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| Thinking of building a cnc... http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=7292 |
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| Author: | Don Williams [ Tue Jun 27, 2006 12:18 am ] |
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I'm tossing around the idea of building a small cnc. And I mean small. I want just to be able to do small scale stuff, like cut rosettes, maybe some inlays etc. Nothing big. I'd like to keep the size of the thing very small, maybe only big enough to cover a 2' x 4' area. No bigger, maybe smaller. So my question is, how many folks here have built there own, and how happy were you with the results? How inexpensively can they be done and still maintain good accuracy? Thanks. |
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| Author: | John How [ Tue Jun 27, 2006 2:55 am ] |
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So your just talking two dimensional huh, That does sound interesting. I hope someone will respond that knows something, cause I sure don't and I'd like too. |
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| Author: | Scott Thompson [ Tue Jun 27, 2006 3:30 am ] |
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This isn't a build your own, but I thought I'd mention that at the GAL convention, Chris Klumper from LuthierTool was showing the prototype for his new small CNC machine. The one he had there had a table made to fit a guitar fingerboard, but he said that the table could be made for any configuration. One nice thing is that it will sale for around $2,500 Here is the picture from his site.  |
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| Author: | Don Williams [ Tue Jun 27, 2006 3:53 am ] |
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I would want it to have some Z axis capability of course, I just won't do large stuff like necks. Although, eventually, I would want to be able to probe the perimeter edges of a guitar body and cut binding & purfling channels. 
I would like to do other things too. I've always had a desire to make wooden backgammon boards out of really great woods, but cutting little triangles could be tough by hand or with conventional power tools. It would be a snap with a cnc... |
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| Author: | Marty M. [ Tue Jun 27, 2006 9:04 pm ] |
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I've built 2 at this point. As I've mentioned in a couple of threads, John Kleinbauer has some nice plans at around 35 dollars. He is at crankorgan.com. I first made one from his plans and then moved on to a machine of my own design that was large enough to rout bodies and necks. I purchased a motor/controller system to avoid problems in that area. You can probably get a machine up and running for 300 dollars or so. There is a lot of freeware/shareware out there, but I've never had good results with them. hobbycnc.com sells kits of motors and controllers and may wire them for you too. I have an old version of Bobcad to convert DXF ( autocad) files to Gcode ( cnc language). That works great. I am constantly amazed at what even home brew CNC is capable of doing. |
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| Author: | Marty M. [ Tue Jun 27, 2006 9:45 pm ] |
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Here is a picture of it. 
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| Author: | Jeff Doty [ Wed Jun 28, 2006 3:21 am ] |
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What about something like this? A bit more expensive, but maybe closer to turn-key? Jeff CNC Auction link. |
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| Author: | Don Williams [ Wed Jun 28, 2006 3:47 am ] |
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Jeff, That has a $7000 list price...substantially more than I want to invest in something like this. I would like to keep it under $2000 for everything. If possible. I noticed that doesn't even include a router or a spindle. |
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| Author: | Jeff Doty [ Wed Jun 28, 2006 5:04 am ] |
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[QUOTE=Don Williams] Jeff, That has a $7000 list price...substantially more than I want to invest in something like this. I would like to keep it under $2000 for everything. If possible. I noticed that doesn't even include a router or a spindle. [/QUOTE] Ooops! Sorry Don, I saw the $850.00 bid, and neglected to look at the "reserve not met." My bad. I will try to be more aware next time I have a bright idea. 
Jeff |
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| Author: | Bob Garrish [ Wed Jun 28, 2006 5:34 am ] |
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DynaCNC is sort of on shaky ground anyways. According to their eBay feedback they've sold two machines on there, max, and they could be shell users for all we can tell. There are also no reviews to be found on the web of any of their routers minus two very negative ones on WoodWeb. CNCZone.com is the place to find out about this sort of thing, BTW. It's the best single source of CNC related info on the web right now, specifically 'homebrew' or small shop type setups. They've got endless stuff in the forums on kits and plans etc. |
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| Author: | Jim Watts [ Wed Jun 28, 2006 5:51 am ] |
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Don, I recently purchased a used cnc router and it has what I consider to be a fatal flaw in that the builder of this machine used standard acme nuts welded to a plate to provide the motion along the lead screw of the axis. Sounds reasonable on the surface, however the problem comes in that standard nuts have too much play in them resulting in backlash, that is that when the machine changes directions the screw has to turn some amount to engage the nut. This ruins any chance for repeatability with the machine, which is why I consider it to be a fatal flaw. I bring this up for a couple of reasons; 1) If you’re thinking of building a machine don’t do it this way as there are good alternatives to this such as anti-backlash nuts or precision screws that have matching plastic nuts that engage both sides of the thread, or even preloaded ball screws (probably the best). I know plastic nuts don’t sound so good but they’re actually made for motion control application because of the backlash issue, they’re also designed in such a way to be mounted onto a block so that they are replaceable. And 2) If you are thinking of buying a machine ask the seller to measure the back lash or have him cut a sample part such as a diamond in multiple Z depths, a circle and a square. This would tell you a lot about the machine. Cutting the diamond should highlight any backlash issues. I’m also convinced that you could build a decent machine for around $3,000 or so and not have a problem with the above. So.. I have to rebuild my X axis, any words of wisdom here from others would be appreciated. Unfortunately I won’t be able get to it till the end of summer. |
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| Author: | Don Williams [ Wed Jun 28, 2006 6:19 am ] |
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Interesting information Jim, thanks. I'll keep that well in mind when it comes time to do this. I don't know if it even will ever happen, but I'd like to start thinking in that direction. Maybe bit by bit I can by good parts and work at it slowly. |
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| Author: | John Watkins [ Wed Jun 28, 2006 6:40 am ] |
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That's the only way to do it, Don. You'll never find a good deal on everything you need all at once. Plan to shop for a year before beginning the design process if you really want to use good stuff and get it done cheap. For example, I have four SKF ball screws in the rafters in my garage. They're 40mm screws and each one is 5' long. I bought em' cause they were a steal, not cause I needed them at the moment. When I'm ready to build another machine, that'll be $1,500 that I don't have to shell out for brand new screws of the same quality. Coincidentally, I found those puppies in the CNCzone classifieds. If you're serious about this, you'll watch that thing like a hawk. Good stuff doesn't last more than an hour or two. |
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| Author: | Jeff Doty [ Wed Jun 28, 2006 7:59 am ] |
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Don, Ok, trying to redeem myself here. Would this one be of any use? Jeff CNC, No reserve price! |
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