Mobile version / mount frame

It fits, but only after I flipped the bolts like you suggested. The other way around it would not fit: the tip of the bolt would collide with the frame. It’s still a bit close this way, if it wasn’t for the rounded corners on the 4040 it might be too close.

[attachment file=65000]

The upper part was a crude attempt at a conduit leg. I noticed you guys were talking about rubbing, so I figured even a 1 inch piece of conduit would give enough clearance to eliminate that. Was trying to stick with as many of the orignal parts as possible sans feet

Don’t you think 2020 might be a bit too small? That’s why I’ve chosen 4040 here. Another option would be a 2040, which is a double 2020, so twice the rails. I’m not sure what’s best..

I’m a cheap bastard at heart, so was trying to go woth a cheap material that I know first-hand.

If money isn’t an issue, I would ditch the extrusions and go with unistrut, just because it’s easily sourced.

I’m not sure I completely understand this part, but yeah, we’re struggling with the Z height and how to adjust to the shorter legs (see render below). Even though our workpiece will be below the frame, it might still be a bit short compared to the regular legs. Additionally, I expect most of the time we will have the frame bolted on top of a piece of MDF which would be our spoil board, and our workpieces would be on top of this.

With the risk of asking a dumb question: what happens if you increase the “usable height” by increasing the Z rails and leadscrew, but leave the legs? Does the additional length make the tool go lower? If so, the only way to make it go higher is to raise the legs, correct? I guess a lot also depends on how low/high your specific tool/endmill is located when mounted?

Here’s the render of the assembly without legs:

[attachment file=65012]

Well as soon as you build it it will make more sense.

Damn that looks pretty

With the risk of asking a dumb question: what happens if you increase the “usable height” by increasing the Z rails and leadscrew, but leave the legs? Does the additional length make the tool go lower? If so, the only way to make it go higher is to raise the legs, correct? I guess a lot also depends on how low/high your specific tool/endmill is located when mounted?

Z height really shouldn’t be an issue, the way that the mpcnc is designed you could have the gantry 5 feet in the air and only resolution would be affected.

Z is independent of x and y if that makes sense?

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Yeah, my worry is mainly if it can go deep enough (when milling something under the frame) and at the same time go high enough when a spoil board is mounted under the frame and the workpiece is on top of this board.

But I’ll stop trying to figure this out in my head and build it first, like Ryan suggested.

Use the calculator to get your Z rails length but ignore the leg lengths, that should clear it up. If you think about it though, you can not go any deeper than your longest bit…3/4"-1.25" or you will hit the floor/surface.

What if you put angle or square on the outside of the legs?maybe with printed brackets.and have clamps on permanent table for quick mounting?

What legs do you mean? Could you draw a quick picture to help me understand your idea?

We’re definitely going to build a permanent table with a quick mounting solution, which should be very doable due to the versatile nature of the extrusions / rails.

You could look into magnesium Mason screed. Lots of sizes, light weight, but very strong and rigid.

Or did you mean on the outside of the frame, like this?

[attachment file=65258]

I saw this and have been thinking about doing the same sort of thing with mine. But I was wondering if it were a good idea to just use conduit for the bottom frame instead? Maybe rather than have the feet, print more of the corner pieces and mount them similar to the main frame? Has anyone tried this, and does it seem like there would be some stability or squaring issues?

Similar looking to this design: https://www.thingiverse.com/thing:3002700

 

yes thats about what was thinking,easy to bolt to permanent table. not sure for floor .some sort of weight maybe

I think there is indeed someone who tried; came across this a while back: Mostly Printed CNC (IE) -Add On- foot by Arcade_Machine - Thingiverse

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I’ve designed some feet to easily mount the Bottom_Corner to the frame, and give the roller a bit more clearance: https://www.thingiverse.com/thing:3036995

They fit a slide nut:

Nice!

I love this route. I’m still trying to figure out how it would work with the Z axis clearance though. Is this only for shorter Z axis builds?

Z axis really only gives you your maximum material depth once you start cutting. If the MPCNC is clamped onto your work-piece short or tall Z height shouldn’t affect you other than the normal rigidity stuff.

Still going to figure this out as well. Might have to make these mounts a bit higher or add in some conduit legs after all. However, I will be using it mainly for milling, so don’t need that much height. Also, less height equals more rigidity / accuracy is what I read in most discussions here.

Most builds have a table, with the Foot+conduit+Lock_Corner legs and have their spoil board bolted on top of the table. I will have the 4040 extrusion + the above Frame_Corner part and my spoil board will be mounted below the frame. Using the conduit size calculator, I’ve determined this is the same as having 72mm conduit legs, which translates to a 85mm work height. Seems a fair amount?

Here is my calculation for this:

Normal build - standard legs - 72mm conduit - Lock_Corner (adds 7mm on top of conduit, before connecting to Bottom_Corner) - 20mm spoil board

Distance top of the spoil board to bottom of Bottom_Corner = 72 + 7 - 20 = 59mm

4040 build

  • Aluminium extrusion (40mm high)
  • Frame_Corner (19mm high)
  • Spoil board mounted below the frame, thickness irrelevant

Distance top of the spoil board to bottom of Bottom_Corner = 40 + 19 = 59mm

Conclusion

4040 build == normal build with 72mm legs (which means 85mm work height)