Acceleration/Deceleration
http://flickr.com/photos/giseburt/5588101908/
It’s really stopping that’s the hardest
I’m able to print in 3mm PLA, finally. I’m not able to print in 1.75mm PLA without jamming unless I crank the volume up to 11, er, 111%. My best explanation for the latter is a mix of slightly-off pulley diameter with that size of PLA mixed and that it simply provides more pressure. Even at 111% it jams, it just takes an hour.
Nick Starno said…
Nick told me that he believes that acceleration of the filament to speed would work better than going directly to full power. I don’t know if he was speaking of this particular problem, but I think it’s a valid idea.
Also, I had some skipping because I set the feed-rate on bridges to 2*40mm/s. I really don’t think that that should be a problem.
As you can see from the image at the top of this post I’ve been doodling. I haven’t tried any of this yet, but here it goes.
Setup
- Acceleration and deceleration are set independently and for each axis. They will be measured in mm/s/s. That can and probably will be translated to steps/s/s (in ReplicatorG, at least).
- Direction doesn’t matter except for when switching directions, which means stopping first.
- At all times the movement of all axes is to be synchronized.
Rules
- Acceleration happens after a point that sets the speed.
- The speed being accelerated to does not have to be achieved.
- Deceleration happens before the point that sets the speed.
- The speed being decelerated to must be achieved.
- Switching directions implies a stop at the set-point that first goes the opposite direction.
- All of the steps required to reach a set-point must be completed.
Implementation
TBD.
I plan on using the command queue to look ahead and determine the points where deceleration must start. I suspect I may have to implement a minimum speed that applies only to acceleration so that it doesn’t take all day to get moving from a dead stop.
What do you think?
-Rob
