Adjustable X? Is this possible? Needed?

I am not making a 2" build. I have a stick of 1" to compare it to the next most common size Stainless, but I also need to figure out what is common in the rest of the world. If the sizes are too far apart the build isn’t worth it. I still have not came up with a elegant solution for a “universal” type rail mount.

I’m puzzled as to why that would be? I ran two sets of numbers for a 48" span using the calculator that Ryan referenced above: one which considered just the weight of the EMT itself, and one which also added a 5lb load to that. The source for the nominal values was here: https://steeltubeinstitute.org/steel-conduit/types-of-steel-conduit/electrical-metallic-tubing-emt/

In both cases, the deflection of the 2" EMT came out quite a bit less:

 

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It is easier to just go to the hardware store and get it in your hands. That is just a generic calc, not actual material properties. For example, stainless steel will deflect less, all things being equal, but also doesn’t stop bouncing. It acts like a giant spring Emt is almost a better trade off for it s damping capabilities. But the larger conduit is all over the places in terms of tolerances.

Nothing beats real world testing, even if it isn’t super scientific. Plus do you really just want to sit at a computer all day and theorize what will and won’t work or do you want to got get dirty and break stuff?

About 30 minutes ago I actually showed my friend a quick and dirty 1" ID conduit flex test vs 1"OD stainless flex. With a 10lb load the EMT bounced twice, the stainless kept bouncing the entire time. Not what you want to have happen in your actual machine, and I don’t know of a calc out there that will show your damping properties that clearly and easily. Plus one cost $8 the other cost $20

I just now was at Home Depot, and I compared 3/4" EMT to 2" EMT. Without any question, the 2" EMT is far more stiff. And the 2" RGS is even more stiff than that.

From the sounds of things, though, I guess I’ll have to figure out how to scale the design for 2" diameter on my own. Or, maybe punt. Anyhow, good luck.

 

Anything with a larger diameter will be more rigid. 3/4" vs 2"? A comparison is the same or similar OD in different materials.

2" is ridiculous, you will be adding a gas powered spindle and nema 34’s along with there expensive drivers and power supply, ballscrew drives. Not the point of these machines I make. If you have all that money to burn buy a tormach. My machines are fun, and inexpensive to learn and to try, and easily sourced everywhere in the world.

3/4" handles aluminum just fine, giant industrial machines have a hard time with steel, I am not making that a goal. One size bigger as to not increase the foot print very much but increase the cut speeds a bit of the LowRider which has a 4.5’ span.

You could just add a third Z stepper motor on this mobile support.

Sure it is a little bit more complex, but I think it stays reasonably easy.

Does it need more rigidity? Not really.

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We have to support the 2 inch stuff more often because it will sag under it’s own weight horizontally.

Then why have folks been using 1" stainless steel?

cause it looks cooler? It’s smoother? Maybe it’s more accessible to them? I’m using greased raw steel tubing cause it was cheap and my welder recommended it to me.

 

Build it as per the specs then see if you have issues. It’s already been explained why it’s unnecessary.

 

Your variance is more likely to be in the table and the material you’re cutting than the lowrider itself. Cutting 3/4" mdf, you’re probably going to have more issues with finding the correct length bit than with the design of the lowrider - my 2c.

Because you can get 1" stainless steel anywhere in the world. 3/4" emt is easy to get in the States and Canada, but not so much across the pond.

Has anyone looked at chain link fence posts or the top bar. The top bar on a chain link fence is about 1 1/4 round I think, I don’t know how thick but I was leaning on my mother in laws fence talking to her neighbor and started thinking about it, it was really rigid and it was a 10 foot span so it might be worth checking out.

They are more expensive than electrical conduit and the only stiffening advantage is the larger size. They weigh more due to the same larger size.