I am totally putting the cart before the horse here. I realize that.
Question: Can you use the ‘C’ Z Core with the ‘J’ Core Clamps? I.e. Can you run a ¾" z axis on 24.5mm X and Y Rails?
Alternately: Are there any performance tests, forum threads, anecdata on the performance of ¾ EMT vs 1" DOM for a 24"x24" machine?
Background: I started slowly printing the ‘C’ parts almost exactly a year ago. I opted for EMT because with rounds of lockdowns, I was worried that I wouldn’t be able to get my hands on 1" DOM tube. I planned to have the build done by the new year, but i didn’t, and then just after New Years my family grew, then schools shut down, work schedules got weird, summer hit, i found a dollar, and I’m just now getting around to printing the last four parts (the lower belt retainers). I’ve sourced all of my hardware and am waiting on some steppers in the mail.
The thing is, I printed the C Z core very early on and it is a thing of beauty. It took 3 days, and I had to print it at least twice because of late stage print failures.
Now, 1" DOM seems a lot easier to get a hold of. I also am already anticipating wanting a larger build area and a stiffer frame but good lord almighty i do not have the stomach to re-print that z core. So, my question is, is there a world where a ‘C’ Z axis fits on a ‘J’ X and Y? I think I’m just trying to either psychologically prepare myself for starting my mk II just as I am beginning to assemble my mk I.
There is not a way to mix the parts. The offsets are different, and everything needs to be much more precise than that to move smoothly.
There are a ton of variables that determine how well a build can cut. So the whole “system test” that includes the whole machine at a certain size will not be easy to perform. And you can imagine it is expensive to build two nearly identical machines and hope to measure a difference.
What has happened are tests on the raw tubes. You can do deflection tests by mounting the tube off a table or between two chairs of a set length, and hang a weight off the middle. The 3/4 conduit flexes more. There is a thread with a catchy title, but it escapes me ATM. IIRC, it pretty much matches the engineering models for those materials too. That will reflect later as the bit deflecting in the material when it reaches certain loads.
All that said, the 3/4" is plenty for a CNC. The difference is just that you will be able to have higher loads without problems in a 1" build. The 3/4" build will still work, but you may have to go slower, or take more passes to finish. For a hobby machine that is idle most of the time, it’s NBD and not worth starting over for.
My advice is to finish the build you started. Learn a lot, and in a few years when Ryan releases something new, either make a second machine or upgrade. You’ll know a lot more and you’ll have a list of things you’ll want to change together.
EDIT: I remembered the name. Quick and dirty test:
Thanks for the info and for talking me down from the ledge.
My advice is to finish the build you started. Learn a lot, and in a few years when Ryan releases something new, either make a second machine or upgrade. You’ll know a lot more and you’ll have a list of things you’ll want to change together.