Thread: Drilling and tapping a Dorian AXA tool holder

The Dorian catalog says their tool holders are made from "heat treated" steel, but I can't find their hardness given. I would like to tap two 1/4-20 holes in one of their AXA tool holders if it doesn't require superhuman effort. Has anyone done this? Would a cobalt drill and HSS tap work?

I think you might have to go with carbide on this one. I have a couple of import holders that I have drilled with no big problem but I tried to chase the threads on one of my Dorian holders and it pealed the flutes off a HSS tap. Don't hurt to try !
Larry

Funny you mention this, I went to drill and tap an Aloris tool post for a new handle hole yesterday. The original threads were completely shot so I was putting a new hole right beside the existing one. That thing is hard as the hubs of hell! (Kind of made me wonder what kind of monkey it took to wear out the threads) I went to spot drill with a HSS 7/16" and it would barely leave a dimple in that piece, dang it! Thought about using one of the few carbide drills I have but then we have no carbide taps. So I just cleaned up the tool post inside and out and put it back on its lathe.

Originally Posted by Putch

Funny you mention this, I went to drill and tap an Aloris tool post for a new handle hole yesterday... That thing is hard as the hubs of hell!... I went to spot drill with a HSS 7/16" and it would barely leave a dimple in that piece, dang it!

This is very helpful. In light of your experience, I think my tool post is going to remain untapped.

Maybe a phaseII toolholder modified for that one app?

My phaseII are "hard" (about like allen bolt, maybe a little less) but can be filed. Never tried drill & ta but "feels" doable.

smt

I had to drill and tap the underside of my Aloris CA8 threading tool holder for the height adjustment stud so I could use it on a rear mounted toolpost, and it was similar to Stephen Thomas' description of his PhaseII - hard but not too hard to file. I'd at least try before you give up.

As an aside, it struck me as strange that the Aloris holder was setup for mounting the threading tool on the top or bottom side of the holder, but there was no provision for height adjustmnent if you flipped the holder over.

Originally Posted by stephen thomas

My phaseII are "hard" (about like allen bolt, maybe a little less) but can be filed. Never tried drill & ta but "feels" doable.

This is a good suggestion. I can't retitle this thread, but a better one might have been "..an Aloris-like or clone ..."

Originally Posted by stephen thomas

Maybe a phaseII toolholder modified for that one app?

I decided to give this a try, so just added a carbide #7 drill and Cobalt 1/4-20 tap to a larger order I placed. I already have a couple of aftermarket tool posts so I'll try one of them instead of a Dorian. If it works, great, and if it doesn't, I'm out only ~$20 for the cost of the experiment. Plus the embarassment if anyone notices a broken drill or tap sticking out of the holder...

If you can ''just'' drill it, you can loctite in a threaded insert.

Originally Posted by Limy Sami

If you can ''just'' drill it, you can loctite in a threaded insert.

I'm afraid that wouldn't work. I have a Dorian tool holder that has three separate holders for external and internal (L and R) inserts that bolt to it using two 1/4-20 screws. Having to unbolt and rebolt the auxilliary holders sort of conflicts with the principle of "quick change." So, although I don't "need" to do it, I would like to have each of the auxilliarly holders "permanently" attached to its own toolpost. The reason your suggestion of loctite in lieu of tapping wouldn't work is the holders, and hence the 1/4-20 screws, are subjected to the full downward cutting force.

If you made steel bushes say 5/16" in dia tapped 1/4 - 20 at anything over 1.25D in length and fixed them according to spec, with loctite high strength retainer, and the operatoing temperature is not exceeded, bolts will sheer and / or threads strip before they pull out.

Opscimic: If it were me , I would use a torch to "spot" anneal the tool holder before drilling and tapping. You are not going to ruin it.

JH

Originally Posted by Limy Sami

If you made steel bushes say 5/16" in dia tapped 1/4 - 20...

In both cases drilling is necessary, so the issue is whether or not a cobalt tap will be up to the job. If it is, tapping it will be a lot easier and faster than fabricating bushes. I'll know if the loctite doesn't work if it pulls out and ruins a job, whereas I'll know if the tap *doesn't* work if I hear a 'ping' and the wrench becomes easier to turn... If something is to go wrong, I'd prefer it to be the latter.

Originally Posted by James H Clark

Opscimic: If it were me , I would use a torch to "spot" anneal the tool holder before drilling and tapping. You are not going to ruin it.

Any idea how long it would take an oxy/acetylene flame from a, say, #2 tip to work that kind of magic on one end of a tool post?

Don't use an oxy/ace torch to spot anneal,
Use a TIG torch. Much better control.

--Doozer

Now i have only done this once , so it is not a proven process or anything, but it helped:

I had to drill out a 3/8 " pin that got stuck. And i had made that very pin from a 115CrV tool steel. (Cold working steel that goes up into the 60Rcs when drawn to straw color IIRC). Fortunately i had drawn it to a blue, almost black color and a center punch could just dent it.
Was still high tensile and damn hard, but not in the impossible range.
Sounds easy, right ?.

The bad part was that it was located in a rotating assembly that could only be locked with a screw clamp and only haphazardly so....and totally inaccessible to any machine tool....(read bicycle hub).

Took a big electric drill and a 7/16" Bit. No f*cking way. No way, just no way. Edges were gone in seconds , no drilling there.

So i just ground a negative rake on the jobber drill and with some sulfurized cutting oil i got all the way through the damn thing.

As a matter of fact i did look like a zombie with a bloody red face and sweat pouring by the time i got it done, my right arm hurt the next day from all the pressure i had to apply , but hey it worked....

Should work in a good drill press, but tapping may get intresting.....

It can be done, I drilled and tapped 5/16 holes in one of our Dorian holders. The holder is Nitrided per Dorian so once you break through the surface you're good. Used HHS drill and tap...is dificult to tap so use oversize tap drill.

Athack

Originally Posted by athack

The holder is Nitrided per Dorian so once you break through the surface you're good. Used HHS drill and tap...is dificult to tap so use oversize tap drill.

I've already decided to sacrifice an aftermarket holder rather than one of my Dorians, but I have no way of knowing what it is made from nor its heat treatment (or surface treatment), if any. If the carbide #7 drill I have on order can't make a hole, the cobalt tap will stay in its package. Not knowing what I'll be drilling means I'll have to worry about it work hardening, which is yet another concern. I did consider an oversize drill, and maybe I made a mistake in deciding against it, but I'll know in a few days. This is one of those rare times when I hope the term "cheap Chinese junk" applies to the material of the tool holder.

I decided to make some "Victory" tool holders out of regular Dorian and/or Aloris holders. My experience was similar to yours...on the older Dorian and Aloris holders. The Dorian ones with the stamped name and part number are harder than hell. The newer Dorian tool holders with the laser engraved logo and part number are just surface hardened and worked great. Saves me about $50 per tool holder to make a standard one into the coolant-through model.
Eric U

Originally Posted by Eric U

The Dorian ones with the stamped name and part number are harder than hell. The newer Dorian tool holders with the laser engraved logo and part number are just surface hardened and worked great.

My Dorians have the stamped name and part number, so this information seals the deal for me to modify the aftermarket ones instead. Thanks very much.

Originally Posted by opscimc

I've already decided to sacrifice an aftermarket holder rather than one of my Dorians, but I have no way of knowing what it is made from nor its heat treatment (or surface treatment), if any...

To bring this thread to a conclusion, yesterday the supplies I ordered arrived, and today I used a carbide center drill to start the two holes at either end of a Shars-brand AXA tool holder. If there was surface treatment, it wasn't apparent when I started the four holes. I then used a cobalt 13/64" drill (not because it's 2 thou. larger than the proper #7, but because I didn't have a #7 Co drill) to make the four holes ~0.6" deep. Again, if the tool holder was hardened, it wasn't apparent to me when using the Co drill. However, when tapping it with a Co 1/4-20 tap and Moly-Dee fluid the clearance definitely felt tighter than normal. As if the holes had closed up by a few thou. after drilling. But, no taps were broken or wounds opened. I can't comment on whether or not all of this would have been possible with HSS drills and taps, but it was no problem with the ones that I did use.