Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: BR549 on April 11, 2015, 12:14:32 PM
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Finally someone has threading on a small lathe down to a science. They have the Z synced to the spindle as it should be by encoder. AND it works(;-)
https://www.youtube.com/watch?v=_PVYLCoFoK8
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WOW! (Dope slaps head)
1/4" Pressboard ways & a masking tape toolholder...the secret to perfect threading! How come nobody thought of that before. :o
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I think you missed the point 8)
(;-) TP
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Looks like it is working well but as far as I know it has been done before, Linux guys say it works well and Mach3 with the Galil can do it. CSMIO can almost do it with Mach3 as well, slow pullout at the end of each pass being the issue but Z tracking spindle most definitely not.
Have you used the UCNC software TP? I presume it will only work with the UC100?
Hood
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I think you missed the point 8)
No disrespect intended BR, I tend to try & be funny when I get around things I don't understand.:D
So this was done using Mach3 & a USB motion controller? Definitely cool if it's solid, doesn't cost an arm & a leg & ain't Linux.;)
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Think it is UCNC software, certainly seems to be from the title of the video "UCCNC first thread test"
Hood
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YEP it is UCCNC it does have a mach3 plugin. Hopefully it will be ready for ridgid tapping soon.
It will be the Big Dawg for lathe threading AND rigid tapping in mill.
DIckeyBird, I do agree with your humor I was not offended. I had to go back and do a double take myself.
(;-) TP
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Not really clear what you are meaning TP, will the UC100 do the lathe threading as per the video with the Mach3 plugin or is it just using the UCNC software?
Hood
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Hood I am not sure of that part . It may be that Mach3 cannot support it without a few mods AND those mods are never coming . (;-(
(;-) TP
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When I was testing the CSMIO out a year or so back I had the slow pull out issue. I thought it was a problem with their plugin but talked to Steve (Smurph) and he said he had exactly the same issue with the Galil, so looked like it was Mach. I then found it worked better in an old version of Mach, sadly however other features did not work in the CSMIO so I had to go back to the newer version.
Ken Crouch seemingly found a way round the slow pull out issue with his Galil plugin but what/how I have no idea.
Vid of my wee lathe tracking a previously cut thread whilst slowing and speeding the spindle, see here
https://www.youtube.com/watch?v=sKp343Ubf7U
and with the older version of Mach3 showing the quicker pull out see here
https://www.youtube.com/watch?v=8c1sndp-554
Vid of Ken Crouch's with Galil here
https://www.youtube.com/watch?v=JfnQxDPWoEQ
Rigid tapping can be done with CSMIO and Kflop and likely also Galil and others but it requires that you use an MCode rather than let Mach handle it as Mach does not really support G84.
The CSMIO works perfectly with rigid tapping and I assume the others do as well.
With the CSMIO you would call
M84 Q-20 P1.5 S400 R800
That would rotate at 400rpm at a pitch of 1.5mm to a depth of -20mm and reverse out at at 800rpm.
I have my post in BobCAD putting out the correct values for rigid tapping with the CSMIO.
Hood
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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
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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
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Hood, the threading demo was done with UCCNC software.
(;-) TP
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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
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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
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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
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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
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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
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Thanks Hood,
Conversion continues :-)
George
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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.
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You may run in to issues with that as well. What will likely happen is the spindle will slow but the drive then compensates, which sounds good. Problem is Mach has seen the slow down so it too compensates by slowing the axis but by that time the spindle has recovered so Mach has to try and compensate again and very likely can not.
Hood
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Thought you might like this TP.
Someone asked me if it would work so I tried it today.
https://www.youtube.com/watch?v=0-KlHFYxzkM
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SWEET! ;D
Now I know what to ask Santy Claus for this year. ;)
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I like that one Hood,
Years ago, at least 8 years or so, you could slave the Z axis to the spindle when using IMS software ( used an encoder) for threading and do what you showed. What was sweet was one could repair a thread or even just use "manual" spindle power to cut a 0-80 and the
thread would come out perfect.
Maybe someone will figure it out for Mach 5...... ;D
RICH
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Actually one can do THAT magic trick with Mach3 IF you are very very clever.
Just a thought, (;-) TP
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You have me a bit confused TP, first you say
Finally someone has threading on a small lathe down to a science. They have the Z synced to the spindle as it should be by encoder. AND it works(;-)
Then when it has been pointed out that it has already been done for many years with all sorts of hardware/software, you now say.
Actually one can do THAT magic trick with Mach3 IF you are very very clever.
So take it I can look forward to a video from you of Mach3 doing a thread via the parallel port and then you disabling the spindle and running over it again by rotating the spindle by hand?
Hood
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Rich, I think Art was saying it should be possible in Darwin but maybe I am not remembering correctly. Anyway works fine with Mach3 if you have the correct controller or with other software such a LinuxCNC or as you noted IMS.
Hood
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Art suggested it could be done, but, would require a complete testing similar to what was done for threading.
It was requested or suggested but effort required probably wasn't worth the volume of use. That was a rather long time ago.
Terry may have some thoughts on being tricky. If you slave the Z to the spindle you can machine scrolls around a cylinder
with live tooling ( I was using a stepper driven spindle ). Never tried using an MPG to control that total movement, the "cloud" above my head says
it should work, but, may be more a PITA, than it is worth doing.
FWIW.
RICH
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Hey Terry,
Still have some pages left in my screen set. ??? ::)
Feel free to fill them up. :D
RICH
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Yous guys are funny. I said magic trick and that is what it would be(;-). Art did say it was possible in m3 but never would reveal the secret. I think For fear of the kaos it would create with everyone try to do it. More support. I think I figured out his secret.
THink about an MPG. You can simply and accurately drive the Z with an MPG correct ? So if the Spindle was the mpg(encoder) AND you did the math correctly to match rotation of the spindle to movement of the Z you have the magic trick. I did BUILD the basics and it would do exactly what you saw Hood do. And in respect for Art that is where I stopped with it.
And yes it is easy with a step/dir spindle either stepper or servo. You can make it deadly accurate with a servo spindle by having it do indexing as well. Then you can Sync the spindle rotation to the Z axis motion through a MATH channel. THEN the spindle rotations will folllow the Z no matter where it goes. I have done THAT as well in TURN AND in MILL. THE Torus mill that comes with a servo spindle , I help develope a rigid tapping scheme that not only does rigid tapping BUT USES mach3 Gcode canned cycles to do tapping. THAT was the magic trick. The spindle could do RPM or indexing without SWAP AXIS or flipping a switch. You could command EITHER from Gcode.
There ARE still some secrets in the DIY world (;-) Not ALL the cats have gotten out of the bag.
(;-) TP
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Oh Terry you are funny indeed.
You said what I was showing in the vid was simply Z synchronised to spindle, well there was a bit more to it than that. What I was demonstrating was something that was shown in the video you initially posted and hailed a massive breakthrough, now it seems because it has already been done, and for many years, then it is not so much of a wonder ;)
Ok using the spindle with an encoder and making the Z axis the follower, yes it can almost certainly be done. That would make rigid tapping fairly good but you may hit snags with encoder resolution. My memory is a bit hazy as it is a long time since I messed with encoders and the parallel port but I seem to recall 25KHz was about your limit for the input frequency, that would mean either low RPM or low count encoders. Rigid tapping tends to be relatively slow RPMs but lathe threading is normally a lot faster, especially if using carbide.
Now threading on a lathe, well it is, as I am sure you are aware, not just a matter of synchronising Z to spindle, you have to also start the synchronising at an exact point in relation to the Index and have to then de-synchronise at a defined point on the Z axis, you then again have to synch with the index on the next pass but also have to advance the X and Z axes the defined amounts to take the correct amount of material off.
Could it be done via the PP using the spindle as the master and the Z as the follower?
Yes of course it could.
Would it be easy?
No it would not.
Would it be a reliable method for Mach to do lathe threading?
Probably not as if it were then Art would have done so a long time ago.
Anyway looking forward to the video you are going to post showing exactly what the initial video, and the one I posted, are doing but all via your master/follower method via the PP ;)
BTW no rush, I likely won't be around for at least a few days.
Hood
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hIYA hood I was not implying that what you showed was trivial it is not. What I described with M3 was exactly that a magic trick. Can it be done in mach3 sure the magic trick can be done.. I even explained how it could be done. Can encoder threading be done from Mach3. I fully believe it can BUT it would be a BEAST to make it all work reliably as you stated WITH dedicated exact hardware and really NOT worth the effort to develope it for the 10 people that might actually use it. Mach3 is dead and will never be revived or worked on again so what would be the point(;-).
The odd thing is every since Mach3 allowed outside controllers every OEM said oh yea we will have encoder threading out next week. THAT was what 10 years ago ??
I guess next week FINALLY showed up at a very high price for a hobby lathe.
I think Art saw it the same way. Single index threading CAN work depending on the machine and the precision of the thread that is required. Hobby threads sure Precision Gauged threads not so much.
Same with rigid tapping in mach3 it CAN be done but not easily with a normal spindle setup as you do not have full control of the spindle. EVEN if you have spindle following you do not have TRUE rigid tapping as you can NOT control the exact stopping point of the spindle rotation so you cannot predict the EXACT depth it will stop at. You can get close but that is not true ridgid tapping.
Move to a step/direction SERVO spindle then it becomes a piece of cake for Mill or Turn. 1 Mcode to set from RPM mode to index mode function ( no swap axis involved) and I can USE canned Gcode cycles to do the drilling and do the tapping. We have already made that work years ago.
I can do peck tapping and return from anywhere and retap the same hole again EXACTLY true and never tweak a thread. BUT it also takes a properly setup machine to do it.
AND just a note I garrenty you it does not work in the way one would think it does (;-). It to is a magic trick.
SOME magic tricks are best left a secret. (;-)
(;-) TP
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there are really 2 types of controlled tapping.
rigid tapping -> the z axis is geared to the spindle rotation and follows.
synchronous tapping -> the spindle is in effect a rotary axis and the spindle and z axis do synchronized move (exactly like a z - a move.)
Mach seems to use synchronous tapping. (having a servo spindle that can position well enough to tap)
Linuxcnc can do both - although most use rigid tapping. A spindle that can reverse quickly really doesn't over shoot much. (but you do have to take it into account..)
https://www.youtube.com/watch?v=cGr37Dn6YgM
how about gear hobbing... :)
https://www.youtube.com/watch?v=ZhICrb0Tbn4
sam
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Mach3 can do gear hobbing as described in the Video and can do true Rigid tapping IF you have the hardware. Not just Z following the spindle down and back. True rigid tapping will have FULL control of Z depth not just a best guess.
Just a thought, (;-)