[cephjedi]

Hi Gang!

I've been watching buildyourcnc.com with great interest over the winter as I was preparing to build another CNC machine. Originally I was hemming and hawwing over designing my own machine or going with one of the open source plans here...or purchasing a kit.

Patrick figured out a neat way to build a pretty darn good machine with mere hand tools, and filmed the whole process- it's a fun watch for anyone interested in building a machine.

Recently he fleshed out his design and decided to start cutting kits. I really liked his design so I jumped on it. (crossing fingers) My kit should be shipping very soon!

What puzzles me is that, despite authoring such a useful online resource on CNC, I find almost no references to Patrick around CNCzone. Has anyone else built one of his machines, and how's it working out for you? I'd be really curious to hear if there are any other folks waiting for one of the first kits!

Happy friday folks! -Jim

[thestruuus]

I based my design on his method. It works well but here are some of the problems I am having.

1) I used 5/16-18 threaded rod rather than shell out for ACME threads as he did and you will run into 2 problems. I will be tossing the threaded rod and purchasing ACME rods shortly.
a) the rod is never straight and this causes vibrations (find the best you can to minimize this)
b) At 18 (or 20) threads per inch the max IPM is significantly reduced based on the max motor rotation rate. With my nema23 motors I can only get 30-35 IPM.
2) I had to design a method to hold the L bracket down to avoid vibrations
3) you may have to shim the berring guides to keep all 4 bearings tight against the track.
4) He doesnt show wiring, make sure you use shielded wire for the motor and limit switches, no shielding the motor wires from the switches causes unacceptable false limit triggers

Also having only video (this is often overly long and drawn out) without and drawings or photos is a PITA. Overall his design seems good, I build mine out of 12ply birch rather than MDF and used drywall screws.

Photos are avalible on
http://www.woodworking.com/dcforum/DCForumID19/387.html

[GibbonsRock]

thestruus,

Thanks for your perspective. I have already built a CNC machine from eBay junk, and I know very well the limitations of the high tpi screws....I'm using 1/4"-20 and because of it (and some serious construction issues) I can only get about 12 IPM.

My new machine (from patricks Kit) will definitely have 1/2" acme screws...and I'm trying to decide on the pitch and number of starts (any suggestions?) I think I read that Joe's 2006 machine used 1/2-8 with 2 starts with nice results, but that thread is so hard to mine.

I wonder most about the use of aluminum rails with skate bearings- it makes me curious that you encountered alignment errors.

Patrick's new machine still relies on the aluminum rail theory, but it strikes me as very solid.

Thanks for sharing! -Jim

[phooddaniel]

Hey Jim,

Thanks for the kind words here on CNCZone. Through the years, I have learned most of what I have implemented my website from all of the experts here.

I would recommend the 2 starts rod and you can source them from Mcmaster Carr. They have the 1/2"-8 2 starts which will yield 4 revolution per inch. Length are 6" or 3" which can be cut down to proper length. Don't forget the wear compensation nuts. You will reduce backlash with these nuts. I think you can also get wear compensation nuts from dumstercnc that match the mcmaster carr rods.

These compensation nuts will be flanged for easy adaptation to the kit. I will guide you if necessary.

Thanks again, Patrick

[GibbonsRock]

Hi Patrick!

Cool, 1/2-8-2 it is! McMaster Carr is awesome- me being in Maryland I often get my order the next day. I am definitely heading over to Dumpster CNC for my leadnuts and couplers. Will I need any additional nuts for it? On the demo video for your machine the Y-axis leadscrew appears to hang out there without a nut on the end. (I always assumed that the screw should be braced with nuts/clamps because the steppers shouldn't be subjected to the stress.) I just want to be sure so I only have to send one order in to DumpsterCNC.

Rock on, Jim

[phooddaniel]

Yes, you will need extra nuts to stabilize the bearings on both ends of each lead screw. You might want to use a single start lead screw for more precision on the z-axis. If you do use a 2 start on the z-axis, you may need a spring or counterweight mechanism to reduce the necessary torque (imposed by gravity).

[phooddaniel]

Let me add a correction. You won't need extra nut to stabilize the rod at the bearings. You can use screw clamps that dumpsterCNC sells. That would be a much better and less expensive choice.

[gfc62]

Hey Jim,
I'm building a CNC based on Patrick's plans, the version just before yours assuming you're getting the latest version 1.2 kit. I've got the mechanical work done and am working on wiring up the motors and controllers. Hopefully this week I'll have them mounted and start testing the machine under power. So far it's going together well.

I see you live in MD, not too far from me in northern VA. Do you know of any other CNC enthusiasts in our area? I've met with one guy who works in Springfield and lives in Stafford who's building a smaller machine.

Let me know how the kit goes together.

[amigaman]

I am also inthe Northern Virginia area (Reston) looking for others that arer building their own CNC machines. Just ordered the book and plan on starting soon.

Andy
www.r2dc.net

[GibbonsRock]

Hey dude....forget this thread. The real machine is over here:

http://www.cnczone.com/forums/showthread.php?t=62394