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Value of Bridgeport mill ball screws?an

beeser

Cast Iron
Joined
Jan 3, 2015
Value of Bridgeport mill ball screws?

I would like to replace the precision ground ball screws on my '07 Bridgeport mill with standard ACME type screws. What would be a fair price to ask for them including the bracket? I believe the screws are also chrome hardened based on the Hardinge build sheet.
 
Have you actually used them? IMHO i could never grasp why anyone ever want's to go back to acme, but then mine are std 5mm pitch screws, not something stupidly coarse so no real risk of back feeding.
 
I would like to replace the precision ground ball screws on my '07 Bridgeport mill with standard ACME type screws. What would be a fair price to ask for them including the bracket? I believe the screws are also chrome hardened based on the Hardinge build sheet.

What table length 42" or 48"? I might be interested if for a 48" table, a friend might be interested if for a 42" table.
 
What table length 42" or 48"? I might be interested if for a 48" table, a friend might be interested if for a 42" table.

Sorry, I forgot to mention the table is a 48". The screws are OEM from a Bridgeport EZ Plus made in '07. They are also chrome hardened based on the Hardinge build sheet. And no, I have never used them. The mill came to me partially disassembled and sitting in storage since 2010 so I don't believe it had much use. The overall machine doesn't look like it.
 
^ Again, have you actually tried em and decided no or are you just going of speculation? Acme screws, nuts and bracket are not cheap, far easier to adapt if need be the ball screws to work with any std handle and have the superior backlash free system. Your replacing something thats not broken with something thats far far worse to use with a lot shorter life span. Haveing no lash on a manual mill is a truly lovely thing - problem to have. Std acme screws are not even hardened and have well known wear issues as well as backlash to constantly counteract.
 
^ Again, have you actually tried em and decided no or are you just going of speculation? Acme screws, nuts and bracket are not cheap, far easier to adapt if need be the ball screws to work with any std handle and have the superior backlash free system. Your replacing something thats not broken with something thats far far worse to use with a lot shorter life span. Haveing no lash on a manual mill is a truly lovely thing - problem to have. Std acme screws are not even hardened and have well known wear issues as well as backlash to constantly counteract.

No I haven't tried the screws. They haven't been installed after their refurbishing. After reading a lot about the differences between the two setups it seems the machinist community is split on which is better for strictly manual work. Since I'm new to all of this I thought it might be best to start with what was mainly used in the past. I also understand that if a DRO is used backlash isn't so much an issue. I also don't think wear is an issue since the machine will not be used that much. As for cost I'm guestimating that it will be around $1k for the ACME screws and related fittings.
 
I'd think you'll be in the 2k range
Are you selling the rest of the EZ track system the controller the servos the cabinet Etc
I might be interested in buying the complete system

Ps IMHO the eztrak is a massive upgrade
 
I'd think you'll be in the 2k range
Are you selling the rest of the EZ track system the controller the servos the cabinet Etc
I might be interested in buying the complete system

Ps IMHO the eztrak is a massive upgrade

I don't if it makes a vast difference but the screws and bracket are from a Bridgeport EZ Plus not EZ Track. Hardinge tells me the EZ Plus is the newer system. And no, I don't have the rest of the system. I went ahead and listed the items on eBay at $1200.
 
Have you actually used them? IMHO i could never grasp why anyone ever want's to go back to acme, but then mine are std 5mm pitch screws, not something stupidly coarse so no real risk of back feeding.

I have rolled ball screws on my big Webb mill. They were on there when I got it because the machine was originally set up for CNC.

All that is necessary to avoid back feeding is to use the table locks. The Webb has two of them on the X and one on the Y and it's a simple matter to use them.

My machine is a 1987 and it saw a lot of use before I got it and it's still got zero lash on the Y axis and about .008 on the X so I can't complain.

Acme screws will usually develop some backlash after a while. Of course, they can be adjusted, but I'm sticking with my ball screws.

Webb quoted me over $1,200 for new acme screws with the central holder. That convinced me that I would keep what I have.
 
I have rolled ball screws on my big Webb mill. They were on there when I got it because the machine was originally set up for CNC.

All that is necessary to avoid back feeding is to use the table locks. The Webb has two of them on the X and one on the Y and it's a simple matter to use them.

My machine is a 1987 and it saw a lot of use before I got it and it's still got zero lash on the Y axis and about .008 on the X so I can't complain.

Acme screws will usually develop some backlash after a while. Of course, they can be adjusted, but I'm sticking with my ball screws.

Webb quoted me over $1,200 for new acme screws with the central holder. That convinced me that I would keep what I have.

Now I'm teetering in the opposite direction. What did you do to make up the difference in the screw length once the servos were removed? Did you install power feeds?
 
Now I'm teetering in the opposite direction. What did you do to make up the difference in the screw length once the servos were removed? Did you install power feeds?

The original CNC setup had three servo motors on it. The one on the Z Axis was missing. The other two were in place and used belts and pulleys to drive the X and Y axes. The shaft pulleys were mounted in place of the dial holders and dials. I had to purchase those used on eBay since the BP units use the same size shaft (5/8. IIRC). Once the dial holders were replaced, the X and Y Ball screws were still the correct length.

I noticed that the X ball screw came with a 2" extension section that was screwed onto the end of the shaft. That was left in place and I installed an X axis servo drive over the shaft with no spacing problems.

Frankly, I like the smaller backlash with the ball screws. The issue of possible back feed is easily overcome and, after a while, locking the table before a cut on a manual machine becomes second nature.

That said, backlash is not much of a problem with the standard acme screws if you install a DRO. My friend has a BP with a DRO and it's got a full half turn on both screws. He tells me that some say he will go in and split the nuts and adjust it. LOL.

EDIT: If you decide to change to Acme screws, replacing them with a new feed nut bracket (the part that holds the X and Y nuts) and feed nuts would amount to big money. I'm thinking more than $1,000. H&W is an excellent source to purchase or to just check prices.

Good luck.
 
The other factor that comes into play in favor of keeping the ball screws is a Lyman MK-7 Power Feed was included with the mill. It could also be used with ACME screws but it fits on the Y-axis ball screw without an extension.

I checked prices for all of the ACME screw components needed and it comes up to a little over $800 or $1000 if an OEM bracket is used instead of their standard bracket. I don't know what the difference is other than an additional $200. Decisions decisions.
 
I've never had a ball screw Bridgeport take off on me...and axis push off will happen more with a regular acme screw especially with the table not locked.

This thread is flabbergasting, most everyone wants the ballscrews lol.
 
I've never had a ball screw Bridgeport take off on me...and axis push off will happen more with a regular acme screw especially with the table not locked.

This thread is flabbergasting, most everyone wants the ballscrews lol.

I've really never had a problem with movement of the ball screws even when I don't lock the table. It's a 50" table so it's pretty heavy and I seldom take heavy cuts.

Yeah, ball screws are for the elite among us. LOL.
 
I've really never had a problem with movement of the ball screws even when I don't lock the table. It's a 50" table so it's pretty heavy and I seldom take heavy cuts.

Yeah, ball screws are for the elite among us. LOL.

I've seen it creep a few thou but I was taking a massive peripheral cut in 17-4 with a .500 6 flute like .75 depth and .200 axial engagement...you know, stuff the wack jobs do.

But I can take 2.000 deep lighter cuts and the screen doesn't so much as flicker.
 








 
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