Taz6 Extruded Aluminum Frame Non-Standard!?

I bought some M3 and M5 hammer head T-Nuts for an enclosure I am making for the TAZ6. The enclosure uses standard 20mmx20mm extruded aluminum with a 6mm slot (the same stuff I thought the TAZ uses). The T-Nuts I bought (above) worked great in the enclosure frame. I then went to install some in the TAZ6 extruded frame to provide for mounting points with the enclosure - and they don’t fit (!!?!?!). I remeasured the extruded aluminum that the TAZ frame is made of and it is 20mmx20mm with a 5.35mm slot(!?!?!?!). What gives? Did they not use standard materials? I also noticed that they are using a kind of flat T-Nut, which I cannot find.

Does anyone know what’s going on here and where I can find nuts that actually fit this extruded frame??

Thanks!

See T-nuts for TAZ 6 - #3 by mwester

(Looks like the original product url at 8020 got changed: try this one for nuts that should roll into the TAZ-6 extrusions: Fastening Methods )

I bought several hundred feet of 20x20 V slot recently.

On trying to find a decent price I visited a lot of suppliers.

One thing is for certain… there is no real standard… I found slots from 5.25 to 6.4mm depending on where it was made and which country it was destined for.

As you will agree… it’s not really helpful!

I found a slot I liked and then sought the fasteners to fit it