Updated firmware and now homing and bed levelling is broken

After 5 months of work on this printer I finally got it working almost perfectly. The only thing left to get right was the bed wasn't levelling perfectly. I upgraded the firmware from 1.09 to 1.12a and now both the homing and the levelling features are completely screwed.

If I home, the first time it homes, all three axis stop when the first switch is tripped so I have to home at least twice if not three times to get all three axis homed properly.

Then, when it comes to levelling (auto levelling), from the homed position at the top of the axis, it moves the head out to the edge before moving down so smacks the effector into the side of the printer then scrapes it down before attempting to probe the bed.

Even if I adjust the bed.g file with a G1 Z4 line before it moves there to move the head down first, it seems to completely ignore it.

I was so close to having a printer I could actually use and now it's completely out of whack again.
Any tips?

What config.g, homedelta.g and bed.g files are you using? If you updated them when you installed the new firmware, revert to your old ones. I know RepRapPro used to say you should update the SD card contents when you update the firmware, but it's usually not necessary and better not to; except that you should make sure that the files in /www are up to date.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
What config.g, homedelta.g and bed.g files are you using? If you updated them when you installed the new firmware, revert to your old ones. I know RepRapPro used to say you should update the SD card contents when you update the firmware, but it's usually not necessary and better not to; except that you should make sure that the files in /www are up to date.

Ok, thanks Dave, issue sorted. I updated the web code but reverted the sys codes.
However, I did find that whilst before the update, the bed probing file ran fine, even with the same file after the update, it didn't move the effector down before moving it over to the edge of the bed which meant it tried to move one of the axis up despite already being at the top of the rails and therefore losing their positions. I added a "G1 Z4" before the probing began on the bed.g file and now that seems to work without messing up.

Now, although I've overcome that issue, the thing that pushed me to update when I did was that I'm having issues getting the bed to level properly. Regardless of what I do, the printer always seems to print with the nozzel considerably lower on one side than the opposite. Even if I rotate the bed around, it remains the same positions relative to the columns so I'm guessing it isn't due to imperfections in the bed but rather the way the motors are controlling the effector.

I've spoken to a couple of people and they suggested that I generated a bed.g file using your brilliant web-tool on escher3d.com which I did. I set the probing radius to 75, with 10 probe points and 6 factors. However, when I ran this it sent the printer haywire and some suggested I should update and try again. Since getting the homing/probing features running again today I've yet to deviate from the stock bed.g file again but will try your wizard again in a minute.

UPDATE:

I've just switched out the bed.g probing lines with that which was generated by the wizard:

; bed.g file for RepRapFirmware
; 10 points, 6 factors, probing radius: 75, probe offset (0, 0)
G30 P0 X0.00 Y75.00 Z-99999 H0
G30 P1 X64.95 Y37.50 Z-99999 H0
G30 P2 X64.95 Y-37.50 Z-99999 H0
G30 P3 X0.00 Y-75.00 Z-99999 H0
G30 P4 X-64.95 Y-37.50 Z-99999 H0
G30 P5 X-64.95 Y37.50 Z-99999 H0
G30 P6 X0.00 Y37.50 Z-99999 H0
G30 P7 X32.48 Y-18.75 Z-99999 H0
G30 P8 X-32.48 Y-18.75 Z-99999 H0
G30 P9 X0 Y0 Z-99999 S6

P0-P2 Go fine, but then when it hits P3 it tries to move beyond the bed, then skips several steps as the motor keeps running which means every subsequent position is incorrect.

I'm a little lost at what to do here seeing as the coordinates of P3 should be within the correct parameters of a fisher print bed

What is the diameter of the printable area on the Fisher?

If the end stop corrections are a long way off when you start probing, then the XY coordinates will also be off. So you should make the probing radius smaller than the bed radius by about 10mm to allow for that.

You will probably need to adjust the trigger heights using the H parameter on the G30 commands in bed.g, to allow for the variation in probe trigger height with XY position. The RRP bed.g file used G31 commands to do that, but the H parameter provides a simpler method.

The RRP version of bed.g had G4 delay commands between the G30 probe commands. I don't know why it had them, or whether they are needed.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The fisher has a nominal150mm printable diameter, but it can be a little tight, sometimes a badly placed wire can cause obstructions and trying to probe at 75mm radius doesn't give much scope for error on an uncalibrated machine

For probing drop your maximum probing radius down to 65mm.

Nope the G4 commands are not needed

Setting the H parameters on a fisher is essential, the fisher suffers from a problem where different areas on the bed required different pressure to cause the switch to activate, which means the machine deflects different amounts.

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RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

I've overcome the issue of the effector catching thanks to an old post I found of DADIY's where he set it to return to the centre between each move. That allowed me to probe every point successfully.
However, now I'm getting a deviation AFTER probe of between 0.23 and 0.35!

When I watch it probing, especially at the outer points between the pillars it pushes so hard that it actually pushes the effector to quiet a substantial angle, several degrees!

This is after I've gone round each position for each point, manually lowered the head until it is just starting to provide resistance on a piece of paper on the bed, then I've taken those Z axis values (an average over three measurements with a home between each one) and subtracted the point of resistance at the centre and used these for my H values.

The only thing I can think of is that some of the trigger points are a -value as when doing the paper thing, I get down to Z0 and still have no resistance but am unable to move the nozzle any lower

I'm really lost here now :/

Edited 1 time(s). Last edit at 05/25/2016 06:37PM by ByteSlinger.

Its possible that the springs that are supporting the bed are too stiff or over compressed, each spring should be sitting on the axis motor via a hole in the baseplate.

From Memory all the H values should be a negative value, if the Z position on paper test is positive, when the Z position is nagative you should use a positive value.

I cant make out from your description whether your setting the H values correctly, follow the method I outline at the end of this thread [forums.reprap.org] you basically have to probe and test each position individually.
Are you using the stock arms? these should give you a deviation below 0.1, if you want better you need to make carbon arms.

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RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

I thought it could have been the springs before so I ordered a brand new set which, once swapped over, seemed to make no difference.
I'm not using stock arms but custom carbon arms which I made when first building the printer.

I've just re-read your description in the other thread and it seems I've gotten a little confused along the way by the description on the Escher website where it suggests that the H parameter should be the z position at point of contact minus that of the centre position.
I'll re-try this with your plan.

However, I just wanted to check, do I read it from the first point I feel any resistance against the paper, or from the point it pins it almost completely?

Thanks by the way

Its actually fairly hard to get the springs wrong if they are sitting correctly, much of the fisher makes it fairly hard to build wrong.

The problem with the paper test is its all about feel, so its really so you get a consistent feel each time, theoretically if you get a consistent feel the the height should more or less be the same.

BUT, be careful about the point where the paper stops, at this point there will be significant pressure, and you bring the reacting pressure from the springs back into he mix

myself I notice that when the paper is just being touched you can feel thw fan vibration through he paper

Oh, and dont forge tot set the Z axis to the half setting, you should see 0 o.5 and a 0.05mm step option instead of a 1.0 and 0.1 option

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RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

Yes I just saw as I was about to start that I hadn't halved my z axis movements. I've done that now and have also set all my P0-P8 locations as macros to speed up the process. Will check back in in a few minutes
Thanks for your help

Ok, so something really odd is up now.
On my P0 (X-65 Y-37.5) the z measurement I'm getting before deducting the 0.11mm paper is 3.05mm (miles higher than anything I got before speaking a minute ago.
I then go to my P1 (X-52 Y30) and even down to z0 it's still not made contact with the paper.

It's definitely not the springs as the bed it pushed right up again the three sets of contact pins so couldn't be any higher regardless of spring strength. What do you think?

Bugger, ok, I've just noticed one of the bearings has come free of the carriage which would absolutely explain the sudden massive variance. Just trying to figure out how to get that to sit tight now :/

loose bearings will do it, but make sure you follow my instruction exactly, you should be probing each position twice before you do the paper test, the second time without the P parameter, the reason I follow this method is more or less speed efficiency, the first probe move is really just a positioning move but you have to delete the P parameter to get it to do a z offset update.... after the second probe unless there is MAJOR deflection somewhere you should be well within 1mm and always high, so your H parameter shall always be negative

---

RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

Great! I'm confident once I get this bearing issue sorted that may be the solution to my problems.

Unfortunately no matter how much I tighten this nut on the carriage the bearing (the small one) isn't staying put. Any ideas? I'm guessing it's a bad idea to glue/epoxy it?

put some paper between the bearing and the carriage sleeve then clamp on that

.........sounds like your first job after getting your printer working is a new set of carraiges

Edited 1 time(s). Last edit at 05/25/2016 09:04PM by bgkdavis.

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RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

Ah damn, looks like there's a crack down the side of the carriage, No wonder it's not gripping the bearing but god knows how that happened. Only thing I can think of is repetitive vibrations putting strain along a weak point.
Going to epoxy the crack, use some paper around the bearing, then once this is working again, print a new carriage. Either which way, this isn't going to be solved tonight.
Thanks for all your advise and help, will update you with the progress.

after gluing wrap a cable tie around the part to help keep it together

---

RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

Quote
bgkdavis
after gluing wrap a cable tie around the part to help keep it together

Hehe I literally just finished doing this when I came back to read your reply
Thanks again!

I wish there was an automated way we could calibrate the bed. Or at least perhaps we could publish a list of comments to run and what to put in the corresponding H value.

On a side note, I've had quite a few of the orginal green plastic parts fail so its work printing a spares kit once you get your printer working nicely.

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DC42 Kossel 330mm x 2meters
My Thingiverse Creations

It should be possible to find a set of probe points and corresponding H values that work well on most Fishers, or at least provide a good starting point. I don't have a Fisher, so I can't provide that.

One thing I don't like about the Fisher design is the way that the carriages slide pas the microswitches to activate them. It appears to me that the trigger point will depend a lot on the shape of the spring arm on the microswitch. On most delta printers, the carriages drive into the microswitches - but this reduces the available build height by the height of the microswitch.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Ok, I did everything and it looked like it worked. I got it down to a deviation of ~0.05 which stayed stable to 0.001 each time I ran a probing. However it still seems like it's printing too low with the filament coming out very squashed which means that by the time it starts the second loop around the outline, the first one has expanded and causes it to be pushing really hard against it as it extrudes, completely ruining the print.

Here's some photos of how it comes out:

These are of the underneath of the first later of a print:



Here's a shot from the top:


Bare in mind, this is literally the first part of the first layer. It should be nice, smooth and flat, but as soon as it's extruded it comes out flat, and bloats so it's already laying over where the next line of filament is to be placed.

You can fix this by adjusting the h values but the easy fix just do your paper trap test at xy0 and enter g92z0.2 or whatever your paper thickness is, you can automater this by adding a move to end of bed.g to a fixed z height snd then doing a g92 to correct the height by the same amount as your paper test corrected kt.....it if your paper test read z0.3 before and 0.2 after then you could move to z100 and do a g92 z99.9

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RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

Looks like either you are over-extruding (in which case any layer with solid infill will be affected), or you are starting the print with Z=0 too low. If the latter, an easy way to adjust it is to reduce (i.e. make more negative) the Z parameter in the G31 command in config.g.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Cool, I'll give that a try now.
So if I were to do the G92 method, I'm guessing I enter that at the point that the paper is pinned, therefore forcing it to recognise that height as the thickness of the paper above the print bed?

Quote
dc42
It should be possible to find a set of probe points and corresponding H values that work well on most Fishers, or at least provide a good starting point. I don't have a Fisher, so I can't provide that.

One thing I don't like about the Fisher design is the way that the carriages slide pas the microswitches to activate them. It appears to me that the trigger point will depend a lot on the shape of the spring arm on the microswitch. On most delta printers, the carriages drive into the microswitches - but this reduces the available build height by the height of the microswitch.

I have provided my bed.g in the past, but my fisher is fairly heavilly modified.

Using the microswitches as hard stops like most other delta designs is considered bad practice in machine design, the fisher design actually demonstrates the correct way to use axis switches, however, industrial machines dont tend to use the switch trigger position as the 0 point either, their encoders have marker pulses, and the home switch just tells the machine to slow down and find the next encoder marker pulse

---

RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

Another failed evening, now it seems to attempt printing at ~8-10mm above the bed despite what I set the Z on the G31 in the config to.
Hopefully I'll have some time over the weekend, but if I don't get this running soon, I'll have literally have spent half a year working on the damn thing

if your getting repeatable deviations at 005 then it sounds like your nearly there, just got to get teh actual Z height right

---

RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

In config.g near the bottom you should have this line -

G31 X0 Y0 Z-0.1 P200

Increase the Z-0.1 part to change the starting height. I have mine set to Z-0.05 for better results. I also found that when changing these files its best to turn the printer off and back on and re calibrate as when making lots of changes they don't always seem to set right.

I also found that running the bed calibration 3 times makes for more reliable printing, but I have no evidence that would actually make any difference just seems to work better for me.

Also if you are slicing your own part I recommend that you start with the slic3r defaults of

0.2 layer
0.35mm first layer
first layer width 0.7mm

These should give you a good starting point.

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DC42 Kossel 330mm x 2meters
My Thingiverse Creations