Pfierce PNEMAtruder ver1.0
Description
For some reason the derivative feature wasn't working properly :( ...So I made it a new thing.
Here is the PNEMAtruder! The "P" is silent :D
It has all the features of the junior tan's version: thingiverse.com/thing:3178 the rear breach and gear access.
It is a direct drive stepper extruder that uses a high torque NEMA 17 in order to drive filament to extrude. Or a high torque NEMA 23
Also, an optional filament tube clamp can be attached at the top, for those with filament spindles.
This is still a work in progress, but I thought I'd put it out there for all to see and make suggestions, etc.
The center has been changed so I can't use any existing support designs.
What do you guys look for in your supports? low part counts? Easy to print? Function/Flatness? Maximum Z height? Would you want me to make laser cut supports for purchase/download? Does anyone actually read this and answer? So far, no so I'm just designing features I want.
***1/12/11*** I'm currently working on a revised version that axes the NEMA 17 and utilizes a NEMA 23. Most high torque NEMA 17's that I can find just don't have enough torque to get the job done. I uploaded a screenshot of the new design. None of the files are updated, yet.
***6/4/11*** With MBI selling the 100 in-oz NEMA 17 motor in there store you can now use the 17 design.
Instructions
They're 2 flavors, one with a 625 bearing which will fit the NEMA shaft or one with a 626 bearing. The 626 is a cheaper bearing, but has a 6mm ID so you will have to use a nylon shaft adapter or build up a millimeter of tape on the shaft or I suppose you can print one if your bot is calibrated well and you have cooling fans.
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Why not just hobb the shaft and double or quadruple your available force/cut your required torque? Is there a special reason you need the MakerBot drive gear driving the filament?
http://cgi.ebay.com/NEMA-23-St...
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amp;hash=item2eaf25d79b#ht_534wt_905
This is a NEMA 23 @ 76 oz-in. = 5.47 kg/cm. We might be able to do a direct drive with this, plus we can still use our regular stepper drivers (v2.3). I'll start working on a NEMA 23 mount for it and will be ordering one as soon as the break ends. Nice work!
that looks awesome. thanks for uploading it
I will print one out tonight and try it with the geared stepper i just got from makergear. I think that would be the best bet for a strong motor that is not so likely to slip.
Thanks, you're welcome.
I don't think there geared stepper will bolt up to it, because the gearhead has a different bolt pattern, but i'm sure you could design an intermediary...or if there gearhead bolt pattern is the same as the Kysan, try attaching it to your fluorescent red printruder II just to see If the concept wo
rks.
Kysan gear motor at shaft ~8kg-cm the filament should be making ~43.2 kg-cm with a Mk5 gear
This stepper makes 4.8kg-cm, in theory it should make 25.9 kg-cm at the filament with an adapted Mk5 gear. It would require a 18mm diameter drive gear to reach 43.2 kg-cm
I guess, I'll have to just find out if half the torque works.
I don't even know if this is really a good idea, since direct d
rive will put more strain on the motor it may cause reliability issues.
I think you're doing your torque calcs backwards. As the moment of force moves away from the pivot, the required torque to move the arm INCREASES, it doesn't decrease. The mass that a given torque (ie:motor) can move decreases as the diameter grows. For instance, a motor that can move 1kg on a pulley 1cm from the center can only move 100g at a distance of 10cm (yet both of these measurements would be an identical torque of 1kg*cm).
If I'm reading your numbers correctly, (8kg at shaft edge), a Kysan could never hit 43.2 without further gearing and would quickly drop below the 5kg that you say is required.
Files?
Hey Charles, I'll upload them later today.
Also, I have a question for you. When you were designing the Mk5 to direct drive, what high torque NEMA 17 were you considering? Did you do any testing?
The highest torque NEMA 17 I could find for cheap was here:
http://www.solarbotics.com/pro...
thanks,
Brian
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Okay, so the motor came quicker than expected and much to my surprise, it has an 8mm diameter shaft... the specs don't mention that! I assumed it was 6mm like most NEMA 23's. :(
So I took it apart with an arbor press on centers and popped the bearings off and now it's ready to be lathed down to 6mm.
It is tempting to hobb the shaft, but I don't want to have to remodel the pnematruder to take a 608 bearing.