Posting my 1st programs on my Sherline chucker lathe, CAM is coming out of Fusion 360 and having an issue with the motors winding out like they are too slow to keep up with the tool/axis movements. I don't know for sure if these are rapid moves only but it seems to be happing while in the cut on some machining ops as well, for example, it's happing on the finish pass where its running over a chamfer and a on another area going around a fillet. I changed the max feed rate 3 times down to 15 and its still winding out the motor/s. I'm wondering if this is the correct setting to be adjusting or do I need to adjust acceleration or something else? As a result of this I'm having a lot of missed steps on both axis.
One thing im wondering IF it could be an issue is something Keith had pointed out to me a couple of times. In settings, I have my steps per rev set to 800 (as Per Sherline) but Keith has told me 1600 is standard. SO could this have an effect on what is happing? I checked with Sherline on this and they have told me there is a1600 steps per rev chip available. Should I upgrade and will faster chip resolve this issue?
Re: Motors are winding out on rapid moves
Posted: Mon Jan 17, 2022 5:13 pm
by cnckeith
post the offending g code program and a fresh report.zip so we have the information to comment.
Re: Motors are winding out on rapid moves
Posted: Mon Jan 17, 2022 9:49 pm
by martyscncgarage
BillB wrote: ↑Sun Jan 16, 2022 3:13 am
Posting my 1st programs on my Sherline chucker lathe, CAM is coming out of Fusion 360 and having an issue with the motors winding out like they are too slow to keep up with the tool/axis movements. I don't know for sure if these are rapid moves only but it seems to be happing while in the cut on some machining ops as well, for example, it's happing on the finish pass where its running over a chamfer and a on another area going around a fillet. I changed the max feed rate 3 times down to 15 and its still winding out the motor/s. I'm wondering if this is the correct setting to be adjusting or do I need to adjust acceleration or something else? As a result of this I'm having a lot of missed steps on both axis.
One thing im wondering IF it could be an issue is something Keith had pointed out to me a couple of times. In settings, I have my steps per rev set to 800 (as Per Sherline) but Keith has told me 1600 is standard. SO could this have an effect on what is happing? I checked with Sherline on this and they have told me there is a1600 steps per rev chip available. Should I upgrade and will faster chip resolve this issue?
Video clip would be helpful as well. Upload to YouTube, post it unlisted and SHARE a link here....
Not sure what "winding out" means....
Marty
Re: Motors are winding out on rapid moves
Posted: Tue Jan 18, 2022 3:30 am
by BillB
OK guys here is the report, gcode video. LMK if you want the Fusion File.
I think the video is a bit redundant showing where my part X & Z ends up after running the program, sorry.
Re: Motors are winding out on rapid moves
Posted: Tue Jan 18, 2022 10:20 am
by martyscncgarage
Your steppers are not "Winding out" They are stalling.
Unfortunately, you did not keep to ONE build thread. You have posts all over the place.
Be very specific and tell us what make/model stepper motors you are using, and the stepper driver?
I believe you are using the Sherline factory stepper motors and drivers and their power supply?
What does Sherline recommend for max rapid jog rate?
You have now found the problem with open loop steppers.
If the part is cutting fine, what is the feedrate there?
You need to cut down the MAX feedrate in the Wizard and retest.
Marty
Re: Motors are winding out on rapid moves
Posted: Tue Jan 18, 2022 4:42 pm
by cnckeith
as i stated before the answer making this machine perform is to replace the old sherline drives with a modern stepper drives (leadshine or gecko). this is cheap and easy to do.
cnckeith wrote: ↑Tue Jan 18, 2022 4:42 pm
as i stated before the answer making this machine perform is to replace the old sherline drives with a modern stepper drives (leadshine or gecko). this is cheap and easy to do.
cnckeith wrote: ↑Tue Jan 18, 2022 4:42 pm
as i stated before the answer making this machine perform is to replace the old sherline drives with a modern stepper drives (leadshine or gecko). this is cheap and easy to do.
cnckeith wrote: ↑Tue Jan 18, 2022 4:42 pm
as i stated before the answer making this machine perform is to replace the old sherline drives with a modern stepper drives (leadshine or gecko). this is cheap and easy to do.
So you talking about a gecko G540? IF I do it is that the ONLY thing i need to replace?
Bill, its all about your budget, what the machine can tolerate as far as rapids, and your end game.
These day's closed loop steppers have become more affordable. I don't use open loop steppers any more.
Closed loop steppers have an encoder and the motor position is monitored by the axis motor drive. The drive receives pulses from Acorn and commands the motor to turn the proper number of steps and watches the encoder to ensure it is in position. This is a hybrid closed loop system.
There are many vendors that sell them. John at automationtechnologiesinc.com sells these and I have used them on Emco PC5 CNC lathes and they work very well: https://www.automationtechnologiesinc.c ... e-kl-5080h
Gecko G540 will be a more robust drive and cost you about the same as two of the above motors. So if I were presented with the choice, I would take the closed loop stepper motors.
There are other vendors of those hybrid closed loop drives/motors. I prefer to use vendors I can work with should there be any issues down the road.
You should contact Sherline and present your video to them so they can see the performance of their "drive box" you must also provide your min and max jog rate speeds you have programmed. Also ask them what they feel is a reasonable MAX jog rate for that machine. (engineering design question, how much can the machine take mechanically)
Marty
Re: Motors are winding out on rapid moves
Posted: Wed Jan 19, 2022 12:17 pm
by martyscncgarage
From Sherline this morning:
Marty and Bill,
The max feed rate with our stepper motors and drive box is 32 in/min. In the video it looks like Bill is exceeding the max feed rate on his finish pass.
In addition to this. Stepper motors have the highest torque at the lower feed rate. As you increase the feed rate, the torque gets lower.
In our stepper motor specifications we state that the max feed of 32 in/min should be used for positioning the tool, not for cutting due to the much lower torque at the higher feed rate.
If you set the Acorn controller to a max feed rate of 32 in/min, this problem should be taken care of.
I believe that the current feed rate on the finish pass is exceeding the ability of the stepper motors.
I don’t know what size stepper motors Bill has on his machine (standard or hi-torque). The hi-torque stepper motors have plenty of torque for our machine. We have taken extremely deep cuts with these stepper motors to the point where the cut actually stalls the spindle motor and the stepper motor is still driving. Therefore, the problem as I see it in this case is that the feed rate is too high.