I'm looking to build one similar to this: http://www.instructables.com/id/How-to-Make-a-Three-Axis-CNC-Machine-Cheaply-and-/

since the Design school kids are being asshats and not letting me use theirs. Grr.


Any advice? Pitfalls to avoid? Recommended software to run on it?

11/11/2008 1:35:16 PM

Here's my 2 cents.

I went the route of building one from scratch, I am a member at the CNCZone forums (I recommend reading there a LOT before you even start thinking about it).

I was VERY careful building my CNC machine. I built a welded steel frame for more rigidity, etc... In the end, youll spend way more time, money and frustration trying to do this on your own.

My suggestion? Go to Harbor Freight, buy one of the micro or mini manual mills. Then buy the kit to turn it into a CNC mill.

For example, right now since I dont have to make large parts, Im using the following setup:

Harbor Freight Micro Mill:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47158

CNC Fusion Kit:
http://www.cncfusion.com/micromill1.html

Hobby CNC Driver:
http://www.hobbycnc.com/

Mach 3 Software:
http://www.machsupport.com/


Ive upgraded all of my tooling and stuff with a bunch of parts from Little Machine Shop. If you go this route, I can show you some of the stuff that I have found that works out well.

The only reason I really come to this conclusion is that you will never get the accuracy or precision from a homebuilt gantry setup that you will from something like this. While the micro mill leaves a lot to be desired as far as rigidity and stuff goes, its light years ahead of something you will build on your own.

--- Edit

Just to also add, the total cost for what I list above is less than $1000, considerably so if you are creative. The instructables site claims $600. For the difference in price there, I dont see why you wouldnt go the slightly more expensive, but worlds ahead route of buying the premade stuff like I ended up doing.

[Edited on November 11, 2008 at 2:24 PM. Reason : Adding pricing]

11/11/2008 2:21:12 PM

Quote :

"since the Design school kids are being asshats and not letting me use theirs. Grr."

considering the price tag, im not surprised

11/11/2008 2:21:57 PM

What do you want to cut/make?

There's a guy in Garner with a CNC router that is CHEAP. He charged us ~35 bucks for a 4x8 sheet of plywood to be cut, sanded and packed.

The reason the CoD is stingy about their router is because people CONSTANTLY fuck it up, not having any clue what they are doing. The damn thing seemed to be broken half the time I was in school because of retards coming at night and fucking it up.

Based on the fact you are asking about the basics of building your own, it's probably a good thing they didn't let you on it. I wouldn't even bother trying to build one. The one you linked to is a piece of shit and a complete waste of 600 bucks. If you want something small like that: http://www.shopbottools.com/shopbot_buddy.htm

ShopBot is a local company, it's the same brand the CoD uses. Not a super high quality router, but it's one of the few affordable options out there. You can probably find a used buddy system for 3k or so.

---------------

^^He said we wanted a CNC Router, not a mill. Two completely different uses. Though he may not actually have any idea what he needs.

[Edited on November 11, 2008 at 2:25 PM. Reason : .]

11/11/2008 2:23:34 PM

Quote :

"^^He said we wanted a CNC Router, not a mill. Two completely different uses. Though he may not actually have any idea what he needs. "

He actually asked how to build a CNC machine (not a router or a mill), and if you look at the specs in the instructables link, the envelope is only:

Quote :

"Usable working envelope (10" X-axis, 14" Y-Axis, 4" Z-Axis) "

Thats a pretty small envelope for a "router". (Even though the picture in the instructable shows a gantry style router).

11/11/2008 2:36:46 PM

Yeah, I know about ShopBot. I've been considering taking one of their classes.


We used that instructables as a starting point, and redesigned the plans to allow for more Z-travel, larger size, etc.


But more specifically, how is it trash and "a waste of 600$" ? Yeah, we're not going to see incredible resolutions out of a homebuilt rig, but I'm failing to see how proper carpentry and/or metal working would fail to produce at the very least, a basic CNC router.


And yeah, I know CoD doesn't make a habit of letting kids with no practical exp randomly play with their expensive toys. Especially kids who are not even currently students.


I want a CNC router to assist in basic rapid prototyping. Mostly for hobby prop making. It would be incredibly helpful in building that suit of Ironman armor I've been working on for the past few months. So the primary mat I'd be cutting is foam. I doubt this thing could cut hard woods or aluminum unless you went ridiculously slow. *shrug*

11/11/2008 2:37:48 PM

Here is a prelim render of our redesign:

11/11/2008 2:39:06 PM

You will be extremely lucky to even get 1/32" precision out of a wooden-framed CNC router. It's going to be more like 1/16" which is absolute trash for any model making, or anything else beyond a tech demo.

I had to stop using the shotbot for the same reason. Even it only gets to like 1/32" on plywood, and MAYBE 1/64th on foam models if you have everything really clean and well calibrated.

a) you need metal
b) you need a MILL for what you are doing, follow Wolfmarsh's advice. You can probably build something "good enough" for ~6-700 bucks.

11/11/2008 3:54:05 PM

Actually, I'd probably be okay with 1/16" resolution. Everything that I cut on this table will have to be hand detailed and cleaned before molding anyhow.

Now would this lack of resolution come from a torquing of the frame when the bit cuts through whatever material is on the table? Or is this a result of vibrations from the cutting tool or what? I'm not seeing how a properly constructed MDF board table would be any less "sturdy" than a welded aluminum table for basic foam cutting.

11/11/2008 4:06:07 PM

you're making the assumption that 1/16th is in a single direction

and it's both. torque of the bit, vibration of the entire jig, momentum during movement, the jerk of whatever you use for the axial movement.

even with a solid steel frame there's movement. hence why GOOD mills and routers usually have a thousand pounds or so of ballast weight to dampen vibration. go ahead and build the MDF thing, but you are going to spend a shitload of time with fill putty and a hand sander to fix all the fuckups

11/11/2008 5:08:49 PM

*shrug* It's a learning process, and something I've wanted to build for a while now.

Learn by doing, I say.

11/11/2008 5:12:43 PM

Quote :

"CoD doesn't make a habit of letting kids with no practical exp randomly play with their expensive toys"

never stopped me the handful of times i tried

[Edited on November 11, 2008 at 10:43 PM. Reason : get a block of UHMW for the base - it'll give you weight and low friction for the x-y planar slide]

11/11/2008 10:37:32 PM