Designing a backlash-free drive with a worm screw. To eliminate the backlash, 2 worm screws are required that have a small shift. With only 1 worm screw you have about 0.6mm of backlash which is a lot.
A custom housing now contains 2 worm screws at the right distance. These can easily be mounted on the standard base plate 120x60mm. In the setup I use shafts of 500mm length. To increase stability another 4 small support wheels are added that run on a flat surface. This way the carriage can not tilt and remains very stable. With an XM-motor and a gear reduction of 3 times the drive goes quite smoothly. At the end I made a worm screw stop (yellow plug). Also the gear of 30T contains an adjustment for the worm screw. In the foreground of the picture you see the details of the housing. I also made a quadrature decoder with home point with a ball bearing D8x4x3mm With an encoder disc with 15 neodymium magnets you get 60 pulses per tour or 0.0785 mm per pulse.
All files on Thingiverse: https://www.thingiverse.com/thing:3323197
A few pictures:
HD: https://www.flickr.com/photos/fotoopa_hs/31587974067
HD: https://www.flickr.com/photos/fotoopa_hs/31587973697
HD: https://www.flickr.com/photos/fotoopa_hs/31587973327
HD: https://www.flickr.com/photos/fotoopa_hs/32654940448
HD: https://www.flickr.com/photos/fotoopa_hs/32654940218
Frans.
Designing a backlash-free drive with a worm screw.
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Re: Designing a backlash-free drive with a worm screw.
Hello Frans,
afaik, two worm screws put directly behind another and one turned 90° gives a fine result also. So you can just fix the two work screws with, say, a single BS30.
Best Regards,
Stefan
afaik, two worm screws put directly behind another and one turned 90° gives a fine result also. So you can just fix the two work screws with, say, a single BS30.
Best Regards,
Stefan
Re: Designing a backlash-free drive with a worm screw.
Thanks Stefan,
I've tested it now and it's going pretty well. That's easier. However, the amount of backlash depends a little on the position of both nuts. Best suited for normal use.
The 3D block is slightly more robust as a whole.
Well, there are still some other blocks left, like the worm stop and the worm gears. I ordered 10 pieces D4x500mm shaft together with 50 worm pieces FI-37926 to make all kinds of transmissions.
I have to fill my days with all kinds of tests and sometimes the solutions are much simpler than I thought.
Update:
My 3D print version has better support because both worm nuts are at a slightly greater distance (31.5 center to center instead of 15mm). This makes the backlash more constant and the shaft is more stable. If you also use a distance of 30mm and twist the worm screw 90 degrees there is hardly any difference.
Frans
I've tested it now and it's going pretty well. That's easier. However, the amount of backlash depends a little on the position of both nuts. Best suited for normal use.
The 3D block is slightly more robust as a whole.
Well, there are still some other blocks left, like the worm stop and the worm gears. I ordered 10 pieces D4x500mm shaft together with 50 worm pieces FI-37926 to make all kinds of transmissions.
I have to fill my days with all kinds of tests and sometimes the solutions are much simpler than I thought.
Update:
My 3D print version has better support because both worm nuts are at a slightly greater distance (31.5 center to center instead of 15mm). This makes the backlash more constant and the shaft is more stable. If you also use a distance of 30mm and twist the worm screw 90 degrees there is hardly any difference.
Frans