Custom Printer Build

MicroFarmModels · May 15, 2023, 2:48pm

Heater Question for Electrical Engineers and Other Knowledgeable on the Subject

With regards to the Exoslides, how are you planning on implementing them? I’ve played around with them a bit and they’re probably well suited to something long like yours but I don’t love them. They’re 80mm long, which is a potential problem as they add considerably to the size of a traditional printer (not an issue with yours) and they’re more expensive than other approaches for linear movement (but would be cheaper than linear rails in an application like yours). The big thing I didn’t like about them is that they work best when four are used to a rail and that complicates things like cable management (can’t have drag chains with them).

I’m curious, how are you keeping sag in the middle (I think you have a fair amount of mass on your gantry, if I remember correctly, you’re putting your spool on it) to a minimum? Are you using something like 20x40 or 20x60 V-Slot for rigidity because I know you’ll get a noticeable amount of sag with basic 20x20.

You are right, they take up more room, which shouldn’t be an issue for this build, as you say.

Not sure why drag chains aren’t an option, at least for this build. The stationary end would have to be located beyond the end of the exoslide’s path, but that is no big deal.

So my plan for the frame is this, if you are looking at the printer from the end, the profile will be a 4020 lying horizontal on top of a 2020. The 20mm overhang will be to the outside. There will be a mirror image of it on the other side of the bed. The two rails will be joined by 4020 extrusions lying horizontal spaced every 230mm or so(depending on bed heater size, as I will use openbuilds 90° brackets rotated 90° to mount the bed to these extrusions via the bed mount bolts I was talking about earlier). The rails on either side of the bed will be somewhere between 1.6 and 2 meters long. The exoslides will run on them, a 40P on top, and a 20P on the outside. There will be two such carriages on each side. One will have the gantry directly attached to it, and the other will be about 100mm along the rail with a 45° brace going from it to the top of the gantry, as well as an extrusion running directly from carriage to carriage.

As to sag, the idea is that these extrusions will all be sitting either directly on the shelf surface, or with lots of printed TPU feet between the extrusions and shelf to reduce vibration transfer. If I do things right, the extrusions won’t really need to span anything.

No, the spool will definitely not be moving with the gantry. It is going to be situated on the shelf above the one the printer is on(hence my prior limited z axis space comments). It will be centered over the printer, to limit the length of ptfe tube that I will have running through the shelf to the extruder. I will probably use 2.85mm ptfe tubing to limit friction as much as possible for that guide tube.

What will be moving will be the gantry, with attached x axis stepper, z axis stepper, and extruder stepper with attached BMG. It won’t be light, but it won’t be having a 1 kg spool attached up top to throw around, that would be asking for trouble.