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Lyman's Spool Winder Tweaks

by ianjohnson, published

Lyman's Spool Winder Tweaks by ianjohnson Jan 24, 2013

Description

I built Lyman's spooler to go along with my Filastruder. I made a couple of small tweaks. -

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.

Update-

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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Instructions

Follow the directions for the original spooler. I used more lock nuts to keep the rollers in place. Spin the threaded rods with a drill to make it easier to place the lock nuts. Figuring out what order to put them all on and in what direction is a bit tricky.

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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Revolve3D on Apr 28, 2013 said:

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?

charliearmorycom on Mar 6, 2013 said:

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.

ianjohnson on Mar 6, 2013 said:

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.

charliearmorycom on Mar 6, 2013 said:

In model railroading they have the same problem of not being able to run the DC motor below a certain voltage (for super-slow operation) and still have enough torque. What the high end power supplies do is use Pulse Width Modulation (PWM). Rather than changing the voltage they change the duty-cycle of the pulses. Perhaps this would help.

skovgaar on Jan 25, 2013 said:

I wish I had seen this project before you got so far along on it, because I think there is a much better way to go about it. I used to work at a movie theater as a projectionist back in the days of actual film, and the projectors I used employed a very good solution to the exact challenge you're facing here. With a film projector (the newer ones, not like in Fight Club and Inglorious Basterds, this kind http://www.youtube.com/watch?v... the film must be unspooled/spooled from a 3' reel. The projector would feed the film at a constant rate, but the rate that the big horizontal platters would need to spin varied depending on how much film had been spooled/unspooled since the radius of the reel was constantly changing. There were various tension sensors that were used to control the motor speed depending on how much slack was there. What you're doing has obviously worked, but modulating motor speeds/torques based on direct measurement of tension seems like it would be way less finicky than relying on slippage (which can be quite inconsistent)

ianjohnson on Jan 25, 2013 said:

Does the tension sensor look like this - http://www.youtube.com/watch?f... The slipping is simple to execute. Maybe there would be a way to make a lever that will actually turn the knob on the voltage regulator as the filament pushes it up and down. The tension on the reel isn't that critical though, it's the tension of the rollers pulling the filament from the extruder that must be absolutely consistent. That said, the tension from the reel can't be so much that it starts to drag the filament through the rollers.

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