Denford Software & Machines

Hi i have recently purchased a easiturn 3 and in am having trouble getting a decent thread, it does nt seem to be picking up the same cutting pass in Z when it goes to take another cut. nothing seems to be loose.

Also, can anyone tell me how accurate the spindle speed should be. If i program it to 1300 rpm it reads 1260 or there abouts. Any answers or advice would be much appreciated.

Cheers Steve

Hi Steve...

Firstly about the spindle speed. That's pretty good! I'd say +/- 10% is normal.

About the threading...
1) Make sure the your spindle speed isn't too high. Try spindle speeds around 200 - 400rpm
2) There is a sensor disk in the headstock at the back of the spindle. This has a series of holes in it to with a sensor to measure speed, and one long hole on its own to synchronise the start point of threading passes. You can test these sensors by doing the "T Test" (search the forum for other info on this test too)...
- turn on the machine
- press 'drives on'
- press 'T'
This shows a test menu. Somewhere on the screen you'll see the 2 x spindle sensors showing 0 or 1. You can slowly rotate the spindle by hand to check the sensors are working OK

HTH
James

are you using a ridgid tapping chuck ?

if not make sure your feed rate is as near the tpi of the thread your tapping

Hi James

Thanks for the reply. I ve carried out the T test and both the 1 & 0 change as i turn the spindle but all the holes in the spindle disc are exactly the same. Does this seem correct.

Cheers Steve

The synch hole is elongated and separate to the others (it's on the inside of them - on a smaller diameter). It has its own sensor too so the T test should show one input changing many times per spindle rev, and another input changin once per rev.

I ve looked and looked again at the spindle disc but all the holes are elongated and are all on the same diametre. Any ideas?

Cheers Steve

Nah, I thinkyou're mistaken Mr Magoo, my easiturn just had a load of slots all the same. I think the issue is speed - in this case too fast. Those 8086 computers can't count very quick

I think old age is finally catching up with me!
I expected the disk to be about 7" to 8" in diameter & brown coloured (plastic I think). I'm wondering if the disk has been replaced at some time, or the machine is before my time (I worked there from around 1986). Perhaps there's another sensor somewhere that give the reerence pulse?
Threading needs a rerference sensor on the spindle in order to know when to start a threading pass so without it it'll not thread correctly. Any chance of posting some photos?

But Triac Whizz is right - the Easiturn never did like threading at anything other than slow RPMs

Yup, you're right Mr Magoo, they were about that size. made out of tufnol. so full marks for your memory
There wasn't a different slot, they were all the same. I can give you a photo I machined mine off to drill one index hole for Mach.
Could it be possible that the old PNC used to count upto the number of holes on the disc and use something electronically to say that was a revolution, for example count 30 holes and send out one pluse? I dunno electronically but I'm sure there never was an index notch/hole.
There's a chart in the easiturn manual that shows how slow to go when cutting threads.

Thanks for all your help everyone. i ll try lowering the speed even more to see if the thread improves. cant try it now though as i ve got another problem with the z axis drive.

Cheers Steve