accuracy drilling small holes

[PStechPaul]

You might also try small carbide end mills like these:





They all have a standard 1/8" shank so you can use a collet, which will usually have much better runout than a chuck. I haven't used these yet, but they look pretty good, and the entire set was (IIRC) well under $10 from Banggood. Like these from AliExpress:

https://www.aliexpress.com/item/10Pc...AbTest=ae803_4

Or get a set of 10 pieces 0.8 mm (0.031") PCB bits for under $2:
https://www.aliexpress.com/item/10Pc...AbTest=ae803_4



A 90 degree chamfering end mill might be useful as a spotting drill or in place of a center punch:

https://www.aliexpress.com/item/1pc-...AbTest=ae803_4

[J Tiers]

They made things to do this co-ordinate based drilling...... Jig borers. Drill the hole, then bore it out to size, all on location to a tenth or maybe less.

If you DID use bushings, you could do the job with a drill press, outfitted with a bushing holder, and an x-y table. X-Y table to be as accurate as your needs require, possibly with a DRO or the like.

Of course your mill could do that too, and already has an X-Y table attached to it, all you need is the drill bushings and holder. I betcha you could make the holder, and choose a suitable size drill to use as the pilot for your holes. Then you could drill pilots for all holes, and maybe that is good enough.

If not, make more bushings for the sizes you need, and drill all the holes with them.

[BCRider]

I suspect it would be fair to warn about chuck runout if using the carbide PCB drills. As mentioned even .003, which may or may not be visible, will be a large part of the hole size and likely enough to snap a really small solid carbide drill. So we're talking about swapping from our usual drill chuck over to a really good small size chuck or a good collet setup.

And I also suspect that making up a sensitive drive chuck and arbor to fit the drill press would not be a bad option too. My DP is pretty good even down to working with 1/16 and 3/64 size drills. It's well enough broken in that I can "feel" those drills back through the quill and arms. But a couple of holes I've done which were smaller were in brass and pretty much a case of trust.

I think I'd prefer the solid carbide drills for this. But there again it would cost a small fortune to amass a complete small number collection. Not so bad to buy a few sizes but we're talking about special ordering rather than using what is on hand.

Depending on the material and setup I really like that suggestion for a small hardened point punch in the drill press used to mark a center. And along that line the idea of perhaps grinding away half to form what is essentially a sharp pointed engraver cutter?

[Tundra Twin Track]

This 1/16" hole drilled in 1/8" ER 308 SS Tig rod dead center,rotated 180 deg after drilling bit slid right thru.Sir John swore by these Reglus Drill Jigs,I have to agree with him.

[BCRider]

Your drill jig reminds me of a similar product that was showcased in a YT video. Sure enough I found it. Mr Pete222 showcasing the Heinrich Cross Hole Drill Jig.

Not to try to compare mind you. But it IS an interesting idea. Could be a good home shop project. Proper hardened bushings aren't cheap though. And we'd need the same tools in a couple of sizes to let us cross drill from your 1/8" example up to something like 1/2 to 3/4".

[Tundra Twin Track]

Your drill jig reminds me of a similar product that was showcased in a YT video. Sure enough I found it. Mr Pete222 showcasing the Heinrich Cross Hole Drill Jig.

Not to try to compare mind you. But it IS an interesting idea. Could be a good home shop project. Proper hardened bushings aren't cheap though. And we'd need the same tools in a couple of sizes to let us cross drill from your 1/8" example up to something like 1/2 to 3/4".

Yes the Heinrich Jig is pretty cool and is real cheap to purchase new compared to Reglus.I contacted Reglus in Switzerland to get a price on a Lettered&Numbers set.I just about $hit myself $65.00 for EACH DRILL BUSHING and nearly $4000.00 for Drill Jig with all the Bells&Whistles.

This thing will do more than I will ever need(Thanks to past member JC Hannum for parting with it) but is very versatile.It will take round stock up to 1-3/4" dia. And can hold flat material as well.I think the Small Engine Builders could use it to it's potential.

[fixerdave]

I've read about but never needed to try this:

If you want to cross-drill a rod, take an extra short chunk of it and drill the hole size desired in a lathe down through the center, being as accurate as you feel necessary. Then, clamp that section vertically in a vice over where you want the hole drilled in your rod... can't help but at least start in the right position, side to side anyway.

Quick and easy for the one-offs that need to be right.

Oh, being a jig, the drill should be long enough to flex so that it can follow rather than try to lead.

That's the theory anyway.

David...

[old mart]

One of the most difficult small hole drilling is for wire locking holes in bolt heads when they go through the corners. My old firm always used to jig drill them in custom bushed blocks on the manual drills despite having lots of NC mills.

[Tundra Twin Track]

One of the most difficult small hole drilling is for wire locking holes in bolt heads when they go through the corners. My old firm always used to jig drill them in custom bushed blocks on the manual drills despite having lots of NC mills.

Are you meaning like the bolt in pic on post#36 ?

[MattiJ]

One of the most difficult small hole drilling is for wire locking holes in bolt heads when they go through the corners. My old firm always used to jig drill them in custom bushed blocks on the manual drills despite having lots of NC mills.

Hard on the drill bit even with guide bushing, end mill works better.