Grinding the seam!

OK Guys (?);
I finally got my 7" ID .081" 41" LGTH Aluminum tube (Fred Hook - Midland, Ontario) for the price of $110 CDN (US=$80 approx), and it looks fine (6"f6)!
However, the welder of this tube, left the outside weld visible, and I want to file/grind it flush!
There are are a few inside 'incursions' but I can use my "Dremel" to clean up those.
However, there's a LOT of extra weld on the outside of the tube.
I did use my various files and 'wood' rasps to try to get the bulk of the welds down.
Most of the 'grinders' that I use clog up - quick!
Grindstones, sandpaper, work fine, for moments!
Is there anything that works well for clearing out a lot of aluminum welding seam?
Mike 6"f6 - the costliest HB reflector in History!

And fyi, never put anything made of alum to a grinding wheel, it will load it up and may explode on you. I know this is not the case here, but I thought it deserved a mention.

[COLOR="Maroon"]David, another thing you can do is look in your Portland Yellow pages under Welders/Welding and also Motocycle/Hot Rod Builder/Auto Restorer as well as Machine Shops. These guys are Professionals at working with all kinds of metals including Aluminum. It may cost you $25/plus but, at least it will be ground down smooth as a baby's bottom without grinding all the way through. And if by chance they ended up with a pin hole or two they will re-fill/weld so it is like an Extruded tube. These guys work on Hot Rod and Chopper Custom frames and know what they are doing. Trying to do it yourself could cost you twice as much as having a pro do it in short order. Like another poster mentioned, do NOT grind aluminum yourself. Especially if you have hot water heater, lawn mower, chain saw, trimmer, etc. laying around.

Another thing is did the seller tell you about the excess weld on the seam? A welded tube versus an extruded tube can and may cause you collimating problems if this is going to be a Refractor unless your objective lens is in a collimatable cell and the focuser can be aligned as well. If this is the case, Mark @ ClearVue (an AstroMart Sponser) sells 2" Collimatable Diagonals to help correct this problem.

Good Luck with your project.[/COLOR]