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Posted: 2/3/2016 9:44:22 AM EDT
I'm trying to do a little welding project, need to figure out how much steel to buy. I'm lifting my camper 6 inches to level it when towing. I'm building a frame that is out of 2"x6"x11ga box steel. The frame will be 67"x71". I intend to make an X shaped cross brace at the front, middle, and back out of 2"x2"x11ga steel. The brace will run from the existing frame to the additional frame. The three brace locations are front, rear, and middle because of the tandem axle design. How much steel do I need to buy to make the crosses, and does anyone have any ideas what angles I need to cut for pretty fitments?

Thanks

Link Posted: 2/3/2016 9:53:45 AM EDT
[#1]
Are you doing a frame on a frame? I really have no idea what you are doing, but...

A^2+B^2=C^2 is the length, but you have to add for the cuts, this is a point to point equation.

Sin^-1 or cos^-1 for the angles, but I would just eyeball it.

2x6x.120 is going to be pretty flimsy in my opinion.  Big tube for not much wall thickness.  I would go heavier, but I don't have a full picture of what you are doing.

Are you trying to buy exact pieces?  Most steel places have a minimum anyway.  I just buy full sticks.
Link Posted: 2/3/2016 10:08:09 AM EDT
[#2]
Steel: My local yard will cut to length using 24 foot sticks.

Problem:
Camper sits too low when on the truck. The back bumper is very low, excess load is placed on rear camper axle. In order to fix this, the camper has to be lifted 6 inches.

Solution:
Jack camper up, place on jack stands.
Carefully cut existing suspension mounts off existing frame.
Move axles, suspension out of the way.
Fabricate additional box fame, 6" tall. New frame will match width and height of existing frame. I am choosing to use 11 ga (1/8" approx) as this is the thickness of the existing frame.
Weld new frame onto existing frame.
Install cross bracing from old frame to new frame.
Reattach suspension mounts, reinforce because I'm paranoid.
Remove stands
Link Posted: 2/3/2016 10:13:38 AM EDT
[#3]
So frame on frame.  Ok,  I am assuming that you already have/have done spring over?  What about lift blocks?

Anyway I wouldn't have anything cut to size at the steel place, I would just get everything a few inches longer than needed and cut as I go.  As for the exact lengths I can do the math in a few.

http://www.mathwarehouse.com/triangle-calculator/online.php
Link Posted: 2/3/2016 10:17:05 AM EDT
[#4]
Cheaper.

Link Posted: 2/3/2016 10:58:27 AM EDT
[#5]
Discussion ForumsJump to Quoted PostQuote History


Fifth wheel travel trailer. Truck is stock height (1999 F-250) with a Reese sliding hitch that is as low as possible. Camper is a 1992 Sprinter with the pin box lifted fully.

It is already spring over. I looked into lift blocks, but several people have reported serious problems with blocks falling/flying out while turning tandem axle configurations due to side loading of the wheels/suspension. This appears to be the safest route. I have a shop that will do this exact process locally (they do it pretty routinely), but labor will be well in excess of $600
Link Posted: 2/3/2016 11:01:24 AM EDT
[#6]
Then your plan seems ok to me. Stitch welding and not full welding the seam would be my only other advice.
Link Posted: 2/3/2016 7:47:30 PM EDT
[#7]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Then your plan seems ok to me. Stitch welding and not full welding the seam would be my only other advice.
View Quote


I had planned on stitching, then coming back and filling in the gaps between the stitches. Why should I not full weld? I'm a diesel tech by trade, not a welder so I'm trying to learn.

Thank you for the help!
Link Posted: 2/4/2016 6:53:30 PM EDT
[#8]
Why not put the lift blocks (your 6" tubing) between the spring mounts and the frame instead of using all that steel?
Link Posted: 2/5/2016 4:26:24 PM EDT
[#9]
Way to light on your material. I'd suggest going much thicker on your subframe. the 6" vertically will see a lot of lateral stress when turning your trailer with three axles.

One suggestion would to be to use two 2x3" pieces welded together to build your subframe. This would make the unsupported span halved, and thus much stronger. And i'd probably build it out of 1/4-3/8"

Also, building the subframe with ladder crossmembers would simply the design. The major leverage you are trying to support against is lateral from the axles binding in a turn. Ladder cross-members would support this. The forward/back and up/down axis will be supported by the entire length of subframe and thus not require as much bracing. Adding a couple pieces of plate on the inside of the frame rail bracing the main/sub frames together as well perhaps.


Look on google for a bunch of examples of what people have done.. Might give you some more ideas on what would work for you:

https://www.google.com/search?q=lifting+5th+wheel&safe=strict&rlz=1C1VFKB_enUS676US676&espv=2&biw=1920&bih=995&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiQ74jtueHKAhVLwWMKHd8lDsgQ_AUIBygC#safe=strict&tbm=isch&q=5th+wheel+lift+subframe&imgrc=_
Link Posted: 2/5/2016 10:59:31 PM EDT
[#10]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


I had planned on stitching, then coming back and filling in the gaps between the stitches. Why should I not full weld? I'm a diesel tech by trade, not a welder so I'm trying to learn.

Thank you for the help!
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
Then your plan seems ok to me. Stitch welding and not full welding the seam would be my only other advice.


I had planned on stitching, then coming back and filling in the gaps between the stitches. Why should I not full weld? I'm a diesel tech by trade, not a welder so I'm trying to learn.

Thank you for the help!


As a very general rule of thumb, unless you designed it, stitch weld to it.  The idea being to try to not create a point of stress.  Right where your subframe ends you will have a stress point where your old frame starts again.  Basically your new sub frame is going to be really stiff and your old frame will only start to flex right at the end of the subframe.  To ease this as much as you can, stitch welding is a good practice.  It will allow the old and new frame to be a tiny bit loser and allow just a tiny bit of flex along the two.

Link Posted: 2/6/2016 10:56:40 PM EDT
[#11]
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28542413/srt/pd/pging/1.cfm


I would def. use tube steel just as they did in this picture. I have lifted a few campers in the past.  But never anything as large as a 5th wheel camper or a toy hauler.  The only difference was we would bolt  vertical straps to increase surface area for stress.

As someone said earlier, stitch weld when attaching new frame to existing frame.  I would run a filler bead..Then weld from the old frame to the center of my filler bead. Then weld from filler bead to the new frame.

Just my .02
Link Posted: 2/15/2016 2:00:24 AM EDT
[#12]
I would lengthen my fifth wheel hitch to sit 6" lower. My uncle did this to his. He bought a adaptor and I welded it on for him. he's been all over the southwest with it. I'll get a pic tomorrow.

WSS
Link Posted: 2/15/2016 2:28:13 AM EDT
[#13]
How did this come out anyway?
Link Posted: 2/15/2016 1:27:25 PM EDT
[#14]
The temps dropped to near zero again. I'm on hold waiting on weather.
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