I welded together a mobile base for a Bridgeport mill. (the casters are removable so that for stationary operation, they are not interfering and the casters do not get flat spots).
Most steel stock used came from a great Memorial Day garbage find.
Here are the notes:
Pictured here is a homemade base for a Bridgeport mill that runs on casters. Design Objectives
- A failure of the base should not make the mill fall (hence it needed small floor clearance) * The bars with casters should be removable so as not to take valuable floor space and not to be a tripping hazard * During operation, the mill would stand on 2x4s beneath the base, with casters removed * Bars with Casters should be easy to mount again if the mill needs to be moved.
Some notes
The base is made from 1/4" flat stock (1/4" by 5" steel bar) and 1/4" angle iron. The bars holding casters are 3/16" thick 1.25" steel square tubing.
The casters are something to behold, these are NOT the usual Harbor Freight "heavy duty" casters. I bought them on eBay for $40, Here's the auction screenshot. They are rated for 2,400 lbs each, all swivel, and are made from very heavy plate. (1/2" and 3/8")
The welded-on a T-nut with a bolt in it (seen in front) was attached to provide attachment point for an eyebolt in case if the mill needs to be pulled. It is threaded for 1/2"-13 NC. The bolt is there just to show it better, it will be replaced with an eyebolt.
Enjoy the video of this base being gently kicked.
The internal dimensions of the base are 1/2" more than the dimensions of the bridgeport base.
Credits -- the PDF file showing Bridgeport mill base dimensions was created by Richard Kinch (see his shop). As a thank you, here's an SEO friendly organic link to his site: TeX for Windows.
Todo list: remove diagonal bar (tacked there for rigidity while setting up the frame), wire brush and paint the frame, drill 3/4" holes in the bottom of the frame for bolting the mill to the base.
(Click on the thumbnail images to enlarge)
PDF Document: Bridgeport-Mill-Dimensions-By-Richard-Kinch.pdf