Gigantic Bastard CNC

by spiffcow Apr 1, 2017
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Hello, I wanted to ask how precise the CNC is. Meaning, on what scale can you cut with it?

Nice machine, saw the plastic monstrosity a while ago, looks really good. I already built mpcnc(1in), and I plan on taking it apart to build the lowrider 2, but I see you figure the cost here about the same for me... 50 bucks or so either way (of course for this one I can keep using the dw660, win). I've read through all the comments in both builds, and I understand why you built the PM, but would you mind giving your thoughts on PM vs GB vs LR2, especially differences in rigidity and speed? I don't have enough experience to make good guesses from the pictures, etc. Thanks.

How thick is the side materials? The cut out pieces have no size thickness..can I used 1/2" or 3/4"? Also is there a z mount for the Dewalt WDP 611?

I think I used 1/2", but I would recommend 3/4". As for the mount, this just uses the MPCNC Z axis, so any mount for that should work here as well.

Given your comments on upgrade price, Are you driving this all with Nema 17s?

I started out driving it with all NEMA17s, but the final configuration ended up being 4x NEMA17 84 oz/in motors on the long axis, 1x NEMA23 129oz/in on the shorter axis, and 1x NEMA17 for the Z axis. For the long axis I slaved one of the drivers on my MKS Sbase and ran pair of NEMA17s in series.

The cost should be pretty low to convert from an MPCNC -- basically you just need the square steel tubes, a NEMA23, some plastic, and an assortment of 5/8" and 1/4" bolts and nuts, plus a few 608 bearings. But if you're starting from scratch you might want to wait.. I'm finishing up on build I designed from scratch. It's about 95% complete -- I just need to finish the belts and wire everything up. I've taken everything I've learned from the past 2 builds, and I'm confident this one will outperform an OpenBuilds Ox while being able to cut a full 4x8 plywood sheet, and come in around $600 for the full build cost (including the table).

so are building a new design of cnc for full sheet? I want to build one I do not know which one to build beetwen lowrider cnc, CNC Artisan or this Gigantig Bastard CNC

Yep, I've got a new design that will replace my Gigantic Bastard. I have it all put together, but I have a bad wire I'm going to have to track down that's preventing me from running it yet. I plan to release it this weekend :)

very well so I'll wait, thanks for asking and I hope it will be great

I don't have the build instructions up yet, but if you want to check out the new build and start printing my new design is at https://www.thingiverse.com/thing:2471313

Plastic Monstrosity -- The 3D Printed CNC for 4x8' Plywood

I like it I guess it's better and more clear and simply design which stepper motor has it? Nema 23? What is the diameter of the tubes of the y-axis?

Thanks! So far it's turning out really well, and the tweaks that I need to make are pretty minor (basically just belt positioning).

I have 3x NEMA23 270 oz/in that I got on ebay ($70 for the set IIRC) and then one NEMA17 for the Z axis. I'm thinking of switching to a 2HP router for the spindle, and if I do that I'll probably need to switch the Z axis to NEMA23 as well.

The tubes are 2" conduit from Home Depot (roughly $17 each)

Yes I think it will work better,and are u using 608 bearings? I really like this design I probably start to make it on this week

I'm using a combination of 608 and 625 bearings.. The 608 bearings run along the conduit and the Z axis, while the 625 bearings are used for the belts. I'll try to get an approximate parts list ready this week.

If you decide to build it please keep me informed on your progress! And if you run into any trouble with it please post a comment in the entry for the Plastic Monstrosity :)

That new design sounds awesome, I'm trying to make my final decision on what to buy and what to build, $600 is right about where I want to be. I love the idea of the fully supported rails you're doing on your long axis and it reminds me of the solsylva style rails. I was wondering why you only used them on long axis and didn't do a torsion box and attach the rails to that. Maybe that's part of the new design.

Personally I think designing around NEMA23s is the right way to go. Whatever frame I end up going with I'll probably go NEMA23s run by an arduino running grbl and external TB6600 drivers (seems to be the cost effective way to get into higher output steppers. Currently thinking 179oz.in should be about the right size. and with designing for NEMA23 going bigger if necessary is easy.

Any guess on timing for the new build?

I'm guessing it'll be a couple more weeks before I have it fully tested. It's nearly done, the only issue is my lack of free time to finish it up.. I'm thinking of posting it sooner though, since all the mechanical pieces are ready

I certainly understand the lack of free time. When you post it, i'll take a look and probably build it in all of my free time... Thanks

Sorry it's been so long. My new design is at https://www.thingiverse.com/thing:2471313 if you're interested (I don't have the build instructions up yet, but the STL files are up)

Plastic Monstrosity -- The 3D Printed CNC for 4x8' Plywood

Would it be possible for you to provide a list of additional parts to convert an existing MPCNC to one of these? Thanks.

Hello! What is the size in z?

I'll check when I get home.. IIRC the tubes are 11" long, (4" height plugged into the MPCNC calculator). The front plate I used is the one taken from the Root 2.1.4, and the holes in the STL should line up with the holes on the Root 2.1.4 mounting holes for the X axis carriages. It is a bit space constrained. I'll try to get some picks of it tonight.

hi! can you please upload more photos?? i'm trying to assemble it but i have some doubts. thanks

Sure thing. Which parts in particular are you having trouble with?

I added a few pics. Let me know if you need more info

why did u use 3 wheels instead of 4 in y axis

I assume you mean in contrast to the Root 2 CNC... The reason is that the 3 wheel design (taken from the MPCNC) allows for supports, where the Root 2 design does not. Over short distances this is not a big deal, but for longer lengths you need supported rails.

Could you do a video please?

Will do. It'll be a while though -- I'm in the middle of a new iteration of this design using 5 of these things as a base:

I'm guessing this should give me a near-perfect Z height across the entire surface without needing to do a "surface pass", and should further improve the rigidity.

How is the spindle attachment working? Is it this one? http://www.thingiverse.com/thing:1949521

MPCNC 525 52mm Spindle mount for dust collection
by PCFlyer

It is, thank you! And it works well. Thanks for mentioning it, I'll add it to the cited works list :)

Glad to hear it. Nice looking bastard !

Is this much more rigid than mpcnc? I need more robustness around the z-axis when moving X/Y

In my experience it's much more rigid.

Great job! I keep looking at these two thinking I would like the benefits of both. Now I can, thank you!

Thanks! And I hope it helps :)

Impressive! Can you also create modified parts for metric version of MPCNC?

I can generate one, but I can't test it. I'll work on getting it posted soon

25mm parts are up! If you try them out please let me know if there are any issues.

You rock. I've been wondering how to take what I'd learned with the MPCNC and apply it to a 4x8 cutter. Now, if only I could find a workshop big enough to accomodate the "Gigantic Bastard!"

Thanks! And I know the feeling -- luckily I have a very understanding wife who doesn't mind parking outside :)

Awesome looks great... Is that 4by10ft bed?

Thanks! It's actually a 4x8 plywoid sheet. You can build it as long as you want though -- the supported round tubes don't lose any rigidity when you add length