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First Reasonable Mendel Print needs refinement

Posted by olvis 
First Reasonable Mendel Print needs refinement
December 08, 2010 09:16AM
Im not sure if this is the right place to post this but I've managed to get my Mendel to print something reasonable but it could do with some more refinement. I've attached some pictures and would be massively grateful for any feedback on how to refine my print.

My set up is a Mendel with gen 3 Techzone electronics, using the Reprap host software and printing in ABS with adrians geared extruder at 260 deg C (this might not be true temperature but I'm waiting for a separate thermocouple and display to arrive to check this), I'm not using a heated bed (which I know will cause problems with printing and the ABS sticking to the bed, but I have overcome this for the moment by using spray mount although can prove tricky getting the print off the bed).

I modified the standard Extruder 0 settings in the Reprap host to use the following feedrates and the above temperature and left everything
else as default:
Extrude 960mm/min
XY Slow 500mm/min
XY Fast 960mm/min.

Again would be grateful for any help :-)
Attachments:
open | download - DSC00142.jpg (40.4 KB)
open | download - DSC00143.jpg (35 KB)
open | download - DSC00144.jpg (40.6 KB)
open | download - DSC00145.jpg (34.5 KB)
open | download - DSC00146.jpg (36.9 KB)
open | download - DSC00147.jpg (32.6 KB)
Re: First Reasonable Mendel Print needs refinement
December 08, 2010 10:45AM
The main things wrong are the flow rate is a bit low so infill is not solid. The base layer is worse so it looks like the nozzle starts too high, should be one layer above the bed.

The infill does not meet the outline. That could be mainly due to the flow rate, but could be a sign of backlash.

It looks like the extruder does not stop on moves and your fast moves are no faster than the extruding moves so the strings it leaves are pretty much full size filaments. You need to flow to stop by reversing the extruder the correct amount and you could do with moves being faster.


[www.hydraraptor.blogspot.com]
Re: First Reasonable Mendel Print needs refinement
December 09, 2010 01:25AM
Impressive analysis nophead.

I can see the low flow rate and extruding during moves.

But the first layer height being incorrect? I've looked through those pictures and I can't even be sure if I'm looking at the bottom layer or the top. Which feature of which of those pictures gave you that information?


--
I'm building it with Baling Wire
Re: First Reasonable Mendel Print needs refinement
December 09, 2010 02:28AM
I assumed the last picture shows the bottom. I could be wrong, in which case probably the opposite is true. I.e. the bottom layer is a bit low so the lack of plastic is less noticeable.


[www.hydraraptor.blogspot.com]
Re: First Reasonable Mendel Print needs refinement
December 09, 2010 04:55AM
Thanks nophead for the feedback il start having a play about with that today, its actually missing the bottom 2-3 layers as they came away as I was carefully trying to remove it from the bed (Spray mount might be a bit OTT, I might try pritt stick or double sided sticky tape until i can sort out a heated bed). I've attached a couple of pics of the base part.
Attachments:
open | download - BED_SIDE.jpg (301.2 KB)
open | download - PRINT_SIDE.jpg (333.2 KB)
Re: First Reasonable Mendel Print needs refinement
December 09, 2010 05:06AM
Is it possible to incorporate a raft using the Reprap host software? I couldn't see any options for it.
Re: First Reasonable Mendel Print needs refinement
December 09, 2010 06:13AM
Looks like the bed is not level as the first layer starts off solid and then gets sparser. Either that or the extruder flow rate is dropping for some reason.

The base probably came away because of the lack of plastic. When the flow rate is too low the filaments aren't squashed together so don't make strong bonds. A fully solid part should be strong enough to peel away from spray mount.


[www.hydraraptor.blogspot.com]
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