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 Post subject: Re: Welding in the floor
PostPosted: August 13, 2009, 8:48 am 
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I've posted this before.

Black frame tube and seat pan.
Grey floor pan.
Red slider (the bolted down portion).
Green slider (the sliding portion).
Purple bracket welded to green slider, screwed to seat pan.
Blue pull chord to release pawl.

Basically, each slider on the seat is turned on it's side and bolted to the frame rail.


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 Post subject: Re: Welding in the floor
PostPosted: August 13, 2009, 9:00 am 
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motive wrote:
This would make the expansion caused by welding heat to expand the floor sheet out towards the unsecured perimiter instead of towards an already welded seem. When the floor cooled down it contract and be streatched beween the tubes making the floor a drum instead of wrinkly oil can.

Is there any sence to this thinking?


Your floor will be tight as a drum, but your longitudinal frame tubes will be bowed in between the transverse tubes when the floor sheet cools and shrinks. If you preheat sections to different temperatures you can tune the different areas like a steel drum. That would be unique.


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 Post subject: Re: Welding in the floor
PostPosted: August 13, 2009, 11:01 am 
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Also if you weld in the perfect tight floor you need to watch that if you need to go back later and weld a bracket or cross tube or any other thing onto your finished floor that you can run the risk of taking away from what you did earlier. Suddenly you have an oil can where you didn't before.
Though if you are experienced you can heat the floor and cool with a wet rag to shrink it back, that usually takes more knowledge than most of us have.
I used to watch my dad do it when I was a kid, the trick seemed to be just knowing where to do it, he always wanted to show me this stuff, but I was just a dumb kid, wanted to chase girls instead.
If only I had a second chance I would have listened a whole lot more.
Al

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 Post subject: Re: Welding in the floor
PostPosted: August 20, 2009, 7:42 am 
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Joined: August 19, 2009, 6:03 pm
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Novice.1st time poster here:
Has anyone considered using a bead roller (prior to welding) to strengthen floor pan? It would appear to me that process would reduce probability of oil canning and heat shrinking. IMHO do not think it good idea to apply more heat than needed if pan is part of overall load bearing members.
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 Post subject: Floor weld failure
PostPosted: September 10, 2009, 11:29 am 
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Upon stripping my car for paint, I found a bad weld. This is right under the driver's butt. Looks like it had no penetration at all into the floor.
Attachment:
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Attachment:
floor.weld.fail.2.jpg
floor.weld.fail.2.jpg [ 32.34 KiB | Viewed 1300 times ]

I also notice I was a bit stingy with the welding in that area, back when my metal was shiny:
Image

At least it's an easy fix.

-dave

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 Post subject: Re: Welding in the floor
PostPosted: September 10, 2009, 1:09 pm 
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There it is, the infamous MIG cold weld. Thanks for posting that picture. Do you think that was discernable at the time from the ( lack of ) heat discolouration? Could you tell by looking on the far side? The next weld over looks somewhat similar...

Being a novice welder, this is something I'd like to learn to recognize before the weld fails.

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 Post subject: Re: Welding in the floor
PostPosted: September 10, 2009, 10:34 pm 
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I recently welded in my floor. I started with the center tunnel in the typical fasion like the pics Hempy just posted. It didn't go to well. I'd either burn right though or have a cold joint. After just a few welds i decided to flip the chassis over and drill 3/8" holes every 2" into the floor material and plug weld. I could put tons of heat into the weld and not burn through the cassis tubes or burn away the floor. It looks nice from the inside as well.

I also decided to try and preheat the floor so it would be tight when it cooled. Big mistake. I probly only go it 30* hotter than room temp but couldn't get the heat evenly distributed so the floor went all wavy. :BH:

Next time I'd predrill the floor for plug weld and possition it with lots of clecos before welding. then weld up cleco holes.

Flux core wire does do a better job with cold starts. it also helps to cut of the little melted ball on the end of the wire befor starting each weld.

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 Post subject: Re: Welding in the floor
PostPosted: September 11, 2009, 9:01 am 
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I'll be flooring soon and it sounds like plug welds is the way to go. On light metal my mig turns into a plasma cutter.

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 Post subject: Re: Welding in the floor
PostPosted: September 11, 2009, 10:44 am 
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motive wrote:
I recently welded in my floor...Next time I'd predrill the floor for plug weld and possition it with lots of clecos before welding. then weld up cleco holes.

Flux core wire does do a better job with cold starts. it also helps to cut of the little melted ball on the end of the wire befor starting each weld.


Man, that's a really great tip.

Files thread away for later...

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 Post subject: Re: Welding in the floor
PostPosted: September 11, 2009, 4:23 pm 
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What I did was I under cut the floor slightly and then just perimeter welded it all the way around using .035 wire because I was to lazy to change the spool.
I started on one outside edge and jumped from left, right and the middle until one side was done, then I went to the opposite side inside tunnel and did the same, then went to the other outside edge and repeated the steps and finished off with the inside opposite tunnel.

I then ground the weld flat to the bottom surface making sure not to grind the corner edges, I only did this where panels would be later fitted.
Unfortunately I didn't take any good photos, but do have a portion under the fuel tank that shows the what i am talking about before finishing and painting, it is sort of an example of the whole floor.


It seems like less work than drilling a lot of holes and spot welding them all, just my opinion only.
Also if the floor is welded all the way around I think it will provide better protection from the road elements as well because there are no exposed edges or seams to the inside.

Maybe try taking some scrap pieces of sheet used on the floor and clamp them about 1/16 or so in from the edge of a scrap piece of 1 inch tubing, clamp it in a vice and try welding, start the weld on the corner of the tube and blend the weld into the edge of the sheet floor and back down into the corner of the tube in a circular motion maybe going a 1/4 inch at a time.
By doing that you wont weld long enough for any burn through, once you get the feel of doing that, you should be able to change to a stitch type weld if you choose to and not have problems with burning through.
Most people have the settings correct, just need to add a little rythem :P

Al


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 Post subject: Re: Welding in the floor
PostPosted: September 12, 2009, 11:06 am 
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Just doing plug welds on the floor doesn't seem strong enough to me. The folks on the UK board seem to recommend welding all the way around, doing stiches and then going back and filing in between them until ti's all done. That should help make it more water and dirt tight which will help with longevity.

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 Post subject: Re: Welding in the floor
PostPosted: September 12, 2009, 11:51 am 
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horizenjob wrote:
Just doing plug welds on the floor doesn't seem strong enough to me. The folks on the UK board seem to recommend welding all the way around, doing stiches and then going back and filing in between them until ti's all done. That should help make it more water and dirt tight which will help with longevity.


That's what I did with mine, then I went back and put some evenly spaced stich welds across the bottom of the car from the inside.

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