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 » Sun Dec 27, 2015 3:03 am

ErikAkia wrote:I made a video of the modification work I have done so far in solidworks. Would you mind taking a quick look and see if you see any major problems?
It looks pretty good to me. It even looks like you get slightly more range along the X-axis then I do, which I think is due to moving over into the space previously occupied by the Z-knob. I would probably go with a design that adds height to the motor base, because that not only lifts you above the space for the Z-knob and allows you to put some kind of knob back on there, but also it increases your maximum print height. But I stopped short of trying to squeeze every last cubic millimeter out of the print volume; it wasn't worth that much effort to me.

But the only thing I was concerned about when you first said you were going to try this idea with the E3Dv6 hot-ends was the ability for the left extruder to park off of the left side and for the right extruder to park off the right side, and you appear to have those covered. You might want to model the corner brackets around the heated bed plate, mainly the front left one, because I had issues with that corner bracket hitting the wiper on the left parking plate, which is why I don't have a wiper on that side. It can be done, but I haven't gotten around to it, and I'm still evaluating the wiper on the right side, which isn't as useful as I was expecting it to be. In my 2-color 8-sided die test print, the blue filament (left side, no wiper) was better behaved than the white filament (right side with wiper), but that wasn't a very balanced experiment.

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Re: New and different dual extruder idea

Post by ErikAkia » Tue Dec 29, 2015 2:57 am

Tim wrote:You might want to model the corner brackets around the heated bed plate, mainly the front left one, ...
Hi Tim,
I put those corner brackets in and have another question.
https://youtu.be/Y7RNMNnA3ko

Thanks

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Tim
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Re: New and different dual extruder idea

Post by Tim » Tue Dec 29, 2015 5:21 am

ErikAkia wrote:I put those corner brackets in and have another question.
I agree that the corner brackets represent a "worst case scenario"---but more like an "impossible case scenario", since the bed must always be higher than the corner brackets, or else the nozzle is going to collide with them. So that gives you a marginal space where you can put the metal plate where it clears the corner brackets but still fits under the nozzle.

It's true that the flipped v4 does move further to the left, so that the nozzle is inside the bracket area when resting on the metal plate. The metal plate juts out in front of those slots by a few millimeters, but no more than that. But I'm pretty sure you can get everything to fit without collisions. You won't have room for the wiper, certainly, but then I'm not sure how useful the wipers are anyway.

You will have a very small amount of space between the parking plate and the heated bed to use for purging, but you shouldn't need much.

You are correct in your guess at the use of the metal parking plates. They do an excellent job of stopping dripping/oozing completely. I was expecting that you don't need to plug the nozzle tightly, just cover it up, to keep it from losing pressure (the hot filament will keep it plugged up as long as there's nowhere for it to drip). That turned out to be the case. In fact, it really makes the purging almost unnecessary. You don't lose any filament to drips while the extruder is heating up, as long as it's sitting on that plate. So all you really need is a little priming on a skirt and it's ready to go. That also may be why the wiper doesn't seem to be particularly effective. There's just not that much to wipe.

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tks546
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Re: New and different dual extruder idea

Post by tks546 » Fri May 13, 2016 7:39 pm

Tim,

What a simple amazing idea for dual extruder printing!
I looked at your write up on thingiverse and I'm really tempted to try this myself.
I have a couple questions if you don't mind:

Have you found the magnetic connection to cause any quality issues with your prints? It doesn't induce any lag or delay in the print head movement?

Reading your posts, I see you switched to smoothieware, is there a reason for that other than more control of the firmware?

Thanks!

-Tom

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Tim
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Re: New and different dual extruder idea

Post by Tim » Fri May 13, 2016 10:00 pm

tks546 wrote:Have you found the magnetic connection to cause any quality issues with your prints? It doesn't induce any lag or delay in the print head movement?
Not one iota difference in quality. There are a few things to look out for; the two major ones that come to mind is that there is a limit to how fast the switch between the two heads can be done. At a high enough speed, a head can fail to latch on to the magnets. Once it's attached, though, it's not going anywhere. The other thing is that it is possible to knock the hot-end off the magnet by doing something like going in with a pair of tweezers to pick off a wayward glob of filament. But it still takes a pretty hard jolt to knock it loose.
Reading your posts, I see you switched to smoothieware, is there a reason for that other than more control of the firmware?
There were several reasons. The first is that I had an early-generation RAMBo, one that had to be hacked up a bit before I could do the 12V-to-24V conversion. So I was due for a replacement. But I was holding off because it didn't seem all that necessary to replace a good working board, when somebody posted to this forum about the Smoothieboard. It looked interesting, so I took it as a challenge to figure out how to make one drive the M2. And part of that decision was due to various discussions on the forum about whether or not certain printing artifacts were due to the mechanics or the firmware of the M2. Completely swapping out the firmware was an enlightening test.

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Re: New and different dual extruder idea

Post by tks546 » Sat May 14, 2016 1:36 am

Thanks for the fast reply Tim!

Did you find the Smoothie improved your M2 prints?

I found a large improvement on on my delta when I switched to a smoothie, but I read it didn't do as much for a cartesian printer.

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Re: New and different dual extruder idea

Post by Tim » Sat May 14, 2016 2:30 am

tks546 wrote:Did you find the Smoothie improved your M2 prints?

I found a large improvement on on my delta when I switched to a smoothie, but I read it didn't do as much for a cartesian printer.
That sounds about right. What I found was that due to the faster processor speed, I could get the same quality as before at a higher speed. This only works to the extent that the quality is based on the ability of the firmware to look ahead in its calculation. You can't, for example, move ninjaflex any faster than the ninjaflex wants to go. For more forgiving filaments like PLA and PETg, there's always a speed-vs.-quality tradeoff. On the Smoothie, that tradeoff shifts over to a higher speed, maybe 30% or so higher. There are other aspects of the Smoothieware that I like, though, such as the ability to mount the SD card directly onto my computer, the method of updating firmware by just copying the file over to the SD card and then power cycling; and the method of keeping most of the control parameters in a text file that's read in by the Smoothie on startup, so you can tweak most parameters without touching the firmware at all.

The Ethernet port, though, has proved to be almost completely useless. Due to some quirk of the architecture, it can't be run on an interrupt (or so I'm told), and so all Ethernet communications have to wait for the processor to go to idle. This can take up to 10 seconds, even when the processor isn't busy doing a print. It's not very useful to tell the printer to move 10mm in the X direction and nothing happens for the next several seconds.

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Re: New and different dual extruder idea

Post by MikeA » Fri Jun 10, 2016 2:46 am

I'm new to the forum here and just came across this thread, but have had a M2 at work for a year or so and recently got a lightly used one to play with at home. I upgraded the work one a while back to the factory dual extruder but wanted to do something a little different with my personal one. I didn't really want the non printing extruder moving around over the print area. I've mounted the second extruder on a separate carriage by using "Mirrored" Makergear parts. For the left motor mount I just flipped it around and drilled 2 new offset holes in the mount so the motor was positioned correctly. The 2 carriages are tied together with a couple of different lengths of aluminum strips across the back of the motor. This gives me the ability to put them for enough apart that only one at the time is over the print or to space them very close together. I never print anything large but often want to print 2 of something. This gives me the option to place them a little further apart and let them print in sync with other and get 2 parts in the same time as one would take. I also made a mirror of the newest wiring harness mount left side which keeps the wires nice and tidy.

Ultimately I would like to add a second X-axis motor and belt so each extruder can get out of the way while the other is printing or let them print as duals. I originally assumed this would take a lot of firmware but after spending a few night getting familiar with the firmware it appears there is a command M605 that will handle the second extruder and carriage. I've followed it from where it is received and parsed from the serial port up to the point it steps the motor. It appears to be a functional command. In looking at the Rambo board it appears to have provisions to provide extra step and direction signals to an extra stepper driver which would have to be added on a separate board. The 605 command has a couple of options, slicer handles everything, firmware parks and unparks both extruders and finally they can act as dual extruders.

Is there anyone else who is familiar with the M605 command or who has good working knowledge of the firmware?

Mike
dual clipped.JPG

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Tim
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Re: New and different dual extruder idea

Post by Tim » Fri Jun 10, 2016 2:01 pm

MikeA wrote:Is there anyone else who is familiar with the M605 command or who has good working knowledge of the firmware?
Yes, I've looked at some of the command options for independent dual extrusion options and will comment on that eventually (may not get around to it today).

But meanwhile. . . how did you get a mirror-image metal motor mount bracket? I want one of those! I've been wanting to switch to the metal brackets, but with my dual extruder setup, two brackets, as sold, would keep the extruders further apart than I would like. By contrast, a reversed metal motor mount would allow me to get the motors just a little bit closer together than I can do with the printed mounts.

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Re: New and different dual extruder idea

Post by MikeA » Fri Jun 10, 2016 4:49 pm

Tim,
The metal mount normally uses the front 2 holes in the carriage. I just flipped it around and used the back 2 holes. This requires drilling 2 new holes in the motor mount with the new holes being just behind the old ones. You would need to measure and make sure, but I think I remember them being about .160" behind the old holes. The mount is stainless, I used a mill to get them in the exact location. This setup will allow the two motors to actually slide up against each other and touch.

I would be interested in hearing what you have learned about the dual prints. I'm an EE with embedded firmware experience at a previous job, but I do not have any Arduino experience. From the few nights I've spent looking through the code it appears the M605 command has the ability to do dual prints.

The picture below shows them push up together touching. The distance between them is currently set by using a length of aluminum strip of the desired length under one of the corner screw that holds the rear motor cover on.

Update: I had some time this afternoon to play with the firmare and was able to make a few changes and get the M605 S2 command to work as I wanted it to. When the command option S2 is sent the 2nd extruder extrudes in sync with the 1st allowing dual prints. When the S0 option is sent it defaults back to its normal behavior. I also looked more in depth at adding a second motor/belt for the second extruder and the firmware seems to support it. It looks like it will also require a second home switch. For anyone interested look in Configuration_adv.h and scroll down or search for #define DUAL_X_CARRIAGE. The next several lines of code and comments after that describe how the 2nd X carriage works.

Mike
Touching.JPG

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