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Cable Z axis

Posted by Sublime 
Re: Cable Z axis
May 16, 2013 07:03PM
goopyplastic Wrote:
-------------------------------------------------------
> Does the cable just friction fit around the drum?

Yes just friction.

> Like it doesn't go through the the drum like on
> the x/y rods?

No I do not think it is entirely needed on the upper rods either.

Any recommendation for number of
> turns around the drum?

I used 7.5 turns on mine but mine is also 215mm of travel. I think 5 should be good.

Any reason the drum has a
> hole in the top of it?

Do you mean all the way through from end to end? If yes it is so it will be all perimeters regardless of the settings as they keep it rounder, print faster and are stronger then an in-filled part in this orientation. If no maybe there is an error.


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Re: Cable Z axis
May 26, 2013 06:03PM
Been running my cable z for a day or so now, I notice that during printing and maybe during layer changes the z platform will shift laterally a little momentarily but it seems to settle back in place where it should. I seem to recall my screw driven z doing the same, have you ever seen this?

I should also add that it is working great so far!
Re: Cable Z axis
May 27, 2013 05:09PM
My z assembly was a bit loose, maybe because I had to clean out the holes where the z lift attaches to the arms, so I jb-welded the z arms and z lift together. Jb weld made it rock solid.
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Re: Cable Z axis
May 27, 2013 05:38PM
goopyplastic Wrote:
-------------------------------------------------------
> Been running my cable z for a day or so now, I
> notice that during printing and maybe during layer
> changes the z platform will shift laterally a
> little momentarily but it seems to settle back in
> place where it should. I seem to recall my screw
> driven z doing the same, have you ever seen this?
>
> I should also add that it is working great so far!

I can't say I have seen it happen and I am not sure how it would be possible if the bearings fit the rods really well as well as the bed being bolted down really tight. Is it side to side (X direction) or front to back (Y direction)?


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Re: Cable Z axis
May 27, 2013 05:43PM
lajos Wrote:
-------------------------------------------------------
> My z assembly was a bit loose, maybe because I had
> to clean out the holes where the z lift attaches
> to the arms, so I jb-welded the z arms and z lift
> together. Jb weld made it rock solid.

With the lead screw version that is supposed to be a little lose and move around in X and Y to absorb the wobble of the lead screw. With the cable it does not need to be lose but I could see having it glued to narrow or wide possibly over constraining the bearings a little.


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Re: Cable Z axis
May 27, 2013 07:05PM
I printed my tantillus parts on my cnc machine which unfortunatelly can't produce the nice sharp corners like tantillus because there is way too much mass moving around. So I had to do some xacto cleanup on the parts, and probably made them too loose.

I glued the parts with the z carriage assembled and mounted to a board and made sure that everything was moving nice and smooth before the jb welded it.

Now that I have the tantillus near completion, probably the first thing it will make is another set of tantillus parts so I can have a machine that has nicely fitting parts, like it was designed ; )
Re: Cable Z axis
May 28, 2013 04:31PM
It looks like my Z had some user induced play in it. In the process of fixing it up.

I had a question though, what do you think about running the SD8825 stepper drivers from panucatt for 1/32? should give the cable Z back some of it's resolution for low layer heights? Also thinking about running it on my airtripper I hear if you increase the current setting from 1/16 you won't lose torque or generate more heat.
Re: Cable Z axis
May 28, 2013 06:45PM
I have a set of DRV8825 drivers from Pololu that I am yet to put in a Tantillus. My thoughts on it are that our Arduinos and Marlin may not be up to keeping up to the required PPS to drive things at the same speeds (maybe only half the original max speed). Since Z rarely ever gets used at full speed it may be a moot point. The extruder on the other hand requiring as fast as possible retracts may be an issue.


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Re: Cable Z axis
May 29, 2013 06:44PM
I have the SureStepr SD8825s, at 1.2A 1/16 step the 48mm nema17s are running very cool (the steppers are rated 1.68A). The extruder stepper is 92F, xy axis are 87F in 70F ambient.

Haven't tried 1/32.
Re: Cable Z axis
August 01, 2013 09:30AM
How is this cable drive working? Is it worth upgrading?
Re: Cable Z axis
August 01, 2013 10:32PM
Re: Cable Z axis
August 21, 2013 05:26AM
Sublime, what are the possible layers heights with cable?, im assembling a tslot tant with cable on z.

I hope to get it running by this weekend.
Re: Cable Z axis
August 21, 2013 04:03PM
If the steps per mm on Z is equal to 100.66 like the spools I have printed it would be 0.149 and 0.159mm. But with the circumference of the spools being easily changed I would recommend everyone calculate the steps per mm based on measuring the movement and recalculating. So request a movement and measure the actual distance moved to as many decimal places as possible. Then steps_per_mm*(requested_distance/actual_distance_moved) , enter the new steps per mm in the firmware, upload the updated firmware and repeat until correct.

Once you have the steps per mm for your machine then go to the Tantillus calculator and enter your final steps per mm and click calculate. It will then give you a list of possible layer heights and their rounding error per layer.


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Re: Cable Z axis
August 22, 2013 04:42AM
Thanks!
Re: Cable Z axis
August 24, 2013 05:32AM
Hi Sublime!!

I'm designing a resin dlp system, and I'm thinking to make cable based z axis...I don't understand the limiting factor of the layer height....Can I achieve 0'05 mm layer heights??

By the moment i'm using leadscrew with antibacklash nut, but the possibility to use cable is very interesting, for reduce costs and minimize woobling.

What do u think??

I bet the steps unit are related to the diameter of the drum and the microstepping that I use...it's true??

Thanks a lot in advance!!
Re: Cable Z axis
August 24, 2013 11:10AM
With the force required to lift a DLP print from the print bed after each exposure due to the vacuum formed between the object and the glass I do not think a cable Z axis would work that well unless you geared it down a lot to increase the torque and resolution.

The limitation of resolution is a result of the drum size as you speculated combined with the microstepping. For a machine like Tantillus with a light weight bed that moves with gravity we can rely on the microstepping even with the limited resolution it offers. But for a larger/heavier bed you may want it geared in a way that allows for the layer heights you want when using whole steps.


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Re: Cable Z axis
October 20, 2013 11:49AM
Hello Sublime,

I have decided to print up the parts for the cable z but I have a question regarding the drum. How perfectly round does it have to be? I measured the roundness with a caliper and it has a range of .64mm. Will any imperfections on the drum show up in the prints on the Tantillus? I am thinking it must be a calibration error on my machine. But what's strange is at the seam of the print is where the number gets to be the highest, but that's also dead on to be the y axis too.

What do you think?

Thank you,

Cameron

Edited 1 time(s). Last edit at 10/20/2013 02:32PM by cameronm.
Re: Cable Z axis
October 20, 2013 01:12PM
Since the drum is almost 32mm in circumference it should only show a gradual variation in Z height over 32mm's which should not show like the issue with a lead screw. But I guess it could cause an issue with total object height being off by as much as your error in diameter.

To improve the print be sure you have retraction, wipe and seam hiding turned off. You can also try increasing the cooling and if you have enough cooling you can try increasing the print speed and or decreasing the temperature. After that you could try using Jitter to randomize the starting points and hopefully eliminate the line that is causing the issue.


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Re: Cable Z axis
October 20, 2013 04:57PM
Thank you! I played with the settings a little more with your suggestions and got the range down from .64 mm to about .16 mm. Some of the changes I made too were upping the speed of the z axis and the over all speed and setting the Z-Settle down to zero (I don't know if that had anything to do with it but I was thinking it might have just enough time to ooze going up .25mm so I turned it off).

Again thank you,

Cameron
Re: Cable Z axis
October 20, 2013 05:55PM
Glad to hear you got it that good. Are you printing them on a Tantillus?

Z-Settle should only be used on machines that have backlash on the Z axis. If your machine has an antibacklash nut setup with the spring in the middle it should have little to no backlash and not need Z-settle. Z-lift on the other hand should only be used in rare cases where you have collisions with curling edges and possibly small diameter posts that may get broken off.


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Re: Cable Z axis
October 20, 2013 05:58PM
Oh and yes the actual diameter will determine final steps per unit for Z. You can start with the 100.66 I got for mine and then test and recalculate. Others have used the 100.66 for theirs and it sounds like they are getting parts the correct size.


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Re: Cable Z axis
October 21, 2013 04:13PM
Oh no I am printing these parts on a Prusa v2, but I have not played with the settings in Kisslicer that in-depth. Not to sure on what everything does. I probably should take a better look at your Tantillus settings because they are very good! It looks like you put a lot of time and effort in to getting the settings just right. The lead screws drive me nuts so I wanted try out a cable based Z. I wish I could have printed them on my Tantillus but I managed to get the wobble almost completely out of the Z axis with no anti-backlash springs on the Prusa so I decided to print with that. Thanks for explaining the use for the Z-Settle, I will keep an eye out for backlash if I have that setting turned off.

Thanks for the tip about recalculating the steps for the Z axis, I will be sure to do that once I get everything put back together.

Thank you,

Cameron
Re: Cable Z axis
March 15, 2014 05:52PM
Here are some renders of how the cable is routed.






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Re: Cable Z axis
March 26, 2014 07:06AM
Hello all,

I already posted this question but I probably posted it in the wrong thread: Is there a particular reason to use a printed drum to wrap the spectra line on the Z motor instead of using the motor shaft itself?

I was thinking to drill the shaft and use the same principle used for the drives on X and Y. Based on some very simple (and maybe wrong?) calculation that should allow for more resolution in the movement. So I guess Sublime figured out some problem that would come up with this system?
Re: Cable Z axis
March 26, 2014 07:35AM
The reason I did not do that was because of how much the cable would wander having to turn so many times with a small diameter. With the drum it takes three rotations to go the entire 100mm of Z height which means the most wander you will get is three cable diameters wide or 1.5mm of wander side to side.


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Re: Cable Z axis
April 05, 2014 06:03AM
I see. Do you have some guideline to follow on printing the pieces for this mod a part from the drum? I mean number of shells, infill % .. anything.


Thank you in advance.
Re: Cable Z axis
April 05, 2014 09:08AM
Quote
Dansvidania
I see. Do you have some guideline to follow on printing the pieces for this mod a part from the drum? I mean number of shells, infill % .. anything.


Thank you in advance.

The way the parts are designed if you use 2-3 perimeters with 20%-40% octagonal/rounded infill (30%-60% line infill) using a 0.5mm nozzle on all the parts you will end up with almost solid parts. Some of the parts actually have internal cavities to force extra perimeters where needed to make the parts stronger. I would add an extra perimeter if using a 0.35mm nozzle.


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Re: Cable Z axis
May 05, 2014 08:06PM
sublime did you ever try GT2 belt for your Z axis?


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Re: Cable Z axis
May 05, 2014 10:05PM
Quote
jzatopa
sublime did you ever try GT2 belt for your Z axis?

I have not. Ingentis uses them and Printxl and Up to name a few use some kind of belts for their Z axis. It should work well, I just have a fascination with cable drive. I even have a set of gt2 belts and pulleys sitting on my shelf for almost two years that I've yet to use despite designing and building a new machine.


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Re: Cable Z axis
January 23, 2015 11:45AM
Regarding the limit of the layer height: I was able to modify the tantillus belt-driven z-axis (gt2 modified) by a printed gear drive with almost no clearance between the gears. So far, it worked like a charm and the walls of the printed objects are somewhat flat. Only at quite low layer heights a little bit of gear clearance is visible. I solved this problem by "prestressing" the z-axis in the Kisslicer settings with an additional offset.
Has anyone else tried to gear down the z-azis by a printed gear? Results?
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