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Author Topic: Perfect Lathe threading  (Read 7490 times)

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Offline RICH

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Re: Perfect Lathe threading
« Reply #10 on: April 12, 2015, 07:51:56 AM »
Just a point in time .......... some 4 or 5 years ago,
FWIW  :)

The “future” Advanced Threading requires update per the new threading code and will allow for a slotted wheel with index or an encoder. When using an encoder additional parameters will need to be defined to MACH. If using an encoder, you’ll have to set the number of quads per rev and should work fine if one considers just how many lines can be seen per rev at top speed of threading used and limits their speed to that as a maximum. The Advanced Threading will not be available until after the updated version of Mach is released.

An encoder can be used for threading, and it IS on the books to allow an encoder geared output of the stream, but that may take longer to appear since rework of the code is first required  to get it to a more manageable level of interconnection. As the printer port very slowly goes away, it becomes a question of what the new hardware guru's can put in their firmware with application support from ArtSoft's side.

I suspect Electronic gearing is now possible, but will require a defined development procedure similar to what we went through to fix threading.

RICH

Offline BR549

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Re: Perfect Lathe threading
« Reply #11 on: April 12, 2015, 09:12:33 AM »
Seeing that the UC does the threading all it should need from Mach3 is the parameters. Could be that can be gotten through the plugin. Just have to wait to see what Balazs from UCCNC has to say about it.

Even IF  rigid tapping being that you cannot control the spindle as you would a servo you will only have semi rigid tapping. As the machine has no idea where the spindle will actually stop. It will always have and unknown amount of overrun. BUT that is fairly easy to deal with as long as you do not have blind hole tapping . Then it is a guessing game. I did have it down to a +/-  1 turn of the spindle tolerance.

(;-) TP
« Last Edit: April 12, 2015, 09:17:27 AM by BR549 »

Offline BR549

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Re: Perfect Lathe threading
« Reply #12 on: April 12, 2015, 01:09:23 PM »
Hood, the threading demo was done with UCCNC software.

(;-) TP

Offline Hood

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Re: Perfect Lathe threading
« Reply #13 on: April 13, 2015, 02:27:41 PM »
If the UC100 is doing the threading completely externally to Mach then it will almost certainly need to be done in a similar manner as the CSMIO and the Kflop do rigid tapping, ie using a mcode rather than a G code.

Hood

Offline BR549

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Re: Perfect Lathe threading
« Reply #14 on: April 13, 2015, 03:22:58 PM »
NOT neccesarily (;-)  I have a version of mach3 where I synced Z to a servo spindle and I use canned drill cycles to do tapping. May be able to do the same thing here.

(;-) TP
Re: Perfect Lathe threading
« Reply #15 on: April 13, 2015, 03:27:31 PM »
Hood, Rich,

Does this mean I have just dug a big hole for myself. You've probably seen my posts. I'm converting an old Boxford TCL160 and have bought myself a ESS Smooth Stepper and Motion Control card with the view to threading.
I was reading how important it was top synchronise the spindle speed so I will use a Slotted Opto with a disc on the spindle shaft with a single slot.

Even if I do all this it sounds like I'm heading for trouble from reading your posts ?

George
One step at a time!

Offline Hood

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Re: Perfect Lathe threading
« Reply #16 on: April 13, 2015, 03:32:50 PM »
What I am saying is the way the CSMIO does the lathe threading is with the full encoder and the normal G76. There is a problem with the update of info from Mach and that is why there is the pause at the end of each pass as the controller waits for Mach to give it the next move.
Ken found a way around it with the Galil but what it is I have no idea.

Tapping is a bit different  as it is a single down and up but even then Mach does not properly support G84 and thus why the CSMIO and KFlop use m codes so that it is deadly accurate, in other words the controller does the tapping external to Mach and Mach just waits until it is told the macro has finished.
CS-Lab have said they hope to do similar for the lathe threading and just use M76 rather than G76 but they have not got round to it yet, maybe they will find the way around it like Ken did and not have to bother.

.

Hood

Offline Hood

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Re: Perfect Lathe threading
« Reply #17 on: April 13, 2015, 03:36:16 PM »
Hood, Rich,

Does this mean I have just dug a big hole for myself. You've probably seen my posts. I'm converting an old Boxford TCL160 and have bought myself a ESS Smooth Stepper and Motion Control card with the view to threading.
I was reading how important it was top synchronise the spindle speed so I will use a Slotted Opto with a disc on the spindle shaft with a single slot.

Even if I do all this it sounds like I'm heading for trouble from reading your posts ?

George

The ESS will thread fine as long as your spindle does not fluctuate too much under load, I have the ESS on my big lathe and have cut thousands of perfect threads.
 What we are talking about here is fully synchrosied Z axis to spindle, if spindle slows the Z will slow, if spindle stops Z will stop etc.
As said however as long as your spindle is reasonably steady you will not have a problem with the single slot approach.

Hood
Re: Perfect Lathe threading
« Reply #18 on: April 13, 2015, 03:45:01 PM »
Thanks Hood,

Conversion continues :-)

George
One step at a time!
Re: Perfect Lathe threading
« Reply #19 on: April 14, 2015, 11:49:54 AM »
I notice that someone on this forum has added tacho speed control to a Baldor DC motor through a KBE controller to keep its speed constant under load - this is an interesting alternative provided the servo bandwidth is enough to cope with the transient as the tool starts to cut.  In effect you use a multi-slotted disc in a loop external to Mach so Mach can use its single-slot approach with confidence that the spindle speed remains constant.