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Getting skeinforge to print a shield like reprap-host

Posted by jsadusk 
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jsadusk
Getting skeinforge to print a shield like reprap-host
February 20, 2011 08:50PM
I've recently moved to skeinforge over reprap-host, mostly because reprap host had problems generating gcode for some thin walled objects I made. Overall, once its tuned for mendel, skeinforge really seems to do a better job of generating gcode. The only thing reprap-host did that I miss was it had an option to print a shield in front of your object. This worked great at catching the ooze that formed while the head homed between layers. With skeinforge I get a line of blobs on my object on the path from the zero point.

I thought about putting commands to draw a shield in the homing.gcode, but I'm not good enough at reading gcode to pull out the shield section of a reprap-host generated file. Has anyone here done this already? Is there some option burried in skeinforge to do an equivalent that I'm not seeing?
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NewPerfection
Re: Getting skeinforge to print a shield like reprap-host
February 20, 2011 08:54PM
Why do you need to home between layers? As long as your steppers aren't missing steps, then homing is not necessary.
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 20, 2011 10:33PM
I don't usually, but there have been occasions where the nozzle gets stuck on a blob of plastic and then gets slightly out of sync. Homing makes sure that any sync problems, if they happen, only last one layer. I guess its more insurance than anything.
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NewPerfection
Re: Getting skeinforge to print a shield like reprap-host
February 20, 2011 11:11PM
Good point. You could always add shield g-code to the homing.gcode, so that it prints those two lines after each homing. Just leave out any z changes and each shield layer will print at the correct height.
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 01:47PM
That was my original thought, but I was having trouble coming up with the gcode for a shield and was wondering if anyone had already attempted this.
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 02:34PM
One of the first things I turned of in the reprap host is the shield. If you can control the ooze even a little bit, then you don;t need the shield. I've found that the shield has resulted in more problems than it solves when it comes off the bed. If you don't go home before each layer, then you don't need the shield. With skeinforge, you don't need the shield unless you want to use it to control warping in the corners. With retract and retart, you can eliminate ooze altogether. But, as I learned recently, make sure that your thermal break doesn't get too hot or it doesn't work as well. With Adrian's geared extruder, there's not much ventilation to cool the PTFE thermal break so it needs a fan or compressed to keep it cool.
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 02:57PM
Hmm, I'm using Wade's extruder, and I'm using retraction in skeinforge and I always seem to get ooze when it homes. It seems to take a few seconds to start oozing, so it only really happens when I home.
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rhmorrison
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 03:05PM
eye rolling smiley Doctor, Doctor - it hurts when I do this... "THEN DON'T DO THAT!".

You don't need to home.

If you are getting blobs on your object that you catch on THEN you have a problem, homing won't fix it.
I am printing using PLA and if you use a two part nozzle like the big head nozzle you will eventually get blobs on your object because the PLA squeezes between the threads.

The only way to fix this is to use a single piece nozzle (no threads) e.g. Adrians newest hot-end.

With fast retraction and no homing (and no leaking nozzle) you have no problems. spinning smiley sticking its tongue out

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 03:31PM
Bob,
Are you referring to the tip from Mendel-Parts.com? They're currently not taking orders. Also, why is this a single piece nozzle with no threads? I see threads and I see 3 pieces not counting the threaded rods and nuts.
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rhmorrison
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 03:52PM
Actually what I am using doesn't need the threaded rods and nuts.

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 04:49PM
PEEK thermal break with PTFE sleeve? How is the tip attached? I would guess they're threaded together. I wonder if this is available for shipment to the US.
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rhmorrison
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 05:39PM
The hot-end is one solid piece of brass, the PEEK screws into the brass.
You would have to ask Wolfgang if he is willing to ship to the States.

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 06:03PM
Does the PEEK have a PTFE sleeve? If not, do you get problems with PLA sticking to the PEEK?
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rhmorrison
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 06:17PM
Yes, it has a PTFE sleeve.
No problems with sticking...

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 06:25PM
Adrian's revision in the wiki has the PTFE going all the way to the tip of the nozzle. Is that how this one is? I'm actually planning to have one made if I can't find a source.

Edited 1 time(s). Last edit at 02/21/2011 06:28PM by brnrd.
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rhmorrison
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 06:30PM
The PTFE is only inside the PEEK, not inside the brass nozzle.

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 10:48PM
So, I mentioned that I make it home because it gets out of sync sometimes, and I thought it was getting caught on blobs of plastic. But I just caught it in the act, and saw my mendel lose its position in the middle of a layer. It didn't get caught on anything and it didn't look mechanical at all. It was in the middle of drawing an outline and it just paused for a second when it shouldn't have, and then continued on as if it had done a command a second earlier. It was almost as if a line of gcode had just been dropped. And because it was in the middle of a longish side on an outline it was way off when it continued.

What could possibly be going wrong here? Has anyone seen something like this? I'm using techzone electronics, is it possible they're just screwed up?
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 11:21PM
Where are your stepper controller trimpots set? On mine, I have it about 75%. It's a bit tricky to figure it out. I have to use a magnifying glass with my bad eyes. You can adjust it by using the control panel in the reprap host or repsnapper to move each axis while you adjust the trimpot. If it's too low, you'll see it miss. Turn it clockwise until it doesn't miss anymore. Then turn it a little more (1/8 turn?) just to be safe.
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NewPerfection
Re: Getting skeinforge to print a shield like reprap-host
February 21, 2011 11:23PM
Sounds like it is missing a line of gcode. Seems to be a communications error, not sure how I would track it down though.
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 12:03AM
How are you sending the gcode to the printer? If you're using the reprap host, you can watch the console and see what's happening when it pauses. If you're using repsnapper, you can view either the communication log, error log or echo and see where it's getting stuck. If the trimpots are not adjusted right, the motors won't move and it might not even make a sound so I'd still double check that.
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 12:10AM
Thanks for the suggestions, but I found something that seems to fix the problem, though I don't know why. I moved to using replicatorG instead of reprap-host, and all the problems magically went away. Exact same gcode, no changes to hardware. I have no idea what reprap-host could have been doing wrong.
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 12:22AM
Are you able to send Gcodes to your Mendel with ReplicatorG? What firmware did you load? Which techzone electronics? I haven't been successful in doing that. I have to use reprap host or repsnapper to send gcodes.
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 12:42AM
I'm using the standard mendel firmware with the techzone gen3 electronics. ReplicatorG actually has direct support for it if you're using version 023 or later. Open up the preferences and select "Show Experimental Machine Profiles", and then Reprap Mendel will show up in the list of machine types. Once I had that selected it seemed to work fine.

I also have acceleration turned off in the firmware, but that's already necessary for skeinforge gcode to work with mendel.
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 12:53AM
I'm also using ReplicatorG 0023 but only to generate gcode. All my attempts to send gcodes from it have failed using reprap host firmware from 20100719 (64-bit), 20100806 and even the 20110207 release. I wonder if it's because I'm on a Mac (Leopard). What OS are you on?
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 12:55AM
I'm on linux. But I take back my claim that replicatorG fixed the problem. It just took longer for it to happen.
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jsadusk
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 01:03AM
Oh and I'm using replicatorG 0024 and firmware 20100806.
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brnrd
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 01:14AM
Thanks! I didn't notice the new version. I'll give this one a try then.
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makergear
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 08:51AM
@rhmorrison I don't know whose parts you were using but your sweeping claim of "if you use a two part nozzle like the big head nozzle you will eventually get blobs on your object" is nonsense. BigHead nozzles are one of our products and we have many hundreds of hot-ends in the field that are doing just fine and have been for a long time...

Rick
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rhmorrison
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 09:16AM
@Rick: How much printing do you do with PLA?

I have used two piece hot ends from three different suppliers and eventually the PLA leaked through the threads leaving blobs on the object every now and again.

With a one piece design this problem does not (and can not) exist!

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
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makergear
Re: Getting skeinforge to print a shield like reprap-host
February 22, 2011 09:26AM
@RHMorrission Extensive and long-term use of PLA. Like I said we have many hundreds of hot-ends in the field that are doing just fine.
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