Poor quality ACME Die

[Graham WhartonParticipant @grahamwharton]

Hello,

Just looking for some opinions. Received this brand new ACME 1/2 x 10TPI HSS die from one of the mainstream ME suppliers today. Any thoughts on the quality, and its ability to form a decent looking ACME thread.

The intention was to thread 90% of the depth using a form tool on the lathe and clean up with the tap. The test piece I have just run with it came out less than ideal IMHO.

Thanks for the advice. I'm pretty sure this will be returned to the supplier tomorrow.

Graham

[Graham WhartonParticipant @grahamwharton]

[Michael GilliganParticipant @michaelgilligan61133]

Graham,

Dare I mention the Acme Mangle

Or even the Acme Corporation [second paragraph may be relevant]

MichaelG.

.

Seriously though … Send it back !!

Edited By Michael Gilligan on 13/01/2015 21:31:07

[Neil WyattModerator @neilwyatt]

What about the ACME Thunderer!

Neil

H&S warning, don't swallow the pea!

[RobboParticipant @robbo]

Posted by Neil Wyatt on 13/01/2015 21:42:47:

What about the ACME Thunderer

Still have mine, though gave up refereeing 40 years ago!

Phil How do you stop that bloody line coming down?

[nigel jones 5Participant @nigeljones5]

I recall from my youth that Wylee Kyotee had similar issues with reliability.

[Jesse Hancock 1Participant @jessehancock1]

^Fizzy: Tee Hee Me too.

I had a similar problem once when trying to to thread a hole. Ended up with a spiral tap or is that a spinal tap. But yes I suppose you had a Friday die…. one which has escaped the checking processes or deamed ok but a reset due on the machine making the parts. The proverbial one that gat away. If youre not happywith it's performance take it back if you can. Or scrap it. Stings I know but better to throw it out than ruin hours of work.

[Graham WhartonParticipant @grahamwharton]

Actually, here's the picture from the vendors website. I'm not overly convinced the one they photographed was much better than mine. I'm certainly not picking out any flat crests on the cutting teeth there.

Thanks

Graham

[Harry WilkesParticipant @harrywilkes58467]

Posted by fizzy on 13/01/2015 23:54:38:

I recall from my youth that Wylee Kyotee had similar issues with reliability.

Poor Wylee just imagine the life he'd have now what with his poor quality ACME products he'd have the H&S crew knocking on his door as well.

[MuzzerParticipant @muzzer]

Never used an ACME die to cut threads but is it possible that it's supposed to look like this ie different teeth cut different parts of the thread? The ACME thread form has deep valleys and sharp corners, so a different approach may have been taken. Have you tried using it? Could you be thinking too much?

Murray

Sorry – I see you DID try it. May be crap finish but still supposed to (otherwise) look like this.

Edited By Muzzer on 14/01/2015 09:24:13

[Nigel McBurney 1Participant @nigelmcburney1]

Send it back,it looks rubbish to me, bought a tin box of drills a couple of years ago,25% were either ground off centre or wrong point angle, a Whit tap bought in a set shattered as soon as I used it,and further back I bought a bsp tap which jammed solid in the hole as there was negative clearance on the cutting edges. The suppliers take them back with no hassle and replace,they know that there are faults in their products from far away lands and unfortunately use the customer as their quality control.If I was cutting an acme thread for a feedscrew I would screwcut to finish size,its just a case of getting the form on the lathe tool correct or if you cannot get it right then finish off with a thread chaser held in the tool post same as the single point tool,if its a long slender feedscrew then support it with a travelling steady to keep the depth of cut constant,

[Graham WhartonParticipant @grahamwharton]

Posted by Muzzer on 14/01/2015 09:21:46:

Never used an ACME die to cut threads but is it possible that it's supposed to look like this ie different teeth cut different parts of the thread? The ACME thread form has deep valleys and sharp corners, so a different approach may have been taken. Have you tried using it? Could you be thinking too much?

Murray

Sorry – I see you DID try it. May be crap finish but still supposed to (otherwise) look like this.

Edited By Muzzer on 14/01/2015 09:24:13

Murray,

I did try it yes. I had run the piece on the lathe to 90% of the depth with a single point tool first. Then ran the die down it. Prior to running the die, the trough in the thread had a reasonably flat bottom. The first pass left a groove along one side of the trough. I reversed the die and ran it again, this time it put a groove in the other side of the trough. So i'm left with a W shaped trough.

When I first looked, i had thought like you, perhaps to keep the stresses down, each tooth cuts its own slightly different V, all at slightly different positions in the trough so the end result is a "reasonably" flat bottom. But I don't think this is the case.

Thanks

Graham

[Graham WhartonParticipant @grahamwharton]

Posted by Nigel McBurney 1 on 14/01/2015 10:50:03:

Send it back,it looks rubbish to me, bought a tin box of drills a couple of years ago,25% were either ground off centre or wrong point angle, a Whit tap bought in a set shattered as soon as I used it,and further back I bought a bsp tap which jammed solid in the hole as there was negative clearance on the cutting edges. The suppliers take them back with no hassle and replace,they know that there are faults in their products from far away lands and unfortunately use the customer as their quality control.If I was cutting an acme thread for a feedscrew I would screwcut to finish size,its just a case of getting the form on the lathe tool correct or if you cannot get it right then finish off with a thread chaser held in the tool post same as the single point tool,if its a long slender feedscrew then support it with a travelling steady to keep the depth of cut constant,

Nigel,

I'm starting to think I will just finish the thread completely in the lathe too. I'm using a good full form insert from Sandvik. Its a Corothread 266 insert in the right toolholder with the right shim, so should give me extremely good results. The only problem is I have to run it quite slowly and I don't get the best of finishes going slow. I was hoping that the die would just take the burs away and give me that pristine finish. I might look at ways of mounting the piece with extra headroom at the end of the thread so I can thread at a higher speed without worrying about crashing as soon as the insert leaves the thread at the end. I guess I could also use my variable speed to keep it fast for the majority of the threading operation and just slow it down at the end so I can control when it stops easier. I'll try another test piece going to full depth. Ive threaded full form to full depth on the lathe for metric threads without a problem, for some reason, maybe increased surface area of the acme thread, the cuts were not as clean as usual which pointed me towards using a die to cleanup.

Graham

[blowlampParticipant @blowlamp]

If that's the same vendor I purchased a die from recently then poor quality products from them is starting to look like a trend.

I bought an M10 fine die from them and used it in a good tailstock holder to size & finish a couple of lathe-cut threads on parts which had a significant amount of work invested in them. Unfortunately for me I didn't check the first one before doing the second and this resulted in two scrapped components.

When I tried a nut on these parts they were found to be a very sloppy fit, so I screwed the die onto each one in turn and could not believe what I saw. Basically, the thread through the die was out of perpendicular to the front and rear faces by about ten degrees, which is so far out that it made me wonder about their basic manufacturing techniques.

Martin.

[Neil WyattModerator @neilwyatt]

I tried sharpening the picture and the die pictures in it HAS got flat tips to the teeth, but much more pronounced at the cutting edge. It may not win prizes but should make a better thread than the one you have.

I would be surprised if the supplier doesn't exchange or refund, but give them a chance to put things right, they haven't got the time to inspect every item before it goes out, and a duff item is a pain for them as well as you.

Neil

[Graham WhartonParticipant @grahamwharton]

Supplier promptly sent me a replacement die.

Which produced a much better result on my test piece.

Result !

Graham

[Michael GilliganParticipant @michaelgilligan61133]

Graham,

That looks much healthier !!

MichaelG.

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Robbo on 13/01/2015 22:46:27:

Posted by Neil Wyatt on 13/01/2015 21:42:47:

What about the ACME Thunderer

Still have mine, though gave up refereeing 40 years ago!

Phil How do you stop that bloody line coming down?

Hi Robbo, before you start typing your reply, move the cursor out of the quote text by using page down (pg dn) or the down arrow key so that the cursor appears below and to the left of all the lines.

Regards Nick.

[Neil WyattModerator @neilwyatt]

Hi Graham,

Thanks for giving them a chance to get it right rather than jumping into naming and shaming.

I think the first die may have been through the cutting process twice.

Neil

[Graham WhartonParticipant @grahamwharton]

Hi Neil,

Yeahh, there was never any intention of bad mouthing them at all. All suppliers can have quality issues, even the more reputable ones. As usual with this supplier, they dealt with the issue promptly and completely to my satisfaction, so all credit to them.

Also, it shouldn't take long to work out who the supplier is as there only seems to be one supplier of ACME dies in the entire world, as i found out!

Graham

[Anonymous]

Posted by Graham Wharton on 15/01/2015 19:10:35:

Also, it shouldn't take long to work out who the supplier is as there only seems to be one supplier of ACME dies in the entire world, as i found out!

There'll be a reason for that; industry almost never uses them.

Andrew

[Nigel McBurney 1Participant @nigelmcburney1]

Graham When I suggested using a chaser,it was because a HSS chaser with a little top rake ground on it will cut at, low speeds and achieve a good finish.During my apprenticeship as an instrument maker a lot of the threads were cut using chasing attachments on plain lathes.not just one or two ,but a hundred or so at a time,And since then I have aquired a collection of chasers and nowadays tend to thread with a chaser rather than a single point tool as you get a full form with the chaser and besides cutting non ferrous I now cut steel from mild free cutting up to en8. go slow with plenty of lubricant,the tricky bit which some people will not attempt is cutting up to a shoulder as the tool has to be withdrawn and the half nuts disengaged at the same time, If you must finish up with a relief for the chasing tool ,then reduce the width of the chaser down to two full teeth by grinding. The results are good but it does take practice.I also have Kennametal threading tools int and ext with a lot of inserts all brand new ,good buy off a friend for £15 though they do not get a lot of use .the internal tools will go down relatively small bores where as internal chasers are more suitable for larger bores,unless you can find some small circular internal chasers.Tip fro Gand M tools when buying used chasers from a dealer,sale etc make sure they are right hand cutting as occasionally left hand cutting chasers are found in job lots

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