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Posted by stryped on May 9, 2008, 4:01 pm
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>
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> > What acuracy is needed in terms of building a trailer???
>
> I cut the steel for my saw mill to tape measure / pencil line accuracy
> and straightened out welding distortions with a jack.
> The axle seats were aligned parallel with a framing level. I had the
> blade tracking properly 5 minutes after assembly. Your trailer can't
> possibly be as demanding as getting a bandsaw blade to track straight
> on motorcycle tires and that was done with carpentry tools.
>
> When you weld a tapered, badly fitted joint it's likely to warp out of
> square as it cools. As long as you cut each piece to fit you can
> compensate for the distortion. For a trailer this is more of a
> nuisance than a real problem.
>
> Jim Wilkins
Will a heavy 6 foot by 12 foot square stucture made out of 3x3 tubing
warp much when welding if I tack everything first?
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Posted by johnnytorch on May 9, 2008, 4:54 pm
Please log in for more thread options
>
>
>
> > What acuracy is needed in terms of building a trailer???
>
> I cut the steel for my saw mill to tape measure / pencil line accuracy
> and straightened out welding distortions with a jack.
> The axle seats were aligned parallel with a framing level. I had the
> blade tracking properly 5 minutes after assembly. Your trailer can't
> possibly be as demanding as getting a bandsaw blade to track straight
> on motorcycle tires and that was done with carpentry tools.
>
> When you weld a tapered, badly fitted joint it's likely to warp out of
> square as it cools. As long as you cut each piece to fit you can
> compensate for the distortion. For a trailer this is more of a
> nuisance than a real problem.
>
> Jim Wilkins
\Will a heavy 6 foot by 12 foot square stucture made out of 3x3 tubing
\warp much when welding if I tack everything first?
Yes. Its the order in which you weld them that will minimize the
distortion. Practice building small square frame-like things, then you will
understand the order.
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Posted by Jim Wilkins on May 9, 2008, 5:39 pm
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> Will a heavy 6 foot by 12 foot square stucture made out of 3x3 tubing
> warp much when welding if I tack everything first?
That exceeds my limited experience, which is why I describe what I've
already done and how well or badly it worked rather than give general
advise. I'm not qualified to design and fabricate a roadworthy
trailer; I don't even trust my welding skill enough to fix one for
someone else.
The lengthwise rails on the sawmill are 1-1/2 square tubing with 1/8"
walls. When I welded in the 1/4" wall tubing crosspieces near the
center the free ends of the rails pulled inward and I had to jack them
back out parallel. The crosspieces had been milled square on the ends,
then beveled about half way. Clamping and tacking didn't help.
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I think the rails bent because all the beads were all on one side.
Steel shrinks a lot as it cools. Usually I make mitered corners or add
gusset plates and the weld beads are distributed more evenly across
the width of the structural members, so they hold shape better.
Jim Wilkins
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Posted by glyford@gmail.com on May 9, 2008, 1:12 pm
Please log in for more thread options > What acuracy is needed in terms of building a trailer
The biggest need is for the distance from the hitch coupler to the
tire to be the same on each side (means the axle is on straight
relative to the hitch, and the hitch is centered correctly).
Square is nice (matching diagonals).
For the rest, you can probably get away with +/- an 1/8th or more.
For individual joints, this variation can be filled when welding. If
the main frame is accurate the rest of the structure is much less
critical. At that point accuracy becomes more a measure of how hard
do you want to work: The more accurate the cuts, the less work you
have to do to adjust or shim everything when clamping and lining
things up.
I would think that one of the handheld units would be more than
sufficient for what you want to do. Take your time measuring and
calculating (take notes as you go if you find you have to change
things so you can remember why if you have to set it down and come
back to it), mark your lines across the whole piece with a square
rather than just a dot where your measurement is, it will give you
something to follow with the saw. If a cut is starting to stray,
consider starting the cut over again from another side of the piece.
Get extra blades.
--Glenn Lyford
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Posted by stryped on May 9, 2008, 4:03 pm
Please log in for more thread options > > What acuracy is needed in terms of building a trailer
>
> The biggest need is for the distance from the hitch coupler to the
> tire to be the same on each side (means the axle is on straight
> relative to the hitch, and the hitch is centered correctly).
>
> Square is nice (matching diagonals).
>
> For the rest, you can probably get away with +/- an 1/8th or more.
> For individual joints, this variation can be filled when welding. =A0If
> the main frame is accurate the rest of the structure is much less
> critical. =A0At that point accuracy becomes more a measure of how hard
> do you want to work: =A0The more accurate the cuts, the less work you
> have to do to adjust or shim everything when clamping and lining
> things up.
>
> I would think that one of the handheld units would be more than
> sufficient for what you want to do. =A0Take your time measuring and
> calculating (take notes as you go if you find you have to change
> things so you can remember why if you have to set it down and come
> back to it), mark your lines across the whole piece with a square
> rather than just a dot where your measurement is, it will give you
> something to follow with the saw. =A0If a cut is starting to stray,
> consider starting the cut over again from another side of the piece.
> Get extra blades.
> =A0 --Glenn Lyford
Is the key the axle spring seat centers are equal distance from the
hitch on both sides or the tires are on both sides as you said?
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