[myinisjap]

the picture was done extremely fast sorry but i was wondeing what you guys think of the general design the red is a structural I beam and the blue are the bearings
please let me know of any suggestions and or comments

[Zumba]

It won't work... not well, at least. Hot-rolled I-beams are not flat, straight, nor dimensionally consistent enough to be suitable for linear motion rails. Also, the edges are rounded and the undersides are sloped.

If you insist on homemade rails, it's hard to beat cold rolled round bar stock (1018). It's cheap, fairly accurate, and very forgiving to bearing block inaccuracies. It also machines easily for mounting.

[svenakela]

You could do that design if you find someone that sells "pregrinded" fixture steel plates and then assemble the H-profile by yourself with screws. Try to make it as tight as possible though, to avoid flexing.

Regards,
Sven


PS. It's not new, by the way. It's already done.

[myinisjap]

well the reason I was wanting to use an I beam is because they are easily obtainable for me and they are very easy to secure down and the other is they are extremely strong
I think the main reason i do not want to use a pipe or rod as the rail is because i dont like the idea of using anle iron as the carriage

i have seen some other designs but they seem a little too involved for me (the involved casting aluminum and right now i dont have the setup to do so

[svenakela]

well the reason I was wanting to use an I beam is because they are easily obtainable for me and they are very easy to secure down and the other is they are extremely strong
I think the main reason i do not want to use a pipe or rod as the rail is because i dont like the idea of using anle iron as the carriage

i have seen some other designs but they seem a little too involved for me (the involved casting aluminum and right now i dont have the setup to do so

You don't need casting or angle irons or rods, you just need parallel surfaces. As I said, you can do it with grinded steel plates that are assembled together. I-beams are not straight and parallel enough though (as stated by Zumba). As long as you don't have the possibility to at least mill the bearing surfaces, find something else.


Regards,
Sven

[Zumba]

I think the main reason i do not want to use a pipe or rod as the rail is because i dont like the idea of using anle iron as the carriage.

Don't. Use solid 1018 bar stock.

[Jason Marsha]

I tried that design already and unless you find the perfect beam its a real pain.
As stated in the other posts the sides are not flat and the beam generally has imperfections.

Jason