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Jumping in with a CNC build
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10106&t=30059		 Page 1 of 2
Author:  Mike OMelia [ Wed Nov 24, 2010 12:56 pm ]
Post subject:  Jumping in with a CNC build
I finally decided to build a CNC router. Gonna build Joe's Hybrid 4x4 with rack and pinion drive. I will post pics as I go.

Mike
Author:  cyborgcnc [ Wed Nov 24, 2010 7:07 pm ]
Post subject:  Re: Jumping in with a CNC build
Best of luck Mike!

Joe's design is one of the most (if not the most) popular design out there. Many folks have build form his plans, and are getting great results!

He also has a couple of newer design made out of extruded aluminum etc, but even a basic machine out of mdf does a good job. It is a great way to get into CNC, learn how to operate one, etc. without having to dish out 10K+ for a commercial one.

Looking forward to seeing pictures of your work, and if you have any questions we can help with, do not hesitate to ask!

May I also recommend mach3, as compared to EMC...Mach3 is a hell of a controller, with many features, and very easy to set up and get going...

Have you decided on a CAM/CAD package?
Author:  BobK [ Thu Nov 25, 2010 8:38 am ]
Post subject:  Re: Jumping in with a CNC build
Congrats, I think you'll be very happy with it. Mine has lead screws, I'll be interested to hear how the r&p version works for you. Joe's forum is very helpful, but if you have any questions about my build feel free to ask. Lastly, step up to the hardened rails. It'll add something like $500 to the cost of your build but I think it's a much better solution than the angle iron rails.

Good luck and you'll be surprised by how quickly it all comes together.

Bob
Author:  Mike OMelia [ Thu Nov 25, 2010 10:26 pm ]
Post subject:  Re: Jumping in with a CNC build
Hardened rails? Not sure I follow. I've bought the plans and am studying the build threads. Why are hardened rails an issue? As for software, I am an engineer by trade, I actually program C++ simulations. So I know my way around a computer. But as to s/w packages needed, I have no clue. Aspire seems to be popular... But there seem to be two categories, cad/cam for design, and driver s/w (gcode) for driving the machine. Accurate assessment? Is there more?
Author:  turmite [ Thu Nov 25, 2010 10:48 pm ]
Post subject:  Re: Jumping in with a CNC build
Hi Mike,

The design work is done in the cad portion of a cad/cam system, and the code to run the machine is produced by the cam section. It is quite possible to hand write code as well, but it is way over my head when you start getting into simlutaneous (sp) motion of 3 axis for 3d work.

Many, but not all luthiers choose Rhino both for it's cost to benefit factor, plus it is an excellent modeler and a very accurate cad system. As far as cam for Rhino, I rep for Madcam, which is a cam plugin for Rhino, so I am going to be biased, but there are other packages that work with Rhino. Cyborgcnc is a S/W nut laughing6-hehe and quite good at modeling in Solid Works. Cost wise though, Rhino is going to win hands down......or up!

Mike
Author:  Bob Garrish [ Fri Nov 26, 2010 4:05 am ]
Post subject:  Re: Jumping in with a CNC build
I'd recommend giving Moi3D a try, along with Rhino (both have free trials). If Moi is sufficient (and it has 80-90% of Rhino's capability) then you can save a lot of change.

MadCAM is a nice piece of software if you have Rhino, as is Visual Mill (standalone version, don't bother with RhinoCAM as you get less for the same price). If you go with Moi3D then Visual Mill is the best option in a pretty full featured CAM system, and if you go with Rhino then you've got a choice of MadCAM or VM in the lower price range.

CAD makes 3D models
CAM gives you a toolset to generate G-code from your 3D models
Your control software parses G-code to move the machine (it runs the motor amps, switches, etc)

G-code is dead simple, it's really just a list of destination coordinates with velocity, and some other stuff tacked on top (codes to turn the spindle on and off, etc)
Author:  BobK [ Fri Nov 26, 2010 9:42 am ]
Post subject:  Re: Jumping in with a CNC build
Joe's design calls for using V bearings which ride on Home Depot angle iron. It's a cost effective solution, especially for those who only use their machines for cutting 2D parts out of ply or mdf. Angle iron isn't hardened so it doesn't wear evenly and it isn't perfectly flat. The upgrade requires aftermarket rails (I got mine from here, if I remember correctly. http://www.superiorbearing.com/docs/guidewheels.html ). The rails then need to be attached to aluminum plate which is then attached to the 8020 beam. Lot's of drilling and tapping, but the results are worth the extra effort. Or you could upgrade to a linear bearing system. The thing about the Joe design is that it's a proven semi-open source plan. Once you buy the plans you get access to his forum where members freely share mods and build tips that improve the final product. You'll know what works, what could work and what doesn't before you even start your build. You can build strictly per the plans or incorporate any of a number of proven mods or design your own to fit your needs. I built mainly to the original plans. Once done I completely redesigned my X and Z axis and used the original machine to cut the parts out of 1/2" and 3/4" aluminum.

Bob
Author:  Mike OMelia [ Fri Nov 26, 2010 11:29 am ]
Post subject:  Re: Jumping in with a CNC build
Bob, what parts did you cut out of aluminum? The parts made of MDF? Upgrades? Also, what kind of router is used fir cutting aluminum? Is not a standard router too fast?

Mike
Author:  BobK [ Fri Nov 26, 2010 11:40 am ]
Post subject:  Re: Jumping in with a CNC build
Mike,

Here's a link to my build log on Joe's forum. http://www.joescnc.com/forums/viewtopic.php?f=14&t=1321

I didn't go crazy with pictures, but you should get the idea. I used my Milwaukee 5625 router to cut my aluminum parts. I ran full speed at at depth of something like .015" and used thread tapping fluid as a coolant. I didn't say it was fast (nothing at .015 depth of cut is), but it was accurate.

Bob
Author:  Mike OMelia [ Fri Nov 26, 2010 12:25 pm ]
Post subject:  Re: Jumping in with a CNC build
That's cool. I will look at ur build.

Mike.
Author:  Mitch Cain [ Sat Nov 27, 2010 9:18 am ]
Post subject:  Re: Jumping in with a CNC build
Hi Mike
There are a few of us Joe's builders here. Rick Hubka is also building, or built one. Mine is not finished yet, and it's not the fault of the design, but rather the fact that my job moved me to the northeast and my machine is still in Florida. I'm hoping to get it back here soon after the holidays...

CyborgCNC has some really helpful videos on Neck design and machining. I recommend them highly...

I have a thread going here on my build, and you can see about when I had to stop working on it...

Good luck and don't be shy about questions!
Author:  Mike Kroening [ Sat Nov 27, 2010 11:41 am ]
Post subject:  Re: Jumping in with a CNC build
Hi Mike,
Here is a link to some pics of my homebuilt CNC using 80/20 extrusions. The first 4 are at the beginning of the build last year. I was using lead screws at that time (don't waste the money on lead screws). I have learned many things on this build. Including how to eliminate Midband resonance in steppers (common problem with nema23 types). Also eliminating problems with phantom Limit switch triggers. Small things like bearing mounts, and methods of installing Ball screws that add stiffness and help eliminate backlash (something I will be changing soon on mine). Cost wise I have about $2200.00 in the machine itself, That includes the upgrades during the learning and building stage. If I did this again I believe I could keep this under $1700.00. :)

If I can help in anyway please don't hesitate to ask.

Mike
SEE Link below :)
http://www.mikrovisions.com/cnc/
Author:  Mike OMelia [ Sat Nov 27, 2010 3:00 pm ]
Post subject:  Jumping in with a CNC build
Mike, ur build looks like ur own design. I am going with the rack and and pinion 4x4 hybrid. But I am curious about build cost. Does not seem to be much discussion about that at Joe's CNC.
Author:  Mike OMelia [ Mon Nov 29, 2010 3:11 pm ]
Post subject:  Re: Jumping in with a CNC build
Are there cost estimates for Joe's Hybrid?

Mike
Author:  BobK [ Mon Nov 29, 2010 4:09 pm ]
Post subject:  Re: Jumping in with a CNC build
Mike, the answer to that is it depends. I've heard low estimates in the mid to upper teens and high estimates in the 3-4k range. It's all about the the decisions you make for your machine. Personally I didn't really keep track because I knew by the time I was done it would be close to 4k with electronics and software.

Joe's plan and kit something like 450, right? I don't remember exactly off hand.
8020 beams and hardware ~300
V bearings ~$12/each
Rail for bearings $75 to $500
R&P kits don't know$
Flange bearings, leadscrew, ABL and motor connector for Z axis ~150
Angle iron bed mod ~100
Strut ~100+ depending on table
Base table up to $250ish
Controller and motors $400 to 1000+
Router mount ~75
Router 75-200
e chain 30
computer and monitor Dell refurb ~300
Hardware from Tractor Supply ~25-50
Misc parts and materials I'm forgetting (wiring, switches, tools you might not already own, etc) ~500
Software Cam 500-1000, Mach 3 ~200, Cad free to up to 1000
More misc I'm probably forgetting another $250-500.
Author:  Mike OMelia [ Mon Nov 29, 2010 8:37 pm ]
Post subject:  Re: Jumping in with a CNC build
That is sobering! Oh well, do it over time.

Thanks

Mike
Author:  Mike Kroening [ Tue Nov 30, 2010 12:47 pm ]
Post subject:  Re: Jumping in with a CNC build
Mike O'Melia wrote:
Mike, ur build looks like ur own design. I am going with the rack and and pinion 4x4 hybrid. But I am curious about build cost. Does not seem to be much discussion about that at Joe's CNC.

Yes Mike, it is somewhat my design. It was loosely based on some pictures I saw of another persons build. :)

Not sure about a Joe's CNC build cost?

MK
Author:  Mike OMelia [ Tue Nov 30, 2010 2:23 pm ]
Post subject:  Re: Jumping in with a CNC build
Mike, what size is your actual cutting area? I am surprized you can come in at under $2K using ball screws. Using them on all 3 axes? Does that price include controllers? I assume it does not include computer and s/w

Mike
Author:  Mike Kroening [ Tue Nov 30, 2010 3:39 pm ]
Post subject:  Re: Jumping in with a CNC build
Mike O'Melia wrote:
Mike, what size is your actual cutting area? I am surprized you can come in at under $2K using ball screws. Using them on all 3 axes? Does that price include controllers? I assume it does not include computer and s/w

Mike
That included my everything except the PC and software. My cutting area is 39"X 20"Y 6"Z

My mistake when ordering Ballscrews, (originally leadscrews) to 4ft X 2ftY 1ftZ. Did not allow for linear parts lengths and other factors.

Ballscrews I got from Roton.com very reasonable pricing. have approx than 0.0015 backlash in them. They are single start 5TPI used 5/8" for Z and Y and 3/4" for X costs was under $300.00 for them all with ballnuts. I made my own flanges though. They want a fortune for those :)

MK
Author:  BobK [ Tue Nov 30, 2010 6:27 pm ]
Post subject:  Re: Jumping in with a CNC build
Mike, Just curious, how did you handle the Z axis? It's my understanding that a ball screw Z will slip all the way down to the table when you turn off power to the motors. Not enough friction to hold the ABL nut in place is what I've heard. Is that the case or did you come up with some sort of solution for that?

Thanks,

Bob
Author:  Mike Kroening [ Tue Nov 30, 2010 6:50 pm ]
Post subject:  Re: Jumping in with a CNC build
BobK wrote:
Mike, Just curious, how did you handle the Z axis? It's my understanding that a ball screw Z will slip all the way down to the table when you turn off power to the motors. Not enough friction to hold the ABL nut in place is what I've heard. Is that the case or did you come up with some sort of solution for that?

Thanks,

Bob
Not sure about that Bob? My steppers have never given me any problem with that after powering off? Now If I physically disconnect the stepper from the Ball screw, yes it will travel down but there appears to be enough resistance in the stepper to avoid this. Also remember that a there is a certain amount of rotational resistance caused by the thrust bearings as well. Also I am not using any ABL nut, I compensate the backlash with Mach3 since the backlash is minimal.

Mike
Author:  Mike OMelia [ Tue Nov 30, 2010 7:59 pm ]
Post subject:  Jumping in with a CNC build
Mike, Well, the Joe's design seems to be in line with ur cost when you factor out the computer and s/w, and then factor in the size increase. Seem reasonable! I am interested in the z axis / ball screw question as well.
Author:  BobK [ Tue Nov 30, 2010 8:58 pm ]
Post subject:  Re: Jumping in with a CNC build
Thanks Mike. That's good information about the ball screws.

Bob
Author:  Mike Kroening [ Tue Nov 30, 2010 9:05 pm ]
Post subject:  Re: Jumping in with a CNC build
BobK wrote:
Thanks Mike. That's good information about the ball screws.

Bob
Also remember though Bob I am using single start ball screws. Multi start screws may react differently? I just couldn't see any reason to go that route for the extra expense when I am getting excellent results with these.

Mike
Author:  cyborgcnc [ Tue Nov 30, 2010 10:59 pm ]
Post subject:  Re: Jumping in with a CNC build
Another place for ballscrews/steppers/etc is http://www.homeshopcnc.com. They have decent prices, and they will also machine custom lengths etc....

Bear also in mind, there are many folks selling brand name ballscrews from say hiwin, THK and others on Ebay. Some are used, but you can find some great bargains..here is an example:

http://cgi.ebay.com/THK-SX-ground-balls ... 1e5ff6b477

FYI
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