Lyman's Spool Winder Tweaks
by ianjohnson, published
Using nuts inside the latex rollers made for bumpy movement between them, so I simply printed cylinders to put inside the tubes instead.
I mounted the voltage regulators on the front, since I can't walk around to the back to make adjustments. Still to come- knobs for the adjustment screw so I don't have to keep fiddling with a tiny screwdriver. I would also like to dress them up with a cover.
I changed the puller to a Wade's Reloaded extruder with a stepper, but it didn't improve filament tolerance when pulling plastic directly from the die. Variations in pressure in the extruder normally change the speed of output while maintaining the diameter. When stretching the plastic directly from the die, the speed can't change so the diameter did instead. For the sake of simplicity, I switched the motor back to a gear motor and am letting the filament drop into a loop on the way to the puller. I'm still working on a method of syncing the uptake of the puller with the output of the extruder.
Instead of a hobbed bolt in the Wade's, I used a 8mm bolt with a 10mm long section of tubing - McMaster.com #5102K442.
I found that the springs on the motor arms aren't necessary. I need to make a mount for an adjustment bolt for the spool motor arm to rest on. Raising the bolt would lift the arm enough to provide a light enough touch on the spool that it would slip when encountering a little tension. The weight of the motor by itself provides too much traction. Also I need to do the same thing under the arm of the roller motor to dial in the right distance between the gears.
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Im currently starting to build the Lyman filament extruder. This is next on my list once thats done. Unrelated question but do you know that size I should drill out the brass nozzle to for 3mm filament?
I had the same idea, from one I saw in the video he posted. I've since changed the rollers to a stepper controlled extruder driven by an Arduino Uno. The Uno could use PWM to control the spool motor and read the potentiometer. On the other hand, simply keeping a light enough touch between the spool and the roller that a little tension causes the roller to slip is a much simpler solution.
Perhaps to implement skovgaar's suggestion you could put an idler pulley on a spring-loaded arm, then attach the end of the arm to the shaft of a potentiometer and use the potentiometer to control the pulse width. Running too fast -> too much tension -> pulls pulley and arm -> turns pot -> reduces duty-cycle. Running too slow -> not enough tension -> spring pulls arm -> turns pot -> increases duty-cycle.
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The z tabs are for mounting bolts to support the motor arms and raise or lower them precisely.
I also updated the gears to increase the ratio in an attempt to improve accuracy.
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