I built an LR3 a few years ago and built a table with superstruts for the two rails. I am at the point of tearing it down to rebuild up with the LR4, but I am unsure what my conduit lengths should be. I want to make sure I can just drop the LR4 on the superstruts and the running surfaces match up fine. I did already print Doug’s mods for the rail mounts and belt.
I built the LR3 with a 50" cutting area which equated to ~57" conduit. What would I be putting into the calculator for the LR4 as I believe it has a slightly large cut area vs. its width compared to the LR3? If I put in 50" cutting area in the LR4 calculator I get 56.625". Do I want to match the 57" conduit from before with the build area of 50.325"?
The outside corners of the four Y belt holders are the corners of the overall machine envelope. This is also the “Table Size” measurement from the calculator. So measure the outside distance between edges of your superstrut, and make sure it’s approximately equal to the minimum table width for your chosen cutting area. You can leave some margin of course, as long as the strut is wide enough. On the X-min side you need about 2" inboard of the belt holder to have the whole YZ plate over the strut, although I think at 1.5" the bearing would still be supported (barely). On the X-max side you need to hold the Y rail clips which are 3" wide; the outer edge of those is flush with the belt holders. I guess the superstrut mod is different but I don’t know much about that. LowRider CNC V4 - V1 Engineering Documentation
Some measurements from my LR4:
Design cutting area: 25"
X rail: 31.625" (intended, might be slightly over in reality, hard to measure on the assembled machine)
Distance between outer edges of front belt holders: 36.5" (measured, this matches the X table size from the calculator)
OK so I printed a regular Y Rail clip and clipped it on and mounted my rail with the superstrut clips. If I measure from the edge of the normal clip to the other edge of my superstrut I get 60 3/16". Superstrut to Superstrut is 59". What’s odd is that if I put 50" for the x in the Lowrider 3 calculator it says I need a table width of 62.5" so my table was 3.5" shorter than the min needed table per the calculator for an LR3 and it worked just fine. I think I may just need to build up the two carriages and measure XZ to XZ distance before cutting my EMT. I don’t think I can math my way out of this.
Oh! I’m looking for your measurement from the calculator vs what your actual build is. What did you put in for the build volume and then what span of super strut outside edge to super strut outside edge did you need compared to the min table size the calculator output? I think I can scale it from there.
I have a bunch of that stuff on my computer in the office. I’ll see what I can dig up for you when I’m in the office. But genuinely I wouldn’t measure the strut. I would fit it to the machine. Take the length of table from the calculator and cut your struts to that length. Add your y rail to one of of them. Then use the built gantry to line up the other strut exactly where it needs to be. It’s far more accurate than measuring some hypothetical numbers from a web page. That’s not a hit on the calculator, it’s the way precise fitment works. Get your machine built, lock in the Y rail, and let the machine tell what it needs.
When I went from full size lr4 to this snake size, I made my strut plates and fit everything else to that. The only measuring i did was the length of y to fit in the curve of my shop.
I built everything up to the point of being able to measure. Given your math and measurements it sounds like theoretically I would have a build area of 49" on X which using the calculator gets me a 56.625" rail. I sketchily put the units on the rails and ziptied them down so I had my hands free for measuring and taking photos. It looks like I need about a 56" rail so that’s very close approximation.
Now should I error a little long or a little short? Do the tubes need to go right up against the XZ plates? I’m leaning towards doing 49.25" cutting area which results in a 55.875" rail. That gives me a little wiggle room, but not too much that it pulls my X min rail side in too far.
