Replicable Gantry

I’m turning out parts for the LR3, and am considering Gantry options. I’d really like to size it for a 4x8 sheet of plywood, however, shorter gantry options to size the machine for the job was my thought. Basically, built a set of different-length low-cost replicable gantries and reuse the core, controller, and YZ assemblies.

Initially, I thought the gantry could be lifted out of the rail ends and the core slid off, but looking at the pictures it looks like once assembled, disassembly would require a lot of additional removal of parts and wouldn’t be a viable option. The workable mod might be a core that splits horizontally and clamps together with bolts.

This is more of a what-if thought conversation. The gantry itself is a relatively low-cost part with maybe $50-$100 in parts including the carriage block and plates. Maybe 1/10th of the total cost of the machine.


I’m not sure there would be a significant benefit. The larger gantry can still cut, although it might not be as fast as a smaller one.

Removing the core is easy. Just two bearings and it will pop off.

The bigger trouble is the screws attaching the strut from the side plates. It is only 6 screws (IIRC) but they are inside the strut, so you’d need access and that requires removing a plate or very awkward screw driver placement.

I think in this layout, the gantry would include the plates and carriage block. A little extra duplicative cost.

The desire here is to have a machine that can be sized for the job. Perhaps for a Lowrider, we’re outside of the steep part of the overall rigidity curve where a 5’ gantry and a 3’ gantry are functionally equivalent.

You can’t remove the bearing block from the linear rail without the bearings falling out.


They’ll probably stay in when you take them off, putting them back on however is a pain in the ass. Expect several retries after putting balls back in. Trying this with stuff attached is going to cause even more issues.

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I wonder if you could have an extension that gets inserted. If you cut the gantry in half and bolted it back together, assuming it’s stiff and the rails are smooth enough, then you could separate it and insert an extension using the same method. Like a table leaf.

It would need a lot of development to get a good method of attaching the sections. Maybe it will require heroic efforts to avoid sagging in the middle.

Or maybe you have two cuts close to the end plates and variable length middle sections. Then you never use the machine rolling over the joints, except when homing.

What about replicating and modifying the roller portion so it can be duplicated at the 3’ mark and removed when you want it wider. Just rollers to hold up the gantry to increase the ridgity at the smaller length ?

The whole strut lifts though, so you need the Z motor anytime you want to touch the table.

Right. Forgot that idea then… Hehe…

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