A little update…

I’ve been trying to run parts to get a better feeling on what the FDM1650 can/can’t do. I made up a platter of parts for a Mendel Extruder back on 4/13. I hadn’t checked how much of the MG-47 was left, and I ran out of filament early in the run. Sadly, I wasn’t checking the ‘cams, so the machine cooked for more than 22 hours (31 hour run) —rrr… The photo of the partial run shows the parts were looking pretty good, but I doubt the gears would mesh to good with the Y Axis backlash.

Filament Out Error
Filament Out Error

This pointed out two things I need to learn. The first is ‘how to recover’ from this error without throwing away partially completed parts. The second is ‘how to NOT cook the heads’! It took several hours of trying to get the old P400 I had on hand to load and spurt out. Then once loaded, Insight didn’t seem to to want to restart the run. Perhaps there was something I needed to do to save a restore point?

I needed to make some wire spool holders to organize a workbench a bit. I ran these using the old P400 and sliced with Insight using sparse settings. They were tall so the build took forever, and then some. All done, there were a few hairs but not too bad:

Wire Spool Holders Building
Wire Spool Holders Building
Finished Front View
Finished Front View
Finished Left View
Finished Left View

When I went to remove the parts from the foam, I grabbed one of the uprights and tried to pop it off. Instead of seperating, the joint to the base cracked. I guess I need to redesign a bit to strengthen that joint, and quit trying that technique to remove parts. Another thing I noticed is the Stratasys P400 really grips the support compared to the MG-47 I had been running. I still haven’t finished getting it all off!

I’ve only got ~70 wraps of MG-47 on Stratasys spools, so I need to get started  on a respooler setup that doesn’t span two lathes — also, needs a much lower RPM & a way to lay the filaments evenly. The 70 wraps I have left is what wouln’t fit on a spool with a random lay. I used to have an old coil winder I had hoped to duplicate, enlarge, and add a motor — of course I haven’t been able to find where I stored it (if I still have it?), but I did come across a PDF for building a Gingerly Coil Winder. I figure to mesh some of the coil winder features with the respooler HaveBlue found on Thingiverse. Gingerly used a adjustable right-angle drive to drive a circular cam to move a rod having a wire guide across the spool. I’d need a way to get pulses out of each rev of the spool to drive a stepper (that I’ll mount the cam on), so I modeled up a couple of gears to see how they might work:

Gears Front View
Gears Front View
Gears Left View
Gears Left View

As with the spool holders, the support is real hard to remove with the P400 model material. The smaller sector wheel, I’m going to try with an optical sensor, and the larger I’m going to try a mechanical pulse generator with a microswitch. Both are going to take a little playing.

Now for a cam. An offset circle is not going to be linear (0.070″/rev), so I designed up a heart shaped cam that will do that across the 3 1/2″, and return:

CAM Front View
CAM Front View
CAM Left View
CAM Left View

Somehow, these pieces need to fit together with an flea market air drive motor — this guy goes REAL SLOOOOOW, but noisy like all air drives. Hopefully, should work pretty well:

Air Drive Main Drive Motor
Air Drive Main Drive Motor

So, some bench work ahead to see how this all come together….

—-John

2 thoughts on “A little update…”

  1. I’ve been really curious to know how the MG47 compares to the P400 in terms of support adhesion – have you seen any part curling/corner lifting on the MG47 that might be due to reduced adhesion, or does it seem to be a sufficient bond?

  2. I have had only one *major* problem with corner lifting with the MG-47, and that was back on 3/20. I was running two large rectangular parts which had large rectangular pockets in the center. It appeared from looking at the sidewalls that the corners lifted and then the parts were knocked off the foam base. The result was

    Lifted Parts: http://3d4u.org/MyFDM_Files/DSC00954.JPG

    I never did try these parts again, and I wonder if I was too far away from the foam when I started the run, so the support didn’t stick down to the foam like it should. This coupled with the part size/geometry lead the corners to lift, popping the part off the base?

    I had a long part that had a circular boss midway on one side. A little like the clip on a clipboard. These parts ran without breaking loose, but the parts were not flat at all on the extreme ends.

    Other than that one disaster & one wierd part, the parts have been pretty flat on the bottoms and don’t show any corner lifting. Generally looking at the sidewalls, you can see a little thining toward the corners but it is hard to quantify.

    —-John

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