Mounting cylinders on Bridgeport base

[brian257]

I am installing two air cylinders on the knee of my Bridgeport mill to take some of the weight off for my knee motor. I am mounting them on the outside of the knee on each side and they will be in line with the knee lead screw. Each cylinder will have a maximum capacity of about 400 pounds.

The mounting brackets I have at the base of the cylinder are L brackets per the attached picture. I have never looked under a Bridgeport so I don't know how thick the material in that location is. Could be solid or could be hollow with webs in the casting so I don't know if it is O.K. to just bolt these brackets right to the base of the machine or if I need to make a larger steel pad for them to mount to. Lifting the machine and taking a peak under the base is not an option. Any comments?

[derek]

Can't help you with what's under the mill but with my gas spring arrangement on my knee there is so much down force that it does't take much to keep it in place.

Derek

[brian257]

I was not concerned with keeping it in place. I was concerned with mounting it over a potentially too thin section of the casting and cracking the casting.

[derek]

Gotcha. That makes more sense.
Unfortunately I still cant help..
Well actually I may. I have a bridgeport sitting on a pallet that I just picked up. If no one else chimes in I'll lift it up a bit and snap a few pics.
No I won't be laying under it to get the shots

Derek

[derek]

Duplicate

[keebler303]

I have a series 1 CNC machine and the sides of the base casting are about 1/2" thick. In other places farther up it is a similar thickness.

400lbs isn't a whole lot for even 1/4" thick cast iron, and I'm sure it's thicker than that. I would not worry about it. You can drill a mounting hole first, if its too thin, go somewhere else. I'm guessing it's going to be about 1/2" thick no matter where you go. Of course if you hit a web it will be thicker but that's not really important.

Matt