Jump to content
Sign in to follow this  
ayahoo

No pulley simple drive system

Recommended Posts

Posted · No pulley simple drive system

Hi All, again with some crazy idea, in my line of work, we are using a drive system that uses friction to move many shafts over large distance.

The idea is simple, taking the two 8mm shafts, wrapping few wraps of cable (in our systems it is steel cable) then going to the second shaft, wrapping few wraps of cable and then connecting them in the middle with a tensioner.

the only thing that is needed to adopt the system is just to find the correct material (steel cable wire plastic nylon what ever) to use.

then we get cheaper system with less parts & much more accuracy.

I'm attaching some photos :)

Screen

System with plastic cable arrange

 

Untitled 1

just few wraps around the shaft.

waiting to hear what you think.

 

Share this post


Link to post
Share on other sites
Posted · No pulley simple drive system

Great link! this is the same idea :) now it is hard to assemble because he is not using any parts to allow easy assembly, but if we use some printed parts like the plastic part that i showed, it will help with the wrapping & we need just a simple part to connect the ends :), I think I'll try it since the accuracy of the pulley is not high, and using this system will greatly improve the accuracy.

Nice to know somebody already tried it :)

 

Share this post


Link to post
Share on other sites
Posted · No pulley simple drive system

since the accuracy of the pulley is not high

[citation needed]

I've never seen a something that indicated MXL or GT2 pulley accuracy problems. Cable stretching however, can be a real problem. Which is why steel cable is most likely a bad idea.

 

Share this post


Link to post
Share on other sites
Posted · No pulley simple drive system

The problem is not with the belts, the problem lies in the pulleys:

http://umforum.ultimaker.com/index.php?/topic/1611-fixing-pulley-innacuracy/

As you can see there are many complains about it.

Hihi, that's not many complains, just a bunch of people that notice they are not 100% centric.

But only 1 post that might indicate that it causes actual changes in the print.

 

Share this post


Link to post
Share on other sites
Posted · No pulley simple drive system

Nevertheless, a difference in quality, which caused Ultimaking to inquire whether I could produce the pulleys for UM2 :)

But no way for me to meet their price target - what was to be expected.

 

Share this post


Link to post
Share on other sites
Posted · No pulley simple drive system

Steel cables are by no means accurate. They will stretch over time (and a bit with temperature changes, but that shouldn't be enough to be noticable).

Something like Dynema fibers would be a much better option.

 

Share this post


Link to post
Share on other sites
Posted · No pulley simple drive system

I'm sure everyone knows of richrap, but his new delta printer design (the 3DR) uses some sort of wound line instead of timing belts. I think he has versions for belts too.

http://richrap.blogspot.com/

I have lots of respect for that guy, and his design looks very well thought out and simple.

 

Share this post


Link to post
Share on other sites
Posted · No pulley simple drive system

Does it even matter if the steel cables expand / contract? With the right construction this shouldn't matter:

The cables are only used to move the axes, and the endstops provide the "where is my zero" information. If you have a simple construction to even out the cable warping (like some strong spring at the ends of the cable) then it shouldn't matter: The motor makes 10 turns, the cable transmits 10 turns. Doesn't matter if the cable gets longer or shorter with time, or does it?

 

Share this post


Link to post
Share on other sites
Posted · No pulley simple drive system

Cable stretch introduces backlash, and backlash contributes to a number of problems including fills not properly filling, and dimensions not correctly printing. Honestly, the best means of "simplifying" for the sake of accuracy that I've been able to uncover is SG's direct drive conversion. The other option you would have would be to modify the gear ratios of the pulleys, but that has consequences on speed. For what it provides, the UM is a highly accurate FDM printer. If you need more accuracy than what a well built and calibrate UM provides, you likely need to consider some sort of SLS or SLA printer.

 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Our picks

    • Ultimaker Cura 4.0 | Stable available!
      Ultimaker Cura 4.0 is mainly focused on the improved user interface and cloud integration.
      As always, we want to collect your user feedback for this release. If there are any improvements you can think of, feel free to mention it here and help us to shape the next release.
      • 82 replies
×
×
  • Create New...

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!