New and different dual extruder idea

[Vandal968]

Tim,
a possible improvement would be to add a lever-operated cam to each extruder truck. When they bump together the cam rocks the magnets apart to minimize the force that the x-axis motor needs to overcome. This would allow you to use stronger magnets and eliminate any concern about acceleration while keeping the effort required to disconnect to a minimum.

cheers,
c

[Tim]

a possible improvement would be to add a lever-operated cam to each extruder truck. When they bump together the cam rocks the magnets apart to minimize the force that the x-axis motor needs to overcome. This would allow you to use stronger magnets and eliminate any concern about acceleration while keeping the effort required to disconnect to a minimum.

The problem with "larger magnets" is that there is not much room there around the belt. I am using 0.1" cylindrical neodymium magnets (from "Super Magnet Man" on Amazon), which were the smallest neodymium magnets I could find. I have arranged four of them with two on either side of the belt. More than that, or larger magnets, is certainly doable but would require a bit of thought on how to cram them in that space. You don't want to get too strong with the magnets, though, or it will make the motor skip. But I'm pretty sure (understatement!) that my four little cylinder magnets have nowhere near the force needed to overcome the stepper motor.

[Tim]

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.

I was investigating this problem earlier this morning and discovered that the release notes for Simplify3D 3.0.0 states that it supports the creation of skirts by each extruder separately, specifically to solve this problem. But I have tried all different ways and cannot get it to work, so I have a support ticket open with Simplify3D as well as a post on their tech support forum.

Meanwhile I tried an alternative of creating a separate model for the skirt and adding it to the list of models attached to the right extruder process. But no matter how I sized and placed it, Simplify3D would always print the actual model first, and the skirt second. So I will have to wait for an answer from tech support, and the worst-case scenario is going to be splicing the skirt into the gcode with post-processing. Ugh. I hope it doesn't come to that.

[sthone]

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.

I'm a little curious... when you guys say "V4 Clamp Plates" are you referring to the original aluminum piece the actual hot end mounts too? You didn't actual print a new one of those did you? I wouldn't think that would be usable....

-Steve

[Tim]

I'm a little curious... when you guys say "V4 Clamp Plates" are you referring to the original aluminum piece the actual hot end mounts too? You didn't actual print a new one of those did you? I wouldn't think that would be usable....

Maybe a bit of "terminology normalization" is in order here. . .

I would call that a "v4 mount plate" and yes, it should not be done in anything less robust than aluminum. The best way to do this project is to start with a single v4 and then get a v4 upgrade kit plus a stepper motor, in which case the only unprintable part remaining is the extra rail block. By starting with the MakerGear dual extruder, I didn't have any of the single-v4 mount plates, but happily MakerGear provided me with a couple for my project. But they didn't seem too keen on making a general practice out of selling the mount places without the rest of the v4 kit. I expect it messes up their inventory. So the recommendation for this project if you want to do it and don't already have a single v4 is to order two v4 upgrade kits, and make sure one of them is a spare hot-end that you can make good use of, like a stainless steel one or a different diameter nozzle.

So, anyway, I didn't really notice the phrase "clamp plate", but the obvious point in question is what I call the "parking plate", because it is a piece of metal that has the hot nozzle sitting directly on top of it, thermally connected, and the ends of the plate are held by a printed plastic bracket. So melting the plastic bracket is definitely something to be concerned about, and something that I'm watching carefully. So far, no problems, but "so far" does not include much run time yet.

[PcS]

If you add skirt brim and make it really close to the model but place your models further apart s3d will draw a skirt around each model. Try changing skirt distance and just preview it.

[sthone]

From the pictures it looked like you had the aluminum mounting plates already but wasn't sure. I so... wanted to see this project work from the start and I was concerned if that's what you printed it wasn't going to last. I was going to offer to mill you out new mounting plates as I have a piece of flat stock left over from my micron extruder project.

If your parking plate (is the piece I think you're talking about) is mounted to the rear end of actual mounting plate I doubt it will melt. I don't even have a extruder fan on my printer any more and the stock motor mount hasn't melted yet so it should be fine.

-Steve

[Levi8than]

The mounting plates in Tim's pictures are black, not silver with 30 tiny holes like my dual extruder mounting plate.
I REALLY want to duplicate your results and join in the fun. But I am really surprised that magnets are working this well. I guess I shouldn't be that surprised. The carriage bearings are really good, so inertia is the only thing the magnets are fighting. The motors aren't that heavy.

I wouldn't have a problem with buying 2 single extruder upgrade kits from Makergear to get a start on this. Where did you get the extra carriage train (rail-rider/thing that slides on the x rail), from makergear as well?

[Tim]

The mounting plates in Tim's pictures are black, not silver with 30 tiny holes like my dual extruder mounting plate.

I've just been answering questions here while trying to figure out how to solve the Simplify3D problem (need to look into PcS's suggestion), so I haven't been particularly thorough about describing everything. The mount plates are definitely a point of confusion if you don't know all the versions. The v3 mount plates were printed parts, but didn't get anywhere near the hot-end. The v4 mount plates are black anodized aluminum (which apparently the heater blocks are, too, recently), which is different from the dual extruder mount plates, which were regular ol' aluminum (I don't know what the dual extruder kits look like these days). The dual mount plate had lots of holes drilled in it, and the fan had a duct that directs part of the airflow directly onto the top of the array of holes, so the holes are obviously there for cooling purposes. The v4 mount plates are mostly solid with a couple of holes of indeterminate use (but probably to break up heat flow to keep it traveling back to the motor mount).

I REALLY want to duplicate your results and join in the fun. But I am really surprised that magnets are working this well. I guess I shouldn't be that surprised. The carriage bearings are really good, so inertia is the only thing the magnets are fighting. The motors aren't that heavy.

The rails are basically what makes the M2 such a solid and reliable machine. They don't come cheap, either. The ones on the M2 seem to be the ones sold by Misumi USA:

http://www.misumiusa.com/linear-motion/linear-guide/ (Select "standard block", and I'm guessing "precision grade" but I'm not certain.)

and they cost in the range of $100 each for measurements similar to what's on the M2.

I wouldn't have a problem with buying 2 single extruder upgrade kits from Makergear to get a start on this. Where did you get the extra carriage train (rail-rider/thing that slides on the x rail), from makergear as well?

Yes, I got it from MakerGear. I looked at the Misumi website, and while they have lots of selections for rails and blocks, the standard rail on the M2 (height 12mm from rail bottom to block top) comes only as a set; you can't order the block from them separately. Maybe there's someplace else that sells these?

[edit:] By staring hard at the actual rail block on my M2, I can see it is made by CPC Chieftek (Taiwan), miniature linear guide, type CPC-MR12MN.
http://url.chieftek.com/product-mr.asp
I have not yet found a place online where one can be ordered online, either full assembly or just the block, but I'm still looking.

[additional edit:] A few of them pop up on eBay with a search for "CPC MR12MN", but they all are assemblies of rail plus block, and are correspondingly expensive. . .

[mharter]

Did you check HiWin for this rail? www.hiwin.com

They have this type of rail as well as many other linear motion solutions.