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Author Topic: Need help/advice  (Read 1557 times)

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Offline Iawa

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Re: Need help/advice
« Reply #10 on: November 17, 2017, 03:17:59 PM »
Hi again,

Quick (hopefully easy) question;

How much am i looking at price-wise for a ball screw conversion for a bridgeport series 2 mill, and should i be sitting down before i'm given a rough estimate?
Im asking now because i've had to keep everything at a tight budget so far while i've been starting up and (knock on wood) my mill has been somewhat accurate considering its conventional with some years on the clocks (Mach3's backlash setting is a great addition) but i want to eliminate most, if not all the backlash and i've been told that ball screws are the way to go since they have a longer lifespan for wear and whatnot.
Again, thanks for your time and patience,

Alex
Re: Need help/advice
« Reply #11 on: November 17, 2017, 03:35:34 PM »
Hi,
ballcrews are the right solution for backlash. Components for Bridgeports are readily available but they will cost many hundreds if not thousands of dollars
if you buy components specifically intended for Bridgeports.

You can buy cheaper secondhand off Ebay but will have to modify/machine to have them fit your machine. If you have a good lathe and the confidence to use it
it can be done.

Be aware of the difference between ROLLED ballscrews and GROUND ballscrews. Rolled screws a cheap and pretty damn good, say $200 for a largish one, the same size
but ground try $2000 or more....very very good but really expensive.

Craig
My wife left with my best friend...
     and I miss him!

Offline Iawa

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Re: Need help/advice
« Reply #12 on: November 17, 2017, 03:54:09 PM »
Hi,

Thanks for the quick response Craig,
Sadly the lathe i use isn't the best, i couldn't trust myself to turn something of that importance or price on it.
i think a rolled ballscrew is my best option

Many thanks,

Alex
Re: Need help/advice
« Reply #13 on: November 17, 2017, 04:05:22 PM »
Hi,
the only Bridgeport I've really had anything to do with is an Indian made copy of a series 1 I think. Its got a lot of backlash too, the yoke is badly worn.

The yoke is a big lump of brass with two machined ACME threads at right angles to each other for the X and Y lead screws. Its expensive to buy, really hard to
get at an replace. The separation between the axis screws is not that much greater than the diameter of the screws. To make a yoke with ball nuts (with their
much larger diameter) and so retain the existing screw locations is a challenge.

A conversion kit is despite the cost likely the best way to proceed.

A rolled screw will lose you considerable accuracy.

If you can't afford ground screws you might be better off buying another yoke and repairing what you have got. Even worn OEM lead screws are probably better
than rolled screws.

BoschRexroth do a line of ballscrews where they are rolled but subsequently ground. Still not the accuracy of C5 or better ground screws but better than C7 rolled
screws at an intermediate price.

Craig
My wife left with my best friend...
     and I miss him!