CNC Bridgeport

Machining has been a fun hobby for me for quite some time.  I've always been interested in fabrication of just about anything - wood projects (make some of my own furniture), cars (swapped a small block into a 4x4 S10 Blazer), and motorcycles (I race...nuff said).  So it seemed like a logical progression to get a milling machine.

My first machine was an Enco Mill-Drill that a friend had and wanted to sell.  I picked it up for $250 and I was pretty excited.  It was practically brand new.  Not long after I got it home and cleaned it up, I completely redid my garage and finished the ceilings, built a new countertop/workbench and finally epoxied the floor.  Once I was done, I felt empty - I needed a new project.  Eureka!  CNC was it...

Installing the new ceiling..

Floor painted and countertop in progress...

I found some stepper motors on Ebay and purchased some Gecko drivers.  I built my power supply with this enormous torroidal transformer I bought from Canada.  I dusted off the old 486DX2 in the closet and installed TurboCNC.  After a few months of simple fabrication, I cut my first CNC part - a piece of aluminum with my team's logo (SR - Sliderule Racing) in it.  I was the proudest damn guy on the planet!

As picked up...

Upgraded to CNC, Making my first paid-for part, a motorcycle upper triple clamp...

...the finished part...

Not long after playing with the Mill-Drill, I got very tired of re-adjusting everytime you moved the head up.  Also, with the motorcycle pieces I was making, I was using a good sized boring head.  Even with the 300+ pound concrete pad I had bolted the mill-drill to, the complete machine would sway around once it started rotating that boring head - it just didn't have enough mass....enter upgrade plan 1:

I sold the mill drill complete with everything, including the computer and made a decent profit.  This allowed me to start looking for a real machine - a Bridgeport.  I found one about 30 minutes from my house where a fellow was selling basically his whole mini-shop.  It was a 2J Varispeed head, 1.5 HP and had a power drawbar, power feed and parts of a DRO.  I also got an old compressor, vise, clamps, rotary table, indexer, and about 250 pounds worth of cutting tools, many of which were junk.  I sold off much of the real useful stuff on ebay, donated the compressor to one of our racing auctions for injured riders, tossed the junk mills and began the process of rebuilding the Bridgeport:

This is how it looked when I got it....

I took it down to every single nut and bolt.  This was very helpful because it helped me learn a great deal about how the machine worked and where it was important to take good care of it.  I sanded it down, repainted the painted surfaces, de-rusted the rusty pieces and replaced a couple of the really worn out pieces....

This is when it was finished...

I wasn't quite done yet.. afterall, I had gotten quite used to using my computer to cut parts and now I had to manually machine again.. yuck.  So I began the process of upgrading the mill to CNC.  Fortunately for me, I came across some Pac-sci brushless 3 phase AC servo motors with drivers for a very good deal.  These are very small, very high power machines capable of moving my table over 200 inches per minute!  The only problem was that there was not as easy a solution to coming up with the hobby solution for the motor mounts as I had done on the mill-drill.  

I spent a fair amount of time trying to come up with a simple solution and wanted to do it well.  I designed it all up in CAD and manually machined the X and Y axis brackets.  Then, I used 2D CNC to machine out my design for the Z-Axis.  I used that setup for a little while and then made a little mistake on my computer punching and BLAMO! I tried drilling a 1/2" hole through aluminum at about 120 in/min.  The result was a broken Z-axis ballscrew block.

My original Z-design just used some extra parts (ballscrew included) that I already had in my possession.  I decided after that mishap that a more industrial sized solution was necessary and purchased much larger ballscrew components and machined a beefier spindle block.  The design is now much more robust with better accuracy:

CNC done (old Z-axis design in these pics)

UPDATE: I've recently been asked about selling the plans for my CNC Kit and am glad to oblige.  Click here if you are interested in purchasing the plans.

UPDATE 8/30/04:  Wow, what luck!!  About a month ago, I got an email from a friend who is on the Vintage racing list.  There was a fellow who was a friend of a friend and 'had a vertical 2 axis cnc mill that was broken and he wants it gone.  Free for you to pickup'.  I jumped on that FAST.  By the next day I was in contact with the owner of the mill and found out that it was a Bridgeport 2J (same vintage as mine but 8 years newer according to the serial numbers) with a broken 3 axis Bandit CNC.  I've now started pulling it completely apart and repeating the rebuild process.  This machine was FILTHY!!!  Easily the dirtiest thing I've ever worked on.  However, the satisfaction is even greater as I see it getting transformed.  It has ballscrews and direct drive servo motors.  My plan is to replace the old behemoth controller (broken) with a PC running Mach 2 (as I use with my current Bridgeport) and use Geckos to drive the original DC Servo motors.  Checkout my progress below:

After getting it home, this is what it looked like....

Now, its starting to take shape:

More to come!