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Bridgeport Base Hole Size

mrplasma

Aluminum
Joined
Sep 25, 2020
The Bridgeport manual I have says that the base holes are 5/8" diameter. My newly purchased Series I, 1 hp mill has 5/8" holes in the front and 9/16" holes in the rear.

I'm just curious as to whether this is unusual, or if there is a lot of variation in Bridgeport base hole sizes.

base holes front.jpg base holes rear.jpg
 
The Bridgeport manual I have says that the base holes are 5/8" diameter. My newly purchased Series I, 1 hp mill has 5/8" holes in the front and 9/16" holes in the rear.

I'm just curious as to whether this is unusual, or if there is a lot of variation in Bridgeport base hole sizes.
I think there is some variation though not sure if it's factory variation or people modifying them after the fact. Mine are tapped at 3/4x10 with leveling jack screws.
 
In the old days they used those holes to lag it to the shipping skid. In later machines and other copies started to use them for leveling. I used to tap the holes too, or drilled to a tap size and tapped them about half the time. Many could carless if they are leveled. I use to on mine as I like using a level when setting up parts in the vise. Quicker to get it close before indicating it.
 
The front two holes run through about an inch and a half of solid cast iron before reaching the cavity below. The two rear holes have about a half inch of cast iron before opening up. No bondo or other filler.

I'm going to locate two lengths of 5" x 2" x 1/4" wall rectangular tubing across under the front holes and rear holes. I plan to use retractable adjustable casters in each corner.

IMG_9060(2).jpg
 
Many could carless if they are leveled.

We make leveling feet bars and go through them like hot cakes. I know there are a few different bases for Series 1's (Man, JR would have jumped all over me for that one) but to my knowledge, the spacing and hole sizes were all the same. I will get to the graveyard later and check them out.

Jon
 
We make leveling feet bars and go through them like hot cakes.

I've seen that setup you have, looks quite good. I'm curious if you've ever considered using something like the Footmaster casters with it? I keep toying with a setup like that, or just a pallet jack for occasional mobility.

ETA: After I posted this, I realized the appropriate sized Footmaster casters would raise the mill up a good 6" or so, which wouldn't be great for a number of reasons. Would need one of the more complicated bracketed examples I've seen for this to work.
 
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