Need info on the preferences

I've gotten the communications issues mostly fixed - I only get an occasional missed packet now and then, but it's proving quite difficult to pin down, but it's working well enough to extrude, so I want to try extruding actual objects, and maybe the communications issues will either be minor enough to be ignorable, or maybe I can tell what's having trouble communicating by errors in the print.

Currently, when I try to print the minimug.stl from the RepRap object library, the X and Y motors are going WAY too slowly - the printout starts out with a very nice circle, but since the motors are going way too slowly, the CAPA puddles out to about 4mm wide. What preferences precisely affect the movement of the steppers while extruding? The steppers zip by at a nice speed during the stepper testing, and seem to move at the specified FastSpeed when going from the pre-print test blob to the start of the object, but as soon as it starts printing the mug itself, it slows down to about 1/4 speed. I currently have the FastSpeed set to 244 on the main properties page, and I tried setting the Extruder0_XYSpeed to 242 to see if that worked, but it looks like either I'm missing some setting that controls the speed, or my hardware is more borked than I thought. Any advice on what preferences do what would be greatly appreciated.

If you are missing any packets, I would say that it's likely hardware. Make sure you don't induce any noise. The caps are supposed to handle it. Do you have any potential noise sources you need to isolate from the circuit via shielding etc?

I haven't found any noise sources to speak of - whenever I check the power or comms lines everything looks pretty clean. It does seem to run a little better if I have a fan blowing directly on the boards, so at least some of my problem is heat related, but I've also noticed a significant improvement from increasing the torque level of the motors - I'm guessing that something happens when the motor stalls or skips a step that is either causing some form of feedback into the circuit, or perhaps the PIC is getting upset in some way when the motor doesn't respond right.

...But at this point, I'm getting few enough errors, and the errors seem to go away a little more when I tweak the software preferences to more correct values, so at the moment I'm much more interested in making sure that I have all the preferences set correctly so I can assess whether or not the comms issues actually mean anything or are merely a slight annoyance.

Here's a good example of my current status:

I created a simple 2cm X 2cm X 2cm cube in AoI, exported it as an STL, and started printing... So far it's done half of a layer, and only gotten one comms error, but it's traveling at only 1mm a second while it is extruding. I know the extruder can do 4mm/sec easily, and I know the motors can easily move that fast, so that suggests to me that it's a setting somewhere that needs to be changed. If I knew what that setting was, I could be working on real parts. If anyone has any ideas, I'd really appreciate hearing them.

Are you actually printing, that is, extruding or just testing out your positioning system?

Actually printing

Cool! Which plastic?

I'm currently printing in CAPA, but once I'm able to get it to print at full speed, I'm going to verify the calibration on my thermistor and start in on the HDPE printing (I want to make *SURE* it's reading the temp accurately). My goal is to concentrate on getting Lamarck to the point where he can print extruder parts reliably, then print out a few sets for the RRRF store so that other repstrappers can have an easier time.

Nice! Have you thought of using PVC instead of CAPA? They have very nearly the same melting point.

I hadn't thought about PVC yet, though I'm certainly willing to try it out at some point. For now I'm going to use the CAPA to get everything basically calibrated, then switch to HDPE to make parts - I'm using HDPE to ensure that the melting temp is high enough that if I make a part for someone, and it's a hot day, they won't get any significant softening of the part if friction or other factors heat it up a little.

If you have some extra PVC lying around and are interested, perhaps we can arrange a trade of some HDPE for some PVC?

I actually haven't tried the PVC yet, though it's readily available. I'm spending a lot of time learning the ins and outs of dealing with HDPE. It's a tricky plastic to print.

Eric,

I have posted a mildly-hacked Reprap.jar for you (check your email) that adds debugging statements relating to speed setting operations, both as they are called in LayerProducer and as they are sent to the Stepper motors. I'm hoping this will give you/us some insight into what your system is doing.

Jonathan

P.S. I *still* can't seem to attach files in this forum, for some reason.