2 issues

1) I have the same problem I had couple of years back, the middle of the bed (x100y100) the nozzle touches the bed at +0.1mm.

The x0y100 and x180y100 are the same, the nozzle touches the bed at 0.0mm.
I have Daveks aluminium X plate so thats not the issue.
I have also noticed that the +0.1 actually goes from x20y100 to x170y100, so almost the whole length of the bed.

Could it be sligthly bent rod?

2) I set Z0.0 at x0y100. I do the print. When I want to do a second print, the x0y100 is almost never at 0.0, either +/- 0.1, I must re-check every time before a print.

EDIT: I have raised the Z to +40, when I lowered it back down the 0.0 was +0.8 from the bed.

Any ideas what can cause this?

Edited 1 time(s). Last edit at 03/04/2017 10:32AM by Sardi.

Quote
Sardi

EDIT: I have raised the Z to +40, when I lowered it back down the 0.0 was +0.8 from the bed.

Any ideas what can cause this?

Sounds like the axis is losing steps on the drive, check the moving parts for stiffness, lubricate the Z nut maybe, possibly increase z axis motor current

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Another RS Ormerod Mk1 meets the world

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

Hi Davek,

Moving parts all stiff!
Z nut lubricated!

All thats left is the increase in current, but I need to google that

EDIT: Just found out its in my config.g file .. but how much should I increase it?

EDIT2: M906 X800 Y1000 Z800 E800 ; Set motor currents (mA) - im thinking about increasing in intervals of 50 then check if it skips ...

Edited 3 time(s). Last edit at 03/05/2017 08:57AM by Sardi.

If the z on yours can be lifted off the nut, it should glide up and down very smoothly, no sticky spots.

Is there a chance the nut is worn and jamming?

Someone else will have to offer help with motor currents as i have not changed these but i think steps of 100mA will be good to try, I just do not know the upper limit.

---

Another RS Ormerod Mk1 meets the world

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

I think Im gonna change the rod and the nut altogether.

Regarding currents, I will not go higher than 1000, since that is the current for X so I assume 1000 is ok for Y motor as well.

I used to run my Z motor at 900 if that helps

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appjaws - Core XYUV Duet Ethernet Duex5
firmware 3.1.1 Web Interface 3.1.1
Ormerod 1-converted to laser engraver, Duet wifi
OpenSCAD version 2020.07
slic3r-1.3.0, Simplify3D 4.1.2, Cura-4.4.1

Everything helps

My next tryout will be at 900

The apparent difference between the bed height in X at the centre compared with the edges may be due to the force of the Bowden tube tilting the head slightly. Try disconnecting the Bowden tube from the extruder and see if that makes a difference, or clip the extruder on a different place on the X-arm.

Dave

Quote
Sardi
2) I set Z0.0 at x0y100. I do the print. When I want to do a second print, the x0y100 is almost never at 0.0, either +/- 0.1, I must re-check every time before a print.

EDIT: I have raised the Z to +40, when I lowered it back down the 0.0 was +0.8 from the bed.

Any ideas what can cause this?

I have tested the motor currents to solve this with no avail.

Could the accelerations and speeds maybe help with this?

M201 X800 Y800 Z15 E1000            ; Accelerations (mm/s^2)

M203 X15000 Y15000 Z100 E3600       ; Maximum speeds (mm/min)

M566 X600 Y600 Z30 E20              ; Minimum speeds mm/minute

This is my current config.g.

Quote
Sardi
2) I set Z0.0 at x0y100. I do the print. When I want to do a second print, the x0y100 is almost never at 0.0, either +/- 0.1, I must re-check every time before a print.

EDIT: I have raised the Z to +40, when I lowered it back down the 0.0 was +0.8 from the bed.

Any ideas what can cause this?

I had something similar happening when I had a problem with the gear on the Z motor. It cracked or lost its grip on the motor shaft for some other reason, I can't remember the details. I printed a new gear and that fixed it.

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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].

I got myself a new rod, and printed out iamburneys gears for the Z motor - still Im having the same problem.

Quote
Sardi
2) I set Z0.0 at x0y100. I do the print. When I want to do a second print, the x0y100 is almost never at 0.0, either +/- 0.1, I must re-check every time before a print.

Im back to default currents M906 X800 Y1000 Z800.

Next on my mind are the acceleration speeds, could they cause my problem?

Quote
Sardi
Next on my mind are the acceleration speeds, could they cause my problem?

You might try reducing the maximum Z speed rather than acceleration, although if the default is causing the motor to skip, I suspect it is a bad Z rod or nut.

Dave

I just printed a brand new set of iamburneys Z motor gears (the print was in perfect quality), and changed the rod - and still have the same problem.
It does not happen every time, but it does.

I will try changing the nut though.

Z max speed is 100mm/min and minimum speed 30mm/min.

Hmm, maybe if the Z nut trap is a bit off, and pushes the rod away from center and causing it to miss steps? Im just shooting blanks here now ..