caprail vs. MM steel rail ? Pro's and Con's
 

Robert,
I for one, actually made a mock-up of the cap rail and alum angle prior to deciding to use the MM rail system. I like both options for the right reasons. The next machine I build, and it will be soon, will be of the alum rail section for proof-of-concept. Plus, I like a challenge :)

Caprail:
Pro's
- easy to buy - but cost's more than just steel
- easy to drill
- alum ARCHITECTURAL angle easy to cut down to right height - but is an upcharge for alum
- alum ARCHITECTURAL angle has nice geometric shoulder for cap rail to register to with minimum inside fillet to deal with.
- saves oodles of time grinding and cutting down steel.
Con's
- assembled rail is still flexible in x and y direction like steel and requires you to mount it to the main C channel frame for rigidity.

Steel MM option:
Pro's
- steel angle iron easily and readily available
- fairly easy to cut down to required height, but takes time.
- fairly easy to grind profile, but takes time
- skate method is VERY EASY to use and is now included in the laser cut steel package. A luxury I didn't have, but love knowing it's available now. *thanks to JR, Greg, Gerald for helping me work out the kinks*
- many machines on this great planet use it and is a tried and proven method.
Con's
- assembled rail is still flexible in x and y direction like steel and requires you to mount it to the main C channel frame for rigidity.

If you notice, both rail sections require the machine frame to dictate the rigidity of the rail profile....not it's metallurgy. Good design, many choices.

Good luck - choose wisely.

I copied the rail discussion to another place and replied there.