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Need Help to Improve Surface Finish

TomS

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#1
At the suggestion of another forum member I'm starting this thread here for more exposure. A few week ago I opened up this discussion on my PM-932 build there here - http://www.hobby-machinist.com/threads/taking-the-cnc-plunge.24858/. It starts on page 12, post #344.

Now to the issue at hand. A few months back I installed a 3ph motor and VFD to my CNC converted PM-932. This also included upgrading the stock tapered roller spindle bearings to angular contact bearings (ABEC 5 for the top bearing and ABEC 7 for the lower bearing). Then I followed up with new electronics: a PMDX-126 breakout board, a PMDX-107 spindle control board, and a ethernet smoothstepper. All these "improvements" are working well except that since then the surface finish on angular and circular cuts is terrible.

I've tried a multitude of Mach3 CV settings such as CV Distance Tolerance, bumped Look Ahead to 200 lines, made sure G100 Adaptive Nurbs CV was turned off, Shuttle Acceleration, changed speeds, feeds, cutter size, number of flutes, DOC, WOC, feed direction and spindle drive belt. Also made some changes to my CAM program but still no change in surface finish. Even went back and checked gib adjustment, twice. No improvement in surface finish. I'm at a loss as to what's causing this.

Any help is appreciated.

Here are a couple of pictures for reference.

X and Y straight cuts give me a very smooth surface finish.
20170720_083723_resized.jpg

This is the surface finish I get with angular and circular cuts.
20170720_084639_resized.jpg
 

countryguy

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#2
There are a few ideas in this post:
https://www.machsupport.com/forum/index.php?topic=19101.0
.If you are cutting the circle with GCode created from a CAD program then there is a good chance that the circumference consists of many straight lines and depending on the resolution it could be quite rough and lead to the problem you describe.
Try cutting a circle using the Mach wizard which uses circular interpolation, which is as near to a curve as you are going to get, and see if that improves the situation

Some detail in this post maybe could help?
http://www.cnczone.com/forums/mach-mill/213832-cnc-software-posts.html

I was wondering what design CAD tool and which CAM is being used?
 

gradient

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#3
Why not mill the hole almost to size and finish up with a boring tool to get to final size? The boring tool will leave a very smooth and uniform finish since it is not interpolating circular motion.
 

TomS

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#4
There are a few ideas in this post:
https://www.machsupport.com/forum/index.php?topic=19101.0
.If you are cutting the circle with GCode created from a CAD program then there is a good chance that the circumference consists of many straight lines and depending on the resolution it could be quite rough and lead to the problem you describe.
Try cutting a circle using the Mach wizard which uses circular interpolation, which is as near to a curve as you are going to get, and see if that improves the situation

Some detail in this post maybe could help?
http://www.cnczone.com/forums/mach-mill/213832-cnc-software-posts.html

I was wondering what design CAD tool and which CAM is being used?
I'm using CamBam for CAD and CAM but have used Fusion 360 for both as well with the same results. I'll try the Mach wizard and see what happens.

That CNCZone thread was quite interesting. I need to study it further to find out how it compares to my gcode.

Thanks

Edit: I did zoom in on the arcs and did not see any straight line segments. CamBam has an "arc fit" setting. I set this to .002".
 
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TomS

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#5
Why not mill the hole almost to size and finish up with a boring tool to get to final size? The boring tool will leave a very smooth and uniform finish since it is not interpolating circular motion.
The rough/faceted surface is on all internal and external angle and arc cuts. There is an underlying problem that I'm trying to nail down so I can correct it. I didn't have this problem before the VFD/electronics upgrade.
 

spumco

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#6
Ditto above from countryguy.

A very quick way to see if it's hardware or software is to look at the code section with the hole that has unacceptable surface finish. Is the code posted as arc moves or is it G1 X/Y moves? If it's arc moves and it looks like that, you'll be chasing backlash, vibration, chattering, or some other mechanical gremlin. Something to consider is your steps per rev or steps per inch - a coarser setting (no micro steps) will not be able to move in a curve as smoothly as if you're at 5x or 10x microsteps. Linear moves along the x or y will be fine unless you're at extremely low feed rates where the stepper poles are cogging along: thump thump thump.

If you still suspect hardware, either use the Mach wizard or your CAM program to generate a very simple boring operation.

If the moves are posted as G1 linear moves, the the threads above should be helpful. If you don't get it right away, do a little math and see how long each linear segment is. Like this:

001 G1 Fxx X1.002345 Y1.00566 (or whatever)
002 X1.003456 Y1.00666 (again, whatever the values are)

In this case, you can estimate the length of each segment between each code line, given the angle of movement. If the segments are more than .002 (ish) long they'll show up visually in a fresh cut.

With a small diameter cutter longer segment lengths will show up as faceting. [I know, it shouldn't matter about the cutter, but cutter deflection can make it look worse).

So... what CAM are you using? I'm using Fusion 360, and while it's great so far there are a few settings that can output some funky code.
 

spumco

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#8
So, assuming you're not getting a series of coarse resolution linear moves from your CAM, and Mach is displaying the code as arc segments... the next check is the hardware I mentioned above. How many steps per inch is your machine set to?
 

TomS

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#9
Ditto above from countryguy.

A very quick way to see if it's hardware or software is to look at the code section with the hole that has unacceptable surface finish. Is the code posted as arc moves or is it G1 X/Y moves? If it's arc moves and it looks like that, you'll be chasing backlash, vibration, chattering, or some other mechanical gremlin. Something to consider is your steps per rev or steps per inch - a coarser setting (no micro steps) will not be able to move in a curve as smoothly as if you're at 5x or 10x microsteps. Linear moves along the x or y will be fine unless you're at extremely low feed rates where the stepper poles are cogging along: thump thump thump.

If you still suspect hardware, either use the Mach wizard or your CAM program to generate a very simple boring operation.

If the moves are posted as G1 linear moves, the the threads above should be helpful. If you don't get it right away, do a little math and see how long each linear segment is. Like this:

001 G1 Fxx X1.002345 Y1.00566 (or whatever)
002 X1.003456 Y1.00666 (again, whatever the values are)

In this case, you can estimate the length of each segment between each code line, given the angle of movement. If the segments are more than .002 (ish) long they'll show up visually in a fresh cut.

With a small diameter cutter longer segment lengths will show up as faceting. [I know, it shouldn't matter about the cutter, but cutter deflection can make it look worse).

So... what CAM are you using? I'm using Fusion 360, and while it's great so far there are a few settings that can output some funky code.
Heading to the shop this morning to test out the wizards.

I have microstepping set at 1000. My machine has been cutting good surfaces for the past couple of years at this setting. I did try 2000 and 5000 but no change in the finish quality.

CamBam is generating arc moves as you can see in the attached gcode file. Here's a picture of the finish. It's rougher than it looks. The picture I posted above is more representative of the finish.

20170720_084350_resized.jpg
 

Attachments

TomS

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#10
As countryguy suggested I read through the cnczone thread and changed my configuration as follows. Turned off CV Distance and Feedrate on the Settings screen. Went into General Config and made sure all of the CV selections were not checked. I also upped my acceleration from 15 to 25 on the X and Y axis. I then ran the Mach3 circular pocketing wizard. The finish was only marginally better. Tried it again in absolute mode and again with Exact Stop enabled. No noticeable difference in the surface finish. What is interesting is I was expecting a herky jerky motion using Exact Stop but it was very smooth.

If it was mechanical I would expect to see surface roughness on straight line cuts also. But I'm not. Even if I had excessive backlash I would think that it would be taken up on 90 deg. arc cuts. Arc cuts are very rough. Still at a loss.
 

spumco

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#11
Ok, code looks good in simulation mode using UCCNC (seeing if Mach was lying to you). As you said it's a series of arc moves so surface finish isn't in the code.

Not the spindle, even though you recently replaced the bearings and might have possibly gotten that wrong. If that were the case you'd be breaking tools or seeing the same problem on straight axis cuts too.

As you say, it's probably not backlash, as I think that causes out of round at the direction changes and not just a general surface finish problem on arcs. On the other hand, backlash-induced surface problems may not show up in a straight axis cut if the axis with slop is snug due to cutter pressure.

So... If not mechanical, and not the code, then what's left is Mach and your motion control hardware. If you want to rule out the VFD making noise and causing the stepper drivers to freak out, stick a fine point pen in the spindle and have it trace on paper with the spindle off. Just do a series of big arc moves and some direction changes. You might be able to see if there's any jittering in the lines.

The pen might be too coarse to see problems, but a scribe on a flat piece of aluminum going down 0.001" might be fine enough if you put a thin layer of dyekem on it first. Another thing to consider would be to see if your Z is oscillating up and down when the VFD is on. Using another flat piece of aluminum or MDF (or something else really flat), run back and forth with the spindle off and a DTI attached to the head and indicating the surface. Then do it again with the spindle on (no tool needed) and see if the needle is bouncing more. I would think that VFD noise would show up on that axis as well as the X/Y.

I'm also running a 126 and 107 board, so I don't think there's an issue there with steps making it through your BOB to the drivers. If the 107 board were freaking out, you'd hear the spindle throbbing as the RPM changed. Besides the VFD, motor, 126 & 107, what else have you changed? My guess is most of the wiring is new or different, but you'd obviously know better than I. Have you followed best practices and isolated all of your signal wires from the VFD? Is the VFD in a separate enclosure from the BOB & ESS?

I guess another thing to try would be to make a fairly deep cut in two (or three) depths. Then check the surface with a magnifying glass - if the surface lines line up everywhere, the machine is being commanded (by something) to generate that surface you can completely rule out lost motion or mechanical issues. There's no way noise or mechanical problems would duplicate a surface like that in the exact same location over two or three passes.

Seriously not an expert here, but maybe something will help.

-S
 

TomS

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#12
Ok, code looks good in simulation mode using UCCNC (seeing if Mach was lying to you). As you said it's a series of arc moves so surface finish isn't in the code.

Not the spindle, even though you recently replaced the bearings and might have possibly gotten that wrong. If that were the case you'd be breaking tools or seeing the same problem on straight axis cuts too.

As you say, it's probably not backlash, as I think that causes out of round at the direction changes and not just a general surface finish problem on arcs. On the other hand, backlash-induced surface problems may not show up in a straight axis cut if the axis with slop is snug due to cutter pressure.

So... If not mechanical, and not the code, then what's left is Mach and your motion control hardware. If you want to rule out the VFD making noise and causing the stepper drivers to freak out, stick a fine point pen in the spindle and have it trace on paper with the spindle off. Just do a series of big arc moves and some direction changes. You might be able to see if there's any jittering in the lines.

The pen might be too coarse to see problems, but a scribe on a flat piece of aluminum going down 0.001" might be fine enough if you put a thin layer of dyekem on it first. Another thing to consider would be to see if your Z is oscillating up and down when the VFD is on. Using another flat piece of aluminum or MDF (or something else really flat), run back and forth with the spindle off and a DTI attached to the head and indicating the surface. Then do it again with the spindle on (no tool needed) and see if the needle is bouncing more. I would think that VFD noise would show up on that axis as well as the X/Y.

I'm also running a 126 and 107 board, so I don't think there's an issue there with steps making it through your BOB to the drivers. If the 107 board were freaking out, you'd hear the spindle throbbing as the RPM changed. Besides the VFD, motor, 126 & 107, what else have you changed? My guess is most of the wiring is new or different, but you'd obviously know better than I. Have you followed best practices and isolated all of your signal wires from the VFD? Is the VFD in a separate enclosure from the BOB & ESS?

I guess another thing to try would be to make a fairly deep cut in two (or three) depths. Then check the surface with a magnifying glass - if the surface lines line up everywhere, the machine is being commanded (by something) to generate that surface you can completely rule out lost motion or mechanical issues. There's no way noise or mechanical problems would duplicate a surface like that in the exact same location over two or three passes.

Seriously not an expert here, but maybe something will help.

-S
Thanks for your input. Yes, my wiring is new with the electronics installation. All of the spindle control wiring has the drain wire grounded in the VFD enclosure. Limit switch drain wire is grounded in the BoB enclosure. Driver drain wires are grounded in the Driver enclosure. I make it a habit not to bundle power cables with control wiring and do my best to separate them as much as possible. Hope I did this right.

I don't think it's bearings either. The preload is in the ball park because I can run the spindle at 8600 on long runs (more than an hour) I get less than 30 deg. F temperature rise.

Tomorrow I'll run the tests you suggest and see what I get.

For everyone's reference I've attached a few pictures of my control cabinet.

Here's a shot of my BoB/ESS enclosure. 115vac enters at the top. Limit switch and 107 control wiring, ethernet cable, and driver to BoB wiring at the bottom.
20170729_142757.jpg 20170714_152848_resized.jpg

My VFD enclosure. 107 board wiring enters at the top. 230vac comes in on lower left back (black and white wires) and exits to the motor lower left front. PT cable enters above the high voltage wiring.
20170806_165915_resized.jpg

View of my control cabinet. Power panel and e-stop on the upper left. Power supplies and driver are in the lower rollaway drawer. VFD enclosure is lower left and BoB/ESS enclosure is lower right.
20170806_170834_resized.jpg
 

TomS

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#13
I created a 4-1/2" diameter circle and generated gcode so I could monitor Z axis movement as Spumco suggested. The DTI is contacting the top of the moveable jaw on my 5" Kurt clone vise that is held down to the table with four strap clamps. The attached video shows the DTI needle bouncing around quite a bit. Looks like I have some harmonics being fed back into the table. Source of my poor surface finish? Steppers maybe? BTW - this test is with the VFD off.
 

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spumco

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#14
Now we're getting somewhere. Great video, BTW.

Next thing I would check is to see if the PMDX-126 is outputting signals to the Z-driver while you run that test. Open the cabinet and see if the Z pin LED is flickering while the X/Y are doing the circle thing. If it is, then open the Mach diagnostics page to see if Mach is outputting on those pins even though your code isn't commanding any motion.

Or try it with the Z-driver unplugged and see if the Z is being commanded (again, by noise or by Mach or something else) to move or if you're getting mechanical resonance. You can also try it at a different feed rate - I find my steppers hum quite a bit at about 12-15IPM, and I've read that the typical 2-pole steppers are prone to this at about this speed. Can't remember where I read that, but there you go. Maybe it was one of Tormach's white papers, which are excellent by the way.

Run the test(s) again and then we'll start speculating on root cause. And pray it isn't a combination of mechanical AND electrical gremlins...

-S
 

TomS

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#15
Now we're getting somewhere. Great video, BTW.

Next thing I would check is to see if the PMDX-126 is outputting signals to the Z-driver while you run that test. Open the cabinet and see if the Z pin LED is flickering while the X/Y are doing the circle thing. If it is, then open the Mach diagnostics page to see if Mach is outputting on those pins even though your code isn't commanding any motion.

Or try it with the Z-driver unplugged and see if the Z is being commanded (again, by noise or by Mach or something else) to move or if you're getting mechanical resonance. You can also try it at a different feed rate - I find my steppers hum quite a bit at about 12-15IPM, and I've read that the typical 2-pole steppers are prone to this at about this speed. Can't remember where I read that, but there you go. Maybe it was one of Tormach's white papers, which are excellent by the way.

Run the test(s) again and then we'll start speculating on root cause. And pray it isn't a combination of mechanical AND electrical gremlins...

-S
Yeah, I think we've hit on something. I'm going to run the test again with the VFD on and spindle turning and see happens. Yes, I'll mount the DTI on the head before turning on the spindle. Then I'll run it and check the BoB Z axis lights.

I ran the DTI test at 5, 10 and 20 IPM. Didn't notice any significant difference in needle bounce.

And I'll take a look at the Tormach white papers.
 

countryguy

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#16
Awesome stuff Tom and SpumCo... Nice collaboration there for sure. I am not into the smooth-stepper sides much as we moved to Centroid and a server based system for our upgrade. Sounds like you have the source about nailed down. I hope this fix is an easy one!
 

spumco

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#17
As much as I'd like to claim victory, I don't think anything is about nailed down at this point. We know it isn't X/Y backlash, and it isn't spindle bearings. And we know the code is good-to-go.

Depending on what he finds in the next round of testing we may find it's noise (from what?), mechanical vibration (from what?), the ESS flipping out, or Mach causing the issue.

Or some combination of the above, which would suck.

Tom may get lucky and find something silly like a loose drain wire, but if I'm involved my typical luck will rub off and he'll be chasing his tail for a while.

-S
 

jbolt

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#18
*updated for clarity*

Add to when you are troubleshooting and you get into the ground wires try disconnecting all the drain wires except the control wires from the 107 to the VFD. Ground issues can be tricky to figure out. We went through ground issues with the router/mill we built for the school. Our issue was different but we found that even though we thought we had done the grounds correctly we created a condition that was worse than not having a ground at all.


Sent from my SM-G955U using Tapatalk
 
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jbolt

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#19
I created a 4-1/2" diameter circle and generated gcode so I could monitor Z axis movement as Spumco suggested. The DTI is contacting the top of the moveable jaw on my 5" Kurt clone vise that is held down to the table with four strap clamps. The attached video shows the DTI needle bouncing around quite a bit. Looks like I have some harmonics being fed back into the table. Source of my poor surface finish? Steppers maybe? BTW - this test is with the VFD off.
I'm not sure I would read too much into the needle movement running across the top surface of your vice. I would be more inclined to mount the TDI on the head or dovetail plate and measure against a fixed point on the column and take away any variables of the saddle, table and vice.
 

jbolt

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#20
I see in your photos that the enable wires are not connected to the BOB, are they still hooked up to the drives? If so disconnect them at the drives. Also make sure the bare ends are not touching the metal back panel. On the BOB enclosure is the 110vac earth ground attached to anything else besides the back plate?

What we learned from the school ground issues was that terminated wires or improperly terminated wires acted like antennas, the grounding system was undersized and it was easy to create ground loops.

Where the motor drain entered the metal enclosure we had not terminated them at the enclosure wall but had instead ganged the drains inside the enclosure to a single ground lug. By not terminating the drains at the enclosure wall the drain wires inside the enclosure acted as antennas picking up interference from the inside.

Another issue was all the components of the system were grounded but the ground was not robust enough and we had daisy chained the grounds. The best strategy is to do a star ground system where each enclosure or device like the VDF and the machine are grounded to a single point separately and to not daisy chain the grounds. We moved to a 3/8" wide braided ground strap that was grounded to the machine structure, electronic enclosure case and VFD base as separate runs being careful not to inadvertently create loops. The VFD on this machine is mounted outside of the electronics enclosure. The electronics enclosure also contained the main power disconnect so it was also terminated to earth ground. The electronics enclosure was divided inside by full depth metal baffles to separate the high voltage from the low voltage and again for the signal wiring. Basically separate Faraday cages in one enclosure. In the course of troubleshooting the original build we tried separating out the the encoder termination boards in a separate metal enclosure but in the process mistakenly created a ground loop which made things worse.

On my PM-932 CNC conversion I removed any unnecessary wires (stepper enable) and any unused wires from the system. All the motor wires, limit switch wire, and spindle control wire drains terminate at the metal enclosure wall. There are no shielded wires or drain wires inside the electronics enclosure(s).
 

TomS

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#21
I ran the circle test again with the VFD on and spindle running at 2200 rpm. DTI needle bounce was the same as the previous test. Looks like the vfd has no effect, which is good. While running the test I monitored the Z axis step and dir pin lights on the BoB. The step pin light (pin 5) stays on throughout the run. The Dir pin light (pin 4) turns on only at the end during Z retract.

Looking over my driver and BoB wiring, again, and had a "Doh" moment. I have the drain wire connected to ground on both ends. Easy enough to fix but still can't believe I did it. I'll disconnect one end and run the test again and see how the DTI needle responds. If no change then reconnect and disconnect the other end. Going to run the test as jbolt suggested too.
 

TomS

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#22
I see in your photos that the enable wires are not connected to the BOB, are they still hooked up to the drives? If so disconnect them at the drives. Also make sure the bare ends are not touching the metal back panel. On the BOB enclosure is the 110vac earth ground attached to anything else besides the back plate?

What we learned from the school ground issues was that terminated wires or improperly terminated wires acted like antennas, the grounding system was undersized and it was easy to create ground loops.

Where the motor drain entered the metal enclosure we had not terminated them at the enclosure wall but had instead ganged the drains inside the enclosure to a single ground lug. By not terminating the drains at the enclosure wall the drain wires inside the enclosure acted as antennas picking up interference from the inside.

Another issue was all the components of the system were grounded but the ground was not robust enough and we had daisy chained the grounds. The best strategy is to do a star ground system where each enclosure or device like the VDF and the machine are grounded to a single point separately and to not daisy chain the grounds. We moved to a 3/8" wide braided ground strap that was grounded to the machine structure, electronic enclosure case and VFD base as separate runs being careful not to inadvertently create loops. The VFD on this machine is mounted outside of the electronics enclosure. The electronics enclosure also contained the main power disconnect so it was also terminated to earth ground. The electronics enclosure was divided inside by full depth metal baffles to separate the high voltage from the low voltage and again for the signal wiring. Basically separate Faraday cages in one enclosure. In the course of troubleshooting the original build we tried separating out the the encoder termination boards in a separate metal enclosure but in the process mistakenly created a ground loop which made things worse.

On my PM-932 CNC conversion I removed any unnecessary wires (stepper enable) and any unused wires from the system. All the motor wires, limit switch wire, and spindle control wire drains terminate at the metal enclosure wall. There are no shielded wires or drain wires inside the electronics enclosure(s).
All very good points. Thanks.

If I understand correctly you are saying to run a ground from each enclosure to the machine. Then terminate/star ground all incoming cable grounds at the enclosure wall. And yes, the 110vac ground is connected to the back plate only. Probably should ground the back plate too.
 

spumco

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#23
Tom,

Yes - star ground, not daisy chain. Also, PMDX advised me to run a drain from the 126 mounting holes to the star ground point inside the enclosure and not rely on the board to backplane mount screws. This may not be an issue for you, but if you're in there fiddling around and doing some wiring it's easy enough to do.

Good to hear there's no difference in with the VFD on or off. And I'm interested to hear how the DTI responds when you're indicating the head to column.
 

TomS

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#24
Tom,

Yes - star ground, not daisy chain. Also, PMDX advised me to run a drain from the 126 mounting holes to the star ground point inside the enclosure and not rely on the board to backplane mount screws. This may not be an issue for you, but if you're in there fiddling around and doing some wiring it's easy enough to do.

Good to hear there's no difference in with the VFD on or off. And I'm interested to hear how the DTI responds when you're indicating the head to column.
Jbolt's post got me thinking about my wiring. I've gone through 3 upgrades since the initial installation and the wiring is beginning to be a bit untidy. Before doing any more testing I'm going to clean things up. Finding the driver/BoB ground loop may be significant. We'll see. And I will run a drain wire from the BoB to the star ground lug.
 

jbolt

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#26
All very good points. Thanks.

If I understand correctly you are saying to run a ground from each enclosure to the machine. Then terminate/star ground all incoming cable grounds at the enclosure wall. And yes, the 110vac ground is connected to the back plate only. Probably should ground the back plate too.
For the grounding system I use the location of where earth ground enters the system as the starting location for each arm of the ground runs.

On the VFD you have earth ground from the 220vac so nothing else needs to be done there other than the drain wire from the spindle control board to the VFD base ground.

For the BOB enclosure, if you ground the BOB to the ground system, don't run a separate ground to the back plate. I would keep the BOB isolated from the back plate to reduce the chance of the back plate picking up interference.

With your VFD and BOB enclosures being plastic you don't get the added protection of the Faraday cage affect of a full metal enclosure. Even with a full metal enclosure the openings in the enclosure need to be kept as small as possible for it to work properly.
 

homebrewed

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#27
Jbolt's post got me thinking about my wiring. I've gone through 3 upgrades since the initial installation and the wiring is beginning to be a bit untidy. Before doing any more testing I'm going to clean things up. Finding the driver/BoB ground loop may be significant. We'll see. And I will run a drain wire from the BoB to the star ground lug.
Your comment about untidy wiring got my attention.

Cable dress can be important when it comes to reducing magnetic interference. You have a situation where you have conductors carrying high current to your steppers, and conductors that are relatively high impedance signal lines. Magnetic coupling between them can cause problems (ask me how I know). Shielding in the form of copper braid really doesn't address this kind of interference. Good cable dressing, and keeping high current lines separated as far as practically possible from signal lines, is the way to do it. The cable dresing should minimize the area between your drain lines and signal lines. See my illustrations below

Example 1, bad lead dress (lines far apart)
signal line ---------------------------------------------------------------------------



Drain line ---------------------------------------------------------------------------

Example 2, better lead dress
Signal -----------------------------------------------------------------------------
Drain-----------------------------------------------------------------------------

Example 3, Even better lead dress (this is hard to draw so I won't): make a twisted pair using the signal and drain lines. Induced voltages tend to cancel. I've even seen this approach used in high frequency integrated circuits.

Reason: the larger the spacing between the signal and drain lines, the more magnetic flux can pass through the loop that is formed, producing more induced voltage.

Ideally you'd also route your cables so the high current lines are at right angles to the signal lines but that could be difficult to do.
 

TomS

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#28
For the grounding system I use the location of where earth ground enters the system as the starting location for each arm of the ground runs.

On the VFD you have earth ground from the 220vac so nothing else needs to be done there other than the drain wire from the spindle control board to the VFD base ground.

For the BOB enclosure, if you ground the BOB to the ground system, don't run a separate ground to the back plate. I would keep the BOB isolated from the back plate to reduce the chance of the back plate picking up interference.

With your VFD and BOB enclosures being plastic you don't get the added protection of the Faraday cage affect of a full metal enclosure. Even with a full metal enclosure the openings in the enclosure need to be kept as small as possible for it to work properly.
Thanks for the clarifications. We're on the same page.
 

TomS

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#29
My plan for today was to have test data to share. Unfortunately not. I stripped out the unused X and Y Enable - wire and rerouted all of the drain wires. Also added a ground wire from the BoB to the star ground. Ran individual ground wires from the BoB/ESS enclosure and the motor driver enclosure then terminated them at the VFD ground lug. Powered up the system and the Y axis driver fault light is on. Checked all the wiring making sure the termination points were tight then double checked again. Made sure I hadn't crossed a wire and all is good there. Gave up for the day out of utter frustration. Tomorrow I'll swap out the Y driver with the X driver. If the green light comes on then it's the driver. If no green light then it's back to figuring out what changed. Sure would like to be making parts.