How to use a REALLLLY small #68 drill bit .0310"

[George Bulliss]

Though intended only for drilling graphite electrodes for EDM use, the little horizontal drill pictured below does a great job with little drills. I think most of the sizes I used were around .010", as you want the flush hole slightly under the amount of orbit you use on the electrode so the area under the hole gets completely burned away.

The spindles are hollow, which allows you to start the drill with it barely protruding, extending it as the hole progresses. As the hole gets deeper, you set a stop to limit the table so the tip of the drill remains in the hole during the pecks. I often drilled 2"-4" deep and you don't want that much of a .010" drill bit to come out of the hole during a peck. It's pretty exciting, plus the owner reminds you once again how expensive the drills are.

The moving table was very sensitive and intuitive to use, plus the horizontal setup made for better chip removal. The motors on these things are pretty weak and you would have problems with anything other than graphite, but it's an interesting design, so I thought I would toss it in the thread. The last shop I used one of these in just had an auction a few weeks back – I'd be curious if the Westoff even sold.

[Mcgyver]

I thought about getting one of these but those small drills really need to spin a lot faster than my variable speed BP will go.

bports are plenty fast enough. What small drills need is concentricity and sensitivity. I've got a dumore like Rich shows and Servo and drilling at speed is nice, but you can drill small holes easily with a lot less rpm. In fact watchmakers, who drill holes to almost a tenth that size would do so spinning the work at 1500-2000.

The best sensitive rig I ever seen is the one that appeared in HSM ages ago. Better because there is a counter weight so the force caused by the weight of the work/table can be zeroed out. With that, you an really feel the drill drilling. Far better imo than the spindle ones with a spring (where sensitivity is lost overcome the force of the spring). Most of you could build one out of the scrap bin from the following photos

[JoeLee]

You dont need a sensitive drill press. A sensitive drill chuck would work also. See link.
https://www.ebay.com/itm/Albrecht-Ke...-127632-2357-0
I know that they are expensive there are others about half the price of the Albright keyless .
You could do it with a hand drill if your steady?? But you still would need a chuck that will hold a tiny drill bit and it needs to spin FAST. Maybe make a collet for a dremel tool? There are many dremel tool collet sets available on Ebay from China for only a few dollars if you can wait.

I thought about getting one of these but those small drills really need to spin a lot faster than my variable speed BP will go. But if you can use those drills in a pin vise like I have in the past I don't really need one and I'm sure they will work at much lower R's. But I'm curious as to how the bearing on the shaft holds out at those high RPM's.
Does it start to get warm after a while ?

JL...............

[Rich Carlstedt]

For lots of holes, you want a Dumore precision Drill Press
Here is some of the work done on my DP
Now this is way over kill for a one off job as the poster stated.
Also in Post 6 of this thread , I mentioned doing it by hand, which is by far the simplest approach for one off.
The discussion of speed (RPM) is over-rated and is really related to the drill bit profile
When I started the project, I got 3-4 drilled holes before the bit broke and I used new drills from 3 different manufacturers and they all failed.
Then I sharpened the drills by hand and got 100 holes per drill.
The problem with high speed is heat !!! The brass heats up and expands and grabs the drill bit.
I went from 17,000 RPM down to 3,000 and it almost eliminated breakage so forget the guidelines, they are just guidelines.
Actual fabrication issues revise those guidelines to produce real results
Also my hand sharpened drills cut far better than factory bits.
rich

[J Tiers]

Probably not worth the effort for a one-off hole but I'll mention it for the benefit of others who might learn from this thread.

Given the mass of most movable spindles, tactile feedback of the drill's location and the drilling resistance can be difficult. One approach to this is a small, light, counter-balanced table to move the workpiece against the fixed drill. My take on this is discussed here...

https://www.homemadetools.net/forum/...0287#post91042

As mentioned, that is exactly how the Levin drill press works. You can see the lever for it in this pic. There is a substantial need to make the table move with no side-play.

[mklotz]

Probably not worth the effort for a one-off hole but I'll mention it for the benefit of others who might learn from this thread.

Given the mass of most movable spindles, tactile feedback of the drill's location and the drilling resistance can be difficult. One approach to this is a small, light, counter-balanced table to move the workpiece against the fixed drill. My take on this is discussed here...

https://www.homemadetools.net/forum/sensitive-drilling-platform-60287#post91042

[J Tiers]

How do you survive in the shop missing that one .0135 drill ?? I can't remember using my set for anything other than circuit boards and I use a pin vise for that.

I think the smallest I ever drilled under power was .041 through 1" of a stainless TORX screw when I made the guide for my tungsten pointer for the .040 TIG electrode.

JL...............

I have no idea how many holes around 0.031" or so that I drilled decades ago for prototype PC boards. Thousands, I am sure, since we did all our own PC boards to save time, and for a while the new product development department was just me. All drilled using a Dremel tool in one of their ancient "drill presses" where the table was raised to drill the hole, the drill and Dremel were solidly clamped (same way the Levin drill press works).

Back then I did not know that it was so hard to do, so it was not hard at all. Drilled them at 15 or 20 per minute. Hardest thing was sharpening the HSS drill because the glass fiber material dulled them fast.

The plastic PC board material drilled easily so it was not a big issue at all. Did not drill any 0.010" holes, though. Those were reserved for the separations between boards in a "pallet", and we didn't palletize the boards for prototypes.

[JoeLee]

Ya beat me to it --- got the same set .0135" is as small as i go --- and that one is missing so something bad must have happened lol but I still got the next runner up --- .0145"

I just used the larger bits in this index box to clean out a moped pilot and main jet for my neighbor....

How do you survive in the shop missing that one .0135 drill ?? I can't remember using my set for anything other than circuit boards and I use a pin vise for that.

I think the smallest I ever drilled under power was .041 through 1" of a stainless TORX screw when I made the guide for my tungsten pointer for the .040 TIG electrode.



JL...............

[Paul Alciatore]

I suggested a hand held pin vise. That was with the assumption on my part that he was using HSS bits, not carbide. I do have some carbide bits in the range we are talking about but most of my experience has been with HSS. Yes, HSS is more forgiving. I looked up the recommended speed for 1/32" bit in brass and it was about 18,000 RPM. I don't think even the Dremels will go that fast. But most of the work I have done with bits under the Treadmill Motors size has been with HSS in a pin vise. The RPM is probably closer to 18 than 18,000 RPM. But guess what, IT WORKS. They drill holes and do not break while running at 1/1000th of the recommended speed. I have even done it without any coolant or cutting fluid. No need for it at those slow speeds. And between just going at it with a pin vise instead of cautiously pecking with a sensitive drill press, I am not sure that it takes any longer to drill the holes.

I did recommend the pin vise to the OP. But I have also used my Unimat set up as a drill press to drill with these small bits. It's maximum speed is 7,500 RPM and again that works just fine. It is what I use with the carbide bits that I have as well as with the HSS bits on the occasions where it is called for.

I did not recommend a hand held Dremel. I would not recommend that to someone who is not experienced with such work and I would hesitate to use a hand held Dremel for such small carbide bits, even the HSS ones. What I did suggest was a Dremel IN A DREMEL DRILL PRESS. That would perhaps be a minimum level, sensitive drill press. It should provide the feel that is needed.

Nor would I recommend his Sears 1/2" drill press. I doubt that he could feel the progress of the bit with that, even if the run-out was not excessive. He says he has a mill, but does not describe it. So it is hard to say if it would be OK but I doubt it. I still think that his best bet is the pin vise unless he needs to do hundreds of his part. And he should avoid carbide bits.

The problem with really small drills is the speed they require to operate properly. I think this should be in the 10000 - 30000 RPM range.
Another problem is the stability of the drill chuck. HSS drills can get away from some wobble but carbide drills snap off really easily.
Hand held dremel might be used for HSS drills but with 0.3 mm carbide drills it is a no-go.
The good thing with carbide drills is that when they snap, is is usually really easy to get the drill remains out of the hole. HSS drill can jam in there pretty permanently.

In that pic there are some of the smalles drills I have. Those were originally used in a printed circuit board drilling machine. The drills get changed in regular intervals and I was lucky enough to have that bucket filled with these drills. Most of them are really sharp, especially the smaller ones.

[A.K. Boomer]

1/32" isn't small....................This is small.............. .0135 all in a little Huot index.






JL................

Ya beat me to it --- got the same set .0135" is as small as i go --- and that one is missing so something bad must have happened lol but I still got the next runner up --- .0145"

I just used the larger bits in this index box to clean out a moped pilot and main jet for my neighbor....

[J Tiers]

1/32" isn't small....................This is small.............. .0135 all in a little Huot index.

JL................

I have basically the same set, but the case is not Huot..

The 0.0135 drills are surprisingly flexible in HSS, they can deflect a surprising amount and not break. . I don't even want to SEE one in carbide..... I bet they break with a good hard look.

[Tim The Grim]

Brass is chewy when it comes to a standard type twist drill. We used to stone the outside tips of the cutting edge to prevent screw-in as the drill od grabs into the material. On an .031 bit that’s not an option without a microscope or good loupe set up.

You say you have a mill but don’t specify type. As long as you have a quill stop on a threaded post you can use the stop nut and your thumb to meter the down feed - step by step/peck by peck. You’re basically spinning the nut down a few thousands at a time and letting your bit just bite in enough to cut but not over bite and break. The brass is soft and grabby but so easily cut with HSS that you will find a good quick rhythm as you spin and peck, spin and peck You’ll be done In no time with little stress. Practice on a piece or two and then go for it.

I used to drill sixteen .008 holes through D-2 every couple weeks building dies to make .005 gold disks. We used a SERVO brand mini drill press turning about 12,000 rpm and spinning down the quill peck by peck.

Best of luck.

[JoeLee]

1/32" isn't small....................This is small.............. .0135 all in a little Huot index.






JL................

[FinnoUgric]

There is absolutely no requirement to meet any sort of cutting surface speed (30K rpm? give it a break! NOT necessary!)

It is not that much for surface speed but to be able to feed it in slow enough. It is really easy to snap the tiny drill by "feeding" it is too fast when the RPM is slow.

Skip using a twist drill all together. find some wire! Welding filler rod may be ideal. Reduce the diameter of the very end to the diameter required (not critical)

The material seems to be aluminium so almost any hard steel may be just fine. The problem is to be able to get the tip down to the needed diameter. Maybe have the thing attached in a hand drill and then rotate it against some grinding stone.

File a flat to produce a half drill, point it with some relief and put in the hole.

I would love to see someone filing a flat on a 0.3 millimetre wire. I think grinding is a better alternative to create this shape.

Soft materials are the worst ones to drill small holes into. Aluminium tends to gall, bronze and brass tend to grip. If the material is soft, it is not always easier to drill.

[CalM]

Really, Thinking about the spade bit solution. A perfectly suitable drill could be produced using a length of piano wire or a bicycle spoke.

The original application has a pilot of sorts. The accuracy of location is not critical. The material to be drilled is soft, and the hole required is not deep.

There is absolutely no requirement to meet any sort of cutting surface speed (30K rpm? give it a break! NOT necessary!)

Skip using a twist drill all together. find some wire! Welding filler rod may be ideal. Reduce the diameter of the very end to the diameter required (not critical)

File a flat to produce a half drill, point it with some relief and put in the hole.

Done done!