I obviously haven’t built mine yet, but 3/4" plywood sounds like way overkill. The panels are only there (from what I can tell) to help stiffen up the rails and keep them from racking when the gantry moves.
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Would be using the 3/4 ply instead of extrusion. Seal ply real well to help with stability. Climatize before cuts. Maybe run ply long at the back and have mix of dovetails and upright corner extrusion to help stiffen. But squaring should be possible with rebated top and bottom ply panels.
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Ah. I believe the original Repeat build was designed that way.
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Measuring frame for 250x250x250 Usable… But may end up with 235x235 heater bed/build-plate given they’re easier to find than 250x250. Screenshot with my cut list… May oversize corner verticals to help enclose/protect X/Y/Hotend mechanisms.
Decided to reduce risk of build and print issues/delays by using Alu extrusion instead of Ply Panels.
4/6/23 Edit: Using different lengths for upright Z extrusion, details below…
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That’s the build size I ended up with, (300mm for Y and Z rails, 350mm for X rail) Then at the last minute, I found a 200mm heated build plate, and I’ve got it oversized. Can still use the extra Z if needed.
The extrusion does make the build more straight forward, but the panels in addition are nice to have.
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Cheers for the info Dan! Was planning on 300x300 initially, however some of the logic/rationale you’ve shared in multiple topics helped influence me towards ~250x250. I already have a 300x300 3D printer, the largest thing I’ve printed lots of was some 240x240 parts, but even that should be partially CNC’d in the future. Want this MP3DP to be much faster and more capable than my existing one, so building a smaller size will help.
Also, haven’t built a 3D printer from parts before, so am resisting the strong urges to experiment up front. Mostly stock build reduces risk of encountering time consuming issues. My goal is to get baseline functionality working asap, and learn a bunch along the way. After that will reflect, assess and decide what to explore/mod further. My personal deadline is to finish before I get distracted/interested with some other shiny project 
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Might still try 1/4" Ply on inside of extrusion… Calibrated steps and checked square before cuts (e.g. M503, M92, M666, M500).
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Waiting on fasteners, in the meantime, experimenting with Plywood and other materials for panels on the inside of the extrusion.
Still need to add holes for wiring. Curious if anyone has panel designs they’re able to share? Here’s where I’m at currently…
(Recommend not using for now, probably outdated already, shared here to provide jist of what am up to. Will share final version if/when done)
250x250-panel-ply-right.2.zip (51.8 KB)
Contemplating Reflectix and sheet metal even on the inside even instead of 1/4" 6mm ply requiring M3x16mm and M5x16mm, happen to have the right length bolts (M3x8mm or M3x10mm and M5’s) if sheet metal will work.
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Trying out 1/16" polycarbonate interior panel. Spent bunch of time calibrating stepper distance before cutting…
Calibrated using M503 and M92. Squared without M666, instead was shifting clamped Y rails around, used framing square as guide, created test gcode to engrave corners that framing square outer corners should land adjacent to. Finally screwed Y rails to bench top after getting acceptably square corners engraved by the test pattern.
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Are you going to put these on the inside face of the extrusions or captive in the interior slot?
from the picture it looks like you plan to sandwich the rails on the face of the sheet. What about the back corners?
Yep, inside face…
Still figuring out back panel(s). Note slotted holes to accommodate nubs that corner brackets usually have. Holes to route wiring down under, like a Voron Trident. Cut a hole for passive/active cooling of stepper, and routing steppers/endstop wiring. Still don’t know if this is a good idea or not?
Was planning to use green glue left over from a construction project, but learned is not effective at higher temps.
Any higher temp visco elastic sealant recommendations, something that dissipates vibrations to heat? Silicone sealant is my fallback option if unable to find something noise/vibration dampening. Plan is to adhere panels in spots with sealant where fasteners are not.
Maybe slots in the sides that the back can slide into and then you can fasten on the extrusion from there?
Like a dovetail sort of but really big pins and just slots for them to slide through
I wouldn’t use glue. It would be a mess to try to make changes in the future when you have to work on it.
Something like this? Was thinking about dovetail joinery inspired tabs, would help hide fasteners, make fastening easier from outside. Could optionally leave cutouts for the 2020-corner-brackets to make direct contact with extrusion this way. Don’t know if extrusion to extrusion contact is good/bad, am not mech engineer, naively thinking meeting up of different materials helps dampen vibrations. Ended up being too lazy to try out tabbed panels, for this build…
Agree, will probably use silicone if anything at all, no idea if it’ll have noticable impact.
So far the consensus on my printer’s discord is corner brackets are the squarest way to go. The kit comes with corner cubes, but they’re not always square, and the ends of the extrusion isn’t always square either. The general method is to get it mostly tight, add the side panels, then use a 123 block, or other known good square to square the corners and tighten the panels, then the cubes. If you’re not doing side panels, the corner brackets are at least adjustable enough to make the frame square.
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Just like that!
I did blind joints and rigged up an end squaring jig on my belt sander. I think your way makes lots of sense if you dont have the other options.
Hey @probrwr (or anyone else), with a revo hotend and EBB CAN Bus, my build is going to end up similar to yours.
What height/gap above the top Y extrusion is needed to accommodate the hotend/extruder/can-bus and ptfe tube feeding filament from spool-to-hotend-carriage? Planning to enclose, currently have 200mm of extrusion going above the stock Y extrusions, which just looks silly at the moment.
Below is pic of Ryan’s open build
Voron Trident seems to have about 120mm from gantry, but their hotend is different to our BIQU REVO setups. They only plan for PTFE to take 40-50mm height to turn as they route and coil out the back.
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