Amae's Bridgeport Series I BOSS3 retrofit

[damae]

It's here! My 3000lb proof that a bite from the CNC bug is incurable!

Can someone here tell me what WAF is? Because it seems to have skipped over me. At work, we design subwoofers and speakers and talk at length about how to make the product attractive to both target buyers and their spouses, who may not want a big black wooden box sitting next to the computer or TV and looking so, um, big.

My wife must really love me! She let me move a 3000 bridgy in and take over the garage. Hmm. Could it have anything to do with the coincidental and simultaneous arrival of a new puppy for her?? Naw, probably not. She must just love me! =)

I am truly excited about this machine! It seems the right deal came along at the right time! I had five basic requirements. The machine had to be:

-local, within a few hours by truck
-Series I size
-originally designed to be CNC
-in good shape,
-Cheap. cheaper than ebay!

And I happened to find it! A local machine shop was getting rid of their Bridgeport Series I, with BOSS3 control. I didn't care if the control was running or not, but it was, and the shop supervisor demonstrated that everything moved ok and ran fine! The price? Well, let's just say that I could easily spend more money on tooling than I did on the machine itself!

Attached are some images of me getting it home. It cost me $75 to get it from the machine shop to my garage. Hiring a truck with a forklift on the back of it really made this an easy process! Others have hired a tow truck to meet them at their house and use their crane to unload the machine. But then you have to pay two drivers, plus tip, of course. =)

[damae]

I like to keep things together. Here are some related threads I started:


Another thread when I was trying to figure out how to move the machine:
http://www.cnczone.com/forums/showthread.php?t=13216

Questions about which way to go: Just use the existing stepper motors or replace the motors and controllers with modern ones.
http://www.cnczone.com/forums/showthread.php?t=13791

My other CNC machine, the "AKITA CNC" mill. This one is a 4' x 4' router, which will now be much easier to build using the BP!
http://www.cnczone.com/forums/showthread.php?t=11786

[ViperTX]

I suspect that the puppy is distracting her for the moment.....we'll have to see what happens in 6 months.....

[damae]

Originally Posted by ViperTX I suspect that the puppy is distracting her for the moment.....we'll have to see what happens in 6 months.....

Hehe. That's when weighing 3000 lbs and being hard to move come in handy! I just have to find and get a lathe in there before the new puppy effect wears off!

But seriously, she's supportive of the project. We won't be able to fit a car in the garage anymore, but I plan to strip and repaint the machine and keep the areas around it looking nice, painted lines on the floor and all.

Actually, retrofitting will be the easy part, since I have three options:
A. Get a rotary converter and use the working BOSS3 controls as-is
B. Strip off the controls, but use the existing steppers with Gecko drives
C. Fit all-new servos and controls

All three options are pretty quick once I make up my mind. Cleaning up the machine will be the really hard part! Take a look at the attached pictures -- it's like an archaeological dig going down through the layers of metal chips that have built up between the control cabinet and the base casting! I will have to completely disassemble it and repaint. Getting the knee off worries me a bit -- it must weigh a ton. Well, not literally, but maybe 800 pounds? I think I'll just go buy a HF engine hoist. It will probably come in handy more than once!

I'm following with interest the thread titled "how to paint a bridgeport":

http://www.cnczone.com/forums/showthread.php?t=13737

Note: That is the same cable in both pictures. One is looking down, the second is looking up!

[damae]

My NEMA 42 servos are a direct bolt-on replacement on the Z and X axis.

The Y axis is a little tricky because of the limited space under the knee. Including the flange, the motor can't be longer than 8.5". That's a problem for my servos; as you can see from the photo they are too long! If I want to use a my servo on that axis, I'll need to manufacture a new

Servos are right now my first choice for the retrofit, since it means no new cash outlay, and I would not have to build a power supply. Perhaps in the future, I can reuse the stepper motors in another project. Actually, thinking about it, I may have to use the stepper motor on the Y to manufacture a new Y axis motor mount with a large offset to fit the servo. Kind of a boot-strap problem.

In one of the pictures, you can see another serendipity-gone-murphy. The original stepper motors have a 5/8" shaft and 1" wide pulleys with the exact same diameter as some more modern pulleys I have on hand! They even have the same OD! But it was too good to be true. The new pulleys are .375" pitch and the old ones appear to be something like .5" pitch.

Even so, I prefer to replace both old pulleys and the belt, so that I can use my much simpler keyless-bushing-mounted pulleys. If I keep the old pulleys, I need to cut a keyway in my motor shafts. On the other hand, I onyl have 5/8"ID keyless bushings, but the upper pulley needs to fit a 3/4" shaft.

Keyless bushings, by the way are a fantastic! They install without keyways, even on completely smooth shafts and still have the ability to transmit 5x more torque than my 2hp motors can kick out. No gear pullers needed for removal either, just a wrench. McMaster has the 3/4" version I need, but it's $48! And that doesn't include the pulley, just the bushing.

[damae]

I've been investigating my machine and found these three covers on the head that don't seem to have any purpose, at least not for this model. They are blind pockets in the casting, and don't lead anywhere.

Does anyone know what usually is installed in these holes? Perhaps something meant to go on the manual version of this mill?

[damae]

30 min Examining all the cables going in and out of the power box.
1 hour Cutting all the cables, removing screwed-on conduit
1 hour Hoisting the box away!
1 hour A whole hour just raking all the remaining chips out, like an archaeological dig!

My new shop crane (engine hoist) made this a much less dangerous job. Who knows how much the power box really weighs, but with all that copper and iron in those huge transformers, it's HEAVY! The hoist is a Harbor Freight special, $150! I suspect I'll be using it over and over again, especially when I get to painting this beast.

To get the box loose, I had to cut all the wires going in and out. Unfortuntately, there were no connectors that I could unhook, so it is a one-way permanent removal. There's no going back now! I included a picture showing all the blue and red wires going from the transformer box to the control box, all unlabeled, of course. =)

I will gut the remaining metal enclosure, which now houses the "brains" of the BOSS3 control. When I'm done, it should be a pretty lean and tidy outfit, housing everything - computer, controllers, breakout board, relays, etc. The swing-out "pendant" control panel will also get a makeover. I'm replacing the mechanical switches with a 14" LCD monitor and keyboard tray mounted to it. Perhaps something like this:

http://www.cnczone.com/gallery/showp...o/403/si/panel

But I'm getting ahead of myself. I still have a lot of work just to clean up this beast and get it moved into place at the back of the garage. Originally, I hoped to strip each part down and repaint as I did my retrofit.

Instead, I will clean all the thick grease and gunk off the machine as I do the retrofit, but leave the painting until next summer. For now I'm focusing on getting this machine running and operating smoothly. Once I've made all my mistakes and fixed them, I can paint the machine for that final sense of completion.

[damae]

It seems so easy - just remove the old motors, bolt-on the new ones. My motors even have the same 5/8" shaft that the old ones do. So this should be a 20 minute job, right?

Wrong. To use the old pulleys would require machining keyways in the motor shaft. And they're odd sized keyways, seeming way too small to transmit 2HP worth of torque. I really didn't want to use their old-fashioned taper-lock pulleys anyway.

Fortunately I'm sitting on a pile of really nice pulleys with modern keyless bushings so I can quickly clamp them onto any smooth shaft - no keyway required! They just happen to be the same 3 1/8" diameter and the same 1" width! So slip the motor in, fasten new pulleys and I'm done, right?

Wrong again! My aluminum pulleys are .375" pitch, but the Bridgeport pulleys appear to be .5" pitch. Ok, fine, so I simply need all new pulleys for the motors. McMaster has them, but for about $150 (for three) - OUCH! And McMaster's pulleys don't have the correct bore for my keyless bushings.

So back to the drawing boar... er.. uh.. computer!

I'm looking for another vendor that has .5" pitch 1" wide pulleys. SDP-SI doesn't have anything above .375" pitch and .5" wide. Any suggestions?

[damae]

Can a engine hoist really lift a Bridgeport?

Well, last night, I found out the answer -- yes! After removing the control cabinet and disconnecting the final few wires, I slipped the "shop crane" (as Harbor Freight calls it) into place. A handy tip for anyone else trying to move their mill with a shop crane - the 2ton foldable version of HF's shop crane has legs just far enough apart to get around the base of the standard series I main casting.

My son helped me and will probably be telling his friends that he lifted a 1 ton machine into the air with his own arms. He did all the pumping on the hydraulic cylinder, while I monitored all the wheels and ropes to make sure nothing was slipping or about to tip over. When you're pumping on the handle, you can't really see much of what's going on, so I'm glad to have had his help!

Later, my wife stepped in to help me muscle the hovering machine into place. She was definately the brains and I was the brawn -- many of her good ideas of which angle to push at worked out better than my own ideas. I couldn't get it to move on my own, so I would recommend if you try this to have a second person to steer while you push.

So now, it's settled into what I thought would be a permanent location. Now that I see it's not so bad to move it, I can see rearranging the garage some day and moving the mill again if needed.

[damae]

In a moment of unusual .. uh.. is it bravery or stupidity? Anyway, I stuck my hand under the mill to take a picture. I was all ready to move the mill, had it up in the air, when the question struck me: What is up there anyway?

So I snapped a few shots, hoping the mill wouldn't suddenly drop down and sever my hand. Hehe I used my left hand for the second and subsequent pictures. If you're going to lose a hand, at least it won't be the mouse hand!

I was amazed at how much you could see in there. Parting lines, texture, even flash is all still there, same as it was 25 years ago when they cast this beast. The ribbing appears to be 1/2" thick or so. And it was very cool to see the spider that holds the ram onto the turret. I was surprised there isn't any rust above the height of the foot of the casting. By the looks of it, this was an investment casting, or at least a lost-core casting.

And for those of you thinking "I could never fit a Bridgeport in my garage," I included a picture showing how the garage looks from the outside. The Bridgy takes up no more space than a couple of bicycles and a propane grill.

Who knows, after I clean up, I may be able to fit a few more machines in there!

[damae]

Taking things apart is easy but we'll see how putting it back together goes in a month or so!

I gutted the electronics cabinet, scraping it clean with a putty knife. It's amazing that this thing worked at all with metal chips, metal dust, and .. are those... ? Yes, someone left pistachio nut shells in the cabinet!! How did that happen?? The metal, dust, and oil, I can understand -- they came in through the vents and around the heat sinks.

I've been dying to try out my cheap-o Harbor Freight sandblaster, which I'm counting on help me clean up the individual parts for painting. It works great, eating up paint and leaving a fine diamond texture. There are a few catches, however. It takes longer than I expected and sand is expensive! $20 for 25lbs of sand. After 1 minute of blasting, I have to wait 5 or more minutes for the air compressor to catch up.

Some guy on ebay is selling plans for an improved sandblaster he calls a "Pressure Assist" sand blaster. It's caught my attention because my current setup is s-l-o-w.

[damae]

There is a problem with cleaning up your shop (that's another word for "garage" for those of us who haven't yet come to terms with our CNC addiction)

Anyway, the problem with clearing space in your shop is that it makes room for another machine! I'm now the happy owner of a second Bridgeport mill!

This one is a really interesting machine, a "Tracer Mill". The ram on this thing is massive and reminds me of a hammerhead shark. There was real art in the making of these old machines - from the designers to the patternmakers. This particular machine came without a head, but this is more than made up for by the two massive 1.5" diameter precision ballscrews that came with it! The X axis ballscrew alone is likely worth (on ebay) as much as I paid for the whole machine! Some would call that a basket case. I call it a good deal and a new project!

I included some pictures to show a real easy way to lift this machine -- just lift under the head! Worked like a charm to get it onto the truck. When the machine arrived at my house, I learned a valuable lesson: Check all the bolts before you lift!

As we started to lift, I couldn't believe it as I watched a gap open between the ram and the main casting! It hung there in mid-air for a second, then gave way! The main casting slammed back down onto the truck's bed, while the hammerhead shaped ram started sliding down the forks of the forklift, dragging a desperate me with it! As one side came off the forks, it hit the table and began slipping over the edge of the table, threatening to fall all the way to the truck bed, perhaps messing up the Y axis box ways in the process. In one of the pictures, you can see me grappling with it as it teeters! I was just an inch away from letting go (to avoid injury).

In the end, we got it put back together and lifted off. But had I checked the bolts before we lifted, I could have saved myself the scratches on the table, the bent threads in the ram and, of course, a close call. I think the bolts worked their way loose due to vibration during the trip.

Rather than run two seperate logs, I decided to just keep this one log. This should work out nicely, because I will concentrate to finish the BOSS3 mill first, then use it to finish the Tracer.