Build Surfaces for Printing PLA
Harrison
To test ABS, I cut a build plate out of 3/8" ABS sheet and then faced it using a flycutter so that it would be flatter (sheet stock isn't so flat) and fit into the Rep2 snap arms without causing excess deflection. At this point I realized that the nod on my bridgeport was pretty far out so I wasn't cutting perfectly flat. I improved the nod but didn't take the time to get it perfect (too much science to conduct!), hence the visible steps between passes:
I ran a few test prints to see how well everything adhered to (and released from) the build plates. The acrylic plate gave tremendous adhesion, so much so that I couldn't get the first print off (I tried freezing, flexing, and hammering). I forgot to take a picture before throwing away the plate, but suffice to say that the acrylic plate was in 4 pieces and both parts were still stuck to their respective pieces. To alleviate this over-adhesion I sanded the entire surface of a new plate with 300 grit sand paper. I cleaned up (and slightly repaired) the surface by wiping with acetone. This seemed to work pretty well.
Finally, I printed the make magazine torture test (http://www.thingiverse.com/thing:33902) on each surface. The red block is glass + hairspray, the center block is ABS, and the right block is glass/acrylic stacked:
I have gotten better results out of glass/hairspray without "ear rafts" so it may not be a totally fair comparison, but it does illustrate that you can't always get it right. None of the archways fully formed but the part printed onto acrylic was the best print. The part printed onto ABS was OK and removing it was a breeze. It seems to me that printing onto a thermoplastic is the way to go but one needs to be cognizant of the lower stiffness of plastic versus glass (or metal) and how this affects us for bigger prints.
My next step is to get some aluminum tooling plate cut to shape and bolt together a few AL/plastic sandwiches. I then plan to machine those flat so that the whole assembly is both flat and stiff. I'll keep you guys updated on that as it happens. Cheers,
Jameshs
Jay
Jay
Daniel Quaroni
I'm ruling out the makerbot acrylic platform since it'll warp eventually and I want a permanent solution.
I've tried hairspray and diluted PVA without any luck. I did have one amazing success using a glue stick that I then wiped into a very thin film, but I can't reproduce it - pieces aren't even sticking well enough now to print successfully, never mind worrying about warp.
I have two ideas to try, but I want to get opinions on them.
The first is to buy a 3mm acrylic sheet, cut it to size, clamp it onto the glass, and put a 3mm spacer on the part of the built platform unit that hits the z-axis switch to trick the makerbot into accepting my new home position.
The second is to lightly sand the surface of the glass to create a scratched surface and give the print something to stick to.
Enginwiz
BruceA
Sanding a piece of glass is not easy. Having done a lot of cold glass work I can tell you the easiest way to get a mat finish is to get some 800 carborundum powder. Pour a small amount of the powder onto the glass plate and with with another small piece of 4mm or thicker glass rub this over the plate in a figure of 8 motion, keep moving all over the plate so as not to grind a hole in one spot. Make sure the small piece of glass you are using has no sharp edges. Best way to do that is to polish the edges with a sharpening stone, 2 reasons, first saves cutting yourself and second any sharp edges will scratch the surface of your plate. Change the grinding powder often to save contamination with micro pieces of glass, this also will scratch the surface of your plate. It will take you 1/2 hour to fully matt the surface of a Rep 2 build plate. You need to use another piece of glass to do this because it is a hard as what you are grinding and it is flat. Take your time and you will get a great matt smooth finish. If for some reason you can not find any carborundum powder you can use dry type of kitchen cleaning powder ( it is called Ajax in Australia) this will take longer but will do the same job.
Greg Fisk
I was having a similar problem.
The 2 things that solved it:
You need A LOT of hairspray. (I often give a light mist a few minutes before printing too, which seems to help a lot)
Also, support said that the temperature sensors can tend to fail. I started printing everything at 237C and everything is back to perfect.
Harrison
Rob Griesbeck
BruceA
Rob Griesbeck
What's the best thickness to use? Does it take a certain kind of glass? And are you using hair spray, or will it print right onto the glass?
Steve Johnstone
Harrison
Ziggy
most the time I never damage the tape, things stick and pop off.. trick is to put a samll bevel on the bottom of your project and I find a nice RC prop does well as a tool to get under a lift it off..
and APC 12/3.8 Slow fly works great..:)
KBinc
Wayne H
Ninja Printer Plate
I spent several months fine tuning this and should have some ready to sell by next week. Would love to get some feedback from people. Thanks.
Wayne
