wahoo, I get to make the first flatbed post! Over the last month I designed and built a CNC router so I could cut parts out of plexi (2.5D) for a Storage Area Network (SAN) computer case I designed. I'm willing to discuss all the details about the computer and case so ask away in the appropriate forum. All the pics for my build can be seen here: http://www.simmonsclan.net/gallery2/v/Tim/Projects/CNC/ I don't want to bore anyone with all the details I posted over at cnczone so I'll keep it brief. Unfortunately you will find out that is not my strong point . The first step to my build was designing it in Sketchup. I didn't stick to the plan, but it was a starting point. My next step was creating a scrap wood mockup. It kind of worked but I didn't have access to a drill press at the time. This caused a bit of misalignment in the prototype but it was useful. I used the wood mockup to drill pilot holes in the UHMW-PE (ultra high molecular weight polyethelene) I picked up. I replaced all the wood parts with the plastic and ended up with a decent machine that could move a rotozip around the table. My first cut was a trucker lady g-code file I got from a guy on cnczone. That was cut at 36IPM but I have jogged it at 100IPM. I haven't cut at that speed because I'm worried about stripping the threads I tapped in the plastic.
Cool! Thanks for posting. One day I'm gonna get around to building a flatbed too. I want to be able to carve into some thick wood. Shaun
I am in the process of building a Joe's 4x4 Hybrid. So far I have the plans and a little of the components. Going to cut out some of the parts this week at work. It will have a cutting area of 48" x 48" I will than be able to do other signs beside vinyl.....3D signs.
Are you using Linear bearings for each axis? Looks like you are using the lead screws as tortional support on the X axis. Why didn't you go with 2 rails on each side of the X axis? I'm trying to build a JGRO CNC....it's slow going.....I should have done something simple like this..... :?
A couple months ago when I started the project I had no experience with CNC or linear motion. I was planning to use one bearing riding on each rail. This obviously turned out to be a problem since the bearings have a degree of rotational play to account for rails that aren't perfectly parallel. I solved the problem by adding to the blocks that ride the X rails. I intended to install an additional linear bearing but found that a hole cut in the UHMW-PE with a grease pocket was more stable and much cheaper. I also got rid of the delrin nuts. I made a tap out of some spare leadscrew and just tapped the plastic. There is minimal backlash (I won't say zero but I can't detect it) and definitely not enough to matter in my projects. To eliminate the play on the Y and Z I moved the lower rail forward a few inches so that the two rails were no longer on the same vertical plane. The rail runs though the front of the bottom Z support and eliminated the twisting of the vertical rails. I'll post some more pictures today of the changes I made last week. The nice thing about getting rid of the nuts and linear bearings is that I can build an entire new machine including electronics and motors for about $500. All the bearings and nuts increase the price to over $1100. It is far from fast but it cuts 1/4" ply with a 4mm bit at 30IPM.
