Repstrap Stepper Extruder (proto-Wade)
Posted by toomanyplugs
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Repstrap Stepper Extruder (proto-Wade) May 05, 2010 04:36PM |
Registered: 14 years ago Posts: 21 |
I started out building a McWire since that was state-of-the-art for repstraps at the time. Unfortunately, all references to an extruder to fit the McWire assumed one either bought an extruder kit or had parts printed first...which is a little ridiculous for something that is supposed to get you started on printing *without* having access to a printer already...
So I kludged along, and now I think I have a pretty solid stepper-based repstrap extruder. No printed parts, and no tools except for basic garage tools (including dremel and drill press).
I based the design mainly on this extruder from binaryconstruct.
I used a high-torqued Nema 17 stepper motor (Lin engineering 4218L-01) that I got 5 of on ebay for about $8/each including shipping (check out Alltronics' ebay store). The motor shaft includes a D-flat for set/grub screws.
The drive gear shown in the attached picture here is my first try with a hobby pinion, but the spacing of the gear teeth gave the extrudate an inch-worm look as each tooth bit in. I have since made a hobbed worm gear in the manner of Wade's extruder, and with the higher-torque stepper I don't need the gearing (thus no printed parts). My worm gear mounts directly to the motor shaft using a set screw and it works great.
The hot end consists of a 0.6mm welding tip (McMaster 78375A606, 5 for $5.56) drilled out to 3.5mm until the very end. The tip is about 25mm tall and has a recess just under the threads that I fixed an E-clip to.
Grabbed the E-clip with a fender washer and bolts, like the makerbot plastruder, and bolted directly to an aluminum L so that the PTFE is in compression, and the E-clip and fender washer take all of the extrusion load. You can see the side bolts in the picture.
The PTFE insulator now only has to be about 25mm long because the welding tip threads are only about 7mm long. This gives a shorter entry so that there is less friction for the filament. Standard nichrome, heater wire, ceramic insulator kapton from makerbot. The blue part is a chopping board from WalMart that I used for all of the flat pieces for the McWire. 8.5 X 11 X 0.25 thick for about $2.
Used a little drop-down and L-bracket to mount it to McWire z-stage, then used a velcro cable strap to secure the motor to the L-bracket. This makes it easy to disassemble, and allows flex in case I drive the tip into the bed (again).
My next step is to print a set of Vik's ball-chain gears to turn the McWire into a chain-drive, which I hope will increase its speed enough to finish Mendel parts in a reasonable time. (I don't want to devote too much more time into something that is supposed to be a stepping-stone).
Nik
So I kludged along, and now I think I have a pretty solid stepper-based repstrap extruder. No printed parts, and no tools except for basic garage tools (including dremel and drill press).
I based the design mainly on this extruder from binaryconstruct.
I used a high-torqued Nema 17 stepper motor (Lin engineering 4218L-01) that I got 5 of on ebay for about $8/each including shipping (check out Alltronics' ebay store). The motor shaft includes a D-flat for set/grub screws.
The drive gear shown in the attached picture here is my first try with a hobby pinion, but the spacing of the gear teeth gave the extrudate an inch-worm look as each tooth bit in. I have since made a hobbed worm gear in the manner of Wade's extruder, and with the higher-torque stepper I don't need the gearing (thus no printed parts). My worm gear mounts directly to the motor shaft using a set screw and it works great.
The hot end consists of a 0.6mm welding tip (McMaster 78375A606, 5 for $5.56) drilled out to 3.5mm until the very end. The tip is about 25mm tall and has a recess just under the threads that I fixed an E-clip to.
Grabbed the E-clip with a fender washer and bolts, like the makerbot plastruder, and bolted directly to an aluminum L so that the PTFE is in compression, and the E-clip and fender washer take all of the extrusion load. You can see the side bolts in the picture.
The PTFE insulator now only has to be about 25mm long because the welding tip threads are only about 7mm long. This gives a shorter entry so that there is less friction for the filament. Standard nichrome, heater wire, ceramic insulator kapton from makerbot. The blue part is a chopping board from WalMart that I used for all of the flat pieces for the McWire. 8.5 X 11 X 0.25 thick for about $2.
Used a little drop-down and L-bracket to mount it to McWire z-stage, then used a velcro cable strap to secure the motor to the L-bracket. This makes it easy to disassemble, and allows flex in case I drive the tip into the bed (again).
My next step is to print a set of Vik's ball-chain gears to turn the McWire into a chain-drive, which I hope will increase its speed enough to finish Mendel parts in a reasonable time. (I don't want to devote too much more time into something that is supposed to be a stepping-stone).
Nik
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Re: Repstrap Stepper Extruder (proto-Wade) August 13, 2011 11:07PM |
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