Mill build ?

[teamcowboyup]

Been tinkering with the idea of building a mill for sometime and well the itch is bad now. At work I have industrial chrome bars 1 3/4 round and 2 1/2 round I can take home. I was wondering for my up rights, can I use the 1 3/4 round, and the 2 1/2 over the 1 3/4 to attach the carriage?  The 2 1/2 sliding over 1 3/4 had maybe .002 of play. And also if I did the same for the band wheels.  The tensil on the chrome stock is 110,000 lbs so I think it would hold. Just wanted to get an opinion. 

[Den-Den]

Such a nice resource should not be wasted.  If you build a 4 post frame with two of the posts being 1-3/4" round, the snug fit of the larger tube should slide up and down nicely.  Note that getting the 1-3/4" posts parallel will be critical.  I would have to build in some adjustment if I was doing it, the adjustment could be welded up once tuned in.

Using the same material for tension adjustment should also work if the tubes are on both sides of the wheels, that would put the tubes in compression with no bending load.

[Kbeitz]

You could use linear bearings if the chrome plating isn't to thick to let the bearing
slide on.

[Crusarius]

That sounds pretty sweet. I'm in for the ride. My plan was square box with HDPE guides and clamps.

[teamcowboyup]

To help keep the posts parallel I will make the top cross bar a turn buckle deal. As far as the tube for the slide I found brass bushings that are made specifically for 1 3/4 piston inside of a 2 7/8 housing.  Basically I'm going to take a 6 inch piece of the 2 7/8 put the brass bushings in and use set screws to hold them and then put seals on either end and a grease fitting. Now I just gotta figur out how to make a spring tension system but my brain turned off.

[Crusarius]

Garage door springs and a pulley? Mount the springs to the track side then run cable up post over pulley and to end of spring. not sure About lengths.

[JRWoodchuck]

I would make them longer than 6". You get binding for and aft if they are that short. The longer the better for up and down movement.

To help keep the posts parallel I will make the top cross bar a turn buckle deal. As far as the tube for the slide I found brass bushings that are made specifically for 1 3/4 piston inside of a 2 7/8 housing.  Basically I'm going to take a 6 inch piece of the 2 7/8 put the brass bushings in and use set screws to hold them and then put seals on either end and a grease fitting. Now I just gotta figur out how to make a spring tension system but my brain turned off.