What lathe

Ok. I learn something new every day. My old fashioned .22 only goes pop.

regards

I think Jann West’s reply is likely the best one - and probably fits the bill concisely and precisely.

He knows that repositioning the carriage might be quite precise, the actual position of the lead screw has clearly been ignored - or, more likely, not even considered. I doubt he knows if the lathe has a TDI.🙂

Maybe a case of RTFM - or is that hoping for too much?

Mate I know what a thread dial is pal ******************

Edited By SillyOldDuffer on 22/01/2021 20:22:20

I think you may have joined the wrong forum, it is obvious that no one on here is going to be able to help you.

Phil

Joshua,

Nothing personal, believe me. We're trying to tell you there are three things that go wrong with lathes:

1. The machine
2. The material
3. The operator

Many of the questions on this forum are from operators asking how to solve a machining problem. Sometimes the machine is faulty or out of adjustment, more likely the machinist is having bother with an unfamiliar job and is seeking advice.

The problem can be one of technique, or dealing with a difficult material, wrong cutter, rpm or feed-rate, or a bunch of other stuff. Turners once went through a long apprenticeship and those of us who are self-taught make many mistakes. Even the professionals have their moments!

Tracking down what's wrong involves eliminating all the possibilities. It's best not to arrive with fixed ideas! We would do you a grave disservice by suggesting an expensive lathe is the answer when the problem lies elsewhere and might be easily fixed.

For example, my mini-lathe wasn't good at threading under power, The motor was too fast and got hot if run slowly for long periods. My solution was to make a hand crank to turn the spindle manually : much more controllable, and the motor and control board aren't stressed at all.

Dave

Certainly not from many of use unless he moderates his language

I see the mods have been tidying up his comments thankfully

br

Look pal I totally agree with what your saying and yes I am inexperienced but if I’m saying there was a fault with the motor an it took out the board that’s what happened an the second machine had a bad lead screw an yes it wasn’t very good running at low speeds hence why I sent it back for something more suitable. But if I could produce good work on the old myford then I’d expect to be able to on the newer machine. With regards to the back and forth it’s obvious it’s not a forum for me

If I were buying a lathe I would avoid any with a built-in variable speed. At some point the Chinese maker will terminate support for the lathe and parts will become unavailable. Unlike lathes with step pulleys and back gears the available torque does not increase at lower speeds.

I prefer a machine with a standard electric motor that can be sourced anywhere. I favor V ways over flat ways. Even with considerable wear in the V ways it is still possible to hold size. On flat ways the wear is concentrated in a small area near the headstock, If the gibs are adjusted for the un-worn part of the bed there will be slack at the worn end therefore it is impossible to hold size.

I have owned South Bend lathes since the 60s. They have V ways, a standard motor, step pulley drive, and back gears. I believe Boxford is a near clone of the South Bend so I would recommend it. Colchester made great lathes but I am not familiar with the smaller sizes. Emco made some great lathes. Stefan Gotteswinter uses one.

I am not opposed to a Reeves type variable speed for lathes although repair parts are pricey.

Very interesting comments ,John

The three lads and myself have a ML7 and a Unimat 3 each for the simple reason that if a motor goes it is simple to sort. Unimats updated to run 24v dc motors.

br

"I bought a myford ml7 to make up some air rifle silencers an dispute it being a well built quality machine ...."

What was the outcome of the dispute?

Was the problem with the 1.5mm pitch thread not picking up down to the incorrect selection of the module gear being fitted to the TDI?

Edited By Oily Rag on 22/01/2021 22:34:10

Did the ML7 ever come with a metric leadscrew? If not, cutting a 1.5mm thread with an 8TPI leadscrew means the TDI is useless anyway. If it had a 3mm pitch leadscrew, then pickup could be at any point and you don't need the TDI.

Says someone who bought an old English lathe with metric leadscrews that came with all sorts of extras - except the additional worm wheels for the TDI for the full range of pitches. Imperial threads on an imperial lathe are so much easier!

Barrel threads for silencers are air guns are generally 1/2” UNF, so imperial. Of course one can choose any thread for the silencer construction.

That's the cause of your double threads right there. Same starting position means nowt when the leadscrew position is not set to match it either by TDI or marking the change gears and returnnng them to that position by hand rotation until reclasping the half nuts. And even then, it only works for certain threads according to a very strict criteria. Martin Cleeve outlines it in his book Screwcutting in the Lathe if you want to learn it.

Its easier to keep the halfnuts engaged, back the tool out and reverse the lathe when screwcutting metric on imperial machines or vice versa and don't have any problem.

As for the old Myfords -- who would buy a 1955 car and expect to jump in it and drive to and from work in it every day without putting a spanner on it?

Edited By Hopper on 23/01/2021 09:33:50

1/2” x20 unf for the Barrel but 1.5 pitch for the 2 end caps I use a tap for the barrel

I don’t get why you can’t understand that the lead screw was moving when I moved the the carriage that was the reason it was double threaded I’m not guessing this it is a fact

Quote  --    With regards to the back and forth it’s obvious it’s not a forum for me

=============================================================

This is what you said yesterday , So that we know wether to offer help are you staying with us please ?

br

Edited By br on 23/01/2021 09:55:46

Joshua, It is very likely the Myford lathe had/has an imperial leadscrew, so if you were cutting a metric thread on it you must keep the half nuts engaged at all times, after one pass stop the motor, put the motor into reverse & drive the tool back towards the tail stock to start the next cut.

Tony

Edited By Tony Pratt 1 on 23/01/2021 10:04:48

Edited By Tony Pratt 1 on 23/01/2021 10:05:08

I was using tpi on the myford mate

This site is frequented by people of all ages and sensitivities. If you can't keep your posts civil, kindly leave the forum

John Hinkley

I wasn't aware unsilenced air rifles were capable of more than hearing damage!

The OP should be aware there may well be Police Officers subscribing to this forum and if so I would expect them to make enquiries as to the identity of the OP and arrange for his local force to confiscate any weapons and revoke any Firearms or Shotgun permissions whether necessary for the type of weapon described or otherwise. Weapons should not be in the possession of abusive and volatile individuals.

The OP has nothing to learn from any advice given on this site, he has been unlucky with every machine he has purchased. I hope all those firms supplying machines subscribe and take note to avoid supplying the OP it can only end in tears.

If I was the dog poo referred to earlier I would be anxious to extricate myself from the shoe.

It is time the OP was invited to leave this forum .

Robert Butler