Build Thread- Home made CNC

[Crawler374]

Well, as my previous thread, I did not have luck with the "instructable" cnc build. I think that the designer gets 100% credit on his "out of the box" ideas, but personally, I didn't like the belt drive system, along with the weight of the MDF and it's quality. I also thought it could have a little more simplicity to the machine. I like to see complicated vehicles and parts, but not machines. So my new build will consist of a Hybrid style. MDF, aluminum, and steel. So far, my parts list isn't the best, but decent.

I plan on using my skate bearings for the X-Y-Z axis, but instead of the rod-track I am going to use square aluminum. I will explain more later.

My drive system is the HobbyCNC 3-Axis kit, and all driven by shaft (threaded rod).

For my previous build, I used a router as my cutting machine. The router is for wood, obviously; mine will be a different design because i want to mill aluminum. I have an idea on how i'm going to do this.

The router is only usable for 1/4 shank milling bits. but since i will be milling smaller parts that need 1/8 and smaller bits the 1/4 shank to 1/8 milling is expensive. But the 1/8 shank and 1/8 milling is a lot cheaper. So I plan on using an older style drill chuck. This way I can use shanks from 1/8 to 1/4 and in between. My idea is to take the assembly out of an old drill, use the chuck and the gear reduction units. Then, get a high torque-low RPM motor. 550 size. This will be light, and rebuildable and will allow adjustments for higher RPM motors to higher torque motors. Another Pro about this, is weight. The Hobby CNC steppers isn't very strong, so i would like the machine to be light and strong as possible.

so far this is only built in my head, I still need to swipe the easy card to order the stuff .

I should have updates within this next week or so.

[awerby]

of your own, Crawler. Unfortunately, they aren't paticularly good ones...

For my previous build, I used a router as my cutting machine. The router is for wood, obviously; mine will be a different design because i want to mill aluminum. I have an idea on how i'm going to do this. The router is only usable for 1/4 shank milling bits. but since i will be milling smaller parts that need 1/8 and smaller bits the 1/4 shank to 1/8 milling is expensive. But the 1/8 shank and 1/8 milling is a lot cheaper. So I plan on using an older style drill chuck. This way I can use shanks from 1/8 to 1/4 and in between. My idea is to take the assembly out of an old drill, use the chuck and the gear reduction units. Then, get a high torque-low RPM motor. 550 size. This will be light, and rebuildable and will allow adjustments for higher RPM motors to higher torque motors."

First off, a Jacobs chuck isn't the right thing to hold endmills with. The reason people use collets on their CNC equipment is to cut down on run-out, the wobble that will break your tooling and ruin what cuts you manage to make before that happens. The smaller your tool, the more critical this "TIR" factor becomes. Also, you need considerable rotary speed to cut aluminum, especially with small-diameter bits; the router would work better than this geared-down assembly you're talking about.

But even routers don't tend to last too long in CNC metal-cutting applications; they are designed for short periods of use by hand in wood, not long periods of heavy continuous cutting of metal. You'd be better off buying (or building, if you insist) a pulley-driven spindle which could boost the speed of whatever motor you find to 10k rpm or so, and which held its endmills in collets, not a chuck. Taig and Sherline both make spindles like that, either one of which would work much better than what you're proposing above.

Andrew Werby
www.computersculpture.com

[ger21]

Or buy a Bosch Colt and 1/8" collets from Precise Bits. A heck of alot easier than building you're own spindle, that as Andrew said, will more than likely have too much runout.

http://www.precisebits.com/products/...llets_nuts.asp

[Crawler374]

Thanks for the reply's guys. I suppose that's something i will have to consider. This is also a hobby machine, not an industrial. So very very precise and high quality parts isnt completely needed. I will give the Chuck idea a shot and if i see imperfections, I will have to do something else.

[Crawler374]

Here is the pics of the build so far. I decided to use something else for the bearings. I hope it works!


So far, its mostly MDF board, and not supported very well.










the Y axis wont be sliding that far, it will loose 1/2" distance when its done.

thanks for lookin'!

[ger21]

You better get something between those rods, or it'll be unusable.

[Crawler374]

Originally Posted by ger21 You better get something between those rods, or it'll be unusable.

Originally Posted by Crawler374 So far, its mostly MDF board, and not supported very well.

[Crawler374]

Todays progress:

The X axis is supported. I ran some wood on the bottom of the rod to support its weight.

The Y axis is also re built. I used angle steel and ball bearings. I also built a stand for the CNC so its not on a trash can or my work bench


I'll get a few pics tomorrow for y'all

[mmonti]

thats pretty good, I was playing with a small table using those same rollers as a proof of concept for myself instead of the rods I used 1/8 x 1.5 CRS bars Ill see if I can get a pic or to of it up tonight

[amishx64]

Nice start on your machine.

The Y axis looks nice so far. How's the wobble (probably none)? Do you have any bending in the rails?

Are you doing this from design or as-you-go?

P.S. your "driven by shaft (threaded rod)" is called all thread. What side are you using? My build is using 5/16 dia. all thread.

Nice work thus far. Can't wait to see the progress.

[Crawler374]

Thanks for the comments guys. But, actually, this is all built as i go. Nothing was planned besides the materials. I just learned the basics of CNC's and went from there.

The All thread is 1/4-20 X 3'

Sorry about no pictures yet, on a good note, the cnc is actually 90% complete! Most of the design has changed and re-built.

The Bearrings I used work, but have a little bit too much slop for a cnc's X-Y axis. I actually used them for the Z-Axis and it worked great!

For my spindle, I took apart an old Ryobi cordless drill and mounted it up, its not the best, but for cutting plastic, i think its going to work just dandy

[Crawler374]

Well, im getting close! The cnc is almost complete. All thats left is the Z axis to be finished and get my wireing done.