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 » Thu Dec 10, 2015 5:11 pm

mharter wrote:Did you check HiWin for this rail? http://www.hiwin.com
They have this type of rail as well as many other linear motion solutions.
Are they truly compatible? I have not looked at the specifications in detail.

I did ask for a quote from Anaheim Automation http://www.anaheimautomation.com on their website. They have the exact block used on the M2, and quoted me a price of $29 for ordering just the block. They answered my quote request within a day, so they appear to be reasonably responsive even if you can't do an "add to cart" from their web pages. It's a little pricey but you only need one of them for the project.

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Levi8than
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Re: New and different dual extruder idea

Post by Levi8than » Thu Dec 10, 2015 5:23 pm

Tim wrote:They have the exact block used on the M2, and quoted me a price of $29 for ordering just the block.
As long as there is no risk of lost bearings sliding a new one on the end, why didn't you lead with this? That sounds way cheaper than ordering anything available on ebay for this project.

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Re: New and different dual extruder idea

Post by Tim » Thu Dec 10, 2015 6:07 pm

Levi8than wrote:As long as there is no risk of lost bearings sliding a new one on the end, why didn't you lead with this? That sounds way cheaper than ordering anything available on ebay for this project.
Because I just found out. I've been spending time the last couple of days trying to work out a good set of recommendations about where to get these parts in a way that doesn't cause MakerGear to have to act as a parts supplier/broker. Otherwise it's hard to write this up as a viable project, when you have to tell people to go ask MakerGear for special favors. Now it's possible that only three or four people in the world will ever do this modification, and it would not be an undue burden on MakerGear to cough up a handful of rail carriages and mount plates, but you never know.

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Levi8than
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Re: New and different dual extruder idea

Post by Levi8than » Thu Dec 10, 2015 6:13 pm

Tim wrote:
Levi8than wrote:As long as there is no risk of lost bearings sliding a new one on the end, why didn't you lead with this? That sounds way cheaper than ordering anything available on ebay for this project.
Because I just found out. I've been spending time the last couple of days trying to work out a good set of recommendations about where to get these parts in a way that doesn't cause MakerGear to have to act as a parts supplier/broker. Otherwise it's hard to write this up as a viable project, when you have to tell people to go ask MakerGear for special favors. Now it's possible that only three or four people in the world will ever do this modification, and it would not be an undue burden on MakerGear to cough up a handful of rail carriages and mount plates, but you never know.
Sorry. Too excited. I read what I had in my head, not what you meant to say.
I can slow down and wait... nope. Too excited.


Unrelated to the rail/carriage, I was thinking. On my current marlin build, the firmware takes care of shifting the X between the two heads.
You would lose some versatility if we put the head swap code into the firmware instead of letting Simplify take care of it... but really how much? Would it be easier to maintain then?

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Re: New and different dual extruder idea

Post by Tim » Thu Dec 10, 2015 11:40 pm

Levi8than wrote:Sorry. Too excited. I read what I had in my head, not what you meant to say.
I can slow down and wait... nope. Too excited.
I'm working on the instructions now, but I'm still waiting on Simplify3D support and getting more discouraged by my findings. . . which I will post in just a minute. It's looking more like post-processing will be a necessity, at least for the short term.
Unrelated to the rail/carriage, I was thinking. On my current marlin build, the firmware takes care of shifting the X between the two heads.
You would lose some versatility if we put the head swap code into the firmware instead of letting Simplify take care of it... but really how much? Would it be easier to maintain then?
Personally, I can't see why there should be any significant performance difference between compensating for the left-right extruder offset in gcode vs. in firmware. Doing it in software would make it much more easy to calibrate on the fly; as it is, the Smoothie board controller is the next-best thing, as I can change the offsets in the configuration file on the SDcard (which I can mount on my computer directly). But that wouldn't be true of Marlin, which you would have to re-flash every time you make an adjustment. Doing it in software seems much simpler. But I tried messing around with the extruder offsets in Simplify3D, and it didn't appear to have any effect at all. I'm never sure if I'm missing something, or if Simplify3D is.

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Levi8than
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Re: New and different dual extruder idea

Post by Levi8than » Thu Dec 10, 2015 11:50 pm

Tim wrote:...But that wouldn't be true of Marlin, which you would have to re-flash every time you make an adjustment. Doing it in software seems much simpler. But I tried messing around with the extruder offsets in Simplify3D, and it didn't appear to have any effect at all. I'm never sure if I'm missing something, or if Simplify3D is.
As Marlin sits today, you're correct. All configuration changes are in the firmware.
But it doesn't have to stay that way. the board has flash memory that can be written at runtime. So if you have a display, we could put something in the menu to adjust this. We could even support reading the config file from the sd port.

But you're getting further and further from stock firmware, so it means that every new version of Marlin will take work to port.

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Tim
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Re: New and different dual extruder idea

Post by Tim » Thu Dec 10, 2015 11:51 pm

And speaking of not knowing whether I'm missing something or Simplify3D is, here's where I got with the dual extruder skirt problem:

First, I was getting only the left extruder printing a skirt, and I could not get the right extruder to generate a skirt no matter what I did to the setup.

I contacted Simplify3D support, and finally got the answer that I needed for each of the left and right processes to define the other extruder (and. . . why, exactly? And why does that result in only the left extruder printing a skirt? Seems so freaking arbritrary, not to mention arcane).

So I plugged in the modified processes, and I discover that it prints the skirt INTERLEAVED right, left, right, left. But get this---it's PRINTED in that order: left extruder prints a skirt perimeter. Right extruder prints a skirt perimeter. Left extruder prints another skirt perimeter. And so forth. And after the right extruder prints the last skirt perimeter, then the left extruder starts printing the first layer, followed by the right extruder printing its first layer.

If you think about that, you'll realize that it completely undermines the whole purpose of having a skirt in the first place.

Typically the skirt is used to get the filament flowing, because when the extruder sits still for too long, it takes some time to get it going, and that problem is worst when attempting to print the first layer on the bed surface. Hence the need to print the skirt to give a good long time for the filament to get going, then immediately move to the first layer.

Simplify3D's way of doing a dual extrusion skirt means that each nozzle gets primed multiple times, for no particular reason, and that both of them have a significant delay between priming on the skirt and printing the part, which is just wrong, wrong, wrong.

It kind of makes me wonder if the guys who do the programming at Simplify3D have every actually used a 3D printer. . .

Sorry, it has been frustrating working with Simplify3D support, and I had to get that rant off my chest.

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Tim
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Re: New and different dual extruder idea

Post by Tim » Fri Dec 11, 2015 4:40 am

I have started the writeup. It will take a few days to complete.

http://opencircuitdesign.com/~tim/3d_pr ... oject.html

Vandal968
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Re: New and different dual extruder idea

Post by Vandal968 » Fri Dec 11, 2015 4:01 pm

Tim wrote: Now it's possible that only three or four people in the world will ever do this modification,
Oh, I think it's going to be a few more than that....

Can't wait! Thanks for sharing your work.

cheers,
c

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Tim
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Re: New and different dual extruder idea

Post by Tim » Fri Dec 11, 2015 4:25 pm

Levi8than wrote:As long as there is no risk of lost bearings sliding a new one on the end, why didn't you lead with this? That sounds way cheaper than ordering anything available on ebay for this project.
Okay, the real question is why didn't I think to go look at the MakerGear site and see if they actually offer a rail carriage on their spare parts list? Because they do. Just go to "Spare Parts", open the list, and find "Replacement Carriage for either X or Y Rail on M2". $25, and you don't even have to ask for a quote, just put it in the cart and check out.

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