round rails

[martin54]

Sorry hope I'm not hijacking this thread but I was looking for some info on rails & wasn't sure where to look being new to all this. Is there some sort of guide as to what diameter rail should be used when looking to build a machine. Realise there are probably a lot of factors to take in to account but just a very general guide that maybe gives some sort of idea what size rail to use for different length or width tables.

[JAZZCNC]

Sorry hope I'm not hijacking this thread but I was looking for some info on rails & wasn't sure where to look being new to all this. Is there some sort of guide as to what diameter rail should be used when looking to build a machine. Realise there are probably a lot of factors to take in to account but just a very general guide that maybe gives some sort of idea what size rail to use for different length or width tables.

Think Jonathan posted a long head aching thread some where on round rails.? Do a search if you want your brain numbing.!!

Really thou it's not rocket science and it will ultimately boil down to a few factors like Budget and machine size/use. Here's a quick run down for typical DIY use.
Stay away from unsupported round rails unless short lengths =<400mm and even then 20mm or more.

My rule of thumb with Supported round rail is 16mm for small light duty machines =< 600mm. 20mm =< 1500mm 25mm => 1500mm
If Profiled linear rail then it's a completely different and 15mm will be more than most DIY users need in terms of load capacity's but maybe not physical size so 20mm tends to get used often has the bearings sizes etc suit better. It also tends to be more common second hand has it's common size in industry.

hope this helps.