Extruding Problem

[KeithA]

I am looking for some help for a problem I just started having. When I go to print and everything heats up I can manually extrude a nice steady flow of filament. The print begins and seems ok. The initial extrusion happens outside of the plate and is wiped. The problem is it doesn't seem to want to extrude the first layer. I can feel some slight retract but it inst feeding. It has happened multiple times. If left to print it will usually start feeding after awhile. Once it starts it usually continues normally for the duration of the print. If I stop the print when the symptom first occurs and the bed drops I am usually able to manually feed filament as usual. I have manually lowered the bed during a print to see if it would extrude but it hasn't. I have taken the head off to inspect the gear that feeds and all looks fine. I believe the tension screw is properly adjusted. The only other unusual thing I have observed is a brief sound that sounded like something is slipping but it has only happened a time or two and has been brief. I have tried different filaments with the same result. I have also noticed that when I stop the print what material have been laid on the bed are very difficult to remove. I am at my wits end.... thoughts?

[jimc]

usually jam problems are from a couple different things. in no specific order....

1st layer the bed is too close to the nozzle.
tension bolt too tight on filament squishing it out of round making it too wide to feed through the filament drive. this happens less with pla since its so hard. common with abs or softer plastics.
filament too large diameter.
temp too low.
too fast feed rate for a specific plastic type.
clogged nozzle
on v3b the brass tube has become tight with a lining of hard cooked plactic. remove and clean with a 2mm drill bit.

[KeithA]

I will check thew bed height again. What do you suggest to set it at? I have a feeler guage to do it with. Do you set it with the bed hot?

Thanks

[jdacal]

Jim usually recommends .005" which has worked pretty good for me. I didn't use to do it with a hot bed but I do now.

[KeithA]

Readjusting the height did the trick! I first tried another print and manually adjusted the height weith the knob, something I never tried before. It must have been luck but I ended up letting the print finish and it ended up solving another problem I was having. Once the print was complete I noted the edge that has been on on most things I have printed was not there. The edge I am describing is only evident where the item contacts the bed. I have adjusted the bed height to the best of my ability and the pronounced edge still remains. It causes holes to be a little small until I ream them slightly. Is there any other method of getting things fine tuned? I thought it may be possible in simplify 3d somehow.

Thanks

[jimc]

Sounds like your still printing just a hair too close but its hard to say. That edge will vary a little even by where you print on the bed unless you are dead nuts flat and level. To sum it up, the first layer should print exactly the same as all the others. So the extrusion width on the first layer assuming you have it set to 100%, should be the same as the extrusion width on layer 10 and so on. What you want to do is turn your z stop bolt 1/2 a flat at a time until its right. You can do this in s3d with the gcode offsets but imo doing that to make up for a bed thats no adjusted right will just cause confusion and problems down the road. Its just not a good practice.

[KeithA]

Ok, I will try and adjust it, something I haven't had to do yet. The ridge around the perimeter is pretty consistent for items printed in various locations on the plate so I am confident it is pretty close to being level. The first layer width is set to 100%. The extrusion multiplier is currently .93 and the width is manually set at .50mm. I have the standard .35mm nozzle. Does that seem OK?

Thanks

[jsc]

Run an extrusion calibration (there is a thread on it in the Tips forum). That will not only verify your extrusion width setting, but how much your z-height setting is off by. It takes 10 minutes.

[KeithA]

The calibration thread you referenced was simple but genius. I ran it a few times until I got things dialed in. My measurements are very close to the examples given. I am going to print something but expect my issues will be gone or greatly minimized. Thanks for all of your help. I will report back with the final results. I am using a profile I downloaded (rsilvers on thingiverse). It has always worked OK for me as far as I was able to tell. I noticed the extrusion width is .50 instead of the .40 in the example. What benefits would one have over the other?

Thanks

[jsc]

Wider extrusion width gives better layer adhesion for the same layer height, decreases horizontal detail slightly, and very slightly decreases print times. .50mm is just about the widest you can go with a .35mm nozzle, you don't want to go wider than the flat portion of the nozzle. It's a trade off.