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Mach Discussion => General Mach Discussion => Topic started by: boilerbots on March 26, 2009, 05:53:41 AM

Title: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 26, 2009, 05:53:41 AM
Hi,

I have a real problem but I am not sure it belongs to Mach3 or Warp9. I am running a SmoothStepper on my mill.

When an axis is moving, sliding the FRO up or down causes such an abrupt change in velocity that I will loose steps or sometimes totally loose coupling (is that the right word) with the stepper phases. Adjusting the FRO appears to totally ignore the acceleration parameter and will just jump to the new speed.

It would be really great if I could get this solved. I would like to be able to take the feed rate up and down dynamically as the program is running for safety reasons, like when running close to a clamp or fixture for the first time.

Maybe there is a way I could fix this in a Macro or Brain thing?

I plan on cutting a lot tomorrow so shoot me some ideas please......
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 26, 2009, 06:04:17 AM
That reminds me of something else. When can we get acceleration to be something other than linear?

I read under the Quantum thread about "S" curves and that could really help. Most machines could probably accelerate at a higher rate as long as the acceleration decreases with velocity since the steppers loose torque with speed.

I have to keep my acceleration really low just so I can obtain high velocities for rapid moves because of this.

Maybe someone could take that portion of the code and bring it to Mach3?
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Hood on March 26, 2009, 11:09:50 AM
What version of Mach and SS Plugin are you using. I have had the SS since the Beta testing days and have never had that problem, the FRO is maxed at 100% but is nice and smooth below 100%.
 As for S Curve, it will probably be added in the future but it is a long way away, if you are needing speed then the answer is to get servos I am afraid.

Hood
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 26, 2009, 02:22:13 PM
The latest R3.043.000 and SS release  SmoothStepper_Beta2_v015ogb.m3p

Are you running steppers? This wouldn't happen with Servo drives that have their own closed loop position control.

I never need to go above 100% because I am using a CAM program that takes my spindle HP into account along with the cutter and material. It really pushes the tools pretty hard so I am generally down below 80% most of the time.
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Hood on March 26, 2009, 02:30:24 PM
Yes, have steppers on the Bridgeport and coil winder although I never use FRO on the coil winder, my  lathe has servos.
Certainly seems a strange one and may be related to the 043 version of Mach as it is a development version meant mainly as a test for  cutter comp and it has been known to have some weird happenings, did you have this problem with earlier revisions?
Hood
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 26, 2009, 03:04:56 PM
Yes I saw this earlier, but there where bigger problems with the SS so I wasn't focused on this just yet. I believe you have to stick with the latest experimental software for the SS drivers and features to work since they are actively being developed.

The reason I am think about this is because I would like to get/build a pendant. I would like to have a MPG and FRO knobs to make life even better now that I have a CNC mill. I figure if FRO doesn't work reliably through the GUI then it will have similar issues with a pendant.
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Hood on March 26, 2009, 03:15:43 PM
The Dev version as stated was for cutter comp alterations only, the SS will work fine with any of the last revisions. There will be big changes in Mach coming soon and I think the development of that will be advantageous to the SS and then you may well have to have the latest version of Mach. I would strongly advise against  using 043 at the moment unless you are willing to accept risks and actually there are fixes done to previous versions that I know are not in 043.

What other problems have you got with the SS?

I used a PoKeys in my pendant and had FRO from a pot and it worked every bit as smooth as from the screen.

Hood
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 26, 2009, 10:31:44 PM
There are fixes in 042 that are not in 043??? That is a bit interesting.

OK, I am downloading Mach3 R3.042.024 and will give it a try. I am getting ready to do a whole lot of cutting and I need good results.

I better setup some of my test programs to check it out.

Is there any rule as to installing software over the top of previous versions?

I usually just make a backup copy of the directory and then let the installer write over the previous version.

Curt
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 26, 2009, 10:55:16 PM
I just ran my test and 3.042 behaves the same at 3.043.000.

I call on the software gods of Mach3, please make FRO adjustments obey acceleration limits.  :'(

Thanks,
Curt
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Hood on March 27, 2009, 04:12:46 AM
It works correctly for me  and so far I have not seen anyone else say otherwise, they may start now LOL
I however do not have the slider on my screenset and there is a possibility that that may make a difference, I will test it out for you when I get a chance.

As for the 043 not having fixes that the previous 042 versions have there is a reason for that, 043 was put out for  a very specific reason, it had different cutter comp code in it. Ver 043 has not changed for quite a while now where 042 versions have been updated quite a few times, that is why there are at the moment 3 revisions of Mach for download, usually there are only 2, lockdown and release candidate.

If you want to attach your xml I can possibly try out your settings on my mill to see if I have issues with them.
Hood
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 27, 2009, 06:33:34 AM
Right now I am avoiding touching the Feed Override while it is moving. I have to Feed Hold, then adjust, then start again.

By the way I have been making chips all day and am having good results by staying away from buttons and nobs that cause me problems.

Here is a video I just shot, my stepper based mill cutting up to 100IPM.

http://www.youtube.com/watch?v=tTDpoNrs7rI

I don't think my configuration will help, if you have Servos then that is a completely different type of controller.

Curt
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Hood on March 27, 2009, 07:08:41 AM
I have steppers on the Bridgeport, have tested with my screenset and its fine, will load the standard screenset with the slider and see how that performs.
Hood
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Hood on March 27, 2009, 10:52:51 AM
Tested it with the standard screenset which has the slider, as opposed to the buttons I use on mine, and yes it screws up if you slide too fast. This is strange as I have used a pot and can wind fast and it seems to act fine. I dont have my pendant here as I have dismantled it to make a new front plate but will see if I can temporarily cobble it back together to test out tomorrow and see if it does indeed work like I am remembering.
I have also done another test which is to enter the FRO % direct into the DRO and that seems to sort of work, it will work if you slowly enter decreasing values but will stop if you jump too quick but seems not to screw up totally like the slider is doing.
 Seems like there may be a couple of issues on the go here, one is definitely a problem with the SS and one could be with Mach.


 There are big changes coming online shortly in Mach and this should make integrating external devices such as the SS much easier and cleaner. I cant talk for Greg but I suspect¬† you probably wont get any action on the plugin until then as any work done now will have to be redone with the newer version, so it would be a lot of effort for a short term fix. Timescale for the new Mach is in the next month or so but that could vary depending on whether things proceed to plan.

 If you are wanting to use FRO it may be a good idea to remove the slider and add up/down buttons to a screen and you shouldnt have the¬† missing step errors, I certainly dont seem to have them anyway. You will however get the FRO stopping motion once you get down a bit but even resetting direct to 100% seems to be fine and it seems to observe the accel.

Hood
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 30, 2009, 05:34:29 AM
Thanks for confirming at least it isn't just me that can reproduce this problem.

It would be nice if the Mach folks could look into this because I am sure it will be a while before the bugs are worked out of anything new considering how long version 3 has been around and it seems to still have bugs.

I think we should start a thread of things someone should NOT do when using Mach3 with a  SmoothStepper. I have learned to not press a lot of buttons over the past two weeks.
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Overloaded on March 30, 2009, 07:03:54 AM
Quote
I have learned to not press a lot of buttons over the past two weeks.
Please compile a list of the "SS Dont's" and post it here.
I will be hooking one up soon and would like to be aware.
Thanks,
RC
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Hood on March 30, 2009, 07:12:50 AM
Hooked up the pendant yesterday with the pot on it for FRO on it and it seemed to work fine. However I was only feeding at 500mm/min, I bumped the feedrate up to 2500mm/min and it started to act funky just like the slider had been doing. Looks like its if there is a big jump in the feedrate the SS gets confused, 10% of 500 is only a 50mm/min drop but 10% of 2500 is 250 which is a big jump, so  in the mean time stepping down a bit slower is fine, not easy to do with the slider though.
Hood
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: tubular2000 on March 30, 2009, 09:35:33 AM
i have a related question about this issue. i have noticed that on the mill screen, when using the up and down fro button, the dro move by increment of 10%. but on the lathe screen it move by increment of 5 in/min wich is way to much an increment. and if i increment, it will be in effect only after the next G1 command (won't apply in the middle of a G1 move)
Title: Re: Feed Rate Override needs to take acceleration into account
Post by: boilerbots on March 31, 2009, 06:32:33 AM
Quote
I have learned to not press a lot of buttons over the past two weeks.
Please compile a list of the "SS Dont's" and post it here.
I will be hooking one up soon and would like to be aware.
Thanks,
RC

Then you should read this thread over at the Warp9 forums:

TOPIC:  Tips to make your life with Mach3 and SS better
http://www.warp9td.com/index.php?option=com_fireboard&Itemid=33&func=view&id=1608&catid=7

Title: Re: Feed Rate Override needs to take acceleration into account
Post by: Overloaded on March 31, 2009, 07:15:07 AM
Will do....thanks,
RC