# Tool holder height screw



## Susquatch (Aug 27, 2022)

I've been trying to figure out what the height adjusting screws are on my tool holders.

They are all BXA of various brands and types.

All come with a screw. I always thought it was an M10-1.0.  So I bought taps and a die for that.

But they don't seem to fit.

The thread on the screws and holders is almost certainly 1.0 pitch within reasonable measurement. But the diameter is whacky. Almost all of them measure 9.83mm. Not 10. A 10mm stud cut with the 10-1.0 die will not thread into the hole.

If I reduce the diameter and cut it with the die, it still won't go into the hole.

However, if I cut the diameter to 9.8 and then single point thread deeper than spec, they work fine.

Similarly, a hole drilled and tapped to spec is loose as a goose on a factory stud.

Given the number of holders I have and the time between buying my first and my last, I doubt very much that my own experience is unique. I bet most users with BXA toolposts have a similar issue.

Does anyone have any insights on this matter?


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## Dabbler (Aug 27, 2022)

My AXA holders, all from offshore manufacturers, have both metric and imperial fasteners.  Check for 3/8 NF, it might work.  Also most of my AXA holders have very sloppy threads for their thread pitch.  

My BXA holders are a mixed bag, fro at least 5 sources, and they vary from metric to imperial also.  I do not know the history for about 1.3 of my BXA holders.

Just a little of my experience here.

I'm actually transitioning to Dixon these days.


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## PeterT (Aug 27, 2022)

If its truly metric & they were looking for finer adjustment it might be M10x0.75. If its a sub-par manufactured IMP thread, then it makes things harder to guess.
Typically the major diameter is slightly under the nominal diameter based on thread class yada-yada, so OD in itself does not necessarily define the size.





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						Metric screw thread: M Profile calculator
					






					theoreticalmachinist.com


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## VicHobbyGuy (Aug 27, 2022)

Isn't the minimum major diameter for a M10x1.0 around 9.8mm (9.79)? I just measured the post on my Precision Matthews AXA holder and it's under that. But, the new adjuster 'wheels' I made and threaded with a M10x1.0 tap seem to work fine. 
I agree it's a 'pain' when threads aren't 'on spec', and I need to go looking for an adjustable die or some other workaround.


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## Susquatch (Aug 27, 2022)

I don't know for sure about the diameter, but I'm virtually certain that the thread pitch is 1mm.


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## Susquatch (Aug 27, 2022)

VicHobbyGuy said:


> Isn't the minimum major diameter for a M10x1.0 around 9.8mm (9.79)? I just measured the post on my Precision Matthews AXA holder and it's under that. But, the new adjuster 'wheels' I made and threaded with a M10x1.0 tap seem to work fine.
> I agree it's a 'pain' when threads aren't 'on spec', and I need to go looking for an adjustable die or some other workaround.



This might indeed be the issue. Minimum spec posts and holes. 

The trouble with minimum spec or tight fits is that not all fasteners will fit with each other. The tolerances don't always work.

It just seems odd to me that all of my holders are the same. My original BXA holders are 10 years old. Some are just a week old. I've bought them a few at a time since I got the lathe. Nonetheless, they all measure identically and are all totally interchangeable.


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## PeterT (Aug 27, 2022)

M10x1.0 is very common. Do you have a commercial nut to just screw on the adjuster stud & test? My earlier tooling blocks had brutal clamping screws. Same issue, I couldn't figure out if they were poorly made IMP or actually metric. Neither commercial fastener fit very well. Eventually I think I called KBC or found a spec, they were indeed IMP (at that time) probably to act replacement to the name brand blocks. I chased the threads with a tap. There was  lots of grunge, rough threading & maybe a bit of distortion from HT? The material is decently hard so beware with a tap. I then swapped in better quality set screws. I think the included screws were 80% of the problem. Another issue is they were dog point style but the bottoms were lopped off at angles, but that's a separate issue.

Then at some point the blocks became metric from most offshore suppliers & the fastener quality seemed to be improved, more acceptable as-is. So who knows what you have. Maybe Accusize can answer.


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## PeterT (Aug 27, 2022)

I couldn't find a spec in Aloris catalog but this link suggests AXA height adjuster screws are 3/8-24. 
3/8 is 0.375" nominal. 24 TPI is 0.042" pitch ~ 1.06mm. Hmm kinda close but who knows what you have. As mentioned, early on the offshore units were intending to be low cost replacements to N-Am blocks but eventually went to metric (or just did their own thing).









						Aloris AXA: requesting thread size and pitch
					

I'm making some AXA sized tool holders to fit an Armstrong QCTP. Would someone please identify the size and thread pitch for the set screws, height adjustment threaded rod, and the height and diameter of the thumb-wheel I'd sure appreciate it!   I've no complaints about metric, but I'm hoping...




					www.hobby-machinist.com
				






			https://www.aloris.com/aloris_cat/31e970.pdf


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## trlvn (Aug 27, 2022)

PeterT said:


> I couldn't find a spec in Aloris catalog but this link suggests AXA height adjuster screws are 3/8-24.
> 3/8 is 0.375" nominal. 24 TPI is 0.042" pitch ~ 1.06mm. Hmm kinda close


I was curious so I compared my 1.0mm thread pitch gauge to a decent quality 3/8-24 bolt.  Over, say, 5 threads the gauge appears to fit but if you have 10+ threads, it is obviously different.  The OD of the 3/8 bolts was 0.373".

Craig


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## Susquatch (Aug 27, 2022)

PeterT said:


> this link suggests AXA height adjuster screws are 3/8-24.
> 3/8 is 0.375" nominal. 24 TPI is 0.042" pitch ~ 1.06mm. Hmm kinda close





trlvn said:


> I was curious so I compared my 1.0mm thread pitch gauge to a decent quality 3/8-24 bolt. Over, say, 5 threads the gauge appears to fit but if you have 10+ threads, it is obviously different. The OD of the 3/8 bolts was 0.373".



I had that suspicion right away. It's not a good fit at all. 

A 3/8-24 Nut goes onto the stud about 4 turns and then jams. A 3/8-24 bolt also goes in about 4 turns and jams too. 

But reading all your comments makes me wonder. They just might be 3/8" - 1.0mm pitch.... LOL! 

Again though, ALL MY HOLDERS OLD AND NEW ARE THE SAME!! They are also not all the same brand. 

Makes me wonder if this isn't maybe one of those deals where the holder makers don't want people making their own stuff. Sort of like Hornady OAL gauges.


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## Janger (Nov 13, 2022)

The above post from Davia Aero is a spammer. Their email address is in bulgarian and literally translates as "they snorted bearings" - nuking him.


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## jcdammeyer (Nov 13, 2022)

I checked my AXA holders of various brands bought at various times.  The thread gauge says 1.0mm  My Chart of taps and threads says I.S.O. Metric Fine comes as 10mm x 1.0mm.  And my generic metric tap and die set does not contain this size.


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## Dabbler (Nov 13, 2022)

All of my offshore  BXA holders come from 3 different brands and 3 different times.  They all have the same set screws and studs for height adjustment, so I just bought a bag of quality socket head cap screws and  replaced the worst of the Swiss cheese.

The only different ones are the genuine Aloris, which use grd 10.5 set screws and a grd 8 height adjust stud (based on hardness to a file)  all in imperial, of course.


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## BrandonDyer (Nov 22, 2022)

A quick-change tool holder usually includes two components: a tool support element and a cutting head. The tool support element is mounted on the machine, and the cutting head is clamped to the tool support element. Such a construction can be secured with Scrooz screws. Many different types of cutting heads can usually be plugged into the tool support. They can be replaced with each other relatively quickly. Therefore, a quick-change tool greatly reduces set-up time when switching from one machining operation to another. The tool holder height screw can be purchased at the store.


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