Let me start off by saying that I have always wanted a CNC machine since taking a CNC class at my middle school nearly 15 years ago.
About 3 years ago I was going to build a Woodworking mill out of MDF, I had bought a HobbyCNC 4AUPC Board with 3 305oz steppers along with 1/2-10 leadscrews. I abandoned the project since I had too much stuff going on in life. Recently I started 4 wheeling and modifying my own vehicle. Shopping around for parts i quickly realized how many products are made from Plasma CNC machines and how easily I could design and produce my own parts. After looking at the prices of Plasma Cutters I easily realized the money I could save and make by cutting my own parts.
This leads me to my build, since I am not rich by any means and infact i am low on cash due to me getting ready to depart from the US Army, I had to do this thing cheap. I looked at various machines including Torchmate and alot of custom machines on CNC Zone.
I stumbled upon the website Free 3D Models, Free CAD Models and discovered that 8020inc has all of their product CAD files located there for free, in Solidworks format. [B]Amazing[B]. I litterally designed this machine in Solidworks in about 3 hours, then I simply went to the 8020inc Ebay store and bought the exact items I needed. No extra parts, not too few parts. This saved me money by not accidently buying extra parts and time by not waiting for parts to arrive if I did not order enough. Infact I am so pleased with the results I am probably going to build the table "frame" from 8020 too instead of welded steel like I was planning.
Anyways, You may notice that I am using 10 series extrusion. I was a bit weary of using this material at first because of its 1" base thickness, I thought it may not be rigid enough for my needs. I decided the 10 series will suit my needs because a plasma cutting system has no "load" like a mill or router. The only load is the weight of the machine itself and friction. Thus there should be no torsional loading, and no real need for a super rigid material.
When i received the 8020 products I was actually amazed and the weight and strength of the 10 series and in fact I have no doubts it would work excellent in a mill/router if proper bracing was used to stiffen up the design. (NOTE: I would not use this design for a mill/router, but I would use the material)
You will also notice that I am using the 8020 product Linear Bearings (I would call them Slides) They are made from some High Density plastic and have a low amount of Friction. The plastic pads are also easily replaceable and cheap. Again, since a CNC Plasma does not really have a load to it, this IMO is a great alternative to Roller Bearing style bearings. All the "slides" need to do is support the weight of the machine itself, and since I am using 10 series this is not very much.
When I assembled the slides on the 8020 extrusion I was surprised they slid so easily, in fact I can slide the entire gantry assembly with my pinky. I also have some Dry teflon based spray lube from Lowes that makes the slides even easier to operate. I have no doubt in my mind that the 305oz motors will be able to operate the machine with ease.
The only downside to the Slides is if there is an amount of torsional load on them they bind up quickly, thus using them for any type of milling operation is a big no go. On the other hand, I am using 2 leadscrews for the X-Axis, this eliminates and chance of torsional loading and keeps all forces purely linear.
The bearings used in the Solidworks design were ordered from VXB Bearings, unfortunately they sent me the wrong ones and they do not stock the correct ones I need. Instead of sending them back I opted to make them work. As a result VXB sent me a free digital caliper.
Cell phone pics of my progress thus far:
Lee, you have a great start on a machine. I think WWW.precision plasmaLLC.com builds their machines from that stock. I ordered a Piece for my gantry and was pleasantly suprised with it's heft. I wish I had a working knowledge of solidworks, it would save a lot of time. Good luck and I will follow your build...............jb
OK finished the motor wiring but fried the X Axis driver somehow, swapped to the Z Axis channel for testing.
Installed a pen and drew some sort of snowflake thingy.
Heres the video. YouTube - leeleatherwood's Channel
COOL ! Nothing like a plasma machine running in the living room ! Keep us posted with lots of [smaller] pictures ! Way to go .
Just wondering if those really clean screws need to be on the outside away from all the smoke and debris that a plasma cutter sends into the wild.
The 8020 stuff looks great to work with and simple to build and really does look very stable and strong.
I hope it works well for you but I would do something about covering the screws and probably protecting the slides a bit as well. It looks like it wouldn't be much of a problem to swap them to the outside anyway.
Just a thought. :-)
I am not completely useless.......I can always serve as a BAD example.
I got them from here: CNCRouterParts as you can see they have an O-Ring on one end that squeezes tightly to the leadscrew, prevents backlash and also has a side effect of self cleaning.
The wood router guys use them on their machines with the leadscrews in a similar position as mine.
Although if it becomes a problem i will try as you suggested and move them outboard, it should not be too hard.