BillFitzmaurice.info

I might be building another 4 OT12s soon - wondered if anyone on here has reliable/tested CNC files for cutting the panels for them?
Have access to one, and I know it should be possible to convert the sketchup files into something usable on a CNC machine (Gcode?)... but I'm worried I'll mess it up and waste material, so if anyone has already done it and could share files or even just give some pointers, I would be very grateful!

I did a CNC build for a T30 a while back for a 5 axis CNC. It’s not as simple as converting the sketch up model to another format and hitting “print”. Because creating gcode is setting up tool paths for the router to cut shapes from a sheet, the model is really only useful as a reference. I found it was actually more productive to draft all the panels in cad based on Bill’s build plans and then use that as the basis for setting up tool paths on a 4x8 sheet(s). The 3D model (I remodeled one in Rhino from the build plans) was only really useful to work out some of the angled cuts at the panel edges. I’ve not tried to do those edge cuts (not sure if this is applicable to OT12 builds) using a 3 axis CNC but I suspect you’re going to be setting up a bunch of fine profiling paths to get the edges suitably smooth.
All in all, a CNC build requires laying out all the pieces to be cut in plan, setting up the cut paths accounting for bit sizes , plunge depths, speed, etc . It is a modeling process in and of itself and is probably less efficient than doing the build by hand unless you’re making a bunch of cabs. The code that is generated for the cuts is dependent on all sorts of variables specific to your router setup so borrowing someone else’s isn’t likely going to help you.

What you really want are the pieces drafted in 2D in CAD but Bill doesn’t supply those last I checked and you agree not to distribute the plans when you buy them from him. Honestly, you’ll get a much better sense of the build and make a lot fewer mistakes if you draft it all yourself so I’d definitely recommend that exercise if you plan to move forward with a CNC build.

Thanks tactix, yeah I figured there would be a few more steps to the conversion than exporting another format... you're right, for only 4 cabs it seems it might be less efficient trying to redraft all the panels in CAD and getting to grips with that than just cutting by hand.
+ thanks for the warning on sharing code / router-specific variables, I hadn't considered that.
looks like it's back to the tools for me!

monekh wrote: ↑Mon Oct 25, 2021 11:19 am Thanks tactix, yeah I figured there would be a few more steps to the conversion than exporting another format... you're right, for only 4 cabs it seems it might be less efficient trying to redraft all the panels in CAD and getting to grips with that than just cutting by hand.
+ thanks for the warning on sharing code / router-specific variables, I hadn't considered that.
looks like it's back to the tools for me!

NP. At 4 cabs it might make sense to go the CNC route, at least for the smaller fidgety bits. One of the reasons I went the CNC route was that I couldn't leave my project where I had access to tools. The CNC let me pre-cut most of it and then assemble off site. I did waste a half sheet making stupid mistakes like having the tool cut on the inside of a path instead of the outside, so it was definitely a learning process and I had to do some shuttling back and forth. With all the cuts more or less bang on though, assembly was easy. Good luck with the build either way you go.

What really sped-up my builds were router templates and the 2'x4' cutting table that Bill sells plans for. I had a friend with a DIY CNC cut me some templates for various driver sizes, ports, hand-holds, jack-plates, and such. Now all I have to do is mark out my driver hole, clamp the template to the baffle, then cut it out with the router. I wish I had one when I made my 6/9 SLA's.

edit: And the circular saw sled is a big time saver too.