[Darren]

Ok, here it is...hope it worked. Nothing too special yet but for my first 3 hours or so I don't think it's too bad. I added a jpg rough rendering for those who want to peek at that as well. Again, nothing special yet.

The gantry sides are 3/8" aluminum...I'd like it to have been 1/2" but I have what I have. Do you think I should stiffen it with ribs on the outside as shown? Will 3/8" plate be stiff enough with the 3.5" X 7" 80/20 as a bridge?

The rails the gantry travels on are 1" X 48" supported, The rails on the gantry are 3/4" X 24" unsupported and my z axis is 3/4" X 18" supported.

[Darren]

I bought tutorials online for TurboCAD. There was no way I could figure it out on my own. I don't know if it's better or worse than other programs. I just know it has its own peculiarities. Taking the time to follow the tutorials step by step made all the difference for me.

I may have to buy the tutorial, I was a bit leery of it because I didn't know if it would be helpful or not. Sounds like you got some good info from it though. I may have to buy one. We'll see how I progress from here

[CNC Darren]

looks good to me! I sometimes still use Turbocad 2d(very old!) but have for the most part switched over to Rhino. If anyone wants Turbocad 2d soot me a pm or email. Its the full program with the registration key, this is a leagle copy that imsi use to have for free download. Works good for 2 1/2d parts but no 3d.

Darren

[carlnpa]

It looks like you are a quick study.
The K2 3925 machines use 3/4" for the gantry sides on a machine of similar dimensions, yours may be a bit light if precise or heavy cutting intended. The 8020 for the bridge should be way stiff enough.
The unsupported gantry rails will deflect from the weight of the z axis and cutting loads.
The gantry bridge 8020 would be ideal for fully supported linear bearings, look at some K2 machine pictures.

[Darren]

What if I doubled up on the 3/8" plate? Just bolted them together in several places to produce a double thick gantry side? Would that offer sufficient strength? You don't think adding the ribs as I show in the rendering would be sufficient? I'm no structural engineer so I'm just using what I know I'm considering buying supported rails for the gantry, I had intended to go supported for every axis but mistakenly bought the ones I have. I had thought they may work but if they will deflect then that's no good. I'll see if I can get my hands on some supported rails. I guess I'll have to put the ones I'm replacing on ebay

[carlnpa]

Darren,
I need to correct inaccuracy on my part.
The K2 gantry bridge upright is 0.750", the gantry side frame the upright bolts to is 0.500".
I've attached some pictures on how K2 uses the 8020 on the x axis with a linear rail for continuous support. You could do the same for your gantry bridge with continuous support.
Doubling up the 3/8 you have on hand should be fine

[Darren]

I just won an auction for 3/4" X 24" supported rails. A few more tweaks to my design and I think I'll be able to start putting some stuff together.

Quick question. How are people ensuring accuracy while building these machines? Just a good ruler and engineer square or are people breaking out the calipers and dial guages? I want to ensure this thing is true but don't want to waste time on things that aren't as critical. Cutting thick plate aluminum good and square can be difficult though. Is it common practice to leave enough slop in a hole for the screw to have some play for adjustment in squaring pieces up as you assemble?