We are trying to extend the short 19mm mount pole -- to something at least 12 inches -- something out there to slide the existing short stem into --- ??
19mm = 3/4"...most of the kits tubing is the standard 1-1/2" diameter except for the Nitro,Burst kits which have a mixture of 1-1/8" and 1-3/8".
Which kit/rack?..black aluminum or chromed steel?
If it is a chrome rack Gibraltar offers longer straight tubing.
If black you could check black pvc tubing and see if you can match the I/S diameter to the O/S diameter of the rack tubing.
EDIT:
I fabricate a lot of custom work..
I checked and the 1-1/2" Alesis rack tubing..both the Black Aluminum (ribbed interior) and the Chromed steel inside diameters accept the 1-1/4" closet rod from home depot..you would need to use a very fine thread set screw.or drill and use a through bolt/pin..the wall is thin ..
since it's 1-1/4" you wouldn't be able to use typical Alesis clamps so the extension would be on the bottom.pic attached
