I have been a lurker for many years and have finally decided to move forward on my design. I would be interested in any critiques of the design though it is too late for too many changes since I have all of the extrusions and the linear guides. Here is a rundown of the design.
Moving Gantry design
frame is 1400mm wide x 1100mm long
- Misumi 45x45x90 L-shaped extrusions for the gantry and the main router frame.
- Misumi 45x90 and 45x45 extrusions make up the cart.
- 0.5" Mic-6 toolplate sides reinforced with C-channel to add side-to-side stiffness.
Combination of HiWin and NSK 20mm Linear rails and guides for the X and Y axes and NSK 15mm rails for the Z.
Will start out with acme 1/2-10 5-start precision rods and will eventually move towards ballscrews, just don't have the funds to make the jump yet.
Have a Hitachi VFD and Automation Technologies 2.2KW spindle for the router.
A G540 with 381oz/in. steppers will drive all three axis.
The cutting area is roughly 49" wide and 32" long. I chose a wider design so I could accommodate a 4x8 sheet in stages. I didn't feel the need for a full 4x8 capability right now and I believe that this is a better alternative. I'm sure it will only be a matter of time before I move on to 4x8 sized design.
I am currently a grad student at Purdue so my time is limited on building this but I will begin soon. I am currently working on machining my gantry sides on a Haas VM-2 as school.
If you really want the added stiffness, you can change the ball bearings out if you have non preloaded blocks supposing you can feel the slop in them.
I happened to purchase preloaded blocks by accident, if you are buying new this should not be any added cost, the balls are simply .0005" bigger than the non preloaded blocks (depending on the block, might be less than that.)
The added expense of a second ball screw to drive the gantry is worth it, because you can do away with all the extra stiffness needed to keep the bed from racking side to side.
the gantry should be a closed box section. bolt the aluminum extrusions to a square aluminum extruded tube (filled with sand for vibration dampening) if you like.
Thanks for the reply. It's nice to see some action on the boards.
20mm rails are what I have on hand so they stay. Also for the 45mm extrusions, they fit nicely with a good bit of overlay. The blocks are already preloaded so no issues there.
I have been thinking about adding a second screw. When I get the frame and gantry built, I will check to see how much racking I get and then make a determination then. It will not be a big issue to add one based on my current design.
As for the gantry, I tried to incorporate a box-like shape using the L-shaped extrusions. I can always go back and add a plate to the front and back of the gantry if I need to. I need to check into running some FEA simulations to see the difference in stiffness between a straight box and my L-extrusion setup. I am thinking that the L-shape will be stiffer but I do not have any data to back it up.
Main focus is to get the gantry uprights made. Any inputs on how I designed them?
I would change this somehow to increase the area that is bolted together
Either make the gantry risers much thicker or the lower plate they are bolted to thicker.
It would be nice if the lower plate could extend past the bearings enough to triangulate between the lower plate and the gantry risers
also I would get rid of the plate on the rear of the x axis, and use the space to triangulate the gantry risers to the gantry tubes.
New CNC using Misumi Extrusions
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