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Prusa I3 Build Question

Posted by unlucky1 
Prusa I3 Build Question
January 06, 2013 10:06PM
I am building a Prusa I3 and am constructing my frame out of 3/4" melamine/particle board. I want it to be sturdy and 1/2" seems a little thin to be putting screws into the ends of. My question is this, has anyone used 3/4" to build their box from? If so, did you have to modify the y-corners to allow clearance for the board along the bottom plate to allow you to mount the threaded rod to the board? I also noticed that it has you raise the bottom plate by 3mm. Is the 3mm to align the streded rod that will be screwed down to 1/2"? I want to get this figured out before I print my y-ends in case I need to modify them. I currently have a prusa i2. I hope this makes sence, basically my bottom board on my wooden frame will be 3/4 instead of 1/2" and I see that there are mounts to mount the threaded rod to the board and my board will be thicker.

Thanks in advance,
Re: Prusa I3 Build Question
January 07, 2013 10:12AM

Short answer is yes, you will need to increase the height of the y-end corners. Now reason for raising the bottom plate up by 3mm is to allow the box to only contact the table at the corners of the box. This is done to reduce the amount of vibration noise. When I built my i3 box I did not secure the bottom board to the rest of the box until I had already attach the board to the Y-threaded rods. This ensured me that my lower plate was exactly where I needed it rather then slightly to high or too low.

Side note. I built my first box out or 3/4" composite board. It turned out to be junk (due to the material used) and VERY heavy. I rebuilt the box using 1/2 cabinet grade plywood and it works perfectly.
Re: Prusa I3 Build Question
January 07, 2013 11:46AM
Thanks for the reply. Just to let you know, i am not the woodworker. This is my 3rd box I have cut with a table saw. I have cut all my board this time and have made sure that the fence on the table saw was square and used my square to ensure it was as well. I do not mind the extra weight but I am going to mind the confusion I will cause myself with the bottom board. Maybe I will get a piece of 1/2 inch for just the bottom plate. I have not screwed my boards together yet. NOTE: I like your idea on the not mounting the bottom board until I have the Y axis built. This would let me make sure my threaded rods sit exacly on top the board if I am understanding the directions correctly, thats where they need to end up to allow them to be clamped down. The other issue I have fought in the past with the reprap world is that everything is pretty much metric. I am in the US and metric is expensive here and I have to order things. I will still use 5/16" threaded rod but will stick with 8mm smooth rod and the new 5mm threaded for the z axis. The one huge advantage I have now is that I already have a reprap and some expierence (Not an expert but am learning every day). Can anyone think of any other issues that 3/4" will challenge me with aside from the bottom plate with the Y axis?
Re: Prusa I3 Build Question
January 11, 2013 01:51PM
I hear you with the metric to US units. My latest build was a combo of both (5/16 threaded rod, M5 Z and M8 smooth rod). You are correct, that is how I mounted my bottom box plate.

The only other thing that might pop up as far as 3/4 Vs 1/2 is your top board length. The top board length is your bottom board length + two side board thicknesses. Not a huge deal, but if you kept with the suggested board lengths listed your top one might be a little short on the sides. The other would be your Z location to your bed. Since you are using thicker board the Z mounts will be 1/4" further out then using 1/2" boards. This may not be an issue as you should be able to adjust your Y location to the Box to make sure you get full Y travel.
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