Raft Sticking to Part

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motoyoyo
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Raft Sticking to Part

Post by motoyoyo » Mon Oct 28, 2013 10:53 pm

In general, the rafts have been easy to remove from most parts. However, my last print of a flat 2" diameter part had the raft sticking heavily to the part surface. I managed to get it removed but not without great effort. Is there a setting for raft density in the software, or is it determined automatically? Any setup tips on better handling this situation would be appreciated.

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JuliaDee
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Re: Raft Sticking to Part

Post by JuliaDee » Tue Oct 29, 2013 1:20 am

I've been watching closely lately the issue of "dense support" sticking to flat surfaces. Sometimes it pops right off like magic, and other times it's melted into the part and nearly impossible to remove - sometimes in different places on the same surface of a part. My hypothesis is that one trick that pp3dp's software does to make support easily removable involves careful control of the Z axis - I think they leave a tiny bit of extra space between support and the part, for reduced bonding. A consequence of this is that any error in Z axis control results in difficult-to-remove support. And that loss of Z accuracy, in the majority of cases I believe is due to warpage/lift. For easy support/raft removal on large flat surfaces you've got to prevent warpage.

motoyoyo
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Re: Raft Sticking to Part

Post by motoyoyo » Tue Oct 29, 2013 4:02 pm

Thanks for your response. Your Z-axis control and warping theory makes good sense. The area where the raft was fused to the part surface was toward the outer edge where there was some warping. The perfboard does a fine job of securing the raft material, but is apparently a bit too thin to resist distorting while the material cools. Perhaps I will give the glass plate a try for larger parts.

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DrewPetitclerc
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Re: Raft Sticking to Part

Post by DrewPetitclerc » Tue Oct 29, 2013 4:29 pm

JuliaDee wrote:I've been watching closely lately the issue of "dense support" sticking to flat surfaces. Sometimes it pops right off like magic, and other times it's melted into the part and nearly impossible to remove - sometimes in different places on the same surface of a part. My hypothesis is that one trick that pp3dp's software does to make support easily removable involves careful control of the Z axis - I think they leave a tiny bit of extra space between support and the part, for reduced bonding. A consequence of this is that any error in Z axis control results in difficult-to-remove support. And that loss of Z accuracy, in the majority of cases I believe is due to warpage/lift. For easy support/raft removal on large flat surfaces you've got to prevent warpage.
Wonderful catch Julia, yes I've known this for awhile but tired of talking about the importance of the rigidity of the system, build plate to nozzle and tired of not being heard or taken seriously.
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Drew
Drew Petitclerc
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Protolink3d
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Re: Raft Sticking to Part

Post by Protolink3d » Tue Oct 29, 2013 7:48 pm

IMG_00000641.jpg
We are experiencing the same problems. I have two printers, I recently installed the temperature mod from Richard Taylor on my one printer. We were trying to print flat base pieces and the support material was absolutely impossible to remove. The we printed it on the other printer with the modified temp controller and started at 220. Found that the support material on this temp came right off...no problem. BUT...the part was brittle and broke very easily. Tried at 230 with same results. At 240, the raft was impossible to remove again. Plastic we using is the value ABS Royal Blue. So...how do we find the happy medium between the support material being easily removed and still having the strength or is it even possible ?

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JuliaDee
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Re: Raft Sticking to Part

Post by JuliaDee » Wed Oct 30, 2013 2:22 am

A better-quality plastic might help, they're not all the same. OEM is the best. Of the many 3rd-party filaments available I'm liking the "Prototype Supply" (also known as Toybuilder Labs) brand these days myself. The standard Octave brand (not "value") is also quite good.

Protolink3d
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Re: Raft Sticking to Part

Post by Protolink3d » Wed Oct 30, 2013 4:59 am

Thanks Julia,

We have ordered another brand of plastic now and waiting to get it. See how that works out. Will keep you guys posted. One thing I have to say. Judging at the feedback I got from back home in Cape Town where my wife is running the business and printing etc. (I am at work here in Australia) I can see the advantage of the temp mod I bought from Richard. Can't wait ti get home in a few weeks and experiment on it.

motoyoyo
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Re: Raft Sticking to Part

Post by motoyoyo » Fri Nov 01, 2013 2:13 am

I had to make the same 2" diameter flat bottom part again and tried something different with the STL file to keep the raft from fusing to the part. I simply drew a .020" flat disk, the same profile as the part and spaced it .060" below the part and unattached to it. Basically, an extra disk in thin air directly below the part. The intention was for the extra disk to take up the warpage and fusion to the raft and leave the actual part sitting on the support material generated by the software.

It worked quite well. The standard perfboard was much flatter after the part was finished, which showed much less warpage. The secondary raft created by the support material came off the part easily. The finish on the bottom of the part was just as you would have expected if it had been made on the primary raft, except that it was not fused this time. On the other hand, the .020" dummy part bottom was hopelessly fused to the raft and tossed in the trash along with it. This may not be the perfect solution since it uses slightly more material than it could have, but at least it may be a way to successfully use the standard perfboard for larger flat surfaces.

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