About 7 years ago I bought a Bridgeport Boss 5 milling machine from a shop in Rochester, NY. The setup featured a teletype machine interfaced with the BP controller and I could generate tape or drip G code to the machine. Life was good, I got proficient correcting the code BobCad would generate and the machine did all that I could ask of it. After a couple of years and in the middle of parts run though the bugger got REAL erratic. Until that moment, I’d never really routed around inside the cabinet much. I quickly decided that the aging and massive capacitors had seen better days, that there would be no quick fix and that the job still had to go out the door. I finished the job using a conventional mill and figured I'd fix the BP when I had time.
Fast forward thru 4 or 5 years of staring at the non running lump and that brings the story to last November / December when I decided to bite the bullet and do an AJAX / Centroid DIY conversion. I had, by then, read all kinds of literature, pondered numerous options and somewhere in there joined CNCZone. During those non running years I stripped the BP of everything that would not be needed with a conversion. I also rebuilt the ball screws, replaced spindle bearings and patiently waited for "the day." I guess the machine is kinda ugly but really tight. I always seemed to either have the time but no money or money and no time. This, I vowed, would end this winter.
After a fresh quote from Jesse I ordered the kit and three weeks later I drove down to the Altoona exit off of I80 and went to pick up my goodies. I learned that AJAX and Centroid were in the same building. I discovered a very professional operation with everyone helpful but distractedly busy. I always figured busy was a good sign when dealing with a new vendor. Unfortunately, I did not meet Jesse as his mother had died that week. I was treated courteously, given a “grand tour” of the entire Centroid operation, had all of my questions answered and reservations addressed. I came home with several boxes of well packed goodies.
The machine hadn’t been used for several years so I wasn’t in any great hurry to do the conversion and install. I just sort of poked away at it. I restore antique aircraft for a living and at any given moment the shop can be littered with anything (steel tubing, aluminum, spruce, fabric etc). I have a very complete metal and wood shop at home while my maintenance hanger is tucked off in the mountains. Dust can be a problem sometimes so I decided that the conversion needed to be entirely “closed cabinet.” The tape reader cabinet had been disposed of ages ago- along with the guts that were in it. That left only the power cabinet on the back of the machine for the retrofit. Into this I shoe horned a cannibalized PC (the ultimate ‘case mod!’, Variable Frequency Drive (more on this later), various power supplies (transformers) , relays, the AJAX/Centroid ‘brain’ / PLC. It took some planning but nothing too outrageous. The servos installed flawlessly with the only slowdown when I realized that I too would need a spacer for the z axis servo. (I’d been warned in a CNCZone thread- thanks). Apparently this spacer is required on some BP conversions but not others. The only other ‘mod’ required more than straight bolting together was having to open the keyway on the z axis servo pulley. A Dumont broach tackled that issue in short order. After that it was really just a matter of chasing wire. The prints are clear, the manual readable and very utilitarian. The tech pages available on the AJAX website flushed out almost all other issues. When undecipherable issues arose Jesse Meagher provided some of the most timely and useful phone support that I’ve ever gotten anywhere for anything. Most of my problems with the install were self made, but that didn’t deter Jesse from providing continued support until everything was perfect. That had been one of my greatest fears when starting into this. If I had a problem who would really be there to help? That fear disappeared with the first call to AJAX. Actually I can’t say enough good things about the whole experience.
As for the conversion… well here is a summary of thoughts:
In doing the conversion again I would
1.) Replace the quill and motor pulleys on the machine with rigid 1:1 timing belt pulleys and a new belt rather that make the existing variable pulley system work with collars and lock downs.
2.) I would replace the spindle brake solenoid rather than install the dedicated 24VDC power supply just to drive that one unit. The speed control solenoids were removed when I chose to use the VFD.
3.) I would not be so hasty in removing the tape reader cabinet as the extra real estate would greatly simplify the install process. There are oodles of extra cable length to accomodate using multiple cabinets.
4.) I would buy a new micro ATX motherboard, chipset and power supply rather than using the cannibalized spare computer I had sitting around. This would cost an additional $150 (
www.newegg.com) but have a vastly smaller footprint and save the time doing my “case mod”. What is NOT readily apparent from the AJAX site is just how barebones the computer can be.
5.) The software version of Linux and the AJAX/Centroid software will not accommodate a CD drive. If, as I did, you network the CNC to your regular desktop- a hard drive install is both unnecessary and a waste of time. The Linux will recognize a USB thumb drive (it even recognizes the hard drive portion of my iPod using a USB connector!!) but doesn’t want to recognize any other kind of input device except an obsolete 3.5” floppy. So really all you need is the AJAX hard drive, the Ajax interface board, a USB port and an Ethernet port.
My first part off of the machine was milled from a solid billet of 4130, 7” long, 5”wide and 2” thick. I used Solid Works to design the part & Esprit 2007 to generate the 3D tool paths. The part is a governor yoke for a 1929 International Harvester Farm engine. The pic shows the three places cracked original and my freshly CNC’d replacement. The second little task was a science project with my 13 year old son. He did the set-ups and did the drawings to generate code. We’re especially pleased with the spur gears- everything made with MDF and some spare bearings that hadn’t been looked at in years. The goal was a rubber band powered vehicle designed to go the greatest distance. His science teacher provided each in the class with the rubber bands...
In closing, the Intercon milling software package that comes with the AJAX conversion can do about 99% of all the machining that I would normally do. It’s powerful and very intuitive. It has proven sufficient at almost all 2 1/2D tasks. The Esprit and Solid Works fills in around the edges by easily creating true 3D tool paths. I probably wouldn’t / shouldn't have even bothered acquiring a CAD / CAM package in retrospect.
Them’s me thoughts- what do you think?
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www.SpecialtyAero.com