Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: wulkan on February 20, 2009, 12:58:52 PM
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Hello,
I just retrofitted a Hardinge HNC Lathe and encoded the spindle with a (Single Index Pulse). Mach shows actual RPM, so that works good. I am using simple M3, M4 output to start spindle, but Mach does not control RPM. IN G95 mode does Mach use actual Spindle Feedback or does it estimates from the Programmed Feed Rate? Also the Feedrate Display only has 2 digits to the right of the decimal and the Feed Increment only allows a whole number. This renders override useless in IPR mode when you want a chip load of say .012 per revolution.
To restate the question:
How does Mach use the actual spindle speed for IPR or does it use the programmed feedrate, and how do I over ride feed rates in IPR in smaller increments?
Thanks,
Bill
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Mach uses the true feedrate, also make sure you have "Use Spindle Feedback in Sync mode" checked, its on the ports and Pins then Spindle Setup page.
You can change the amount of decimal places by using screen 4, open the screenset, double click on the DRO in question then in the format string put a 3 after the decimal point rather than the 2 it has at the moment.
Not really sure what you are meaning by This renders override useless in IPR mode when you want a chip load of say .012 per revolution.
FRO is a %
Hood
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Hood thank you for your help.
I downloaded Screen 4 and adjusted the DRO's as I wanted, it appears to increment the feed rate in IPR up or down by the number in the increment box. I wanted .012 and needed to adjust by .001 up or down and it seems to be working that way.
I am still puzzled because when I slow my spindle down manually I do not hear the Feedrate slow down. If I do not program a spindle speed it will not interpolate even though it sees the actual spindle speed and Mach gives me the message "No Spindle Feedback seen in (G95) Units/Rev Mode ??. I do have "Spindle Feedback in Sync mode" checked. What else could be wrong ?
Also is there any way to override the rapid Feedrate G0.
Thanks,
Bill
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I dont really have a way of testing it on my lathe but should be able to do it on the mill with a bit of trickery, will try and test tomorrow if I remember.
Not sure what you mean by override the RRO, you can have it locked or unlocked to FRO, is that what you are meaning? Its on General Config page. You can never exceed the Rapid rate set in motor tuning so if you are trying to increase your rapid speed then you need to increase the velocity in motor tuning.
Hood
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Hood,
I got my self straightened out on RRO. I am using the Xbox 360 controller and I had the wrong buttons assigned. Now what I need is the newest version of the Plugin with axis reversal. But I can not find the Yahoo Thread for it.
I am sure the actual spindle speed is not being used in G95 mode so when you have the time could you look into what you think the problem may be, I mean what I am probably doing wrong.
I appreciate your help.
Thank You
Bill
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Ok, sorry forgot to post back.
The true spindle speed is being used for the feed, to make sure I tested it out on my mill, it doesnt have Mach controlling the spindle speed.
What I did was Type G95 into the MDI to put it in FPR then I typed in M3S2000 so as far as Mach was concerned the spindle should be doing 2000rpm, the spindle requested DRO reflected that. Next I started the spindle and adjusted the speed to 200rpm then did a G1X200F0.5 in the MDI and the axis moved slowly, ie it was doing 0.5mm per rev at the spindle speed of 200 and not the 2000 that was set in Mach.
What will not happen, if you alter the spindle speed (once a feed has been set) it will not speed or slow the axis, the Feed OverRide is for doing that, the Spindle OverRide will just override the Spindle but leave the feed at 0.5mm/rev of the initial RPM.
So for example if you originally had spindle at 1000 and fed it at 0.5/rev it would do that, you increase the spindle to 2000rpm and the feed DRO would half to 0.25/rev but the actual feedrate would be constant.
Hood
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Bill,
Lee posted a link for the XBOX with axis reversal. Do a search and you should find it. We tested it out and it works great. Additionaly the XBOX works well along with the SmoothStepper now. That will be in the next posted plugin update.
RICH
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Hood,
I must have a spindle pulse problem because I duplicated your experiment and found my results remained the same regardless of the spindle speed. I would set G95 S1000 M03 G01 Z-1.667 F.01 this should take aprox. 10 seconds, than I would command it back to
Z 0 again 10 seconds.
I always allowed travel to complete before manually adjusting my spindle speed in half and than doubled aprox. back and forth and never saw a change in velocity measured by time each time I cycled.
I duplicated everything in Mach Mill as well and had the same results. I am using a Prox Sensor that has a 1Khz switching frequency.
A 3000 RPM spindle would only be 50 PPS. My DRO reads a smooth RPM only occasional flickering with in 1 RPM. Spindle calibration show a very flat line even though I am not using the PID Loop I just wanted to monitor it there to see if it was erratic.
Constant velocity or exact stop did not seem to alter the results. I have the spindle pulse as an Input on Index and nothing on Timing input as I only have one pulse per revolution. Can you think of any other reason this is not working.
Also thanks for posting the Xbox 360 Controller with Axis reversal. That is a nice plug in for all of us on a budget.
To the author, Thank You very much.
Sincerely,
Bill
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If you are running in G94 feed mode then no matter what you do to the spindle speed the feed will not change when in G97 spindle mode.
If you run in G95 feed mode and G96 spindle mode then the feed and speed are locked together and the feed rate increases/decreases as the spindle speed rises and falls.
In G97 spindle mode with a feed of 1 unit per minute (G94) and a spindle speed of 1000 the feed rate is 1/1000 = .001/rev if you then drop the spindle speed to 500 rpm then the feed is still 1 unit per minute but the feed rate is .002/rev
G94 is feed per minute e.g. F1.0 = 1" or 1 mm per minute, axis will move this distance in 1 minute.
G95 is feed per spindle revolution e.g. F.01 = .010" or .01mm feed per rev
G96 is constant surface speed e.g. S100 = 100 feet or 100 metres/min spindle speed, speed increases as cut diameter gets smaller.
G97 is fixed speed e.g. S1000 = 1000 revs per minute.
Graham
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Graham,
Thank you for the explanation about the distinction between G94 and G95 Feed Rate Modes and G96 and G97 Spindle Modes.
I will be away for a few days but I will try it out as soon as I return. The G96 and G97 are omitted from the turn manual in the list of G Codes. But with a search of the PDF I found the explanation in the verbage. Your explanation is even better than the books.
Thank you all for your support,
Bill
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Your explanation is even better than the books.
Typical ! ;)
Thanks Graham,
RC 8)
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... In G97 spindle mode with a feed of 1 unit per minute (G94) and a spindle speed of 1000 the feed rate is 1/1000 = .001/rev if you then drop the spindle speed to 500 rpm then the feed is still 1 unit per minute but the feed rate is .002/rev...
Graham
Graham,
Bill Wulkan asked me to review your post reply.
On line three, I believe you have mixed apples and oranges. FPM and IPR
In G97, G94:
.001 IPR @ 1000 RPM => 1 IPM
.001 IPR @ 500 RPM => 0.5 IPM - Slower not faster.
In G97, G95:
.001 IPR @ 1000 RPM => Feed rate = .001
,001 IPR @ 500 RPM => Feed rate = .001 The same, because the feed rate is locked to the RPM of the spindle. As it should be with threading on a ANY lathe!
Wayne
Wayne
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Wayne,
I believe Graham is correct.
Where you saidOn line three, I believe you have mixed apples and oranges. FPM and IPR
In G97, G94:
.001 IPR @ 1000 RPM => 1 IPM
.001 IPR @ 500 RPM => 0.5 IPM - Slower not faster.
The G94 is entered and constant at 1 IPM for both instances....Which makes the IPR change to .002 IPR.
RC
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Overloaded,
Yes, for a constant 1 IPM. I was calculating constant .001 IPR. It get confusing when modes are mixed. Bill is having trouble with the threading operation of Mach3 Lathe.
His spindle speed is one PPR encoded and the feed per revolution is loosing position when the RPM changes slightly from thread tool contact with the materail. Bill should start another thread for threading...
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There is already a thread going for problems with lathes with small spindle motors and threading.
However what problems is Bill having?
Hood
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Mangler,
So you are referring to G95 for threading.....
In the quote, it is G94. So the feedrate is constant although the spindle speed can vary, as well as the chip thickness.
RC
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Hello All,
Well I tried my lathe out today and used the following program code. What I found was is if my actual spindle speed matches the programmed spindle speed than the feedrate DRO would reflect the correct .050 per revolution. However if the actual spindle speed was slower than the programmed spindle speed than the feedrate DRO would reflect a slower feedrate, and if the actual spindle speed was faster than the programmed spindle speed the feedrate DRO shows a faster feedrate.
I would think the feedrate DRO should show a constant feedrate regardless of spindle speed. Perhaps actual feedrate is correct and it is just the DRO showing compensation for the programmed spindle speed difference versus actual.
Please note I am not altering the spindle speed during the cut pass. I am using the single step mode and slightly adjusting the spindle speed usually 20-25 RPM prior to each cut pass.
The problem is I manually adjust a potentiometer for spindle speeds on my lathe so I can not program the correct spindle speed unless I stop to monitor it and than enter that speed in a program. And it would be wrong if the spindle speed drifts.
Does anyone have an explanation of how the Feedrate DRO reflects a thread pitch and why it shows a variation according to actual spindle speed changes?
G40 G18 G80 G90 G95 G97 S400 M03
G00 X0.525
G00 Z0.1
G00 X0.5
G76 X0.4 Z-2 Q1 P0.05 J0.006 L45 H0.022 I29 C0.025 B0.0001 T0
M5
M30
Bill
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Deleted because I read wrong :(
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Oh just another thought, make sure you have "Use Spindle feedback in sync mode" checked on Ports and Pins, Spindle Setup page if you want to do threading.
Hood
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I don't have a lathe set up here now to check....or I would. And it doesn't seem to work in simulation.
It sounds as though the DRO is reading in UNITS/MIN even though it's running G95 and labled UNITS/REV.....and like you say, should be constantly showing .05
RC
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Deleted, wrong info :(
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Hood,
Looking at bills code:
G40 G18 G80 G90 G95 G97 S400 M03
G00 X0.525
G00 Z0.1
G00 X0.5
G76 X0.4 Z-2 Q1 P0.05 J0.006 L45 H0.022 I29 C0.025 B0.0001 T0
M5
M30
There is are no G95 feed moves....only rapids and the G76 cycle.
Regardless of the spindle speed, I would expect the dro to be constant at .05
Will check back later.
Thanks,
RC
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Sorry RC, getting late here and not comprehending fully, I was assuming with the initial mentions of of the different spindle speeds and feeds were just when doing G95 and not in G76.
Sleep time, heads screwed up worse than normal (so it must be in a bad state :) )
Hood
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Take care Dude....you're on overtime.
Rest well,
RC
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Hello Again,
Can anyone explain the G95 mode DRO varying according to differences between programmed and actual spindle speed.
I thought I built a lathe that can do threading and right now that is the only thing it does not seem to do.
Let me know if there is an explanation.
THANKS,
Bill
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What is the problem you are having with threading?
Hood
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Hello Hood,
Well I tried out the program previously listed in this topic and actually cut a thread. What I discovered was, as long as the programmed and actual spindle speed matched it cut a good thread. When the actual spindle speed was different even slightly it ruined the existing thread I previously cut when actual and programmed spindle speed matched.
I was talking to codemangler and he suggested trying a macro that could read the actual spindle DRO and insert that into the program as a programmed speed variable that could be constantly updating itself.
Does that seem to to be a logical approach to you?
Bill
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Are you using the Demo? What version are you using?
Threading works well and the Z Axis will track extremely well to changes in spindle speed. There has been a problem seen recently by some where there are big slowdowns in spindle speed during a cut, the X axis will start to move. Art is looking at that one to see if he can find it.
Hood
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Hood,
Well, it is amazing what a little thing like a license can do to solve all my threading issues. What happened was I reloaded Windows and Mach to clear up some freezing up problems and did not put the license file back in the Mach Directory. I do not know how that happened, but the version is 2.45 and it is tracking superbly now.
I appreciate all the support, thanks you all especially Hood.
I feel like the guy who just didnt plug the darn thing in.
Bill ;D
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I feel like the guy who just didnt plug the darn thing in.
Been there....Done that.
It's easy to overlook the obvious.
Glad you're up and running Bill,
RC :)
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If only you had mentioned what your problem was right at the beginning LOL
Good you are now running and as RC says been there done that and bought the rights ;D
Hood