Bridgeport 49" Table Slide Length?

[architect]

So I have a 49" table on the mill with an existing 36" slide that I calculated to provide 33" travel. I had followed this dimension in ordering my slides as it aligns with on various sources that this table is 33" travel with a power feed and 36" without. Now that I think more about this, perhaps I should have gotten a 36" travel slide. There seems to be a these random "bolts" attached to the table (circled) and not sure what they are for. If I can remove them, then I think a longer slide may fit. I would measure the actual full travel but some temporary shelves are in the way and no time/space to move the stuff out for now.

Not the end of the world or anything, but if I have a chance to potential fix it...

So now I'm thinking of ordering a second dro for the lathe, maybe I'll get a 36" travel slide and swap it onto the mill and put the 33" one onto the lathe.

Thoughts?

@Brent H @Susquatch

 

[Stuart Samuel]

View attachment 55429

So I have a 49" table on the mill with an existing 36" slide that I calculated to provide 33" travel. I had followed this dimension in ordering my slides as it aligns with on various sources that this table is 33" travel with a power feed and 36" without. Now that I think more about this, perhaps I should have gotten a 36" travel slide. There seems to be a these random "bolts" attached to the table (circled) and not sure what they are for. If I can remove them, then I think a longer slide may fit. I would measure the actual full travel but some temporary shelves are in the way and no time/space to move the stuff out for now.

Not the end of the world or anything, but if I have a chance to potential fix it...

So now I'm thinking of ordering a second dro for the lathe, maybe I'll get a 36" travel slide and swap it onto the mill and put the 33" one onto the lathe.

Thoughts?

@Brent H @Susquatch

I'm not a real machinist, just play one on TV, but... before we installed a DRO on our mill at work, we used those bolts as stops, for repeat parts. There's a fixed stop/pin at the centre of the machine they run into. With the DRO installed, they're kind of vestigial.

The physical travel limit on Bridgeport style mills is the large ball side of the handles running into the lower casting. It's a bit of a pain to run it out that far, as the cantilevered weight causes more and more resistance (I'm sure you'd get enough distortion from the bed hanging way out there to be an issue with some parts).

 

[architect]

I'm not a real machinist, just play one on TV, but... before we installed a DRO on our mill at work, we used those bolts as stops, for repeat parts. There's a fixed stop/pin at the centre of the machine they run into. With the DRO installed, they're kind of vestigial.

The physical travel limit on Bridgeport style mills is the large ball side of the handles running into the lower casting. It's a bit of a pain to run it out that far, as the cantilevered weight causes more and more resistance (I'm sure you'd get enough distortion from the bed hanging way out there to be an issue with some parts).

Would not have guessed the physical limit is at the handle. I have enough room to slide the table left but stops where the right edge of slide lines up with the reader. Now I wonder what's stopping it because those stop/pins are still further along.

I doubt I would run anything that long as an amateur, but was just thinking of maximizing the slide as a "do it once" thing.

Perhaps swapping the 33" with a 36" with the lathe makes sense...

 

[Susquatch]

Thoughts?

My mill came with a half dozen stops I could use for whatever - eg repeat stops. You can buy extras at places like H&W Machine Repair.
I
My mill/drill also has them, but they are used to trigger the power feed stop mechanism.

I think your idea to get a longer one to swap with your lathe is a good one. I should have done more of that when I got mine. As it turned out, my quill scale was too short so I swapped it with my lathe compound scale.

Long is good.

It's a bit of a pain to run it out that far, as the cantilevered weight causes more and more resistance (I'm sure you'd get enough distortion from the bed hanging way out there to be an issue with some parts).

I think the issue here isn't the table weight. Usually, the leade screw gets worn the most in the middle where it is used the most. As the mill ages, and you tighten the nut to reduce backlash, it gets tight at the two unused ends. It's always a compromise to remove backlash without making the ends so tight that they become unusable. Try loosening your nut to see if the table slides easier at the ends.

I suppose, oil that has hardened could also cause problems.

FWIW, my table travel is limited by the handle casting too.

 

[architect]

At a quick glance, I can't tell where the stopping mechanism is but something is there to stop the power feed from hitting the saddle which makes sense. I measured from the ball handle on the other end and it's exactly 33" from the saddle. I guess that's why it's 33" travel... I guess good to have a longer scale still in case I remove the power feed for whatever reason.

The glass scale that's on it would be blocking mounting points for the stops so that also had me worried about going longer than what's already there. But I guess thinner magnetic solves this.

 

[Stuart Samuel]

My mill came with a half dozen stops I could use for whatever - eg repeat stops. You can buy extras at places like H&W Machine Repair.
I
My mill/drill also has them, but they are used to trigger the power feed stop mechanism.

I think your idea to get a longer one to swap with your lathe is a good one. I should have done more of that when I got mine. As it turned out, my quill scale was too short so I swapped it with my lathe compound scale.

Long is good.




I think the issue here isn't the table weight. Usually, the leade screw gets worn the most in the middle where it is used the most. As the mill ages, and you tighten the nut to reduce backlash, it gets tight at the two unused ends. It's always a compromise to remove backlash without making the ends so tight that they become unusable. Try loosening your nut to see if the table slides easier at the ends.

I suppose, oil that has hardened could also cause problems.

FWIW, my table travel is limited by the handle casting too.

I’m pretty confident weight is a factor. There’s more resistance cranking if the vise is on the end cantilevered out.

I’m actually not sure the nut on our older mill has ever been tightened.

 

[Brent H]

There ya go @architect :

For my table (42”) I am using a 900 mm scale (35”) with the reader it is about 40” total length. It is secured on the back of the table (just below the table coolant drain holes) and the reader is mounted at the centre point of the scale to the base.

You have a 48” table so you can rock an 1150 mm (overall dimension scale) probably a 1000 mm scale with 140 mm for the reader (1140 overall).

My other scales are

For the vertical knee and

For the Y axis.