denford triac rigid tapping

i just got a denford for myself
its fitted with control techniques lynx08 drive- not sprint.
havnt checked fully but according to the manual its isolated on all inputs . (havnt confirmed with meter yet)
problem is its unidirectional.
was thinking it should be ok to tap down, un enable , reverse polarity with contactor and re enable to reverse,
it looks like the tacho feed is fed into a bridge- so was hoping it would be ok running reverse. - anyone know?

anyway- thats preliminary thought. any wise men on here tried it?
or would it be better to swap out the dc motor for ac and run it with vfd?

annoyingly i dont have 3 phase- so il be swapping out the old fanuc drives/motors anyway

Are you sure your spindle only goes one way?
I'm pretty sure mine had a reversing relay, but I've not got the wiring diagrams handy to check.

For rigid tapping, you need reasonably accurate spindle control, along with accurate positional feedback, which the original DC motor definitely doesn't, and I'd suspect a VFD may struggle to respond fast enough, plus you'd struggle to fit a normal AC motor.
I fitted a 110 frame 1.25kw servo motor to mine, which involved making up a quite substantial adapter (I do have a thread on here with details/photos), as space is very limited.

I've still not got as far as trying rigid tapping, but that is one of the reasons I fitted the servo, instead of repairing/replacing the original motor and drive.

theres no reversing contactor in mine. just forward run
the spindle doesnt have to run accurately- just at rough speed required as the z axis will be geared to its encoder (which il have to add) - so will only start back out movement when the spindle is in reverse in a tapping cycle .
i havnt had time to test the lynx drive fully yet- but its ready light is on !
it does look a tight for space fit- was thinking mounting the motor high with a long shaft where the original motor is now if i have to use an ac servo instead.
time for some testing.

You need accurate enough spindle control so that you can stop it within a reasonable tolerance, unless you plan on having a very wide tolerance on tapping depth.

To give you an idea of the space problem, this is a 110mm square plate which the servo motor bolts to on top of the spacer -
https://farm4.staticflickr.com/3855/...26b56e3d_c.jpg

The spacer is high enough to get reasonable bearing spread between the two support bearings for the extension shaft, and a flexible coupler.
I have a model of the Triac head casting in Fusion360 if you want to see what will work.
IIRC you could probably get a 130 frame motor on, if you wanted a bit more power.

This post onwards covers the servo and the mount - http://www.mycncuk.com/threads/10344...9732#post89732

Got some tapmatic tapping heads for my triac, work a treat

as uccnc fully supports rigid tapping- and others are using it daily id like to add it to the triac.
if i run into problems- il go with tapping head .
to be fair with the amount of real paying work i have its going to be a while before the new "hobby machine" gets done.

Is it really worth the cost and effort, use threadmills

Does anyone have a spare encoder cable or just encoder plug for fanuc red cap
Only required for test rig to set up my new drives.
Terminal layout is different to most motors- pain!Attachment 24244

Got the red caps running perfectly on step/ direction
:-)