Max v2 issue with peaks and valleys in bed map[NEW DATA]

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clytle374
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Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Tue Jul 02, 2019 5:08 am

I've been fighting this for a long time. I upgraded to the duetwifi, replaced the skates, balls, springs, re-squared the frame. Picture is worth a lot.

It starts off along X axis(red arrow), reaches the end then steps Y positive and the head comes up. I believe this would occur at the Z tower as well if it was mapping towards/away from it.
Screenshot_20190702_041255.png
I've been through the machine several times. I started doing this manually with an indicator, and finally rigged up this probe... It does repeat.
IMG_20190603_174826.jpg
Springs removed in this picture to see if that helped by chance.
  • Upped motor current
    tightened belts, would love to know how tight they should be
    re-tightened and re-squared the frame
    blamed duet's math skills
    reinstalled rambo board
    uninstalled rambo
    tried 1.5A motor current
    checked steps per mm with gauge block
    shimmed bed to release stresses
    removed motors and belts to check for defects
Thinking about CF arms and metal ball kit from seemecnc, they are a little longer, and hopefully more rigid. Mapping might can help a little, but I think it'll make things worse with those peaks and valleys that don't really exist. It's a function of what direction the last move was. I don't thing effector tilt is causing it. I think I could see the tilt to get that much change.

Any ideas? I'm at the end of my rope, so to speak
Thanks
Cory
Last edited by clytle374 on Thu Jul 11, 2019 4:15 am, edited 1 time in total.

dc42
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Re: Max v2 issue with peaks and valleys in bed map

Post by dc42 » Tue Jul 02, 2019 8:36 am

Ridges along the X axis that turn into valleys at the other end is a classic sign of backlash in the mechanics. They appear because RRF probes along the X axis in opposite directions in alternate passes. With backlash, the exact nozzle height at a particular point depends on the direction in which you approach the point.

So check that the carriages move smoothly along the towers, the ball joints rotate smoothly, the belts are taut. and the motor pulley grub screws are tight.
Last edited by dc42 on Mon Jul 08, 2019 3:10 pm, edited 1 time in total.

clytle374
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Re: Max v2 issue with peaks and valleys in bed map

Post by clytle374 » Wed Jul 03, 2019 1:27 am

Belts too tight is the only option left.
I'll try that when I can get back to it
Thanks
Cory

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Re: Max v2 issue with peaks and valleys in bed map

Post by clytle374 » Fri Jul 05, 2019 1:35 am

Before I had used needle nosed pliers as levers to pry between towers and idlers. I would love to have an idea where tension should be. Doing testing now with loser belts. I can't imagine them being run tighter. Any actual way to know.

At the center of the bed, if I jog up .05mm a few times and back down the same number of times it's within .0127mm. Of course I should try that off to the edge of the bed to be consistent.

Thanks
Cory

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Re: Max v2 issue with peaks and valleys in bed map

Post by clytle374 » Fri Jul 05, 2019 8:31 am

Loosened the belts, then tight again. Found motor current helps.

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Re: Max v2 issue with peaks and valleys in bed map

Post by clytle374 » Sat Jul 06, 2019 5:02 am

I don't have that much backlash in the system. I've check a few different ways. Ordering some .9 degree stepper motors.

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Re: Max v2 issue with peaks and valleys in bed map

Post by dc42 » Mon Jul 08, 2019 3:12 pm

Try moving to X0 Y0, then to X100 Y0, then measure the Z probe trigger height a few times. Then move to X<max> Y0, then X100 Y0, and re-measure the trigger height. That will show up the backlash.

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Re: Max v2 issue with peaks and valleys in bed map

Post by clytle374 » Tue Jul 09, 2019 9:58 pm

dc42 wrote:
Mon Jul 08, 2019 3:12 pm
Try moving to X0 Y0, then to X100 Y0, then measure the Z probe trigger height a few times. Then move to X<max> Y0, then X100 Y0, and re-measure the trigger height. That will show up the backlash.
Thanks, I will try that as soon as I can. I've been thinking it's lost torque in the steps, which is why I ordered the .9 Deg steppers. For some

I had measured back lash by zeroing an indicator on the bed, stepping down a couple mm, then back up the same distance. I was showing about .001"(0.0254mm) backlash that way. I should have repeated this at several Z heights over the distance of a full step since my thinking was that it was sagging in microsteps.

Thanks
Cory

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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Thu Jul 11, 2019 4:15 am

Went ahead a put the .9 deg steppers in. Didn't learn anything there other than a company never to do business with again. If your stock stepper motors have company name that would abbreviate AT, well, you were warned. Refunded parts before shipping that were supposed to be in stock without contacting me, ignored 2 emails, damaged motor.

Code: Select all

Position		Trigger heights
X0 Y0 			6.224, 6.217, 6.224
X100 Y0 		6.235, 6.235, 6.229
X140 Y0 			
X100 Y0			6.210, 6.210, 6.217
Looks pretty good to me.

So I'll try with some numbers over by the towers.

Code: Select all

Position		Trigger Heights
X0 Y0   		6.249, 6.242, 6.242
X86.6 Y-50		6.263, 6.276, 6.263
X121.24 Y-70		
X86.6 Y-50		6.226, 6.226, 6.220
If I go anywhere on the bed and feed Z down to zero the indicator, jog Z negative direction, then back up, I'm within .001" of being back at zero. The numbers in my first test at X100 and X140 matches pretty much exactly the ,001"(.0254mm) backlash I've been seeing. That is how you check machine tools for backlash, seems like it should work here. Actually seems to work, at least in normal realm... Not over near the towers when quantum mechanics seem to take over. But it's still not horrible.

So I wrote a little program to pick back and forth over in the trouble area. My bedmap was done at 13mm spacing. So that is the number I'm using. Points and trigger heights listed, moving one direction, then reversing the path.

Code: Select all

G28
G1 X120. Y-70. Z11. F1500. ;point #1 Stopped at height 6.383 mm
G1 X120. Y-57. Z11. F1500. ;point #2 Stopped at height 6.295 mm
G1 X120. Y-44. Z11. F1500. ;point #3 Stopped at height 6.271 mm
G1 X107. Y-44. Z11. F1500. ;point #4 Stopped at height 6.232 mm
G1 X107. Y-57. Z11. F1500. ;point #5  Stopped at height 6.310 mm
G1 X107. Y-70. Z11. F1500. ;point #6 Stopped at height 6.315 mm
G1 X107. Y-57. Z11. F1500. ;point #5 Stopped at height 6.260 mm
G1 X107. Y-44. Z11. F1500. ;point #4 Stopped at height 6.244 mm
G1 X120. Y-44. Z11. F1500. ;point #3 Stopped at height 6.340 mm
G1 X120. Y-57. Z11. F1500. ;point #2 Stopped at height 6.364 mm
G1 X120. Y-70. Z11. F1500. ;point #1 Stopped at height 6.364 mm
These seem to sometimes look like backlash, but other times be pretty good.

Am I asking too much from the printer? Is this normal? I've burnt up so much time on this it's getting ridiculous.
Thanks
Cory

Machine info:
.config

Code: Select all

M665 L291.060:291.060:291.060 R144.257 H368.890 B140.0 X-0.009 Y0.368 Z0.000
M666 X0.088 Y0.191 Z-0.279 A-0.09 B-0.24

; Drives
M569 P0 S0                                  ; Drive 0 goes forwards
M569 P1 S1                                  ; Drive 1 goes forwards
M569 P2 S0                                  ; Drive 2 goes forwards
M569 P3 S0                                  ; Drive 3 goes forwards
M350 X16 Y16 Z16 E16 I1                     ; Configure microstepping with interpolation
M92 X160.0 Y160.0 Z160. E92.5            ;92.65 Set steps per mm
M566 X800.00 Y800.00 Z800.00 E1200.00    ; Set maximum instantaneous speed changes (mm/min)
M203 X18000.00 Y18000.00 Z18000.00 E1200.00 ; Set maximum speeds (mm/min)
M201 X2000.00 Y2000.00 Z2000.00 E2000.00    ; Set accelerations (mm/s^2)
M906 X1500.00 Y1500.00 Z1500.00 E800.00 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30                                     ; Set idle timeout

; Axis Limits
M208 Z0 S1                                  ; Set minimum Z

; Endstops
M574 X2 Y2 Z2 S1                            ; Set active high endstops

; Z-Probe
M558 P4 H3.3 F30 T1800                     ; Disable Z probe but set dive height, probe speed and travel speed
M557 R140 S13                               ; Define mesh grid
G31 Z6.256
; Heaters
M307 H0 B0 S1.00                            ; Disable bang-bang mode for the bed heater and set PWM limit
;M305 P0 T100000 B4138 R4700                 ; Set thermistor + ADC parameters for heater 0
M305 P0 T100000 B4425 R4700 L0
M143 H0 S120                                ; Set temperature limit for heater 0 to 120C
;M305 P1 T100000 B4138 R4700                 ; Set thermistor + ADC parameters for heater 1
M305 P1 T100000 B4725 C7.060000e-8 
M143 H1 S280                                ; Set temperature limit for heater 1 to 280C

; Fans
M106 P0 I0 F500 H-1                      ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
M106 P1 S1 I0 F500 H1 T45                   ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on

; Tools
M563 P0 D0 H1                               ; Define tool 0
G10 P0 X0 Y0 Z0                             ; Set tool 0 axis offsets
G10 P0 R0 S0                                ; Set initial tool 0 active and standby temperatures to 0C

; Automatic saving after power loss is not enabled

; Custom settings are not configured

; Miscellaneous
T0                                          ; Select first tool

Bed map file
heightmap.csv
(3.68 KiB) Downloaded 2 times
Last edited by clytle374 on Sun Jul 14, 2019 5:07 am, edited 1 time in total.

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geneb
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by geneb » Thu Jul 11, 2019 8:31 am

Dumb question(s) - is the bed heater visually flat? Are all the mounting screws tight? Without any clips on the glass, does it "rock" on the bed heater?

g.
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Thu Jul 11, 2019 5:15 pm

geneb wrote:
Thu Jul 11, 2019 8:31 am
Dumb question(s) - is the bed heater visually flat? Are all the mounting screws tight? Without any clips on the glass, does it "rock" on the bed heater?

g.
Not a dumb question at all. Found that a few weeks back. Wood plate was bowed up in the middle. I flipped it over, so it's pretty much just the peice of glass now.

Thanks
Cory

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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by geneb » Fri Jul 12, 2019 7:37 am

Try flipping the glass over and see if you get a vastly different probing map.

g.
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Sat Jul 13, 2019 9:24 pm

geneb wrote:
Fri Jul 12, 2019 7:37 am
Try flipping the glass over and see if you get a vastly different probing map.

g.
I flipped the glass over, same probing results.

Thanks
Cory

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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by geneb » Mon Jul 15, 2019 8:42 am

Have you tried a 16 point calibration before you do the bed mapping? If not, give it a try.

g.
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Mon Jul 15, 2019 11:32 pm

geneb wrote:
Mon Jul 15, 2019 8:42 am
Have you tried a 16 point calibration before you do the bed mapping? If not, give it a try.

g.
I'm actually using 19 points. I've tried less and more. I have 12 around the outside of the bed, 6 halfway points, and bed origin.
dc42 wrote:
Mon Jul 08, 2019 3:12 pm
Try moving to X0 Y0, then to X100 Y0, then measure the Z probe trigger height a few times. Then move to X<max> Y0, then X100 Y0, and re-measure the trigger height. That will show up the backlash.
I found a macro posted by you to do this, I lost the results, but they were good at the X100 Y0 points. Then I rotated the program to run to the X tower and back, then the backlash shows up there.

I tightened the belts tighter again, I have washers under the heads and nuts so they hold without pulling into the wood(whatever it's spelled). Not much improvement there. They are too tight in my experience with timing belts, but I'm aware my experience isn't really valid here. At home position, the resonate frequency of the belt below the skate is around 130hz. Anyone know a good number? (disregard the 130hz number, I believe the phone is picking up the 2nd harmonic here.)

The only play I can find in the system is that end play in the R4ZZ bearings in the cheapskates. The old ones had it and the new ones have it too. I looked for a couple hours in vain to be sure no one made a suitable bearing this small. It does make sense that it only shows up when the arms are so horizontal and the load is sideways on the skate. Another plus for longer arms, they'll shift that play into a direction of less influence. But there goes more build height. I was sure it wasn't effector tilt, because I assumed it would tilt about the center and that would take an obvious amount to create the error. But no, it tilts about the balls on the arm that is vertical.

So the auto-calibration route is obviously messed with by the crazy numbers at the towers. I added g1 x0 y0 z10 f6000 before every probing point in bed.g to pull the lash the same direction. Looking at the new bed map I should feed inwards before probing instead.

But this map is better for using the machine, I ran a large test print last night and got good results.
Screenshot_20190715_043301.png
Coming from it as a machinist, then machine tool repair tech, I nearly have a new printer designed in my head. I'm certain that I'd be assembling it by now if I'd not spent all this time on this printer. And at this point I feel it is the next step.

Thanks
Cory
Last edited by clytle374 on Thu Jul 18, 2019 10:23 pm, edited 1 time in total.

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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by geneb » Tue Jul 16, 2019 10:50 am

How can you be using 19 points when the firmware can only work with 16?
Use this wizard to generate the bed.g calibration file:
http://www.escher3d.com/pages/wizards/wizardbed.php
Pick 10 peripheral points, 6 halfway points, and 6 calibration factors. (NEVER pick 7! It will fiddle with the arm length and you'll end up with scaling problems.)

g.
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Tue Jul 16, 2019 5:53 pm

geneb wrote:
Tue Jul 16, 2019 10:50 am
How can you be using 19 points when the firmware can only work with 16?
Use this wizard to generate the bed.g calibration file:
http://www.escher3d.com/pages/wizards/wizardbed.php
Pick 10 peripheral points, 6 halfway points, and 6 calibration factors. (NEVER pick 7! It will fiddle with the arm length and you'll end up with scaling problems.)

g.
Well I add extra points to bed.g, and never complained during 5he g32 cycle. I'll fix that. I'm wondering if it just throws away the extra values. I added them in about a week ago to try and average out the ridges.

I wrote another one feeding to the probe points, but it was worse than feeding out to them. Might be because I changed the order and it discarded one quadrant of the bed.

Does order of the probe points matter?

I've been running 8 factor after running 6 a couple times, is that not advisable? I thought dc42 had suggested using that at some point. Off to work the next couple days.

Thanks
Cory

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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by geneb » Wed Jul 17, 2019 12:02 pm

I don't know that there is an "8 factor", but 7 factor messes with the arm lengths and that will cause part scaling problems.
As to the order of the probes, you'd have to consult with dc42 on that. I suspect the order is important.

g.
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Wed Jul 17, 2019 5:40 pm

8 factor is like 6 factor, except it sets bed tilt but doesn't set rod length.

Ran out and did a calibration real quick, it's reporting the number of points I feed it
Screenshot_20190717-173832.png

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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by geneb » Thu Jul 18, 2019 9:35 am

Today I Learned! :)

g.
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Sat Jul 20, 2019 3:33 am

geneb wrote:
Thu Jul 18, 2019 9:35 am
Today I Learned! :)

g.
Good deal, I always say I should get the rest of the day off when I learn something...

I'm actually excited, I got worse results. The difference is that the pattern has changed a little. Not completely dependent on the direction on travel anymore. This time I ran the belts as tight as I had adjustment for. Now the axis feel pretty bad.
Screenshot_20190720_024414.png
I have checked the bearings and belts several times at this point. Maybe a bearing is going lumpy under load, so hard to tell with the steppers in the system. The servo systems I'm used to don't ever feel rough, unless they are bad. Of course lots of times manually moving them isn't an option at all when they weight tons.

I keep ruling the bearings, pulleys, and belts out since the axis are consistent. But it's the only thing left to try IMO, it's either backlash from belts, or backlash from tight axis. Or both at the same time I think.

Seemecnc sells a flanged bearing for idlers on some other printers. Does anyone have an easy hack for the max v2? Maybe a toothed idler in in the places where the teeth are against the idler? Seems like that would be a smoother solution. I don't know if any line up on the V2. I'm thinking that I might machine out some replacement metal holders for the idlers, maybe screw them together through the bearing so the bearings will stay squared to the frame? Jack screws for the ones to tension the belts? I've tried over and over to get the belts to track perfectly, very little luck there.

Any thoughts on this? I"m going to at least replace the belts, pulleys, and bearings. Since I don't feel like I'm ordering parts that will fix the machine, I'm trying to upgrade as I do it. maker713's metal frame looks interesting, but at that cost I want the V3's bed mount and go with the AC heated bed. Then a 24V power supply would be easier and cheaper. The V3 frame is available but it looks like I'd be missing parts(like motor mounts) if I order the V3 frame kit from there.

Thanks
Cory

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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by geneb » Sat Jul 20, 2019 10:20 am

If you're going to go with a 713 metal v3 frame, just email them and ask - I'd be surprised if the motor mounts were missing.

You may also be over-probing. 357 points is kind of nuts. :) I think the recommended is something like 69 or 70.

g.
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Sat Jul 20, 2019 7:22 pm

geneb wrote:
Sat Jul 20, 2019 10:20 am
If you're going to go with a 713 metal v3 frame, just email them and ask - I'd be surprised if the motor mounts were missing.

You may also be over-probing. 357 points is kind of nuts. :) I think the recommended is something like 69 or 70.

g.
I think the v3 has plastic motor/tower ends. I emailed them a few days ago and haven't heard back.

I agree on the number of points, but it was what really shows the problem.

I dug around on the internet for hours last night looking for idlers and pulleys. Not any luck with the large idlers. Looks like they need to be 36 tooth.

Thanks
Cory

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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by geneb » Sun Jul 21, 2019 9:51 am

36 tooth? For what? The only thing in the entire drive system that has teeth is the pulley mounted to the stepper motors.

g.
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Re: Max v2 issue with peaks and valleys in bed map[NEW DATA]

Post by clytle374 » Mon Jul 22, 2019 3:53 am

geneb wrote:
Sun Jul 21, 2019 9:51 am
36 tooth? For what? The only thing in the entire drive system that has teeth is the pulley mounted to the stepper motors.

g.
The 36 tooth 8s for the idlers that run belt teeth towards the idlers. Not sure how much difference it'll make, but I've disliked running the teeth on a smooth surface.
Cory

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