Keith Davis published a new build:

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I think you would probably experience failure with using linear bearings in place of rotational bearings if the bearing was was being used to position the linear rod. In this usage the rod's position is defined by regular bearings at both ends and the linear bearings "allow" rotation while carrying the weight of the center rods and extruder. I actually use 45mm long bearings (although the drawing shows only 25mm ones) that have the ball rows in a spiral instead of straight lines.

 

I used Sketchup Make. That dual hot end is a Chimera. Google it by that name.

 

I saw this on a high end printer a couple if weeks ago. At the time I didn't think too much about it so I don't remember which one it was. I don't have any 3mm ID so I hooked up a 50mm blower fan to a 2mm ID tube yesterday and it delivered a pretty strong jet stream.

I saw it when I was searching for clues as to why some desktop printers sell for $2500 while most others are 2 grand less. I have a customer (TrueUp LZ) who's company is looking to buy a dozen Ultimakers, so...... Of course Ultimaker's obvious secret sauce is their incredibly light X & Y system. But, Eric at Ultimaker pioneered the use of a bowden filament feed and there's a secret there too. It uses a 50 in/oz motor, but it's geared 3:1 so it delivers an incredible 150 in/oz power.

Ahhh... found some 4mm ID 6mm OD PTFE tubing. Easy adaptation. Thanks Steve, I'll try it too.

 

Only because the "client" wants a 8" x 8" x 18" build area. LM8LUU (45mm long). I've had really good luck with this guy, the rod ends are polished to prevent damage to the bearing balls when putting them on. 2 x 8mm 15" Hardened Shafts with 2 LM8LUU Rod Rail Long Linear Bearing Motion | eBay