New Machine Build- New 2' x 8' Machine Build

[adt2]

Hello, all -

I am about halfway through my first machine build and thought now would be a good time to start a build thread for it. I am building my machine based on the 2' x 4' plans available at FineLineAutomation.com. I need to mill long, skinny pieces out of MDF and/or plywood (primarily patterns for boatbuilding), hence the odd size of this machine. My intent was to duplicate the machine in the plans except for the X-axis rails, which I would make 8' long. Things didn't exactly happen that way (see below).

I am a technical writer by day, and I'm keeping a build manual with a complete BOM and step-by-step procedures for building the machine and getting it set up - which is kind of a neat trick since I've never built one or set one up.

I have the machine base, X-axis rails, gantry, and Z-carriage assembled. The X-axis rails are 96" long, which will provide something less than 8' of travel. The gantry is a duplicate of the one in the 2' x 4' drawings, except that the 3030 T-slot extrusion is 48" long instead of 42.5". I had to order a 48" length, and it seemed foolish to cut it and waste 5.5" of potential...so I left it long. As a result, there's 37.5" between the 3" x 3" aluminum tubing that forms the X-axis rails. I can see maybe upgrading to a bigger machine in the future by simply replacing the 48" gantry and the Y-axis lead screw with longer versions. I could easily (I think) jump up to a full 4' x 8' machine.

The Y-axis and Z-axis are Acme 5-start screws. I somehow managed to order the Y-axis screw a few inches short, so for the time being, I won't be getting as much travel in the Y-direction as I could, but that's no big deal based on the parts I need to mill (remember: long and skinny). I ordered a router mount from K2CNC.com and my big Milwaukee is ready to rock.

I haven't ordered my rack-and-pinion hardware for the X-axis yet, nor have I ordered any of the electronics. I'm planning to get the electronics package from CNCRP, as I like the idea of Ahren's plug-and-play setup with the four motors all ready to go. I'm still working on the R&P setup; I didn't order 8020 T-slot for the X-axis because, frankly, it costs a metric buttload. I ended up ordering 3" square aluminum tube from onlinemetals.com and drilling it myself, which was easy enough but has necessitated some design changes. I'll need to figure out how to mount the racks to the tubes before I can order anything. I'm guessing I'll end up drilling holes in the sides of the tubes and using screws/lock nuts.

Anyhow, the photo below is a mockup of the machine (sans Ahren's rack-and-pinion hardware and the lead screws, which I didn't see any point in modeling).

[LazyMan]

I need to mill long, skinny pieces out of MDF and/or plywood (primarily patterns for boatbuilding), hence the odd size of this machine.

It just seems like not much extra work to go full 4x8 size plus if you are cutting out of sheet goods it all going to come in at least 8x4 foot sizes and it would likely be annoying having to rip them down each time, not to mention you would be able to cut two long skinny parts at a time instead of one. I know you are decided on 2x8 but it's just a thought.

[adt2]

No, it wouldn't be much extra work...but it would be more expense. I'd have to replace the 8020 and the screw on the gantry, and re-work the table base I've already completed. I'm sure when it comes time to expand, I'll regret not having done it up-front, but right now, as I'm busy writing checks all over town for parts and pieces, the thought of spending the extra jack just doesn't appeal to me.

I'm already getting the stink-eye from the significant other about the cost of this little experiment...

[LazyMan]

I suspected that my post would not be warmly welcomed. I just commented about going 4x8 because in you original post you were already talking about the possibility of changing to 4x8 in the future and if you you have not yet built the frame, it would be the ideal time to reconsider as it would save you money in the long run. I have regretted not building my machine larger for years. Anyways it's none of my business, so continue on. I would be interested in seeing the boat parts that you cut on it.

[adt2]

No worries; I wasn't offended or anything. Just meant to say, I think the 2' x 8' capacity will serve me okay for a while, and if I can put off the expense (however incremental) of building a larger machine, it'll save me some, uh, hassle in the short term.

If I was building smaller boats with frames that could be cut out of 4x4 or 4x8 sheets in a single piece, the 4x8 machine would be a no-brainer, even with the added up-front cost. But since I'm talking about 30'+ boats, the frames have to be cut in pieces anyway, and they're mostly 3'-5' long and 6" wide. Depending on the curvature of the part, I figure I'll be able to cut a minimum of 2 and possibly 3 or 4 pieces out of a single 2' x 8' piece of stock.