More on 80/20

July 18th, 2008 Comments Off on More on 80/20

Fabr is built using the 80/20 T-Slot fractional building system. ‘New Stock’ items were purchased from the 80/20 Garage Sale on eBay. The service was excellent. Just make sure when you purchase that you wait for the invoice as they combine shipping.

The Fabr frame is a 1″ profile ‘1010’, 12 total, each 14″ in length. I paid $2.75 each, for a total of $33.

I used 8 three-way nylon connectors to complete the cube – each was $2.85, for a total of $22.80.

(Similar to these 2-way connectors; couldn’t find a 3 way image at the time of writing)

$60 or so is very reasonable for the superstructure of the printer. I’d certainly use this system again.

The ‘linear bearings’ are ‘h’ shaped extrusions with a sandwich 3 ultra-high molecular weight shims between it and the t-slot extrusion.

I assumed that these bearings would glide smoothly over the t-slot. After assembly, I discovered that the bearings were very tight which required more than an acceptable amount of force to overcome the friction.

Disappointment set in. 

I attempted some minor changes to the bearing pads in order to reduce the size. Sanding nor scraping were successful (too much fuzz was generated causing more friction). However, removing a single pad reduced the friction to acceptable levels, but the loose fit could result in a loss of precision.

The bearings themselves were very expensive compared to the other components – $34 each x 3 = $102.

I also purchased an additional extrusion for the X-Axis, connectors and t-nuts.

The total with shipping was $192.90.

If I had to do it again, I would use the 80/20 super structure, but would investigate other options before buying the bearings. It seems that from time to time, the garage sale offers a ‘build your own bearing’ which may affect the final cost, but ymmv.

(naked bearing pictured here is $8. There is also ‘overstock’ UHMW material in the bearing profile for $7 at this time.)


I’ve been playing around with the idea of using an ACME lead screw with a traveler which not only engages with the screw, but also uses the screw as a guide rail (2 birds one stone). This would need to be fixed at both sides using a bearing block. (sorry, just idea at this point).

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