How Expensive Is A Sloppy Table On A Mill???

[B.R. McCall]

If you're truly interested find out the cost of replacing the lead screws and nuts this company specializes in rebuilding and selling parts for Bridgeport's, and Bridgeport clones.
http://www.machinerypartsdepot.com/

As a side note a new Bridgeport comes from the factory with specifications that there should be no more than .007" back lash n the X axis and .005" in the Y axis. My machine was originally purchased new in 1972 by a local high school for $1,675.00. The price included a 6" Bridgeport swivel base vise, an auto lube system, a power feed on the X axis, and a set of R8 collets. Mine is the J2J model with a 1.5 hp motor and variable speed head. It was used in their shop classes from 1972 to 1990. It was retired until I purchased it in 2000.

You may be able to bring down the play depending on the style of lead screw nuts used in the machine. The earlier models used a single "split nut". This nut is roughly 6" long and cut half way through in the center. If it has this style nut you can remove it, finish cutting it in half and reinstall it. By using the adjusting screw you may be able to bring down the backlash considerably. If it doesn't have this style nut you'll have to replace at least the 2 nuts in each axis. New nuts can be purchased for about $35.00 per pair. The downside is that you may also have to replace both lead screws. Each screw costs in the neighborhood of $350.00.

I was able to reduce the backlash on my 1972 series I machine from .060" on the X axis to .007 by removing and splitting the original nut. That was 15 years ago and in all that time the backlash is still below .015".

In all likelihood the power feed motor burned out long ago. There are several manufacturers that make quality replacements for less than $300.00. My mill was originally equipped with an F style feed motor on the X axis. I simply made a shaft extension and reinstalled the original bearing and crank handle. Since I didn't replace the lead screw it has about 2" less travel in the X axis the normal 9" x 42" manual machine.

The DRO is another story. You didn't mention the brand, but most older versions are either no longer repairable, or cost more to repair than they are worth. You can buy new ones for $300.000 to $3,000.00 depending on the brand and model. If you're truly interested in this machine I wouldn't pay more than $1,000.00 for it. You'll be putting several hundred dollars into it just to bring it back to operating condition. Tooling will be another big expense. A vise will cost $200.00 to$300.00, and end mills will run anywhere from $3.00 each to $50.00 each depending on size style and construction.

Over time tooling will be your biggest investment. In the long run you'll spend at least double the cost of the mill to get the tooling necessary to complete most jobs.

Thank you, thank you, thank you!!!!

I appreciate every one who took the time to respond, telling me to move on, but this is the information I was really looking for! Your very detailed explanation is what I need as a noob, and your examples of the amount of work and price for each problem was what I was wanting so I had the information to make an informed decision. Again, thank you.

Bryant

 

[B.R. McCall]

That table should not move at all by tugging on it, unless it has missing parts (gibs) or is totally trashed, as others have pointed out.

Not familiar with that brand, but factory parts might not be readily available and Bridgeport parts may not be "drop-in" compatible.

For reference, I paid $900 for a 1967 Bridgeport series 1 J-head that had almost nothing wrong with it. The few parts I needed for the auto down-feed were readily available numerous places.

Pass on this one and widen your search.

Thanks for the info.
I wish there were machines to be had around central Florida (or anywhere in Florida) for those kind of prices!
A heavy duty bench or full size knee mill start about $2500 if they don't need "much" work.
Add about a grand to that starting price if it is one of the big names.
This is not from just a quick glance at Craigs List, but keeping an eye out over the couple of years.

I have been very, very closer to buying a mini mill several times in those last couple of years, but I keep thinking, even though it will do what i want now, I have not doubt that once I get a pile of chips on the floor, my project list will grow to bigger and bigger things. And all the money spent on tooling, that (as far as I can tell) will be of little or maybe no use on a larger machine would be wasted, as would the price of a mini mill.
So I keep testing my patience and waiting on that "deal of a lifetime".... problem is, I think it may take a lifetime to find it in Florida!