post by Harold_V »

Conrad_R_Hoffman wrote: Wed Oct 20, 2021 3:41 pm Just recently I needed some small holes and bought some 0.0085" cobalt drill bits. They were far easier to use than I would have thought and I have little fear of going smaller, if necessary. No doubt I'd snap carbide instantly.
Wow! That's really impressive! The machine must have exceptional alignment, headstock to tailstock. Spells instant death for fragile cutters.

What speeds are at your disposal? Such a tiny drill would easily tolerate more than 10,000 rpm.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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