[rotccapt]

hi guys i am the proud new owner of a hobbycnc.com 3 axis router. this router was built by my friend and he decided he did not want it anymore so now it is mine. so overall i am happy with the router but i really dont like the gantry on it. although it is functional for the original purpose i would like to do some 3d carving with the machine so i will need more z travel than the current design allows.

so my plan is to keep the base platform for the gantry and just build a new top for it. so my question is can i use 1/2 inch cell cast acrylic to build the support structure for my new gantry? the original gantry was built with 1/2 inch plywood so i think my new gantry should be just as strong with the acrylic. but since i have never built a machine before i thought i would ask for your opinions.

thanks for you help.

[Dr.Fiero]

I built my first router out of HDPE. Far easier to cut than acrylic (which has a tendency to melt), and its not as brittle. Very easy to tap as well. It acts like soft aluminum in a way!

[jckstrthmghty]

What are your machine specs? How much do you want to extend the z?

[rotccapt]

currently the usable bed is 12x24 inches and i have a max z travel of 1 inch. my plan is to give myself around 3 inches of z travel. my current gantry has a base that is 7 inches long and the total gantry height is 10 inches. the width of the gantry is 15 inches wide. in the current configuration the z axis is limeted by the guide rods for the y axis. also the current gantry is 1 inch off the bed.

so my plan is to use the same basic design but raise the top bar of the gantry up 2 inches and move the z axis so that the entire availible z travel would be limeted by the screw length instead of the distance between the guide rods for the y

[jckstrthmghty]

1" of z travel? ok makes sense that you want to extend. I've seen a few plastic builds that were ok. Depends on the material you want to cut. For most I would rather use 3/4 ply or mdf, or even two 1/2" mdf or ply glued together rather than acrylic. Both are cheaper and very durable. For the cost of acrylic you could get aluminum.

[JerryBurks]

Most regular plastics (not reinforced with glass fiber) have really lousy stiffness compared to any kind of wood, even MDF. The Acrylic may look pretty but is expensive and will make the machines rigidity significantly worse. That said, if it is a really small machine for small bits that may not be a big deal but your machine's size is not insignificant

For a comparison look here. The important figures are elastic modulus and tensile stiffness/weight ratio.

[rotccapt]

i already have the 1/2 inch acrylic from another project. i also have 3/4 inch ply that i can use as well. for the most part i will be cutting balsa and plywood up to 1/4 inch thick and foam.