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 » Sat Oct 24, 2015 4:10 pm

innkeeper wrote:i've thought about perhaps getting a single and/or dual v4 head for the m2, but i've thrown a lot of money at the m2 printer fixing or finding issues that existed from the day it was made so i was in no rush to spend more on it. so all i can do for now is relate my experiences with my replicator 1 ..
The risk of being an early adopter is having to correct problems, spend money on upgrades, and sometimes to find yourself stuck with a non-upgradable incompatibility. Open hardware/open software products don't really have any such thing as a "non-upgradable incompatibility", which is one reason I like them. Mostly it's a matter of whether or not an upgrade costs more than you want to pay for.
innkeeper wrote:i think the best of both worlds would be if you could easily swap out single and dual extruders depending on your project
That's part of what I am aiming for in this modification. I only see a small drawback in using the right extruder only, in that the right extruder can't trigger the X-min endstop, so you would have to connect to the left extruder when homing the X axis, then move all the way to the right to make the right extruder active, then back left to park the left extruder. But that's a fairly quick one-time-only startup maneuver. Alternately, an X-max endstop could be added on the right and everything mirror-imaged, but I think that's more complicated than it's worth.

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innkeeper
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Re: New and different dual extruder idea

Post by innkeeper » Sat Oct 24, 2015 7:46 pm

The only real practical issue i see with this is that one of the critical alignments you do with a dual head is alignments between heads for the x and y offsets.
every time you work on a dual extruder it seems, you have to re calibrate it. so if your splitting the left and right extruders then connecting them back together... your going to need tor e calibrate each time.
i think you have the same issue with swapping extruders because even though the head distance likely wouln't change, you cant as easily garentee your going to be in the exact same spot axialy without a total redesign of the mount.

remember when aligning the heads we are talking getting it re-aligned within perhaps 10 microns if you plan to print at 100 microns, and frankly id bet the alignment on mine is even lower then that
M2 - MKS SBase w Smoothieware, GLCD, 24v, Upg Z & extruder stepper - IR bed leveling, Astrosyn dampers X/Y/Z, MIC 6, Zebra, PEI, & glass Build Plates - E3D, V3B Hotends, & more - many other 3d printers - production printing.

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Tim
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Re: New and different dual extruder idea

Post by Tim » Sat Oct 24, 2015 11:13 pm

innkeeper wrote:The only real practical issue i see with this is that one of the critical alignments you do with a dual head is alignments between heads for the x and y offsets.
Well, yeah, that's the main issue, I have no illusions about that. But I don't think 10 microns is a realistic goal under any circumstance---the belts flex more than that. But the firmware only knows the X and Y alignments in terms of stepper motor steps, and the stepper motors are connected directly to the belt, so it's a matter of keeping the nozzle in the same position relative to the belt. I think my proposed idea is doing that. The Y axis is not a problem; it's a matter of alignment between the nozzle and the X rail, which only depends on how much free play is in the rail carriage, and this proposed idea doesn't change that at all.

I thought briefly about an idea in which each extruder would grab and release the belt, but that clearly has alignment problems, as you need to know that each time you grab the belt, you grab it in exactly the same place.

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Re: New and different dual extruder idea

Post by Matt_Sharkey » Sun Oct 25, 2015 3:33 pm

You would want strong magnets to keep it reliable on calibration, but strong magnets will work against your head changing. Perhaps an electromagnet on the carriage would be an easier solution? that way you won't have to worry about belt skips or wearing out the belt.

otherwise, I think this is a pretty good idea I know id like to see a working model!

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innkeeper
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Re: New and different dual extruder idea

Post by innkeeper » Sun Oct 25, 2015 5:13 pm

i cant come up with a better concept that dosn't ad significant weight to the carriage. I was thinking about a quick release on one of the hot ends, but i think that would still require re-alignment each time.

the only alterative i can think of is that Micron (3dp) has a dual extruder design where the head and barrel unscrew from the heatsink and heater, and they give you spares.... that might not be so bad, jsut unscrew the unused one and you get an extra few mm of clearance. they make use of nema 11 geared steppers, allowing them to keep the heads closerr to each other. .. i they are geared on the high side... and a bit costly like 400 bucks or something. looks like they resolved the flexable filament issue with a new extruder design called cobra

I'm not a big fan of micron / 3dp though due to some recent misleading practices, and the fact that they still sell thier older flawed extruder.. i simply don't trust them.
M2 - MKS SBase w Smoothieware, GLCD, 24v, Upg Z & extruder stepper - IR bed leveling, Astrosyn dampers X/Y/Z, MIC 6, Zebra, PEI, & glass Build Plates - E3D, V3B Hotends, & more - many other 3d printers - production printing.

mharter
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Re: New and different dual extruder idea

Post by mharter » Mon Oct 26, 2015 11:53 am

Are you talking about something similar to this? https://www.bcn3dtechnologies.com/en/ca ... cn3d-sigma

My next project was a dual x carriage 3d printer to park the non active extruder off the build platform.

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Re: New and different dual extruder idea

Post by mharter » Mon Oct 26, 2015 12:00 pm

Tim wrote:
nirfriedman wrote:If you go for two separate heads, why not have them on two separate belts? as far as I can see, you can put two belt drives in parallel (add one behind the current one) and have one carriage with longer extension backward. The price is that you have another motor and need firmware changes. The benefit is that you avoid the headache of reattaching heads which seems to me highly non-trivial.
I think rewriting the firmware for two separate X steppers is highly non-trivial. There's also the point that very few controller boards support that many motors (the Fastbot bbp1s that was mentioned recently by PcS is one exception, but I don't have one of those). I guess I've concluded that just about any way you do a dual-extruder setup, something is going to end up being non-trivial. The way I'm trying to do it, though, has a pretty low overhead on extra hardware. Although once I've gone halfway through prototyping it, I may very well end up agreeing with you. I won't know until I've tried it.

There is actually plans for a dual carriage bukobot on their website: http://bukobot.com/creating-a-dual-x-carriage-bukobot. firmware changes and all. This modification uses the dual belt system. I have a Fastbot bbp1s on order just for this occasion (when I get to it that is). The dual carriage with dual belts is a ver simple implementation. If only the M2 frame was wider by some inches to accommodate two carriages. I don't feel confident the M2 would handle the faster print speeds of the Fastbot as the y axis moves via the bed. I would be worried that taller prints would get wobbly and break off from the quick back and forth jerks of the high speed board. Interesting times ahead!

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Tim
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Re: New and different dual extruder idea

Post by Tim » Mon Oct 26, 2015 2:28 pm

mharter wrote:There is actually plans for a dual carriage bukobot on their website: http://bukobot.com/creating-a-dual-x-carriage-bukobot. firmware changes and all.
I must say I had not considered parking the nozzle on top of a $2 egg-beater blade.

"When I get to it" is always a limitation, but I hope I can see your Fastbot solution sooner rather than later.

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Re: New and different dual extruder idea

Post by mharter » Mon Oct 26, 2015 3:08 pm

Tim wrote:
mharter wrote:There is actually plans for a dual carriage bukobot on their website: http://bukobot.com/creating-a-dual-x-carriage-bukobot. firmware changes and all.
I must say I had not considered parking the nozzle on top of a $2 egg-beater blade.

"When I get to it" is always a limitation, but I hope I can see your Fastbot solution sooner rather than later.
I have the last 2 weeks of the year off for vacation, so the design will be more than likely realized then. Will keep you posted.

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innkeeper
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Re: New and different dual extruder idea

Post by innkeeper » Mon Oct 26, 2015 3:33 pm

mharter wrote: There is actually plans for a dual carriage bukobot on their website: http://bukobot.com/creating-a-dual-x-carriage-bukobot. firmware changes and all.
I would bet we can find someone to make up some custom chassis and cut a longer top plate
though at this rate, the m2 will become a bit like Lincolns ax, its all original except we had to replaced the handle and the ax blade.
M2 - MKS SBase w Smoothieware, GLCD, 24v, Upg Z & extruder stepper - IR bed leveling, Astrosyn dampers X/Y/Z, MIC 6, Zebra, PEI, & glass Build Plates - E3D, V3B Hotends, & more - many other 3d printers - production printing.

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