Inner radius of hardtube bends

I'm doing some loop planning, and in order to make everything look its best, I need to take tubing into account. I've searched a lot on the world wide web, but I can't seem to find any information.

I'm going to be using 12/10 tubing. What's the smallest/tightest bend I can make without the tube collapsing on itself?

 

probably 4-5 cm

 

The tightest bend will only be possible with fittings, otherwise as above. I reckon you can get it a little tighter, but I’m not experienced with it.

 

IIRC 2x the diameter of the tube is realisitcally as tight as you can bend most tubing without having to use mandrels or the like...

 

Thanks a lot for the answers. I might have to look into buying some L-connectors then

 

I 3D printed some mandrels to get a 16mm centerline radius out of 12mm acrylic tube because I need some ungodly tight bends but don't have the space to use 90 degree fittings. That makes the inner radius 10mm. I need to make a few tweaks to the design but it works for the most part.

To get that tight though you need the bending cord inside to be very flexible. Originally I used 9.5mm diameter nitrile cord but in itself it doesn't bend tightly enough, so I swapped to some silicone fuel hose with (I think) a 3mm wall. That bends tightly.