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  1. #1
    Join Date
    Dec 2004
    Posts
    293

    JDs BP J-Head CNC Conversion Blog

    OK, well I'm over a year into this so it's a little late to get started, but I have pretty good notes and the machine is there as a record of what's going on.

    I've decided to post here as I can keep it all in one thread -vs- the deal on Yahoo where it's all chopped up. I can post photos in line here as well. That will add to the context. Some photos later.

    Here's where I am at.

    First off what am I doing? I want to enter the insanely competitive world of kitchen gadgets to supplement my income. We live in "The OC" and things are just crazy expensive here. Everyone I know has something on the side going.

    Why on earth would I do this? Well, I need a business partner and after 20 years of marriage I think my best bet is my wife. She likes to cook and loves kitchen gadgets. So, given that everything is competitive, this seems like a way to go. Maybe not the way, but a way.

    2nd, these are relatively low tolerance products. +/- .005 is fine 90% of the time. Heck +/- .01 is OK some of the time. You don't have customers Micing a bottle openner.

    3rd, design is important. I have a knack for design. I get 50 design ideas in my head every week. It's easy for me. Something I do well by nature. I also know that if I am successful that I will be ripped off, but I don't care. I'll just keep moving. My angle is to keep changing it up with short run products. If one of them goes hot, I'll license it to someone who does the high volume thing and keep going.

    Ok that's the plan, we'll see how many ways I can screw that up.

    The machine:

    Given all that a three axis CNC machine seemed to be a natural fit. Part of this is about buying some U.S. made stuff so I decided to go with a Bridgeport.

    So on about December 4th, 2003 I found an '82 J head on e-Bay and bought it. This was after visiting it at a more or less local machinery dealer and hour away. I'm convinced I paid too much. $3425.00. 48 inch bed, power feed on X, and a DRO, which I am not using at present. In good shape. Everything works pretty good on it. The power down feed needs some adjusting and there's something goofy in the vari speed, but it runs and is square. Not to bad for a Noobie I suppose.

    It was delivered buy a nice guy named Gabriel. He hoisted it off his truck and rolled it into my Garage where it has been holding down the concreted since.

    BTW - I have a Grizzly G1005 mill drill too. That was my first mill. I learned all about rigidity on that one. I also have a 7 x 12 mini lathe. Again, not too rigid. Turning AL is OK. Bronze starts to get interesting and steel is a real crap shoot anything better than +/- .005. On the Bridgy even I can eek out +/- .001 and I think I'll get better with time. So mass counts for a lot.

    So now for the CNC stuff.

    All the motor calc stuff went right over my head and I just did not have the patience for it then. I may yet be paying for that decision. But I winged it with some Reliance Micro 100 motors I found on e-Bay. 1/3 HP. 100 volts. The 100 V is going to be the issue.

    I then got the Gecko drives and the Campbell / Sound Logic break out board. ( http://www.geckodrive.com/ http://www.campbelldesigns.com/ )

    I have spun these motors succesfully under Mach2 and will go to Mach3 when I get back 'round to that. So I'll be writing about that real time.

    One of the first things I decided to tackle was the electronics cabinet. I found a surplus cabinet at Youngs Surplus. ( http://www.youngssurplus.com/ ) It came with a bunch of relays and stuff in it too. Quite the find. It is big enough to house my mini tower clone PC, the DC power supply the relays, and the Geckos.

    I did a whole DC power supply on my own. That's a whole story in and of it self. More on that later.

    At this point the Bridgy has yet to be turned on. This 2200 pound paper weight was just a nice home to a bunch of electrical components. So how to power it up with my Dryer circuit? Well I did the whole research dance with phase converters, changing out the motor, rigging some crazy jack shaft thing, and the VFD. I bought a Leeson VFD in the end. I've never been happier with a power tool in my life as a result. The VFD not only takes care of the single phase to three phase problem it makes operating the machine a piece of cake. I can't wait to see how cool it can be with Mach2 controlling it.

    Fortunately it powered up and ran good enough. I was afraid of some $1500 repair bill lurking in the J-Head. It was a little noisy, but once I got it greased and oiled it settled down. Before I go full production I need to take a deeper look in there.

    Then I tackled the ball screws. I went with Rockford. I am happy. Rolled screws were fine given the products I want to make. Replacing them was a chore. My Dad helped me. It can be a one person job, but having someone there for safety is important. That table is really heavy.

    We did discover that if the table is supported with some adjustable roller stands that it does not have to be taken all the way off. You can slide it to within about six inches of the end and avoid the whole hoist thing. We did the hoist thing on the first atempt.

    I had purchased a shorter Y-screw to use for the Z-Drive and mistakenly installed that first. Then I ran the nut off the end of that and we had to redo the job and re load the other screw. Photo's of that eventually too. Not as bad as I thought.

    So at that point I had power, computer, motors spinning, and X-Y screws installed. Yay!

    It is now November 2004. Thanksgiving weekend. Now to mount the motors. I'm thinking now that I'll get the project in under a year.

    Then a major set back. My z-Drive design was totally wrong. I was going to bolt this big ol' 1/2" AL plate to the tram bolts and mount everything on there. No go. WAY too much material and WAY too much flex as a result. I also started burning time making the bearing blocks.

    This is when I started to learn about machine work for real. All of the sudden my world became about getting something, anything, within +/- .002. Well, several micrometers and several paper weights later, I can at least make the parts I need to.

    So I am currently redesigning the z-Axis. Well that's all for today. Hopefully I'll get some pics and drawing and such posted here shortly.

    Just added pics of the electrical cabinet and the big z-Drive plate of design number one.
    Attached Thumbnails Attached Thumbnails ElecCab01.jpg   ElecCab02.jpg   Bad Z-Drive Design.jpg  

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