Hi all
I designed and built a circular knitting machine or CSM, mainly using 3d printed parts. There are many aspects in existing designs I did not like. Among these are bevel gear drive, sub-ideal bearing surfaces, difficult to implement moving parts etc.
This design uses a different approach to needle movement. There are basically 3 phases:
Another way I have seen is by implementing a second pull-down phase, making the movement symmetrical, but creating a lot of un-necessary drag. (JeepingJohnny)
My solution is to implement a second push-up phase after the new stitch is created. Now the needles are up during the third (do nothing) phase.
This would create problems when certain actions are required; for instance when a dropped stitch needs to be picked up. Therefore the needles can be pushed down during most of the third phase. These needles will be pushed up normally by the first push-up cam (but you need to make sure the latches are open!)
Instead of bevel gears I use a timing belt to drive the unit. This introduces a lot less friction. Also the machine rotates on 3d-printed ball bearings using cheap steel 4.5mm (.177 cal) BBs.
Finally to reduce friction I glued annealed steel wires into the push-up and pull-down cams. This eliminates the need for sanding these cams smooth, it creates a superior bearing surface for the needle movement and eliminates wear of the cams. It also reduces the need to lubricate. (the steel wire can be replaced)
I found that fluffy yarn tends to snag on 3D-printed parts, so I reduced yarn-on-plastic contact by using piano wire guides most of the time.
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I have been using this machine for a while now and it behaves very well. It does not like heavy yarns or very shallow stitches. It will require excessive force during these circumstances. I leave the timing belt relatively loose, so when it skips, you know not to continue.
I built the whole machine for less than 50 dollars, It needs about 45 hours to print, with one part 20 hours (the central cylinder). The assembly is straight forward with only the ball bearings needing some attention. Also sanding is kept to a minimum.
You can find the design on thingiverse (thing:6273014). It includes all the printable files and the OpenSCAD design. You can change it at will, or contact me to implement your wishes. ( I may help you out
)
I designed and built a circular knitting machine or CSM, mainly using 3d printed parts. There are many aspects in existing designs I did not like. Among these are bevel gear drive, sub-ideal bearing surfaces, difficult to implement moving parts etc.
This design uses a different approach to needle movement. There are basically 3 phases:
- a needle moves up to place the previous stitch under the needle latch and accept the yarn in the hook to form the new stitch;
- the needle is pulled down creating the new stitch;
- the needle comes back up and does nothing.
Another way I have seen is by implementing a second pull-down phase, making the movement symmetrical, but creating a lot of un-necessary drag. (JeepingJohnny)
My solution is to implement a second push-up phase after the new stitch is created. Now the needles are up during the third (do nothing) phase.
This would create problems when certain actions are required; for instance when a dropped stitch needs to be picked up. Therefore the needles can be pushed down during most of the third phase. These needles will be pushed up normally by the first push-up cam (but you need to make sure the latches are open!)
Instead of bevel gears I use a timing belt to drive the unit. This introduces a lot less friction. Also the machine rotates on 3d-printed ball bearings using cheap steel 4.5mm (.177 cal) BBs.
Finally to reduce friction I glued annealed steel wires into the push-up and pull-down cams. This eliminates the need for sanding these cams smooth, it creates a superior bearing surface for the needle movement and eliminates wear of the cams. It also reduces the need to lubricate. (the steel wire can be replaced)
I found that fluffy yarn tends to snag on 3D-printed parts, so I reduced yarn-on-plastic contact by using piano wire guides most of the time.
I have been using this machine for a while now and it behaves very well. It does not like heavy yarns or very shallow stitches. It will require excessive force during these circumstances. I leave the timing belt relatively loose, so when it skips, you know not to continue.
I built the whole machine for less than 50 dollars, It needs about 45 hours to print, with one part 20 hours (the central cylinder). The assembly is straight forward with only the ball bearings needing some attention. Also sanding is kept to a minimum.
You can find the design on thingiverse (thing:6273014). It includes all the printable files and the OpenSCAD design. You can change it at will, or contact me to implement your wishes. ( I may help you out
)
