Cnc Help/set Up

SweetJesus

In Memoriam
OK guys, as some of you know, I am in the process of getting a CNC machine up and running. I know some of you have to use this stuff out there. I have a custom gantry being built 4'X8'

The rack and pinion gearing is 1 revolution = 2.375" for x and Y and
the Z axis .100" per revolution

So I am looking at either servo motors or stepper motors NEMA size 23, at least 250oz holding if not bigger, actually prefer bigger. Also looking for an appropriate controller and software to run this beast. Of course not looking to spend more than I have to! Any leads or ideas where i can get this stuff? How about anyone who has some experience setting this up?

I guess my priorities are getting the motors and an appropriate controller which I can run off the PC which translates .dxf files into G code and then sends it to the controller which runs the CNC machine!
 
Lets trade info! How much for the gantry?

I found looking for steppers on eBay to be the best bet.

As for the controller, there are many DIY plans on the net or go with a Gecko Drive. Goes for about ~$150.

http://www.geckodrive.com/products.htbml

Software wise, I was going to use EMC, since I like *nix and it runs on RTOS.

http://www.linuxcnc.org/

Here is the "Brain Dead Install", which is EMC already installed on the Linux RTOS.

http://www.linuxcnc.org/bdi/

Here is the info on using Penguin CNC with Eagle:
http://www.yty.net/cnc/

Also if you join the yahoo group:
CAD_CAM_EDM_DRO

The people on there are pretty helpful.

As for the dxf files, you'll have to get a conversion program to make the G code for EMC. (I think I've seen some of those?!??!)
 
Gantry is $990 plus shipping. You will have to talk to me like a 3yr old about this! Because I am in way over my head!
 
Hey guys- Before this gets pulled for being off topic-

Drop in on www.cnczone.com, that is where we talk all things CNC.

That sounds like a lot of travel/rev. It's about 0.012 per step, or 0.001 per micro-step. I've been afraid that a rack/pinion setup might not be ridged enough for cutting thick acrylic. I've not found anyone who could definitively answer that one yet, so I'm still waffling on rack/pinion or ball screw.

Check out the plans on www.data-cut.com. I have not bought them yet, but that is the style I'm going to build.

I'm working on designing a 5'x9' gantry style CNC router. Gecko servo drives on all axis, Mach5 control software under Windows 2000, with an upgrade to the new Mach controller later this year. No purchases for it yet, still planning, but I've got to get it going by fall to keep up with orders.

I've looked at the spec's on EMC, and that sounds nice, but I want to be able to open Autocad on the machine, tweak stuff, and regenerate code without having to have another box around.

I'm stoked about the CNC though- :)


Zeph
 
I've been afraid that a rack/pinion setup might not be ridged enough for cutting thick acrylic.

I must say. I too was unsure if rack/pinion would work for thick acrylic until i finished my machine. It is a 10' x 16' table. I used 2 Pacsci powerpac steppers model K43HRHK-LNK-NS-01 for the x axis and Pacsci steppers modle N32HRHJ-LDK-NS-01 for y and z. I use this machine to cut aluminum and acryllic with a thickness for .032" - 3" with +/-.004" tolerance. I used a Galil 4 axis pci interface for motion control. The spindle is a 10HP Columbo. The Table has a 15,000 CFM blower to generate the vaccum hold down. here is a pic of the whole machine
 

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Oh my God I'm drooling!!! I would love to learn CAD CAM. Talk about whipping out parts.:eek2:
Awesome,
Chris
 
Wow, very nice machine. You built that monster?

Can you post some pictures of milling acrylic, and some more close-ups of the rack and pinion?

Chris- When I get mine built, I'll let you come up and play once in a while. :)

Thanks-

Zeph
 
yes, it is a monster. I also used the thompson rail and linear bearings and recieve no noticable deflection during milling. I made it so big because i had room and wanted to make sure that if i need to mill a part, that my table would be large enough. As for the shopbot, I have two of them at work (PRT-144-60 and PRT-60-216 palsma cutter) No compalints on either just VERY expensive . Built this beast for under 20k. i have used it to mill all the parts for my sump and refugium. I have just bought enough 1" acryllic to make my new tank. As soon as the material comes in, I will post milling pics and assembly pics
 
i use an onsrud single flute spiral up cutter @18,000 - 20,000 RPM
and a feed rate @150 - 250 ipm depending on the type of acryllic. I use both 1/4' and 3/16" cutters and never remove more than the diameter of the bit per pass ( depth per pass). (ie. 1/4" bit/ 3/4" plex = three passses) i then make a fouth pass, to mill the edge, removing .025" to make sure that i have a very smooth edge. i usually drop the feed down @ 25% here just to be safe
 
I want one I want one!!! Anybody know of a source for a kit for a gantry? I can handle all the electronics and assembly type stuff. I just don't trust myself with the mechanics.

Ideally about 2'x4' but I will probably use it for milling circuit boards more than anything else.

Thanks.
 
The single flute doesnt gum up?

No problem with gum up. it is a spiral up not a staight flute so i get really good chip ejection. I buy my cutter from Hartlauer bits. They have a web page. Just search for it. very good cutters IMO. The ones i use are made like the Belin Just not as expensive. Very high grade carbide.
 
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