[53w]

I have 2 Bridgeport milling machines, one is a j head step pully the other is an variable speed head. Both are 9x42" machines and recently been scraped in with DRO's.
I want to do it myself and make the adaptor plates and other simple stuff. Where do I get a accurate ball screw kit at a good price? I want it to be ran off of a labtop computer and software. I am looking at both 3 axis or 2 axis and maybe capable of running and 4th axis indexer head. What are my options with these machines?
Darrel

[jeff parsons]

retrofitting a machine with cnc controls gets pricey. you're almost better off selling one of those, and putting the money towards a used cnc. if youre dead set on converting one of those, check out what retrofit packages Centroid has.

[mactec54]

53W

Hiwin sell a nice Ballscrew package for the Bridgeport, Rockford also have a Ballscrew package for your machine, make sure that they are a least a C5 grade Ballscrew



jeff parsons
You don't need to spend that kind of money for a Centroid package, Mach3 control does a good job on these machines, with Dmm ac servo's motors/ drives

[53w]

what are the differences from kit to kit? I see some new china made "2 axis kits" on ebay that are stepper motors and drives/control box and soft ware. but you need to build and find every thing else? like pulleys, ball screws, belts, brackets, ect.

[jeff parsons]

yes, some kits include everything you need, others are just the controls. many are generic kits that require you to make the adapting brackets, while others are made for specific machines. make sure you are getting what you expect. if you are going for quality, dont get a kit with stepper motors. you want to use good quality servo motors, otherwise you either wont get the accuracy you need, or you'll be burning out and replacing crappy chinese motors regularly. make sure you price everything out before you jump at this. with having to get ball screws, motors, controls, a cad/cam program to write programs if you dont have one, etc... you can easily drop 10k into converting one of these thing. it often is better money spent to find a used machine thats already converted, or an older machining center with an automatic tool changer.

[metal mite]

I would start with the hiwin ball screws.the have kits for the Bridgeport. I have converted mine and it is a lot of work.

[metal mite]

I looked at what I spent ,about 5 thou for a 3 axis conversion . I built all the x y and z housings ordered the htd gears and belts. Bought the electronics ps ,controller and servos for $2700.00 The good part is that you won't have to pay a 3 thou fee for a board that burns out . I would do it again . Also you have another bpt ,where can make the parts.

[mactec54]

53W

I found this for Ballscrews sets I did not see what grade they are, but the prices are quite good, You want C5 grade if you are serious about how good you want your machine

I just found the accuracy for these screws, these are not what you want, they are around a C7/C10 grade

accuracy of +/-.003" per foot

[mactec54]

53W

Here is one that looks as good as the Hiwin Ballscrews in terms of accuracy, the ballscrews may be Hiwin

CNC XY Ball Screws

[krutch]

I may be talking out my other end on this, but I don't think a laptop will control a mill. If what I once heard is true, there is not enough computer "guts" to power the mill path. That is said in my words not the technical terms I heard it in.

That said, go for it. But make sure you have control of the quill. I have a SMX-3 Trak retro fit and the Z axis is not a true 3rd axis. I may have been mistaken in thinking it was when I purchased the package. I have to work around the fact that the Z is not completely controlled.

[krutch]

To avoid confusion, I must say.
The Z on my SMX-3 is controlled but it seems to have issues with changing from Z+ to Z- and keeping its' location completely "known". Some of my problem may be tool pressure, but milling a concave or convex in the Z plane is a guess instead of a known result. I can mill a Z down move (as in a ramp), but a Z up mill won't come out as I program it.
This is on a knee mill and is a retro fit on other than a Trak milling machine. So I am not trying to "down talk" the Trak products.
I don't have control the Z by G-code and so can't rely on it doing exactly as I want it to. If I were to buy another CNC mill it would be one with better Z control system.

[BOSS5]

I'd sell one one the 2 machines (probably the step head) and buy a stepper motor driven Bridgeport BOSS (version 6.X or lower) to replace it with. Essentially the factory Bridgeport BOSS will have all the hardware (ball screws / motors / belt enclosures / limit switches) for 3 axis. Worst case is you junk all the old controls and use a breakout board, new stepper drivers, Mach3 or similar software, and a new power supply to get you up and running as a CNC with "modern controls". The spindle motor will be 3 phase, if that is a problem, power it via a VFD from single phase. Laptop is no problem, just use smoothstepper adaptor / breakout board on USB port. Reason: Your total investment will be lower than any other approach, less time spent building pieces and the factory hardware is simply second to none.