Controlling oozing at the start of prints
March 26, 2014 08:19AM
Been trying to think of ways to remove the ooze that occurs when the hot end is getting up to temperature. On some occasions it is caught by the edge of the bed and drops off harmlessly, on others it gets pushed up onto the face of the nozzle and attempts to wreak havoc on the first layer...

Initially I though about a wiping plate at Z=5 but this would require some careful g-code trickery to prevent the nozzle ever crashing into the plate.

I then thought about a small but relatively long-bristled brush mounted at the edge of the bed (attached to the aluminium extrusion, not the bed), so that after the hot end has finished heating up at Z=5 it passes over the brush and deposits the ooze. It would need to be long bristled so that if/when the nozzle passes the brush at Z=0 it would pass through the bristles without getting caught. Thoughts?

My bed is finely tuned now (thanks to Davek0974's aluminium plate) such that I can confidently leave the printer to it once I've sat and waited for it to heat up and caught the ooze manually. Just trying to come up with a way to remove that last bit of waiting smiling smiley
Re: Controlling oozing at the start of prints
March 26, 2014 08:24AM
The problems I can see with using a brush are (a) the bristles will need to be heat-resistant, and (b) the plastic it picks up will glue the bristles together. How about a domed, spring-loaded cleaning plate?



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].
Re: Controlling oozing at the start of prints
March 26, 2014 08:47AM
I have been trying this with some good success...

Heat the bed, home the X + Y axes, then heat the nozzle, move to 100,100, set Z zero by dropping onto a slip of paper until the fan vibrations are gripping it, pull the slip out - this cleans the nozzle, G92 Z0 then press print.

Leaving the nozzle on the bed, centre-zero, seems to stop all ooze and works pretty well.

I was thinking of adding a 4mm retract at slic3r custom end code and a 4mm feed at custom start code, might work, not tried it yet.


Another RS Ormerod Mk1 meets the world smiling smiley

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.
Re: Controlling oozing at the start of prints
March 26, 2014 11:42AM
I put a small bit of paper under the glass in front of the park position and fold it up over the edge of the glass so the nozzle wipes over it when it heads off to start a print. It usually catches the ooze.

Dave
(#106)
Re: Controlling oozing at the start of prints
March 26, 2014 04:19PM
I've found that using a leather gardening glove (with the rough leather on it) the best, and brings the gooy nozzle up as new (Nice and shiny).
I'm thinking that a padded leather roller withe the noxxle crossing it at a fine angle oh it's way to the print should do it a treat, and it would rotate the roller a fraction ready for next time. The gloves are dirt cheap, but you can peal the plastic off quite easily.

(Now to put the printer back together, as I'm starting to twitch each time I see it).
Kim..


Please send me a PM if you have suggestions, or problems with Big Blue 360.
I won't see comments in threads, as I move around to much.
Working Link to Big Blue 360 Complete
Re: Controlling oozing at the start of prints
March 27, 2014 03:52AM
I was thinking of trying a few mm retract at the beginning. If your brim is set large enough then the filament will get flowing eventually but with no drips at the start. I have had many prints fail on the first layer due to this.


Ormerod 313
Re: Controlling oozing at the start of prints
March 27, 2014 05:20AM
Seven year old solution from nophead (prehistory for most of us!) [hydraraptor.blogspot.co.uk]

Ray
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