A clever gadget for a Lathe.

I have just been sent this link to a video of a great idea to turn a manual lathe into a CNC. I don't know if it's original or not but I was very impressed with it.

Thats quite cunning, I like it.

That is basically a neat DIY version of a commercially made "Audit" add-on CNC slide unit.

These were UK made 2 axis slide units, frequently fitted with an indexing turret, designed to bolt on to the rear of the saddle of manual lathes to give CNC functionality. Their advantage came mainly on larger lathes for operations like taper threading drill tubes for the oil industry. I just had a look for them, but the company appears to have been wound up in November this year.

Less work than a full-on CNC conversion, but with capacity somewhat limited due to the compound slide stroke.

It will be interesting to see if he can get threading to work, but I have a vague recollection that Mach 3 was lacking in this regard.

Nigel B.

(edit for spelling)

Edited By mgnbuk on 31/12/2022 12:26:54

Fasinating - I love the guys humour - The end bit is good ! Noel

I've often wondered whether if you put a stepper on the topslide and swung it round to 45 degrees you could achieve the same effect as a hydraulic copy attachment. The control system would need to monitor the DRO on long travel and then you'd manually disengage the long travel at the end of the cut. The topslide travel commands would then need to be massaged to suit a sort of saw tooth profile. If the topslide is retracted at root 2 times the long travel speed, the tool would just retract radially, not advance.

There is no problem threading with Mach3 on a suitable machine. The main issue is with some of the lathes it is used with. Mach3 requires just one indexing pulse per rev. It uses this pulse to synchronise the start of the z axis motion and to set the correct feed rate for the required pitch. If you have a lathe with an underpowered motor or you are too aggressive with depth of cut for the available power the resulting reduction in RPM throws the calculations done by Mach3 off. If you are threading on a lathe with plenty of power for the work being done then Mach3 can cut threads without issue. Trying to use a lathe with electronic speed control at low speed and with no back gear for example is likely to fail.

Martin C

Excellent video … Thanks for the link, Buffer

Anyone fancy scaling it all down to suit a Pultra 17/70 ?

MichaelG.

Yes, thanks for that.

Unfortunately I now want one. I can feel another "going off at a tangent" coming on..