New and different dual extruder idea

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Tim
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Re: New and different dual extruder idea

Post by Tim » Tue Dec 08, 2015 3:49 pm

Tim wrote:Photos will be uploaded soon
Here's a few. . .

This is an assortment of hardware I printed, including the standalone belt clamp with magnets, and the two mount plates with magnetic blocks. The magnetic blocks have four magnets on one side to grip the belt clamp firmly, and two on the other side to grip the parking position end stop a bit less firmly. Later I had to re-print the left extruder drive and left magnetic block in reverse (flipped across the X axis), so this hardware design is not final.
m2_twin_hardware.jpg
Here's some of the hardware, although I later determined that I needed to reverse the left side extruder.
This is the left side end stop block with holes for two magnets (not yet installed). It is bolted to the frame using the machine screws that hold the X endstop switch. The belt passes through the slots without touching.
m2_twin_left_park.jpg
Left side parking (without magnets installed)
This is the right side end stop block with holes for two magnets (not yet installed). It is bolted to the frame with one of the X axis motor screws, and the screw holding the X axis nylon stop post. Again, the belt passes through the slots without touching.
m2_twin_right_park.jpg
Right side parking
In mid-project, with the second linear rail block on the rail, and both mount plates bolted down along with the motor mounts. This was when I realized that the left side extruder, mount plate, and motor mount would all have to be reversed so that the left extruder could be off of the bed when in the parked position.
m2_twin_mounts.jpg
Mount plates and motor mounts assembled (although later modified).
More to come in the next post!

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Tim
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Re: New and different dual extruder idea

Post by Tim » Tue Dec 08, 2015 4:10 pm

Here's the second set of photos from the project build:

In this photo, the left side assembly has been completed; it is basically a standard V4 single extruder except that everything has been flipped left to right, so that the nozzle is positioned further to the left and is off of the plate when the assembly is pushed all the way to the left. In operation, the left side assembly will purge and wipe from the left, and the right side assembly will purge and wipe from the right.
m2_twin_left_complete.jpg
Completed left side, reversed so that the nozzle is off of the heated bed when the assembly is pushed all the way to the left.
Here, the left side assembly is up and running and busy printing parts for the right side. The right side is partially assembled and managing not to get in the way of the left side printing. Note that there is a spare hot-end tied to the cable. . . I had to connect this into the wiring, or else Simplify3D hangs up when it receives an "inf" value from the thermistor and tries to plot that on the temperature plot! It still has the fans connected into the right extruder wiring, which had to be later rewired inside the electronics box.
m2_twin_left_printing.jpg
Here is the left side printing the right side.
This is a close-up of the right side parking plate and wiper. The right side assembly sits here when not in use. At the moment, the wiper is missing from the left side due to lack of room between the parking plate and the heated bed frame. It will need a bit of a redesign. So far, it appears that the parking plates act like heat sinks and are not getting excessively hot. I will probably print the brackets again in polycarb, to be on the safe side.
m2_twin_right_wiper.jpg
Right side wipe plate, made from a scrap piece of brass and the rubber wiper that MakerGear ships with the M2 dual extruder kit.
This is the completed project, with both right and left extruders and parking plates assembled and installed. The fan wiring has been separated out between right and left, and parking plates are installed on both sides. Project ready for testing!
m2_twin_complete2.jpg
Completed twin extruder project

mharter
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Re: New and different dual extruder idea

Post by mharter » Tue Dec 08, 2015 10:55 pm

Tim!!! This is great work!

My BBP1S arrived last week and I just dove into solidworks to start planning out my machine. I am going to go with a fresh build as I would like to have a printer with a larger build area. (I love my M2 Dual just the way it is, prints better than any other printer I've seen...kudos Rick!) I am also going with a stepper motor for each carriage. But I am super curious as to your mechanism.

Anyway, great stuff! I was working on another project and didn't visit the forum for two weeks and look what happens...bam, Tim got it all worked out. Impressive to say the least!

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Levi8than
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Re: New and different dual extruder idea

Post by Levi8than » Tue Dec 08, 2015 11:57 pm

Did you print the v4 clamp plates? Won't those melt or at least deform?

I'm really excited about this. Keep the info coming.

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Tim
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Re: New and different dual extruder idea

Post by Tim » Wed Dec 09, 2015 1:06 am

Levi8than wrote:Did you print the v4 clamp plates? Won't those melt or at least deform?
Yes, maybe. So far I haven't noticed them getting hot enough to melt the surrounding plastic, but I haven't had them sitting there for very long, either. On the plus side, the thin metal plate is a bit like a heat sink fin, and since the bed fans are (electrically) tied together, as long as the bed fan is running on the active extruder, the plate has a fan directly on it as well. And if that doesn't work, I'll re-print it in polycarbonate. And if that doesn't work, I'll just bend a piece of metal into shape and bolt it to the frame.

[edit: For anybody reading through this thread, I got confused about the clamp plate thing, thought it referred to the plates where the heads are parked. The problem was that the MakerGear dual extruder mount plate is plain aluminum, but the new v4 mount plates are black anodized, and it's impossible to tell that they are not printed parts from a photo. For the record, my extruders are mounted on official MakerGear black anodized aluminum mount plates.]
Last edited by Tim on Wed Dec 23, 2015 2:33 pm, edited 1 time in total.

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Levi8than
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Re: New and different dual extruder idea

Post by Levi8than » Wed Dec 09, 2015 1:27 am

I think I'd rather see this piece milled from aluminum as Makergear's versions are.
But we can wait until you've finalized the design to do that.

How about those magnets. Did you need to reduce the maximum X jerk/acceleration?

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PcS
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Re: New and different dual extruder idea

Post by PcS » Wed Dec 09, 2015 2:48 am

This is interesting to say the least. I do wonder how fast you can run with this setup though ? I can picture bad things at breakneck speed !!! Very cool Tim !!! I applaud your progress !!! :D

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Tim
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Re: New and different dual extruder idea

Post by Tim » Wed Dec 09, 2015 3:43 am

Levi8than wrote:I think I'd rather see this piece milled from aluminum as Makergear's versions are.
But we can wait until you've finalized the design to do that.
Agreed. But I don't have a milling machine. . .
How about those magnets. Did you need to reduce the maximum X jerk/acceleration?
I have not seen any problems due simply to acceleration. I did have some trouble with the magnet coming loose as the right extruder collided with the left one. I got the impression that it wasn't the force of the impact that was knocking it loose, but that maybe the extruder was binding against the other briefly. To be on the safe side, I reduced the velocity from about 10000 for traveling to about 3000 just as it gets close to the ends. I'll be tweaking that over time. But I would point out that the MakerGear dual extruder needs to retract one side by up to 15mm or so and re-extrude the other side by 15mm, and because the firmware uses the same code (why??) for both (context switching using T0 or T1) you can't retract one and extrude the other at the same time. All the back-and-forth movement in my setup, although cumbersome, doesn't really take much more time to do than the long retracts and extrudes.

Because the linear rails are so good at what they do, the magnetic coupling is as good as it can get: All the force is in the direction of the magnet's axis, where the magnetic field is strongest. There's no shear force or bending or any of those things that you can do to separate magnets by taking advantage of their weak spots.

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Tim
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Re: New and different dual extruder idea

Post by Tim » Wed Dec 09, 2015 3:55 am

Here's a calibration print I just made. One of the drawbacks compared to the MakerGear dual extruder is that because the extruders are on different mounts, the nozzles have an unknown relative offset in both X and Y that has to be calibrated out. The good news is that those dimensions are relative to the fixed rails, so as long as you don't dismantle the mount plates, the calibrated values will remain good once they're dialed in.
dual_calibrate.jpg
Calibration piece I just printed
There's not a drip of the wrong color plastic anywhere on this piece.

I did have some difficulty getting the right extruder started on the first layer, which looks like it will be a perennial problem. What it needs is for the left extruder to purge, go print a skirt, do the first layer; and then the right extruder should purge, print some more skirt, and do its first layer. Unfortunately, Simplify3D doesn't have a way to do this. So I have to purge the right extruder first, re-park it, then the left extruder purges and prints through the first layer, and then finally the right extruder is supposed to go lay down its first layer after sitting on the plate for a while, and without the benefit of drawing a skirt. I will probably need to fake something by drawing a right-extruder skirt as part of the model, something to give the right extruder a chance to get going.

Other than that, my start script now purges both extruders, and my tool change script does a small bit of retraction, which helps a bit. Both still need tweaking. Tomorrow I will print something more than just a calibration piece, and maybe by Thursday I can start posting the project models, parts list, and instructions.

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Levi8than
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Re: New and different dual extruder idea

Post by Levi8than » Wed Dec 09, 2015 4:05 am

Sounds like in the short term we should post process with a perl script to clean this up. Then give it to the S3D guys as a proof of concept.

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