Belt drive Z-axis
Posted: Thu May 01, 2014 10:57 am
I'm looking for an example of a belt, and pulley Z-axis drive being applied to a DLP-SLA printer.
My math indicates it's not possible, but maybe there is a workaround that I have not considered. I have read of one person saying they saw an example of a belt driven DLP-SLA printer, but a reference was provided, or notes of it's performance.
With a PDMS film (Silicone) on the vat bottom, the separation force is ~100 oz (27.8 N) for an image area of 625 mm2 (25 mmx25 mm). The separation force can go as high as ~140 oz, and it goes higher as the exposure time increases.
Digital Material Fabrication Using Mask-Image-Projection-based Stereolithography
http://www-bcf.usc.edu/~yongchen/Resear ... l_2012.pdf
Using a force of 100 oz, and my proposed build platform area of 7.5 in x 4.25 in x 100 oz = 3187.5 oz force, or 199 pounds of separation force. My NEMA17 stepper motor is rated at 76 oz-in, and a GT2 belt is rated for 5.8 lbs. So it's easy to see that it will not work on it's own, and why a tilting, and/or sliding vat to over come the Van der Waals force is employed.
I'm also aiming for a Z-axis resolution of 0.010 mm, (0.0004 in).
If I use a threaded rod I'm considering using a Roton 10 mm x 2 mm pitch Trapezoidal thread.
http://www.roton.com/Mating_Components. ... ly=7060746
2 mm pitch/200 steps = 0.010 mm
GT2 belt: 2 mm pitch, 6 mm wide.
Allowable Working Tension Per 1 Inch of Belt Width 25 lbs (111 N). 25.54 mm/6 mm = 4.26, 25 lbs /4.26 = 5.8 lbs max working load.
http://www.sdp-si.com/D265/PDF/D265T015.pdf
My math indicates it's not possible, but maybe there is a workaround that I have not considered. I have read of one person saying they saw an example of a belt driven DLP-SLA printer, but a reference was provided, or notes of it's performance.
With a PDMS film (Silicone) on the vat bottom, the separation force is ~100 oz (27.8 N) for an image area of 625 mm2 (25 mmx25 mm). The separation force can go as high as ~140 oz, and it goes higher as the exposure time increases.
Digital Material Fabrication Using Mask-Image-Projection-based Stereolithography
http://www-bcf.usc.edu/~yongchen/Resear ... l_2012.pdf
Using a force of 100 oz, and my proposed build platform area of 7.5 in x 4.25 in x 100 oz = 3187.5 oz force, or 199 pounds of separation force. My NEMA17 stepper motor is rated at 76 oz-in, and a GT2 belt is rated for 5.8 lbs. So it's easy to see that it will not work on it's own, and why a tilting, and/or sliding vat to over come the Van der Waals force is employed.
I'm also aiming for a Z-axis resolution of 0.010 mm, (0.0004 in).
If I use a threaded rod I'm considering using a Roton 10 mm x 2 mm pitch Trapezoidal thread.
http://www.roton.com/Mating_Components. ... ly=7060746
2 mm pitch/200 steps = 0.010 mm
GT2 belt: 2 mm pitch, 6 mm wide.
Allowable Working Tension Per 1 Inch of Belt Width 25 lbs (111 N). 25.54 mm/6 mm = 4.26, 25 lbs /4.26 = 5.8 lbs max working load.
http://www.sdp-si.com/D265/PDF/D265T015.pdf