Printing prusa bar clamp

Trying to print the Prusa bar-clamp.
After a few goes, this is the best so far:








Size is about 25mm long in the first pic.

Prusa Mendel, printing on heated mirror glass 3mm thick, set to 70 deg C in pronterface.
3mm PLA (glacial blue from faberdashery). 0.5mm nozzle. temp set to 182 deg for hot end
40% infill, perimeters, solid infill at 10mm/sec. Infill & bridges at 20mm/sec.
travel speed 40mm/sec. Bottomlayer speed ratio 0.25. Extrusion multiplier 0.8. Retraction speed 30mm/sec.

Previous attempts not as good as this. Mostly the head would hit the thin uprights & in time push the piece from the bed.
Slowing down helped, the best relative improvement was changing extrusion multiplier from 1 to 0.8.

Any suggestions welcome.

Thanks in advance

Mike

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Prusa Mendel /Parcan Mk 2/1280 RAMPS 1.4/PC XP OS/Pronterface/Slic3r

In the UK, down south & over to the left you'll find the West of England RUG.
For details, visit tiny.cc/woereprap or tiny.cc/woerug

It looks like it doesn't cool fast enough. Try printing four at a time. If it improves that will show if it is the problem.

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[www.hydraraptor.blogspot.com]

Ok, tried with 4 at once. About a quarter way up one, then another, came away from the bed.
At that point bed temp = 65 reported (edge of the PCB under the mirror glass).

Neverthelss, what did get printed looks better than before, so I suspect its on the right lines.
I have an idea to improve the HBP insulation, so will try that next and go for 4 again.

Mike

I often use Z lift on those because the small contact area with the bed means they do come off easily.

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[www.hydraraptor.blogspot.com]

I tried the Z lift (0.3 mm = layer height) instead of my idea to mod the HBP.
I also got impatient & increased speeds by 10mm across the board.

Generally improved. This time about half way up before they started to come off. Bed then at 67 when the first one came loose.

On the right lines, will try some more on the weekend.

Is your nozzle hitting the plastic as it goes up.. ?

It seems like it from
If when you command the nozzle go up z by 10mm in pronterface i t actually does, (your z steps are good)
If not make those higher, but if the steps are ok then your actually pushing out too much plastic.

If so it could be probably any of these things:
too high temperature
too high extruder steps
too high extrusion ratio

too hot, put a fan on it and insulate your hot end.

dustynus / aplavins

Thanks for the replies, I'd actually stopped looking at this thread, having moved on to other challenges.
But yes putting a fan on is on my Prusa-to-do list.
Having other fun at the moment with z axis lash.

Mike