I got a chance to get out to the shop tonight and work on the 81 again, Tonight I removed two tubs, one from the 81A thats being built, the other from a Vendo 80 parts machine. The bottom of the 81 tub is badly rotted, The 80 tub has a very clean bottom. I used a spot weld bit to drill out the existing spot welds. I will sandblast and tack weld the 80 bottom into the 81 tub. In the past I have drilled new holes in 80 tubs and converted them over to 81, in this case the 80 had a waterfountain installed at one time and it was easier to just drill out the bottom.
Bad pic but this is the spot weld bit that I used you can buy these at most automitive finish supply stores. I bought the one with the replacement teeth and it cost around $30.00. To use this you simply predrill the area with a normal bit to get a good starting point, then use the spot weld bit to drill through the actual weld itself. When finished you have a good area to weld where the old spot weld was located.
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The bottom of the Vendo 80 tub.
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The Vendo 81 tub after the rotten area was drilled out.
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And last a pic of both bottoms top 81 bottom 80, tommorow weather allowing I will sandblast and weld the 80 bottom onto the 81 tub.
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Joey