Learning to build a 5x8 square drop

[DesertApprentice]

After contemplating and discussing for a while viewtopic.php?f=62&t=73811, I finally tip-toed into the frame build.
Barely one day into the build, I already came to a halt. The frame doesn't appear to be a true square This is my first time welding for real.
I have a big decision to make: should I cut it up and redo it? That's what I lean towards. I'd like to hear advice.

It's a big decision, let me list all the details here. Assuming my measuring tools are "accurate" and I have taken the correct measurements, here is what I got:

frame-0.jpg (179.7 KiB) Viewed 2931 times

Distance measurements - width: top side 5'-1/16, bottom side 5', length is 8'+1/16 for either side. Diagonals are 1/8 off. Details are below:
Width:
top of the frame is 5' - 1/16
bottom of the frame is 5'
Length:
both left and right are 8' + 1/16 (same)
Diagonal:
One is 113", the other is 113" + 1/8. That's 1/8 off.
Square angle measurements - the square tools indicate all corners are less than 90 deg, which is impossible. I tried 3 different square tools, they all indicate the same All sides have to be bowed inward for that to happen, that's practically impossible (I have attached an exaggerated illustration). I have manually "verified" the square tools, they all seem to be correct (drawing two overlapping vertical lines while flipping the square tool horizontally).

frame-angle.jpg (177.15 KiB) Viewed 2931 times

I'm stumped. I'm leaning towards cutting it up. Any advice is appreciated!

[tony.latham]

Well... 1/8" on the diagonals is fine for the frame.

What's most important is getting the axle squared with the tongue.





I use three plumb bobs for this. Clamp one side of the axle in place and adjust the other side. Don't try to fight both ends.

Tony

[TimC]

- Relax

- Listen to Tony

- Have a barley pop and get back to it

[DesertApprentice]

Well... 1/8" on the diagonals is fine for the frame.

What's most important is getting the axle squared with the tongue.

I use three plumb bobs for this. Clamp one side of the axle in place and adjust the other side. Don't try to fight both ends.

Tony

Thank you very much for your response. I'll definitely square the axle and tongue carefully.

I also realized I should have cut the width to 59 1/2". I believe you said there may be challenges with materials with the exact 5' frame. If I want to change, this is the last chance.

If exact 5' is not a big problem, I'll move on with the Timbren axle install. Will be another learning process. I have been checking online resources and youtube links. I'm hoping no big surprises, fingers crossed!

Thank you very much!

[DesertApprentice]

- Relax

- Listen to Tony

- Have a barley pop and get back to it

I'm indeed very nervous. Until it's finished, many more things to learn ahead. Hope my confidence grows with the build

[tony.latham]

I also realized I should have cut the width to 59 1/2".

That's not standard. I do that primarily so that an aluminum-clad teardrop doesn't rest on its lower trim.

Tony

[MickinOz]

So you set out to construct an 8 x 5 frame with mitred corner joints.
It came out 8' 1/16" x 5' 1/16"., and 1/16" out of square.
That's bloody good work mate.
Reckon a pro would do any better? Pros probably work on a bigger tolerance than that.

You know 1 eighth inch/3mm across the diagonals is actually only 1 sixteenth inch / 1.5mm out of square, right? i.e. you'd only have to pull the long diagonal 1/16 of an inch to get the two sides to match.
As square as you'll ever get.

As for the potentially bowed in sides, don't stress.
Run a string line and see if the long sides are straight.
If the long sides bow in a bit, cut your cross members long enough to spread the sides back to straight. They'd have to be a very long way out to be unable to flex the long sides straight.
Or build the cabin on top. That way you can run your outer measurements at the 60 inch mark.
The only question I have - did you manage to build the frame without a twist?
i.e. when you sight across the side rail from one side, is the other rail parallel?
Looks pretty good from here.

[TimC]

...

I'm indeed very nervous. Until it's finished, many more things to learn ahead. Hope my confidence grows with the build

You are doing fine. Welding scares me so I hired out the custom chassis on my first teardrop. The pro welder produced a "square" 5x8 frame but I didn't notice until I was adding the floor that the roadside front corner took a 3/4" nosedive from about a foot from the corner. A few shims and some trim along the bottom and nobody but me knows. Well the tnttt world knows...

I don't use custom chassis' anymore because the cost of my first was double what a NT trailer costs even after wheel upgrades. If I had the skills I would weld my own, but I prefer focusing on the rest of the build.

Keep picking away at it and ask, ask, ask questions.

[DesertApprentice]

...

I'm indeed very nervous. Until it's finished, many more things to learn ahead. Hope my confidence grows with the build

You are doing fine. Welding scares me so I hired out the custom chassis on my first teardrop. The pro welder produced a "square" 5x8 frame but I didn't notice until I was adding the floor that the roadside front corner took a 3/4" nosedive from about a foot from the corner. A few shims and some trim along the bottom and nobody but me knows. Well the tnttt world knows...

I don't use custom chassis' anymore because the cost of my first was double what a NT trailer costs even after wheel upgrades. If I had the skills I would weld my own, but I prefer focusing on the rest of the build.

Keep picking away at it and ask, ask, ask questions.

I was worried I have been asking too many silly questions. Great to hear your encouragement. I'm going to finish up the frame and move on to the Timbren alxe-less suspension. I will keep updating progress here.

Thanks again!

[DesertApprentice]

So you set out to construct an 8 x 5 frame with mitred corner joints.
It came out 8' 1/16" x 5' 1/16"., and 1/16" out of square.
That's bloody good work mate.
Reckon a pro would do any better? Pros probably work on a bigger tolerance than that.

thank you for the encouragement!

[rjgimp]

Looks pretty good from here.

That's easy for you to say, mate. You're 12,000 miles away!

[MickinOz]

Looks pretty good from here.

That's easy for you to say, mate. You're 12,000 miles away!

But, my optometrist says I'm long sighted mate

[DrewsBrews]

Weld shrinks when it cools. This usually winds up pulling both pieces towards the welded side. If you welded the inside of the corners first then, yes, it would bow all the bars inwards. I'd bet the longer measured length was one of the corners you started on.

https://www.youtube.com/watch?v=2vuGlcbDwKY

I would not sweat 1/8" on the diagonals. That is very close. That method of measurement exaggerates how out of square it actually is IMO.

[DesertApprentice]

Weld shrinks when it cools. This usually winds up pulling both pieces towards the welded side. If you welded the inside of the corners first then, yes, it would bow all the bars inwards. I'd bet the longer measured length was one of the corners you started on.
https://www.youtube.com/watch?v=2vuGlcbDwKY
I would not sweat 1/8" on the diagonals. That is very close. That method of measurement exaggerates how out of square it actually is IMO.

DrewsBrews - Thank you for your response. I'm going to stop worry the minuscule measurement errors. I actually cut it up and re-welding it now. I'm putting the inside cross members before the final welds. The heat appears to alter the dimension even with the spot welds. I'm learning to put all these into perspective now.

I think I'm getting a new worry now I need expert input again.

I plan to use my Rubicon JL factory 33" tires for the trailer. That was actually part of the motivation I started this project after I lifted my Jeep to 37" tires. I ordered the Timbren axle-less suspension with hubs/brakes. According to the Timbren document, the distance between the trailer and the lug nut thread hole (indicated as "K" in the diagram) is 8.5". I just measured my wheel, from the lug nut thread hole to the tire outside wall, it's 7+5/16". Theoretically, the gap between the tire and trailer frame is ~11/16". The fender wall also need to fit into this space. Is this feasible?

timbren-diag.png (318.64 KiB) Viewed 2664 times

tire.jpg (197.96 KiB) Viewed 2664 times

I'm worried the gap is too narrow.

[DesertApprentice]

gee, it's getting worse. I tried to do a mockup dry fit, I noticed a bolt sticks out 3/4" from the frame with the Timbren assembly, the spindle is 14" away, so this bolt lines up exactly against the tire wall.

axle-bolt.jpg (159.32 KiB) Viewed 2653 times

I'm not sure if I can even fit the tire in, let alone any gap between the tire and the frame. Any possible workaround other than going to smaller tire? I swear I saw in youtube, some teardrop was using Timbren axle with 33". Not sure how they did it. Maybe my tire is just too fat, i have 285/70/R17.
I did some quick reading on wheel spacers, not sure I want to go that route.