Stiffer Raft?
I'm trying to print using various materials like ABS and PC which have a tendency to shrink even when using an enclosure. Specifically I am trying out different materials that have good heat resistance characteristics to print my RC airplanes with. Since they are a thin wall print very similar to a vase print they have a very high tendency to shrink and will actually pull the PEI build plate off of my Prusa's magnetic heated bed. So I was thinking perhaps using a raft would help to reduce or solve this issue. If I can get a raft stiff enough to resist the warping of the part then I should have a lot more success with these types of materials. So I was thinking using a different pattern for the raft like the infill patterns could help with the stiffness. Maybe use a honeycomb pattern for the inside of the raft. The software itself doesn't have an option for different patterns, so does anyone know of a different way to do a raft that will let me use a different pattern?
Re: Stiffer Raft?
Have you tried a skirt for your abs parts? 6 outlines .02 or .03mm from part. This can be remove fairly easy from the part and holds well on the build plate. You can also try adding some polyimide tape to the build plate, I have very good results with polymide tape and ABS. Starting height has to be perfect for good hold and less warping. Also if you are designing the parts try and eliminate sharp edges at the build plate.. use fillets where possible and round corners. Hope that helps.. rafts have never been something i liked too much time and filament wasted..
Re: Stiffer Raft?
I have. The parts warp and pull the metal PEI plate off of the bed even worse with a skirt/brim.
Re: Stiffer Raft?
How hot is your enclosure?
My Railcore has a part-insulated enclosure and reaches 60C with the heated bed at 100C. Stratasys uses a 100C ambient for ABS (and doesn't bother with a heated bed).
My Railcore has a part-insulated enclosure and reaches 60C with the heated bed at 100C. Stratasys uses a 100C ambient for ABS (and doesn't bother with a heated bed).
Re: Stiffer Raft?
I haven't put a thermometer in the enclosure yet but it gets quite hot. Hot enough that my motors are getting very hot and I bought some heat sinks for them.
Re: Stiffer Raft?
Yes, having a hot enclosure is non-trivial. My coreXY machine has steppers outside the build volume, except the extruder motor. It seems to cope at 60C ambient but more intrepid Railcore users have upgraded to a stepper that has special high temperature windings. I find my belts tighten at higher temperatures, presumably because the frame expands. So loosen the belts (Railcore users use the "Gates Carbon Drive" app to measure the frequency of their belts when twanged to gauge tension) so optimum tension is reached when machine is at temperature. Could go on.
In any case, you could design a "raft" in CAD as a part of your model, then allocate a simplify3d process to it (using start/stop heights) in which you specify appropriate slicer characteristics. Using a "pattern" function in CAD software might even create something quite detailed - down to the width and height of an individual extrusion if desired. Laborious perhaps but worth it if you find a magic recipe?
In any case, you could design a "raft" in CAD as a part of your model, then allocate a simplify3d process to it (using start/stop heights) in which you specify appropriate slicer characteristics. Using a "pattern" function in CAD software might even create something quite detailed - down to the width and height of an individual extrusion if desired. Laborious perhaps but worth it if you find a magic recipe?
Re: Stiffer Raft?
That's kind of what I was thinking...I could easily design a platform then specify the infill type...but then how do I do the transition from the platform to the part? I'm going to pick up a thermometer today just to see where I'm at. I really want to be able to use PC for my RC airplanes but if I can't get the shrinkage under control it's just not going to work.
Anyone know how high of an enclosure temp the Prusa i3 MK3S can handle? I'm currently using that printer while I rebuild my Anet A8. After that is rebuilt I'll be using both printers.
Anyone know how high of an enclosure temp the Prusa i3 MK3S can handle? I'm currently using that printer while I rebuild my Anet A8. After that is rebuilt I'll be using both printers.
Re: Stiffer Raft?
Create two printing processes. In the one intended to slice the Raft part of the Model set "Stop printing at height X" (in the Advanced Tab). In the one for the part (the upper part of the Model) set "Start printing at height X" in it's Advanced Tab. Ensure you slice the entire Model using both processes.
Re: Stiffer Raft?
If you stop the base at height X and start the part at the same height the 2 will fuse together pretty strongly. A raft has a separation between them with small areas of contact between. I'll have to figure out how to make those small contact points.
