Printer Geometry Numbers? New vs. Old Carriages and Repetier 0.91 vs 0.92

[gchristopher]

I'm trying to get the Dinosaurs set up to test the new effector platform plates by http://713maker.com/ and want to upgrade and recalibrate the printer first, so the new parts get a fair trial run without unrelated issues reducing print quality.

Backstory: After a lot of printing, I'm starting to see print quality issues that might be due to backlash. (Asymmetrical print artifacts appearing when the print path changes direction.) For a while, the carriage bearings have been occasionally squealing and clicking, and re-tightening the belts and carriage wheels reduced but didn't eliminate the problem. Rather than fiddle with that any more, I'm installing the new injection molded carriages.

I think the only firmware change for the new bearings should be the horizontal radius. Can anyone here review my summary of the change needed and help me verify the numbers as I've diagrammed them below?

I searched for the geometry change and found an official Carriage Horizontal Offset posted by jjjohnson here. I wasn't able to find a really comprehensive writeup so I'm posting the diagram below, just to be extra sure I understand the change 100% correctly.

There are two changes I need to consider:

- Changing from the old CheapSkates to the new Injection Molded Carriages
- Using Repetier 0.92, configured using their online tool, instead of Repetier 0.91 as provided by SeeMeCNC.

I stole the diagram from the Repetier configuration page and relabeled it with as the dimensions appear in the Repetier 0.91 firmware distributed by SeeMeCNC:

[img]http://gchristopher.net/3dprinting/rost ... iagram.jpg[/img]

In the 0.91 firmware for the old cheapskates, the values were:

End Effector Horizontal Offset: 33.0
Carriage Horizontal Offset: 38.4
Printer Radius: 198.25
Delta Radius = [Printer Radius] - [End Effector Horizontal Offset] - [Carriage Horizontal Offset] = 126.85

So for 0.91 firmware, the only change per jjjohnson should be that the End Effector Horizontal Offset is now 27.97. That means the calculated Delta Radius will change to 137.28.

That seems straightforward. Where I've gotten confused somewhere is on the Repetier 0.92 firmware.

Repetier 0.92 solicits the radius a little bit differently:

[img]http://gchristopher.net/3dprinting/repe ... iagram.jpg[/img]

Instead of calculating it, Repetier 0.92 just asks you for the Delta Radius, calling it Horizontal Radius ("ROD_RADIUS" is the constant).

Where I'm confused is that I downloaded someone else's sample firmware to get started with 0.92, and the value is currently set at 130, instead of 126.85. Presumably I'll want to increase the Horizontal Radius to accommodate changing from the CheapSkates to the Injection Molded carriages, but am I even starting with the right value in that constant?

Did I miss something in my interpretation of 0.91 and 0.92 geometry measurements? Have I been using the wrong number there since switching to 0.92?

Thanks in advance to anyone that can help me determine the correct values!

[Tincho85]

So for 0.91 firmware, the only change per jjjohnson should be that the End Effector Horizontal Offset is now 27.97. That means the calculated Delta Radius will change to 137.28.

Hi, if you update to the new ball-cups other parameters will change too, not just the END_EFFECTOR_HORIZONTAL_OFFSET.
According to the 0.91 firmware provided by SeeMeCNC these are the correct values:

#define DELTA_DIAGONAL_ROD 290.8
#define END_EFFECTOR_HORIZONTAL_OFFSET 30.22
#define CARRIAGE_HORIZONTAL_OFFSET 27.1
#define PRINTER_RADIUS 200.0


Best of luck!
My ball-cup set it's on transit, I'm eager to update too

[U.S. Water Rockets]

After 2 years of daily use, my original u-joints were literally flopping around on the axles so I ordered the injection molded carriages and arms and ball joint barbells and installed them in one evening. Then I followed the user manual setup for a new printer, downloading the latest software and just playing along like this was a brand new printer I just built. That worked great for me, and I was surprised by how much nicer the new prints were compared to what was printing before the upgrade.

[gchristopher]

Hi, if you update to the new ball-cups other parameters will change too, not just the END_EFFECTOR_HORIZONTAL_OFFSET.

Good point. I'm using the Tricklaser Carbon Fiber arms with the metal joints, so it's be good to have numbers for both setups.

After 2 years of daily use, my original u-joints were literally flopping around on the axles so I ordered the injection molded carriages and arms and ball joint barbells and installed them in one evening. Then I followed the user manual setup for a new printer, downloading the latest software and just playing along like this was a brand new printer I just built. That worked great for me, and I was surprised by how much nicer the new prints were compared to what was printing before the upgrade.

Awesome to hear! I'm running a newer version of Repetier (0.92) than what SeeMeCNC is distributing (0.91). The challenge is that SeeMeCNC made some pretty big improvements to the configuration.h file for their redistribution of Repetier 0.91. The SeeMeCNC one is a lot easier to read and use than the stock 0.91 configuration.h file.

Repetier went in a different direction with improving configuration for their 0.92 release. They built a web-based tool, where you upload your configuration.h file, and then it gives you diagrams and forms to fill out to change any settings, and then you download the modified configuration.h file with the changes you made in the web interface applied.

The only downside is that the two approaches aren't directly compatible, so if you want to move to Repetier 0.92, it takes quite a bit of expertise to make sure you've translated all the settings as they appear in SeeMeCNC's 0.91 file and entered them correctly in the 0.92 format.

I'm not confident enough to think I have everything right, so I asked here. Hopefully someone here can double-check my numbers and help me figure out the right value to enter for the 0.92 Horizontal Radius.

[gchristopher]

Found it. The 130mm horizontal/delta radius number came from a 0.92 configuration.h file shared by Nylocke. I think I should probably change it to the 126.85 value from the default firmware before adjusting for the injection molded carriages. I'm just worried because I was getting good leveling and dimensional accuracy using the incorrect number, so what am I impacting by changing the value?

[geneb]

The current firmware distributed by SeeMeCNC is NOT .91! The current release is based on the most current Repetier Firmware release.

g.

[gchristopher]

The current firmware distributed by SeeMeCNC is NOT .91! The current release is based on the most current Repetier Firmware release.

g.

Ooh, thanks! Good to know. I was looking at the commit history on the SeeMeCNC github and having a hard time lining it up with what I'm seeing on the main Repetier repo.

I don't suppose you know if the horizontal radius is 137.28mm for a Rostock that's been upgraded to the new Injection Molded Carriages, but not using the ball-cup arms? (So the effector platform still has the 33mm distance from center to the arm pivot point.) That's the value I'm going to try first.

[Tincho85]

Hi Christopher, just to be clear... I'm here learning with you

One question, why do you need the delta radius? Isn't that a value that it's calculated by the firmware?
I've just opened the repetier.ino and I don't see the option to change it.


Also, I think that you should use this values:

CARRIAGE_HORIZONTAL_OFFSET
By cad analysis the injection molded carriage + ball cup is 26.5mm but in reality it's set to 27.1mm (+0.6mm)
By cad analysis the injection molded carriage + axle adapter is: 27.97mm, so +0.6mm = 28.57mm
#define CARRIAGE_HORIZONTAL_OFFSET 28.57

DELTA_DIAGONAL_ROD
I assume your TrickLaser's carbon fiber arms are 300mm long.
#define DELTA_DIAGONAL_ROD 300

END_EFFECTOR_HORIZONTAL_OFFSET
If you are going to use 713maker.com aluminum effector + the TrickLaser arms I suppose the values are the same as the ball-cup, not as the old v2 u-joint style platform.
#define END_EFFECTOR_HORIZONTAL_OFFSET 30.22

PRINTER_RADIUS
With Printer Radius I'm lost, It should be greater than 200mm as the arms are longer than the 290.8mm ball-cup rods.
#define PRINTER_RADIUS 200.0 ??


We need some assistance here, and I really want to learn about this geometry

PS> Sorry Gene, my mistake also. I assumed it was 0.91 because the GitHub repository it's called "Repetier-091-ROSTOCKMAX". Didn't know it was based on the last release.

[U.S. Water Rockets]

The current firmware distributed by SeeMeCNC is NOT .91! The current release is based on the most current Repetier Firmware release.

g.

You beat me to it!

I was going to mention that the reason I went ahead and treated my machine as if it were a freshly built machine had a lot to do with the new version of the firmware. I wanted to make sure I didn't screw up any of the settings, so I blanked the EEPROM and went ahead and built the firmware and did all the steps to set up a fresh machine, so I would know I had not missed something.

[gchristopher]

One question, why do you need the delta radius? Isn't that a value that it's calculated by the firmware?
I've just opened the repetier.ino and I don't see the option to change it.

I switched to Repetier 0.92 a while ago. When I did, SeeMeCNC definitely was still distributing 0.91. I switched to a higher version for better support of things like dual extruders and a second bluetooth serial connection so I can run the printer from across the room. (Which is silly, but kinda neat sometimes.)

That means I need to know what number to type into the Repetier configuration tool at https://www.repetier.com/firmware/v092/ . Instead of calculating the horizontal radius, it asks for the value directly.

CARRIAGE_HORIZONTAL_OFFSET
By cad analysis the injection molded carriage + ball cup is 26.5mm but in reality it's set to 27.1mm (+0.6mm)
By cad analysis the injection molded carriage + axle adapter is: 27.97mm, so +0.6mm = 28.57mm
#define CARRIAGE_HORIZONTAL_OFFSET 28.57

Argh. The number I got from jjjohnson's post on the forums was 27.97. And not using the ball cup bearings, so does the "axle adapter" adjustment apply?

#define DELTA_DIAGONAL_ROD 300

They're 269mm to match the arms that originally came in the Rostock Max V2 kit.

END_EFFECTOR_HORIZONTAL_OFFSET
If you are going to use 713maker.com aluminum effector + the TrickLaser arms I suppose the values are the same as the ball-cup, not as the old v2 u-joint style platform.
#define END_EFFECTOR_HORIZONTAL_OFFSET 30.22

He's made two versions. One for ball cup joints and one for the original axle style. (And the tricklaser arms use the metal ball joints on axles like the older Rostocks.) I'm trying to test the one that matches the original effector plate radius of 33.0.

PRINTER_RADIUS
With Printer Radius I'm lost, It should be greater than 200mm as the arms are longer than the 290.8mm ball-cup rods.
#define PRINTER_RADIUS 200.0 ??

I need to reread the code, but IIRC that number might be one that doesn't affect position calculations? I think it might just be the limit of the radius of allowable permissions for the print head.

We need some assistance here, and I really want to learn about this geometry

Me too! I hope Gene or someone else can help clarify if my interpretation of the printer dimensions in the original post are correct. I wouldn't be so worried if I didn't keep finding conflicting numbers in forum posts or example configuration settings.

[gchristopher]

You know what? This whole thread might be an idiotic question!

Horizontal radius is the value you calibrate in EEPROM using Gene's 3-point method and override using firmware. (Hint, when you switch to injection molded carriages, it'll be off by at least 11, so you'll crash the head on that first trip near Z0 near a tower. )

Even if I calculate 137.28 as the starting point and what I put in the firmware, isn't that going to be overridden by the horizontal radius I set in EEPROM as part of re-leveling the bed?

So the number I arrive at experimentally through tuning will be the real number, regardless of that I calculate? (That also explains why having it set to 130 in the sample configuration.h didn't hurt anything, because I tuned it back down to the actual number through the bed leveling procedure.)

[bot]

Yes, horizontal radius in eeprom is the only value that matters. the offsets don't matter either, you can simply declare the variable in the firmware directly rather than subtracting any offsets. That is just for human (mis)understandability.

[geneb]

FYI, the correct firmware URL is https://github.com/seemecnc/Firmware, not the "Repetier-091-ROSTOCKMAX" one.

g.