Dorian BXA tool holder, what miracle metal?!?

jermfab · Dec 10, 2019

I generally keep my most common tools in holders, preset and ready to use on the lathe headstock. I also keep a couple other tool holders open for use in a drawer. Whenever possible I use 3/4” shank tools, but today I tried to mount a 1/2” shank tool in a Dorian D30-BXA-1 holder. Set screws jammed tight before hitting the tool. No problem, I’ll just chase them with a tap and get them to snug against the tool shank, right? Wrong... not sure what sort of unobtanium metal or heat treat Dorian uses on their holders, but I burned up a tap per hole. Broke the first tap clean, I’ll take the blame on that. But destroyed three more taps, ostensibly chasing an already tapped hole!! The tool holder literally pulled the cutting surfaces off of two taps and you can see the wear starting on the third. I can now get my set screws to seat and hold a tool, but it took some doing. I’ve never encountered this before in something that shouldn’t be much more than rather hard steel...

Hopefully I won’t encounter this again, but wondering what the PM community’s thoughts are.

Jeremy

dalmatiangirl61 · Dec 10, 2019

What size tap/bolts? I was trying to get some 3/8-16 bolts into a hole last night, even started trying to tap them, but it did not feel right so stopped and did some checking. Turns out 3/8-16 is just a wee bit smaller than an M10-1.5 (=16.something tpi). I'm going to say tool block is too hard to tap, and you are using a standard tap in a metric hole, or vice versa.

Milland · Dec 10, 2019

Probably just a case-hardened low alloy steel, nothing fancy but the HT. Would also explain the poor threads, distorted from the HT and maybe buildup of casing. Dovetail would be finish ground after treatment so not an issue.

Oh, and crappy taps. Dude, don't buy cheap taps, they suck major billabong.

john.k · Dec 10, 2019

Could be right about the taps ,too......I bought a set (3) to tap some holes in a Wisconsin flywheel,asked for good quality from a engr supply house,the cast iron simply crumbled the leading edges on all three taps,had to sharpen them for each hole so they wouldnt jam...Is everything rubbish today?.....and then another gripe about taps.....is it so expensive to mark them properly....a faint smudge of etch doesnt last one use,and every tap has to be measured before use.

9100 · Dec 11, 2019

There is a fundamental flaw here. I don't have a Dorian toolpost but I have an Aloris one. The screws in question on mine are headless set screws that will screw all the way through the holder. If something stops them on the Dorian post, the problem is with the set screws, not the holder.

Bill

BSCustoms · Dec 11, 2019

Dorian should have metric screws in it...

jermfab · Dec 11, 2019

I don’t have the tool holder at hand right now, but I’m almost certain these holders don’t use metric screws. 10x1.5mm is LARGER than 3/8-16, so the 3/8-16 tap should fall in if the case was mistaking metric threads for SAE. Additionally a 3/16” Allen key went snugly into the set screw head. 3/16” falls pretty squarely between 4 and 5mm. No chance of forcing a 5mm and 4mm would be sloppy enough to strip the screw. This was an eBay purchase, so there’s a chance the previous owner made the same mistake and forced 3/8-16 set screws into the holder, but it still strikes me that the screws would be loose and cross threaded, not too tight to bottom, which was my original problem.
As far as taps go, the first tap that broke was a fresh Widia, the second was a used Champion. After that I had to dig. Most of the taps I stock are spiral flute machine style taps, Widia. Since I believed I was just chasing threads I wanted to stick with a plug style tap, instead of the spiral taps. In any case, I can’t remember the last time I personally purchased a tap, work does that for me. Generally it’s stuff from McMaster-Carr, though we’ll buy from Fastenal at times as well.

Jeremy

mTeryk · Dec 11, 2019

Dorian's are US made. Can't see why they would be metric.

Website states they are ion nitrided. That could mean up to low 70's RC .02" deep depending on base material and process. I could see how that could be hard to tap.

Sent from my XT1710-02 using Tapatalk

4GSR · Dec 11, 2019

I was told they are 4140HT and like you said ion nitrided for surface hardening. I can get carbide drills to penetrate the surface, no tapping holes. As far as I recall, most everything is standard UNF-UNF threads. Their plant is just up the road from me.
Once a surface is ion nitrided, it's very difficult the attempt to anneal it. Oh, some of the holders/tooling may be QPQ, too, just as bad!

dalmatiangirl61 · Dec 11, 2019

I have not tried an M10-1.5 bolt or tap yet to verify that was my problem. I had no existing bolts to know for sure what the size/thread pattern is. 3/8-16 bolt would screw into 1 of the holes just fine, other 10 holes bolt goes 4 threads deep and binds. 3/8-16 tap would go in 4 threads, then bind. Dug thru tap selection and found a custom chasing tap (regular tap cut down to just upper 3 threads), that tap screwed in just fine, removed lots of crud from threads, thought that fixed it, went to insert bolt, again 4 threads and binds. Waiting on some metric bolts to see if that is the problem.

4GSR · Dec 11, 2019

There's a very good chance, someone didn't do their job at Dorian inspecting the threads on a run of them, maybe even several runs on these and reprogram how deep the tap goes in before retracting. I doubt a metric bolt will go in any more that 1-1/2 to 2 threads in IMO. Dorian just flat messed up not catching this in production. "We make no scrap!!!"

john.k · Dec 11, 2019

If all else fails,lap the threads with a selection of brass screws and fine 400 grit paste.

mTeryk · Dec 12, 2019

4GSR said:
I doubt a metric bolt will go in any more that 1-1/2 to 2 threads in IMO. Dorian just flat messed up not catching this in production. "We make no scrap!!!"

You'd be surprised.

I worked at a school shop which had both inch and metric QCTP's. Every term I would go through and make sure each toolholder had the correct set screws. No matter how much I lectured on the topic, students would use a 3/16 hex wrench on a 5mm bolt head and strip it out. They would then go and grab a 3/8-16 set screw and screw it into the metric tool holder.

I'm pretty sure with a soft enough set screw and the right kind of student you can get an M10 to thread all the way through a 3/8-16 hole as well.

I'm not saying that happened here. I'd bet on a manufacturing defect from Dorian.

Sent from my XT1710-02 using Tapatalk

4GSR · Dec 12, 2019

Not speaking for Dorian, but unless they have changed the design and put metric threads in place of inch threads in the last year or two, they are inch threads. One way to determine that, look at the thread on the adjusting stud, if it's inch, the set screw holes will be too. I've seen over the years where people have re-engineered threaded holes to fit what was on hand, too. It can be a mess, especially with M8 set screws in a AXA size tool holder and some of the BXA no-name holders out there too.

Ron Hofer · Dec 12, 2019

Jeremy,

You been buying pewter taps again?

Ron

Cole2534 · Dec 12, 2019

Milland said:
Probably just a case-hardened low alloy steel, nothing fancy but the HT. Would also explain the poor threads, distorted from the HT and maybe buildup of casing. Dovetail would be finish ground after treatment so not an issue.

Oh, and crappy taps. Dude, don't buy cheap taps, they suck major billabong.

Cheap taps have gotta be the largest false economy in a shop.

Sent from my SM-G973U using Tapatalk

crossthread · Dec 13, 2019

I think cheap hacksaw blades have got the cheap taps beat in the false economy department.

Milland · Dec 13, 2019

crossthread said:
I think cheap hacksaw blades have got the cheap taps beat in the false economy department.

I'd still go with taps. Hacksaw blades don't remain in the cut if they break, and dulling makes them easier to remove.

Going back to my previous comment, even if the taps are from a quality vendor, the style sucks due to the (relatively) poor cutting edge and weak flute design. Give me gun, even spiral flute taps over hand taps any day.

ken moss · Dec 14, 2019

I have a fair number of Dorian A & B size tool holders some I bought new 20+ years ago and they are all Metric don't amuse anything measure. Ken

number 2 · Dec 15, 2019

As already mentioned, the problem is likely the screw. If it’s old the part of the thread that gets used is probably stretched differently to the upper part and has pitch error. Or it might be simply rusty/ dirty. If I were you I’d just get a 1/4 packer and put it on the top or bottom of the tool and carry on.

Dorian BXA tool holder, what miracle metal?!?

Cast Iron

Diamond

Diamond

Diamond

Diamond

Cast Iron

Cast Iron

Hot Rolled

Diamond

Diamond

Diamond

Diamond

Hot Rolled

Diamond

Hot Rolled

Diamond

Titanium

Diamond

Stainless

Hot Rolled

Similar threads