retrofit bridgeport cnc

[supahonkey]

I have an old bridgeport mill that I just finished restoring. I was toying with the possiblity of doing a cnc retrofit. A quick google search brought me to cnczone. I have no experience with CNC retrofitting of bridgeport mills. Can anyone offer any suggestions/links? Thank you.

Brenton

[mxtras]

Read, read, read. Lots of good stuff in cnczone.

I am in the middle of a BP retrofit myself - the write-up is in the Bridgeport forum...as are a few others. There are links all over the place - you gotta do a little digging, but you will likely find everything you need to know in life right here at cnczone...well - about Bridgeports and CNC, anyway.

Scott

[jdelaney44]

At the risk of blatant self promotion try my thread at

JDs BP J-Head CNC Conversion Blog

I'm maybe half done.....................

-jd

[mxtras]

At the risk of blatant self promotion try my thread at

JDs BP J-Head CNC Conversion Blog

I'm maybe half done.....................

-jd

Yours is one of the better threads, jd.

Scott

[supahonkey]

Hey guys. Thanks for the replies. I still am very new to this whole BP CNC retrofit thing, so I'll just keep reading. So far, it seems that my main problem is that most of the writeups are written for someone who already knows a bit about CNC stuff... no problem, I'm sure that will come with time and research on my behalf. Thanks!

[ViperTX]

Supa...check our Home Shop Machinist....there was a Bridgeport Boss conversion...oops just noticed that you're rebuilding an old Bridgeport....since you're rebuilding....you might as well use ballscrews...you'll want them for your CNC stuff.

[supahonkey]

Thanks. I was talking to two guys who specialize in resurfacing precision surfaces, and they told me that I could easily get away with using Hot roll ball screws rather than ground ball screws, they told me that you save a lot more money, and a hot roll ball screw can still hold .001" tolerance. What is this Bridgeport Boss that people keep talking about? How good of a candidate is an old Bridgeport series 1 mill for a retrofit? Last night, as I was thinking about all of the possibilities with a CNC, I started thinking about possibly attaching my hypertherm 1000 plasma cutter torch to an arm, which bolts to the table of the mill. I could program the mill to cut out the desired shape, while the table moves the plasma torch. Has anyone done this before? If it would work that would be another reason why this whole CNC retrofit is worth it. Anyway, thanks.

[Hood]

Dont worry about not knowing the first thing about CNC I was in exactly the same boat as you about 8 months ago. I have now almost finished my conversion and its amazing.
First thing I would suggest you do is download a trial version of the software you plan to use, and you will be able to pretend machine and get the hang of it. I tried a few but thought Mach2/3 was the best for me, the trial version is fully functioning and the only restriction is its limited to 1000 lines of code, and support from Art and the guys is amazing, and the full version is only $150
I made a big mistake of buying drives off a guy on eBay, took about 4months to actually get them, couldnt get the motors running at all with them, eventually got them working but the fastest they would turn is 78 rpm, I now have Geckos and 700RPM
Keep a look out eBay for things like Ballscrews. If you have the means to adapt them to fit it works out very cheap. Also a VFD for the motor will be a big help, I have 3 phase power but the VFD allows me to change speed at the turn of a Pot and eventually I hope to control with the PC.
I got 916oz/in motors for the X and Y and they are powerfull enough, have a 2:1 reduction. I got a 260 oz/in motor for the Z but was worried it wouldnt be good enough but now I have it completed my fears were unfounded, it works great, I have a 3:1 reduction on it.
Have fun
Hood

[supahonkey]

Thanks for the reply. I was hoping that I would be able to create my drawings in Autodesk Inventor and Autocad 2006. I would save them as a dxf file, but it gets kind of blury after that. I know that I need a program that will tell the machine what to do. Does mach 2/3 do this? Can I import cad drawings into Mach 2/3?
What does VFD stand for... variable feed something? I have 3 phase at my shop also. What do you mean by having the means to adapt ball screws? My grandpa owns a very large Tool and Die shop, so I will probably be able to make/modify things easily. I have noticed how many people are making their own parts for their CNC retrofit. Obviously this is much cheaper, but are there kits out there where everything is ready to be bolted on? I probably wouldn't go with that, but I'd just like to get a price.

Lastly, what is everyone doing to control the speed of the tool? I don't have the variable speed control on the head of the mill, so I have to move the belts around to change speeds. Is there any solution to this, or is this just how it is? Thanks.

[Hood]

Mach 2 is the control program, but its much more as well. The guys on the Yahoo community have written wizards for yer basic stuff like surfacing, key ways, pockets etc etc All you do is enter dimensions and the wizzard produces the code. Also one of the guys has a sort of conversational program that walks through all the wizards and you end up with a complex parts code, he sells it for $50. Mach imports from DXF, HPGL, BMP and JPG, but I have never used that so cant comment on how it works.
VFD is Variable Frequency Drive and its used to alter the frequency to your motor and thus you can control the speed from zero to probably double your motors speed, its great as it means no more belt changes and you always have the right speed for your job.
Yes if you have access to a machine shop then you will be able to utelise ball screws off eBay. I had to do various things including turning ends for the ballscrews, machining sleeves so they fitted the yolk, but its all part of the fun.

Hood