contraction problems with seamer

[macforce]

How can i keep 1/16 in gap on 3/16 in plate on a 6` weld on a seamer

[bennyswill]

If you can go ahead and tack every 6-10" with another welder, removing slag and partially grinding the tacks down before running the seamer may prevent seperation and keep things straight.

[Blacksmith]

Pennies work good as spacers; right size and made of copper.

[aametalmaster]

Pennies work good as spacers; right size and made of copper.

If your Lincoln Memorial penny has a date before 1982, it is made of 95% copper. If the date is 1983 or later, it is made of 97.5% zinc and plated with a thin copper coating...Bob

[Hotfoot]

I use Panel Clamps. They work great! These are from the Eastwood site, I bought a couple dozen at Harbor Freight for MUCH less, and work fine.

[Blacksmith]

I forgot about the alloy pennies Bob; showing my age.

[DrIQ]

If I understand correctly you have a 6' seamer and the joint is closing up while welding. The normal fix is to add start and run off tabs to the part and weld them on to the plate. If the hold down fingers in the seamer are set correctly the gap should not close up using this procedure unless the clamp pressure is to low.