Tab and Slot design methods

[Scott_F]

I'm curious how different fabricators design their tabs and slots. Do you make your tabs flush with the mating surface, or do you recess the tab in the slot? If so, how much? Do you fusion weld if flush, or add filler if recessed? What clearance do you prefer on the width and length of the slot vs tab? I have my own ideas on this, but I want to see what others think. For reference, from the Pretty Welds thread:

http://www.race-dezert.com/forum/att...1&d=1237480206

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[scottm]

I make the tab 1/2 to 2/3 the thickness of the sheet, with .010" or sometimes more, clearance on each side of the tab. Steel should always be welded with filler. Stainless can be fused, but carbon steel, esp high carbon like cro-mo, requires filler metal to reduce carbide formation and cracking.

[sickrick]

Flush and add filler is what we do to the tab pictured. If it had to be flush to fit inside of another assembly we would recess it slightly and add filler so it would end up flush.

We have just fused them together with out filler, we don't do that now.

[L&LMotorsports]

The tabs and slots that were designed for our truck by CRD are about .040 below the surface of the plate so there is a little space to get some good filler in there. The weld ends up flush with the surface for a clean appearance. Side and end clearance is minimal.

[Scott_F]

Sickrick, thanks for the clarification.

[CRAIG_HALL]

I'll usually make them about a third the material thick tall. ( .090 material, .03 tall or .060 below surface.) This is only for parts that are to be welded from the outside. I usually try to make the majority of a part welded that way. To me this will let the welder assemble the part with the most amount of pieces to help minimize distortion from weld. (more pieces to hold it in shape). Sheet metal can be very tricky if you have too many welds in one area and it's tig welded it can warp pretty bad. I try to keep the amount of welds on any part equal to minimze pulled parts..

Depending on the parts or customer preference, I'll make the internal rib with as much weld surface as possible. I've done 2" weld with 1/4" tab then 2" more weld. Also stagered 1" weld-1"tab-1"weld...

[hrtmotorsports]

I'll usually make them about a third the material thick tall. ( .090 material, .03 tall or .060 below surface.) This is only for parts that are to be welded from the outside. I usually try to make the majority of a part welded that way. To me this will let the welder assemble the part with the most amount of pieces to help minimize distortion from weld. (more pieces to hold it in shape). Sheet metal can be very tricky if you have too many welds in one area and it's tig welded it can warp pretty bad. I try to keep the amount of welds on any part equal to minimze pulled parts..

Depending on the parts or customer preference, I'll make the internal rib with as much weld surface as possible. I've done 2" weld with 1/4" tab then 2" more weld. Also stagered 1" weld-1"tab-1"weld...

Nice looking parts Craig!

[DUMP!]

Playing devils advocate, I question why anyone would use this method for a race car part. Play car I can see this would be a viable method but in a racing application it seems like you would be designing on the edge of efficiency to save weight. It seems like using this method on a race car part would mean that material thicknesses would need to be increased to compensate for the fact that the joint is not welded 100%. Just my thoughts, when I have used this method for play stuff I made the tab .020 below the surface of the adjacent part and the slot .010 wider and longer then the tab. This was for 4130 parts.

Dump

[Scott_F]

Ah, that brings up another question. When welding tabs on the outside only, does anyone prefer long tabs with short spaces between them?

[Triaged]

I make sure that if the sheet is on the thick side of the tolerance that it will fit. That normally means .005"-.010" over the thickness for the width of the slot for cold rolled. I normally make the slot longer than the tab by about .050". After bends or rolls (or even during rolls) I make the tabs as small as half the length of the slot. Tabs are no taller than 1/2 of the thickness of the sheet they are going into.

Edit: For outside only welded tabs I don't go any longer than 4" but more often shorter. I normally divide them up rather than making them a set length.