Extending the Bed

#1
So after quite a bit of learning and breaking and fixing and learning and breaking and fixing I have a much better understanding of the gMax capabilities, at what point PLA parts can melt, at how many point something can break, and why you really should use the ini files with the slic3r program. All good lessons. I definitely have a better appreciate for v-slots.

Before I decide that I need to raise the printing height 10", I thought I might instead extend the printing bed 10". I'm looking to print enclosure frames for 20H aquariums which have a standard width of 12" and height of 24". I'm wondering if it might be better to extend the bed father than 10" and rebuild the acrylic where the wheels for the v-slots are located, so there is a larger distribution of space to handle the size of the bed.

Any thoughts on the matter are appreciated. It's nice to have a fully working machine! My only wish is that there was a way not to have the bed move at all.

Justin
 
#2
Considering that the gMAX has a horizontally moving bed, I think that increasing the height would be a far better proposition than lengthening the bed. The extra weight imposed by the larger bed would create inertia that might strain the servo and belt. Slinging the heavier bed back and forth might introduce vibration the could affect print quality. Adding height seems much simpler.

My second printer has an 18x18x24 build area. The weight of the 3/8" heated aluminum bed makes a gMAX design, where the bed moves horizontally, impossible. Instead, this machine moves the bed vertically while X and Y axes are controlled by printhead movement instead of bed movement. Changing the gMAX to such a stationary bed design would be quite costly.

Lastly, printing such large parts is problematic. I bought my non-gMAX first machine 4 months ago with the idealistic notion that I would print large parts my family business. Like you, I spent months learning the ins and outs of 3d printing. I'm close to a guru now and am still enthused enough to have purchased a second, smaller printer, the gMax. But my thoughts of printing out 13" x 17" parts has take a back burner. I've printed some large things, but anything with lengthy straight lines, such as an aquarium enclosure has proved problematic for me due to warping and delamination.

Though my words sound discouraging, there are others out there who have better insight than me and who may post a solution to enable your bigger bed dreams.
 
#3
Thanks for the advice. I agree, the more I think about it the less I'm interested in doing more than adding a printed bed to the gmax. But my main goal right now is printing something 10"x20" which is only 1/2" tall. Adding even an extra 4 inches to meet that goal would be ideal. But maybe I should focus on using ABS cement. Thanks for the advice.

BTW: What printer did you get that was 18x18x24. I bet it takes a long time to print something that size.

Justin
 
#4
" But maybe I should focus on using ABS cement"

I assume you mean printing the 20" and 10" frame pieces so they snap together and then securing them in place with acetone (ABS glue). That sounds like a good plan to start with. I tried printing out some 17" x 8" x 1" pieces (jewelry tray inserts for my wife's business) and had a lot of problems with warping and delamination. This was with the other printer I mentioned, which was a prototype for a Kickstarter project that never got funded. I bought it from the designer four months ago and used it as a self-taught crash course in 3D printing. Back then I didn't know what I was doing and could probably get the pieces to print out much better now.

Though I have not tried it yet, the gMAX should be able to print a 20" frame bar fairly easily in PLA. But ABS shrinks when it cools which causes warping. This effect is exaggerated in long, straight parts, which is why I had so much trouble with the 17" jewelry trays. You can mitigate these problems by breaking up the straight line or by adding arches or holes in the long part. You mention a heated bed which would also help a lot. I'm going over stuff you probably already know but thanks for reading anyway. Good luck with the project.