Drilling Very Small Holes

[krypto]

I think these were available in the 1950's. I have attached fliers that were in the tool box that was built into the custom cabinet that housed Dumore.

Wow! Thanks for going through the effort to scan your documentation! I think you have something that's very rare.

I can find very little information on this model via search. Vintagemachinery.org has a scanned manual (pages out-of-order) and a vintage Dumore ad showing your drill. Someone on eBay is trying to sell just the magnetic chuck for $250!

I would imagine that it was quite costly back in the day! That's probably why someone went through the effort to make a custom cabinet which kept it in wonderful condition for all these years.

 

[petertha]

Thanks for providing these documents. That magnetic chuck piece of information is fascinating. I never heard of it before now.

It always struck me that the 3-jaw chuck one typically sees mounted on these units would be subject to the same issues as modern chucks - low runout like say 0.0005" range means precision components & that typically costs big money. At least it does today.

 

[BobsModels]

krypto

I have those in a PDF, also lots of views of the machine. I will make up a file containing all the info I have and upload it. I have uploaded stuff to vintagemachinery before, Laidlaw Bandsaw and All American Die Filer details and drawings.

I never looked for any information on vintage on the Dumore, not sure why, thanks for the finds. I downloaded them.

Bob

 

[timo_gross]

Knowing now how to break those small drills How can they be manufactured ( 0.002") that remains a mystery. (at least to me)

 

[Steamchick]

Ian, Been there, done that. NOT fouled a finger either! Glad to see a Graver - a rare beast indeed (the person, not the tool). A skill declining in use?
I enjoyed the interruption by the small person.
Theatrical caution: "never work with animals and children!" (The script and stage management go out of the window!).
Thanks for posting the videos.
K2

 

[Steamchick]

I see a project developing to make the magnetic chuck/collet holder for my Unimat...
THANKS!
K2

 

[ajoeiam]

Knowing now how to break those small drills How can they be manufactured ( 0.002") that remains a mystery. (at least to me)

Dunno about manufacturing but I do know that Mikron tools (iirc the actual name) sells them down to 0.002" as a special - - - at least it did the last time I looked.

Grinding a bit that small would take some interesting equipment imo - - - - that would make a hobby inside another hobby - - - lol - - - I have too much of that already.

 

[terryd]

Hey Krypto, that looks a really neat set-up. I drill 0.3, 0.25. and 0.2mm drills, using the carbide drills with 3mm shank. But have always used the lathe approach of rotating work and stationary drill bit.
What speed do you use with your smallest size bit?
K2

Hi K2,
I do the same when making bits such as gas jets by rotating the work in the lathe but I use a modified circular pin chuck to hold the small drills (I use small HSS drills down to 0.2mm Minimum). The pin chuck itself is held in the tailstock Jacobs chuck with a sliding fit I can then control the drill with my fingers and can 'feel' the action of the drill and have had very few failures (actually I can't remember any) using such a set up. I hope that description makes sense

As an aside this topic reminds me of a design engineer I was working with who, as a freelancer, was commisioned to develop a machine to drill very small holes in intricate cast iron vehicle components for the then British Motor Corp. who were having problems with drill breakage and scrappage of components, due to hard spots in the castings - not so much for the cost of the scrap but the cost of production down time. The guy managed to conquer the problem with sensors on his machine which stopped the drill descending on meeting a hard spot and then used fast, light 'pecks' until the hard spot was passed. He was well rewarded for his efforts in 1969.

Regards,
TerryD

 

[stanstocker]

Hi Folks,

Here's a video on making small drill bits commercially:



It is sadly one of those somewhat fluffy and "Gee-whiz general audience" sorts of videos, so details are limited, but all the general steps are there.

Harvey Tools carries bits down to 0.002 inch:

https://www.harveytool.com/products/miniature-drills
Spade style pivot drills are a production item for the watch trade, Esslinger and others carry Mascot brand down to 0.004 inch:

https://www.esslinger.com/mascot-flat-pivot-drills-004-to-050-inch-sold-individually/
For anyone who needs to make small bits for limited use, any of the old traditional watchmaking books will have instructions for making drills as needed for watch sized work. I've made spade bits down in the 0.2mm / 0.008 inch range, can't say I remember making any smaller than that. Snapped a few in process, seems a good idea to always start with a few spare blanks on hand. To folks raised on using machines for everything, it's surprising how much you can accomplish with a few quality stones and a pin vise. Hardening is the trickiest bit to get right, using an alcohol lamp and having the quench cup right at the edge of the flame is the only way I could both avoid burning the steel and get the hot bit into the quench fast enough to harden.

Cheers,
Stan

 

[WisJim]

I missed a Dumore sensitive drill at a garage sale by a minute. It was $15.

 

[petertha]

I do the same when making bits such as gas jets by rotating the work in the lathe but I use a modified circular pin chuck to hold the small drills (I use small HSS drills down to 0.2mm Minimum). The pin chuck itself is held in the tailstock Jacobs chuck with a sliding fit I can then control the drill with my fingers and can 'feel' the action of the drill and have had very few failure

Can you post a picture of your setup? If I understand the description, you have sensitive infeed control, maybe somewhat analogous to an Albrecht style?
But that Dumore mag chuck has a means to pre-correct any the radial runout. That relieves the chuck/collet responsibility of having perfect TIR. I'm interested to make something like this - adapting a small chuck. Just wondering about the delicate balance of enough magnetic strength to laterally displace under rotation to set nil runout, but then sufficiently staying put during drilling. Maybe it only works best at teeny drill sizes?

 

[Steamchick]

Terry D: I first encountered a mass production problem of small holes on steel oil spray bars that were fitted onto car engines and sprayed oil onto cams and followers of valve gear. When drilled, there would be drill breakage devices on the machines to identify the parts and automatically scrap them - maybe 1 /1000? (Typically 16 holes drilled simultaneously in the bars!). When a drill broke, all 16 drill bits were changed, with consequential high cost of manufacture. Also, any burr on the inside of the drilled hole that had not been cleared away would trap organic sludge "stuff" formed in the oil, which eventually would lead to a blob of goo that blocked the hole = another warranty failure.
Of course, there were those that slipped the controls and got on cars... with subsequent warranty failures of short-life of the affected cam/follower.
So I found a supplier who could laser drill the holes. No drill material or swarf to block holes, as the laser simply vaporised the metal to form holes. Scrap went to zero, Warranty was zero, for this blocked hole or inadequate hole from drill breakage. The laser "drilled" a series holes in a circle, partly overlapping, to give the correct oil feed area, after a bit of simple tuning. I think it used a beam about 0.004" diameter?
But I can't afford a laser drill for my garage...
K2

 

[Zeb]

For those here working with tool steel at an angle, some of the 3D printer based DIY EDM drilling machines look interesting.
New processes have upgraded to lasers, but inconel/ceramic coated turbine blades had impingement jets made that way.

Some applications might include miniature nozzles where the surface is conical or steel bolts with drilled heads.

Not very practical but an interesting project for sure.

 

[stanstocker]

For those contemplating the EDM rabbit hole, we had a thread on building EDM devices a couple a while back:

https://www.homemodelenginemachinist.com/threads/edm-build.27000/
Cheers,
Stan

 

[Steamchick]

Can rabbits get down such small holes as micro- drilled, or EDM with fine wire?
K2

 

[Zeb]

Can rabbits get down such small holes as micro- drilled, or EDM with fine wire?
K2

Certainly for a moss piglet.

I used to make and burn electrodes for injection molds and even with a commercial setup it still felt pretty hacky. Nice results though.
Good to see some activity on the subject.

 

[lkrestorer]

Interesting comments from all you folks. It's always fun learning how other people do unusual things.

I do believe my problem is solved. The company I bought the micro drill chuck from has offered to take it back and refund my money. I ordered, and received, an ER11 chuck and collets from 0.5 mm to 3.5 mm which will accommodate everything from #76 to #29. The little chuck was sized at 1/8" so these replacements will cover that range nicely. I didn't buy the most expensive I found, but these are U.S. made and fall somewhere in the middle of the price range. Craftsman Industries: https://www.suncoasttools.com/PDFFILES/CraftmanIndustries/CraftmanMain.pdf

And, wow, are they tiny! You'll say: "of course, they have to be" but, just like the talk of how the tiny drill bits are made, I have to marvel at how these must be made with such precision. The chuck sales information says it has a 0.0003 T.I.R. I think that will be good enough for me. I've experimented with these and holding the chuck in an R8 collet and I'm impressed.

That's my "new tool of the month".

 

[krypto]

That looks like some quality gear and shouldn't give you any problems. The collets will grip a drill better than a chuck. I've added a bookmark for that retailer for whenever I get around to replacing the lousy ER11 collet set I have.

I found this last video from ToT about collets to be especially apt and funny:



I think what surprised me the most was that all the ER32 collets I've bought over the years have been pretty good, with only a few tenths of run-out difference between decent and no-name versions. Not with these little ones though, they just suck. Something like .004 TIR and they didn't get much better when I cleaned-out the metal shavings. A broken belt-buckle indeed.

 

[lkrestorer]

I'm kind of liking the way these work and maybe I'll have to expand my collection of sizes in the future. I was lucky enough to catch a sale from Suncoast when I went looking. I've bought other tooling from them and it has all been very good. Every once in a while they have a free shipping deal, also. Along with this sale it was free for orders over $60.

I went to YouTube and watched "This Old Tony" talk about the collets before I made my purchase. He has a way of telling a good story and spicing it up with some good humor. There is a lot to be said about buying good tools.