Thought I’d share a little progress with the build. I had the water table for a few months and it is working great, but had no easy way to drain it. It’s been pretty hot here lately, so most of the water has evaporated out of the pan. I thought it would be a good opportunity to clean it all up and finally install a tank for filling/storing water when not in use.
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I bought a 55 gallon drum and installed an air fitting in one port and some 3/4" PVC on the bottom port. When the drum is pressurized (~3 psi only, it can burst at like 20-30 psi, maybe lower), it presses the water down and up through the PVC pipes, through a ball valve and up to the table. This can fill the table 2.5" deep in about a minute or less. To drain I just open the valve and gravity does all of the work, it’s great. I can clean the pan out and retrieve small pieces that get lost in the water. Video here: https://photos.app.goo.gl/zk7txapKUcswcytz6
Got back to making something for a coworker, thought it came out pretty nicely (the lighting didn’t do the blue color justice). Size is roughly 12.5"x12"
Yes, just compressed air in the top. However it’s critical that you don’t use more than 3-5 psi in these plastic tanks. I haven’t done the stress calcs personally, but have heard they can burst as low as 15-30 psi.
It takes about 80 seconds to fill 48"x48"x2.5" of water.
Hey Brian, I wanted to check in with you to ask how the floating z mount you designed is working out for you? And double check if the design you posted at thingiverse is still your latest one?
Yes the floating torch mount has been working great. Haven’t had any issues with it at all, I think the 4 sets of linear bearings helps to keep it stable and prevent it from binding under the weight of the torch.
And yes, the link on Thingiverse is the most up to date. I never went back to modify it as it was working very well for my torch
Thanks for the quick reply! I had to tweak the float switch mount for my relatively jumbo limit switches. Where did you pick up those proximity sensors? And why use those instead of mechanical switches?
And yet another question: how far below the 611 plate would you reckon the torch sticks down?
I’m guessing you want the torch to be gripped by the mount right in the middle of it’s length for proper balance?
The reason I’m asking is because I’m rethinking my own table design a little bit to raise the y rails above the slats rather than being flush as in a standard lowrider configuration. I’m just trying to decide how much to raise it.
My controller wanted PNP sensors and I run 24V logic levels so they worked out. I picked those over mechanical as I’ve always had a preference for non contact limit sensors when possible.
What torch are you using on your build?
My torch was about an inch below the 611 plate. I had to make sure after homing my machine that I raised the Z to the max so I could clear the side of my water pan before lowering it back. It would be nice to have it all at the same level though
I’ll be using a machine torch. I’m was thinking I’d mount the y-rails 1.5" above the cutting slats so that would give me plenty of room to find the right place to grip the torch without sacrificing z travel. Thoughts?
It would also be convenient for me to take out the slats and slide and mdf box in there and convert it to a milling machine when needed.
Another idea I had was to flip the 611 plate / roller assembly upside down, with the plate on top the x rails, to gain that clearance.
Switching gears here slightly, have you ever felt the need for a breakaway switch? And do you think your mount would work with some strong magnets instead of being screwed down to the 611 plate? This might also be convenient for switching back and forth from a router.
eg https://www.youtube.com/watch?v=YAptoQWHLWk
Something tells me the nema17s just aren’t strong enough to need a breakaway mount?
The y rails need to be such that the bit (if routing) or torch nozzle is able to at least go below the cutting surface by 1/4" or so. This allows you to ensure through cuts for wood or to account for an uneven work surface. With the plasma, you can easily account for this by installing the torch lower in the mount, but you can only do so much with the 611. I’d locate the y rails for routing, and then you’ll be fine for plasma cutting. When I set mine up, I made it such that the y rails were more or less coplanar with 2 0.75" thicknesses of MDF stacked. The slats sit about 2" above the y rails as a result when the mdf was removed. Since there are no cutting forces, having a higher Z axis is not as detrimental. Yes, it loses rigidity, but I was still able to rapid quickly with little noticeable effects while cutting.
About the breakaway switch: I never put one on my machine because I was mostly cutting 16ga (thin stuff) and 90%+ of the time I was monitoring the cuts. When I did have tip ups hit the torch, it would cause the steppers to lose steps, so no harm done to the torch. Stronger steppers or a stiffer gantry will damage the torch, it just wasn’t a priority at the time. I don’t think my mount is well suited for mag breakaway. They are usually mounted such that the magnets are sheared off, instead of putting them in tension. Magnets are much worse in shear and I’m sure even low power nema 17s could do it. But probably not in this configuration as a replacement for the screws. When you’re cutting at 200+ ipm, the steppers don’t have much torque available so they lose steps fairly easily which saves the torch. Not the best excuse, but it’s what I depended on for a few times it happened
I didn’t put my mdf on top of the slats, I would remove the whole water pan and replace it with the mdf. If you look at this picture, you can see 1"x2" tubing running parallel with the X Axis. There’s 4 or 5 of those supports. That is what the water table sits on and it is what the mdf would sit on as well.
