I experimented a bit with trying to do some kind of guided grinding in the past. Yeah, it didn't work. You really need a proper surface grinder. That pig's not going to fly without throwing lots of money and time at it.
In my case, the pieces were 48" long, so there was only one place in town that could do it, and they wanted a huge amount of money.
You can do it by hand though. As long as you're "handy" with an angle grinder and high grit sandpaper flap disks. Lol. Get it, by hand, and handy, I crack myself up.
I'd actually like to get myself some good hand scraping tools to complement this technique. Don't laugh, it actually works, but requires oh, so much patience.
Is this your latest design?
If you stich weld some steel flat bar onto the columns, the rails can mount to the flatbar, and you only have to worry about making the flatbar flat. I used 1.5 x 0.5 flatbar for 25mm rails.
I'm guessing that you will be adding feet to the bases of the columns to bolt them to the base and that the columns will be welded together.
We certainly do put alot of effort into our projects. I know I'm certainly not very efficient at this, or in making decisions when it comes to my own personal projects.
I came across this the other day:
https://www.kijiji.ca/v-other-busine...ect/1483778127
but I have no space for it!