How does one cut the metric thread pitch with a lathe that has a SAE quick change gear box? Is there any way to cheat, or must you purchase a die?

Thanks,
Axel

[ 01-31-2003, 21:17: Message edited by: Axel ]

Whatcha doing, Axel?

Arisaka?

No CZ. Also, just generally curious.

Axel

You have to interpose a 127 tooth gear in your gear train.

After changing the gear I DO NOT disengage the half nut after I have started cutting the thread.
I just pull out & reverse the machine (and the feed) back to the starting point at the end of each pass. I also feed straight in & don't use the compound but thats just me. Like my old machine shop instructor used to tell us (keep all your marbles in one sack) meaning you better be focused on what you're doing or you'll screw up big time.

An interesting note, I just made a MG34 barrel in 308 from a blank copying the original (8mm of course) & the barrel thread is the same as the Jap Arisaka, Colt JP Saur, Weatherby Vanguard, Howa/S&W 1500. 1.5 mm pitch or in english about 16.92 tpi.

[ 01-31-2003, 22:22: Message edited by: Bear Claw ]

t_bob38,

How did you come up with a 127 tooth gear?

Axel

Hi Axel

In 1" there are 25.4 mm.

The least count that throws out a whole number is 5" which is 127 mm. So if you have a 127 tooth wheel in the gear train you end up with a perfect correlation from Imperial to Metric.

cheers edi

My lathe will cut 12.5 tpi. Do you guys think that will be close enough to 2mm? The difference in pitch is only 0.0012". I am buying a PacNor prefitted barrel so I should only need to thread if I screw-up badly.

Thanks,
Axel

Problem solved. I am going to use a M70 Winchester instead of a CZ550.

Axel

Would that be a Winchester that has been made to look like a CZ, with custom scope mounts and bolt shroud?

Kristofer

Pecos 45 was quicker to catch on than the rest of us. I can't believe I thought Axel was, for once, not full of crap!
Anyone with extensive lathe experience (as the axel claimed)would not have to ask how to cut metric threads. If he is truly an engineer it only goes to show what a sad state todays engineering profession is in.
After reading this thread I have to say that Axel should not handle power tools or anything sharper than a Twinkie. To do so will only risk harm to him/her self and others. Regards, Bill.

Bill L., et al.

Do you have any idea how many engineers have NEVER seen a lathe.
Class and office are the extent of some folks life experiences.

LouisB

If you ask a manufacturing engineer this question today, the answer is simple.

Every modern lathe is equipped with an inch metric switch. So to convert the machine to metric you just flip the switch.

Now if your lathe is originally built by the Japanease as many are, you need to flip the switch to operate and program the machine in decimal inch. While the machine is operating in metric, all the read outs and programs are in inch.

While I am a manufacturing/Industrial engineer and not a programmer, I believe there are M and G codes which can change this functionality on the fly.

If you are still operating a manual lathe, like many gunsmiths are, this requires a second machine with a metric thread screw and hand wheels.

Simple isn't it!

[ 02-01-2003, 22:49: Message edited by: DMCI* ]

Bill,

I have experience with CNC lathes. Believe me they do not require gear changes to cut metric threads! The do not have gear heads powering their lead screws, they have servo step motors powering ball screws. These ball screws are often equipped with glass scales for positioning, this is couple with the encoder in the step motor.

If I had $150,000 laying around I would simply buy a cheap CNC lathe and be in business. I do not so I am asking a few questions, forgive my for being ignorant.

I truly would appreciate your input with regard to which action wrenches and barrels vises are the best!

Axel

Hi Axel
$150,000 for a lathe, I know good ones are expensive, but $10,000 would buy a good quality colchester, which would have metric screw cutting!

Unless your going in for large batches why a cnc?

Jeffeosso, what does RTFM mean? If it means "rent the f&^^ing machine" I am afraid I do not know of anyone that rents CNC lathes! Most of these machines are not even leased, because they are quite frankly disposable. Meaning they cannot be rebuilt.

Axel

Bill - The only "engineering" Axel does is on this website. He "engineers" bullshit almost daily

I wouldn't have bothered posting again on this thread except that there is a little more BS coming out from (who else) Axel.
The last CNC lathe (Cincinatti) the hydraulic shop I was working at bought was about 55,000CDN. Still outrageous for any kind of one off type work although you could do some pretty neat stuff with it. My bolt handles were made with this machine.
They can be rebuilt and it's a damn good thing since they seem to need it at least once a year. Both the lathes and milling machines lose bearings just like a manual machine can and probably more often. Programming errors can put some real abuse on these machines. Regards, Bill.

Normally, every lathe has the possibility to cut metric and inch tread.If not, you have to check the lead spindle:is it metric or inch?Usually inch,in that case ad the 127 gear and calculate the pitch.In case you are not capable to do that, it is hopeless.
Hugh.

Hello All - what gives? A man asks a reasonable question, admits that he doesn't know and needs a bit of assistance - he gets two/three replies that address that question and a whole host of irrelevancies.

CNC machines are wonderful things - I wish that we could have one in everybody's workshop - starting with mine. I would even settle just for a DRO.

However until they are given away in popcorn boxes some if us will be stuck with Imperial only lathes/Metric only lathes and those which can do both.

I know a fair number of turners who haven't a clue as to how to set up a gear train to give the feed that is needed on the leadscrew. It seems to have become a lost art - one of those fields of knowledge that have been left behind in the steady march of improvements - like gearboxes and now CNC stepper motors.

t_bob38 mentioned the 127 tooth gear and I made an over-quick comment on why the 127 was the magic number. Both of us assumed that we had given enough information for Axel to carry on and sort out his problem - our mistake. Sorry.

So - if Axel will open up the side of his lathe and table the full details of his gear train and the tpi of the lead screw I'll give a tutorial on what is needed to cut metric threads.

Never try a "close" match - 0.0015" difference doesn't sound like much - but an interference of "10 thou" in a receiver is a no-no. It will only lead to damaged thread profiles and high levels of stress in an already pretty highly stressed component.

OK let me haul out that asbestos fire suit .... cheers edi

Mr Leeper,

I do not know what I did to you, but the Cinnci you bought was a cheapy entry level model and they are crap, like all the other entry machines. The last Cinnci CNCs I purchased were 6 axis lathes and ran $250,000 without tooling. You obviously do not understand a machine rebuild either. The ability to change out spent bearings and drive motors does not constitute a rebuildable machine. A rebuildable machine must have removeable and replaceable ways, and cross slides. The beds must have been designed up front to be rigid and essentially impervious to damage from, as you stated, crashes among other things.

An old Detroit tracer lathe is rebuildable, and I have ordered rebuilds on many of them. As a matter of fact, I helped engineer three of these old lathes into CNCs.

The modern CNC is not typically designed to be rebuilt (more accurately stated remanufactured), but is designed to be run in a modern production facility for 5-7 years and then thrown out. More accurately, sold off to some ignorant idividual that doesn't know any better.

Excuse me for asking any questions around here!

Axel

[ 02-03-2003, 01:48: Message edited by: Axel ]

This is where you confuse me, Axel. One minute you try to act like the poor, little village idiot who doesn't know how to find the on/off switch on a lathe. Then in the next post you are claiming that you invented the lathe and every lathe turning in the civilized world today is full of your great engineering ideas.

(All this after you have admitted elsewhere many times that you are NOT AN ENGINEER but rather a lowly salesman who "works with engineers." May I suggest to you there is a difference? Example: I went to the dentist last week...but I don't think you want me cleaning and filling your teeth do you? )

Since you are clearly determined to run some sort of big lying scam on this board at all time, at least be clever enough to decided which scam it is going to be....expert or idiot? I suggest you go the idiot route. You are much better suited for it and your idiot comments far more believable. But do stop trying to play both sides of the street. That comes out REALLY DUMB.

I've been to the dentist several times over the years. Now I can do root canals without anathesia.

Pecos45, echoed my thought exactly! I have a sneakin suspision that if Pecos got Axel in a chair under anathesia, it would be to stitch his lyin lips SHUT!!! And maybe castrate him too, for good reason I might add!

You're a freak!!

Axel perhaps you chould check out Bill Leeper's
credentials before you make a larger ass out of yourself than you just did.