Print Quality Woes

[zanthor]

So... I've got two printers and I'm having trouble getting one to cooperate and reliably give quality prints...

I print exclusively with NinjaFlex SemiFlex...
I use a heated print bed, I've experimented with temps and have found that 40c is a very reliable place for adhesion, with the exception noted below.
I print on pyrex glass using 3M repositionable spray adhesive as a pre-print treatment.

Bob - The one that works is an ebay special Makerbot knock off, the CTC3D with a MK10 style extruder... running Sailfish firmware, whatever was current in May when I got the printer... its not broken, so I'm not fixing it .
Robert - The one that's inconsistent is a Prusa i3 Rework variant I built myself, running Repetier firmware using a PrintrBot Alu Extruder v2 and their ceramic hot end.

Using Simplify3d for the slicer on both of these... The attached images are of successful prints off Bob, Robert can print the taller hollow square (gopro camera mount) just fine, but he has trouble with the mounts base (the flat piece with the small holes up the middle.)

Robert does fine on prints with long lines and minimal direction changes. He has some problems with smaller circles, and utterly fails to print small squares side by side like you see in the base. This is particularly visible on the first layer in that the longer lines stick to the print bed just fine but the smaller moves tend to not adhere reliably.

I've bumped MAX_JERK down to 10mm/s, I've dropped X and Y accelleration down to 500mm/s^2... I've lowered my overall print speed to 13mm/s...

On Bob I can reliably print the same items @ 16mm/s.

I level my glass using a .05mm feeler gauge (only the best that amazon had on sale for $3) and then tweak the offset via the slicer.

Any help figuring this out would be greatly appreciated...

[billyd]

40 C on the bed seems really low. What is your material?

Using hairspray on glass (Garnier Fructese extreme hold #5) I use:

60 C for PLA
100 C for ABS

Also for extrusion temps I like at least 240 C for ABS as a minimum. I hardly ever print in PLA so I don't recall those temps but I remember the stock numbers working well. I mention these temps because I see a lot of disinformation about ABS extruder temps, they are always listed way too low. Frankly with darker colors, you probably want 250 C. (On lighter colors they can get altered above 245 C in my experience).

As far as your quality well that is a direct result of how well made your printer is. How good your extruder is, or your entire hot end for that matter. So on a hand made printer, I can't really comment outside of in general terms. Fit and tolerance is king on all moving parts. Mechanical accuracy is everything. Other areas such as filament quality, and consistency in size. Of course the slicer settings have to be right and your extrusion needs to match expected results from the slicer. All of this can be accomplished with trial and error and calibration prints.