8'x3' Laser Build- Barracuda RC Boats

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8'x3' Laser Build- Barracuda RC Boats

Postby F15pilot » Mon Apr 13, 2015 4:11 am

Hi everyone!

This is my second CNC/Laser build. Last year I built a DIY version of the CNCRouterparts.com 5'x5' CNC machine. With that experience, I hope to avoid a few hurtles on this large laser build.

Long story short, I build custom 3D CAD designed wood boat kits for customers. I have a Precix 9100 Industrial CNC machine but I'd like to have something to laser engrave and cut small parts, specifically 3mm poplar. My company produces a decent amount of boats so I'd like to have this as an addition to my shop.

The only reason I am doing this build is that I stumbled upon THK linear bearings in great condition... FOR CRAZY CHEAP. Without revealing my sources, I picked up (2) 8.15ft THK HSR25 linear rails with (4) bearing blocks for only $5 each and (2) 4ft THK HSR20 linear rails with (4) bearing blocks for only $1.50 each. These required a serious amount of cleaning as they were gunked up. I disassembled each bearing block, cleaned, and repacked. I also took each rail and cleaned each one meticulously. They turned out close to new. :mrgreen: I also picked up a THK KR33 4" Linear Actuator with ball screw for.... ready?.... $4. Again, just needed cleaning. The tolerances measure very tight and nothing shows signs of wear other than a scuff hear and there.

I still paid $125 for the ultra heavy duty steel table and the list price for the Moore Gear Rack. I did save by buying the 80/20 for $1/lb so I will probably go back and get some more for the enclosure.

SO yeah... this table is perfect for my needs. I really wanted a 4'x8' to take a whole sheet of ply, but I can't say no to cheap parts. I've cleaned up all the parts pictured. It took me 9 hours to remove all the rust from the table and do an initial primer paint job.

I plan on mounting the linear rails along the side of the table and mounting the Moore Gear rack below it. There is barely enough room, but it will fit without a problem. This does cause an issue for enclosing the unit. Any ideas? I am also juggling how to mount the laser tube. Thoughts?

Here are a few pictures of my work so far and the parts I've assembled. (And pictures of just a couple of the boats we produce.)

A couple of the boats we cut:


The initial parts gathered:


How I received the parts:

After cleaning:
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Joined: Sun Apr 12, 2015 2:40 pm

Re: 8'x3' Laser Build- Barracuda RC Boats

Postby sshwarts » Mon Apr 13, 2015 10:07 pm

That's very cool you got all that cheap. Question (and I don't know a lot about rack and pinion systems), but can you get the kind of speeds you want out of it to do engraving? How fine are racks in other words the pitch (I think they use another term for them)

Posts: 93
Joined: Tue Apr 22, 2014 6:37 pm

Re: 8'x3' Laser Build- Barracuda RC Boats

Postby Halfdead » Mon Apr 13, 2015 10:26 pm

That Rack and Pinion doesn't seem like it would be all that accurate for something like this.

I'd sure love to know how you got the linear rails for so cheap.
Posts: 51
Joined: Wed Feb 08, 2012 9:35 pm

Re: 8'x3' Laser Build- Barracuda RC Boats

Postby F15pilot » Tue Apr 14, 2015 2:50 am

Hey Guys,

The more I think about it, the more I am leaning towards a belt system. R&P does have great accuracy but the speed is only 1000ipm for rapids and the acceleration is probably not as good as belt driven. I had most of this stuff left over from my CNC 5x5' build.

Can someone please clue me in on a large scale belt drive for something like this?

I'm also considering a movable bed instead of the Z-axis. I have a great supply of 80/20 and would make the frame from that. If I mount that bed to (4) linear bearings on the inside of the table vertically, I raise and lower the bed up to 25". This would be nice to do tall pieces like chests or similar items. I would just cut out the center support. This would keep things simple by allowing the laser projection to remain flat.

Quick MSpaint of the bed I would make from 80/20 and mount to some SBR16 round bearings. Makes sense to me. Red is the 80/20 and the blue is the SBR16 guide rails. Thoughts?

Sorry, can't disclose my source for the bearings. Wish I could get a constant supply!
moveable table.jpg
Posts: 3
Joined: Sun Apr 12, 2015 2:40 pm

Re: 8'x3' Laser Build- Barracuda RC Boats

Postby greenvandan » Sun Apr 19, 2015 2:03 am

Seems like you would be better off running a hefty Acme screw up each corner rather than the SBR16. You could belt drive all 4 screws together pretty easy if you can find long enough belts

I'm curious, are you planning on mounting the laser tube on the gantry, or stationary?
Posts: 59
Joined: Mon May 28, 2012 1:41 am
Location: Baltimore, MD

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