Printing imperfection: need advice

I'm bought the ormerod kit from RS in Feb just to explore this new technology
Spend quite some time following this forum to gain some some tip in building and improving
The printer I assembled. Thanks to all people contribute a lot in this forum i got so much knowledge on the ormerod.
I'm quite satisfied with my current print quality of the part produced by it but still there are som imperfection exists on
The printed part. My setting on slic3r was copied from the forum uploaded to a thread (it seem was uploaded by dc42, thanks)
I made some setting according to the owner of the model i download from thingiverse (.20 mm 50%fill honeycomb pattern)
The result is as picture attached. There are some excessive PLA deposit On certain area on every part printed.
I do not have setbed.g for bed compensation. Only perform the homing and manually adjust the bed with 3 screw
as accurately as i can. I need advice on how to get rid of the imperfection on the print.

Thanks for all advice

Your prints look quite good to me. The imperfections I can see are:

1. Blobs of PLA. Did you print directly from web or from Pronterface? If so, try uploading the file to SD card first and printing from SD card instead. At times, the upload rate can't keep up with the printer, e.g. when printing direct from web and you put the browser tab in the background while you do something else on the PC.

2. Slight stepping on one of the axes. This can be difficult to eliminate entirely, however the first step is to eliminate Y-belt slippage and set the correct tension in the X and Y belts. I use Matt's y-belt fasteners to eliminate y-belt slippage, and my own spacers to adjust the tension. See [github.com] for more.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The blobbing is probably due to extruder lag - the Bowden tube creates a delay between the time the extruder starts and when plastic starts coming out the nozzle, and also a delay between the time the extruder stops and the time plastic stops coming out. So when the head stops at the end of an X or Y move, a little blob of plastic continues to extrude.

To try to reduce the amount & effect, you can try increasing the retraction speed, and/or tick the "wipe on retract" box in Slic3r that tries to move the nozzle out of the way quickly before a blob is created. If you do the latter however, be sure to install DC42's latest firmware - earlier versions had a bug that would cause the steppers to miss steps when retracting with "wipe on retract" set. Slowing down the print speed also helps reduce the effect - especially on small perimeters (slic3r allows you to set a different speed for small perimeters).

I think however that it is something that you cannot entirely eliminate on a Bowden tube based extruder - and it is possible that your prints are pretty close to the best achievable quality with this hardware.

I theorised that perhaps firmware could be created to compensate by making the XY moves lag behind the extruder move, but I have no idea whether that would work in practice.

Dave
(#106)

Thanks for all good advices. I try to adjust both x and y tension and also upgrade the firmware first.
BTW. The print was from sd via web interface.