buscht's cnc router

[buscht]

Here is my drawing for my CNC router.

I have enjoyed reading about other people's successes and problems so I thought I'd share my experiences.

Here's my budget

XYLOTEX 3 AXIS BOARD $125
3 116 OZ-IN MOTORS $60
24V FAN $5
SHIPPING FOR ABOVE $17
BALL SCREWS AND NUTS $145
MILLING ON BALL SCREWS $105
BISHOP WISECARVER SLIDES (SCROUNGED) $0
ADDITIONAL ROLLERS $90
BALTIC BIRCH FRAME (SCROUNGED) $0
EBAY BALL BEARINGS FOR BALL SCREWS $16
EBAY 24 VOLT POWER SUPPLY (PAID TOO MUCH)$76
TURBOCNC SOFTWARE $20
EXISTING PC $0
GAS SPRING COUNTERBALANCE (SCROUNGED) $0
3 SMALL ROUTER MOTORS $225
ELECTRICAL BOX FOR XYLOTEX $25

[B]PLANNED COSTS $909

UNPLANNED COSTS SO FAR
PARALLEL CORD EXTENDER $12
REPAIR WORK TO XYLOTEX BOARD $17
FLANGES FOR BALL NUTS $64

TOTAL COSTS FAR $1002

I have several things that I want to accomplish with this machine.

1. Awhile back, I had posted an inquiry about a CNC scroll saw application. Not getting any bites, I decided that I would have to build a 2 axis machine and test out my theories myself.

That is why both the X and Y axis are stacked and move. I want to clamp a board to the moving table and process it through a scroll saw. I'll post my results once this has been tested.

2. I want to do some carving work with the router. I figured that I would need 3 bits (1/4" dia, 1/8" ball nose, and a 1/16" ball nose). I did not want to exchange bits during the program, so I came up with the idea of using 3 router heads.

These heads are spaced 7" apart and are on a common Z axis. I plan on counterbalancing the Z axis with a gas spring. My idea is that if my parts are less than 7" wide in width, I can simply move the table over under the appropriate router bit using a fixture offset.

3. The other thing I am trying to accomplish is to learn how to create carving type programs.

4. Once all these things are accomplished, I want to add a 4th axis for doing carvings in the round.

My machine capacity is 12" in X, 7" in Y (if you use all 3 heads) 21" if only one head is used. and 5" in Z.

I have almost all the parts in my shop, except that the ball screws are out for machining.

I still have to cut the wood to size. That will take me the better part of the next two weeks.

Unexpected expenses are always important to know.

1. I did not like the short parallel port cable that came with the Xylotex board, so I went to the computer store and bought a longer one.

2. I didn't follow the Xylotex instructions very well, and I think I blew up the X axis driver. I have this board in for repair.

3. The ball screw nuts that I bought through McMaster Carr came with a 15/16-16 thread for mounting. I spent most of a day trying to find a nut to fit this. I gave up and ordered a flange from Nook Industries. At $20 per axis, this was kind of irritating. You can get these from McMaster already on the nut, but they cost $30 more.

4. I bought an adjustable voltage power supply of of Ebay 0-40 volts, 5 amp. It cost me $55, plus $21 for shipping. I had this great idea that I could play with the voltages to learn how applying voltages and amps affect the drives. I should have bought a fixed output 24volt power supply for about half that cost as I am finding out that I don't really want to know all that, I want to make parts.

T

[xairflyer]

Hi,

Very interesting machine.

What by the way are the wisecarver slides like (look like)

[buscht]

The Bishop Wisecarver slides are a Vee track with a cam rollers that match.
http://www.bwc.com/html/dualvee.html

They are pretty inexpensive when compared to new THK ways, but not being as popular, they are hard to find on the used market. If I didn't have some track already, I probably would have bought THK slides on Ebay.

[balsaman]

Nice machine. I like the 3 router idea.

Eric

[xairflyer]

What sort of price is the rail and the rollars ?

[buscht]

These are rough prices, but for two pieces of track, 72" (1828mm) long its about $106US.

The rollers cost about $19 each and you need 4 per axis. So new pricing would be $334 total for all 3 axis. You can cut the track down into smaller sizes. I am cutting mine down to 36",24", and 12" for the 3 axis.

You don't have to use the Wisecarver track. Any 90 degree shape that you can mount on a 45 degree angle should work. A piece of angle iron for example.

You mount two concentric rollers on one side of a rail, and two eccentric rollers on the other side of the other rail. Then you can tighten up the slide with a pair of wrenches.

I think the way that you are doing your machine with the adjustable cam followers accomplishes the same thing.

[ljoe1969]

who is a supplier for the rails and bearings?

[ljoe1969]

fyi.

these are the same bearings used on the shopbot.

[buscht]

www.bwc.com. I can buy them direct, or you can contact them for distribution information.
T

[buscht]

http://www.bwc.com/html/index.cfm
Sorry about that link

[buscht]

I have made alot of mistakes and still not done, but here are some photos of the machine.

I went against everyone's advice and bought the motors and controller first. This was my biggest concern and I couldn't wait to make sure that I could actually controll stepper motors with my computer.

I also posted my CAD design before building my actual machine. Balsaman was afraid that this was the kiss of death. Luckily, I was able to overcome this obstacle. HA

I am very happy with the ball screws and my decision to use them instead of an ACME rod. Even with the 116 OZ-in motors, the X-Y can rapid at over 100"/ min. My machinist is still cussing me though. THe screws are case hardened and he had a tough time turning the ends down for the bearings and threading the shaft.

Being worried about shaft whip, I used a double bearing support on each end of the shaft and a lovejoy couple between the shaft and the motor.

[buscht]

This is the top of the X-Y table. I am planning on building a vacuum table to sit on top of this, so the bolt heads sticking up won't be an issue. Actually this tabletop has 4 tee nuts in the corners so I can attach various jigs and spoil boards to my table.

I taped a piece of paper to the table and clamped a marker to the Z axis and ran my first program to check accuracies. THe ink leeched through the paper and marked the top of the table.