Z-axis alternative rod

Like many people know the standard M5 Z-rod is not that great quality. I don't use bed compensation and still the rod shows traces of wear.
I found an alternative , buttress screwthread. TR10x2 (so thread is 2 instead off the standard 0.8) in steanless steel and with a bronze nut. (thats the only good combination when u use the rod for an automated dynamic movement, steel on steel will allways wear and tear)
But the big question is, where can i change the Z step?
I know the nema 14 makes 200 steps. Not sure what the microstep for the ormerod is. I hear people say 8 but also 16, so...
Anyone know where i can find the settings for the Z -axis movement. Is it in the firmware, on the sd-card?

I can easely connect this rod to the x-axis plate because i made a new alu x-axis plate.
When it works i post some pics.

Use M92 Znnn where nnn is the number of microsteps per mm. There are 3200 microsteps per revolution, so the value of nnn is 4000 for the standard 0.8mm pitch rod.

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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 motors we supply are 200 steps per revolution (1.8 degree per step) and we use 16x microstepping. You can also use Josef Prusa's calculator to calculate the steps per mm, knowing these values: [calculator.josefprusa.cz]

For the Z axis, we use threaded rod with pitch of 0.8mm. The steps per mm are calculated with the following formula:
Steps per mm for leadscrew = ( motor steps per revolution * microstepping ) / leadscrew thread pitch
So ( 200 * 16 ) / 0.8 = 4000

For your TR10x2 leadscrew, with a 2mm pitch, it's:
( 200 * 16 ) / 2 = 1600

Add the following to your sys/config.g on the SD card:
M92 Z1600

Ian
RepRapPro tech support

Quote
Melmie
I can easely connect this rod to the x-axis plate because i made a new alu x-axis plate.

Not sure what your setup looks like at the moment. but with the standard x motor position and using the standard z gear position a tr10x2 will clash

Thats only a problem in a perfect world Zeb00. Every ormerod owner has to tighten the X-belt.
And your drawing shows the motor in his farthest position to the right. So if you put tension on the belt and the engine moves 1mm to the left the tr10x2 fits like it's made for it.
Also, the drawing is not correct i see, the allu back and front plate off the motor stick out a bit more than the black part in the middle.
As promised some pics.

Edited 1 time(s). Last edit at 09/27/2014 08:13AM by Melmie.

Quote
Melmie
Thats only a problem in a perfect world Zeb00. Every ormerod owner has to tighten the X-belt.

Great point. Mine is the whole way in but i will loosen by one tooth and and slide it out a little.
i have a TR10 all ready to go but was waiting to do my 4020 x axis. but looks like it will work anyway

Yep, just go for it it works great. And i can't complain about precision. Still more than you need. I hope you have the 2mm thread. Was hard to find here. Standard seems to be 3mm and that is to much i think.

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Melmie
Yep, just go for it it works great. And i can't complain about precision. Still more than you need. I hope you have the 2mm thread. Was hard to find here. Standard seems to be 3mm and that is to much i think.

Yep TR10x2 had from another project just turned down one end to 8mm and cut to length. the only nuts i had that were suitable were delrin which would not have been my first choice.
think last time i calculated it it was 0.01 mm full steps with a 2mm pitch which is good as i dont run any bed or orth comp it means the z axis will allways stop on a full step and not be sitting in a microstep

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Zeb00
i dont run any bed or orth comp

Thats indeed the best way.
Hear a lot off people who destroy there threaded rod because they use the bed compensation.
0.01mm was also what i was thinking the step should be now. Don't think anyone is going to make smaller steps than that.
I work with a professional printer at work and the smallest z-step is 0.01. And usually i don't go bellow 0.03 or 0.04mm. So i guess where safe

Just as background info, I used TR8 x 1.5mm rod for my mod a while back...

[forums.reprap.org]

It might give you some ideas.

Dave

Edited 1 time(s). Last edit at 09/27/2014 08:10PM by epninety.

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epninety
[forums.reprap.org]
It might give you some ideas.

Just looked at your post. tr8x1.5 will do the job just as good indeed. Not sure if the step size is easy to work with? 0.0075mm

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epninety
he bronze nut has some serious backlash

Strange, i have almost no backlash. Nut is made with a H7 allowance. And also like said in your post, the weight off the arm compensates that effect. My arm weighs around 1.2kg, so that will do the job

Step size isn't ideal, but in reality it's not an issue. All that happens is that layers steps get rounded up or down to an exact number of steps. So once in every so many passes, the exact layer step changes by a tiny fraction.

You can see some banding in the sides of the box print in that thread, it may be an effect of the rounding. Equally it may be an effect of the stepper and microstepping driver, which suffers variable torque (and hence positional accuracy) between the unit steps. Print quality is high enough for my purposes so I've never investigated further.

Backlash hasn't been an issue, but I was a little dissapointed when it arrived. Then again, we all know that if you can't cope with occasional dissapointment, don't buy cheap carp off of ebay

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epninety
..Backlash hasn't been an issue, but I was a little dissapointed when it arrived. Then again, we all know that if you can't cope with occasional dissapointment, don't buy cheap carp off of ebay

any backlash in the z-treaded rod is a non-issue as gravity will take up the slack, the Ormerod, like most things depend on this to function

Erik

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epninety
don't buy cheap carp off of ebay

Hehehe funny but true.

Edited 1 time(s). Last edit at 09/29/2014 01:01AM by Melmie.

All done. runs a lot smother then the 5mm version.

printer just needs a clean then i will be back to printing

Looking good!

Looks a lot more solid now. I see your still using the acrylic arms. How's that working for you?
I never really used it, I directly manufactured an aluminum one.

I replaced my acrylic plate+rib for aluminium ones, and to be honest I didn't notice any big difference in print quality or precision. The X movement is as far as I can tell a little bit more "straight" (it droops down less at the far end, making the bed seem flatter), but it is by a small amount.

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jstck
but it is by a small amount.

Every little bit helps to make a big one