Welding to Frame Rails?

The Slims · 08-11-2006, 11:51 AM

Hello All,

I'm the proud new owner of future Skoolie conversion and still making my way around all the potential and potential pitfalls. I was "creeping" around underneath the bus the other day and noticed a label indicating that I should NOT drill holes in the frame rails. Since I really don't have any first-hand experience in what I'm doing, I wondered...

When I start putting components under the bus should I refrain from welding to the frame rails? To what should I attach holding tanks, generator, etc.? Should I be considering options other than welding?

By the way, I love this site and look forward to some insightful feedback. Thanks in advance and Happy Trails.

Take Care
Slim

bdavis441 · 08-11-2006, 04:48 PM

I'm also curious about this. I see that label on semi trucks all the time. If I recall, they say something about heat treating. I haven't seen that label on my bus, but it may have been there at one time. I don't know. However, I am taking my chances as I'm sure most of us are. I weld to and drill holes in the frame as needed.

lapeer20m · 08-11-2006, 06:07 PM

i agree with the above post. I also drill and weld to the frame as necessary to attach various components.

waywardfool · 08-11-2006, 06:23 PM

first rule of welding to a frame is to never weld any bracket or patch straight up and down, always about 30* from the rail, and never steeper than 45* to the rail.

as for holes, I've always figured small is OK -- like up to 3/8 to mount something -- certainly never a 2" to run a pipe thru.

the_experience03 · 08-11-2006, 10:40 PM

Agreed on the welding at an angle. Diamond shaped plates (kind of like a kite) are what I've always seen used. When you weld it, make sure you do short welds and alternate sides so that you don't overheat things.

The Slims · 08-13-2006, 08:57 AM

Alrighty then, I appreciate the responses. Is there a particular reason not to weld straight up-and-down in relation to the frame rail?

elkoskoolie · 08-13-2006, 10:54 AM

Cracking!!! As the frame flexes up and down, one side is under tension, the other compression. A vertical weak point (weld) between the sides will be where it tends to break. The angle "spreads the load" over a larger area, and in different directions.

the_experience03 · 08-13-2006, 07:24 PM

The weld itself is not the weak point unless the heat treating of a piece is trukly compromised. Instead it's the rigidity of the weld that causes the problem. It concentrates all that stress right at the edge then. If you ever look at a failed weld, it often isn't the weld itself that failed, but the surrounding material assuming the weld had proper penetration, etc to begin with.

The Slims · 08-14-2006, 11:20 AM

Once again, thanks for the info. I can already tell that you folks and the information on this site are going to be an invaluable resource during my conversion. I'm looking forward to having "experience" so that I can contribute as well. I know what I'm doing, I just haven't figured it out yet. Great work.

Slim

sportyrick · 08-15-2006, 11:14 AM

newer truck frames are heat treated steel (to make them lighter and stronger) and should never be welded on. use your head and make clever brackets/mounts and just drill holes and bolt whatever you need to to them. You will find that even drilling them will be a chore because of the hardness and alloying elements that were added to them to make them heat treatable (chrome, molly etc). Look at them, do you see a weld anywhere on them, they are all bolted and rivetted together, no welding allowed or you will have a crack later on, then how do you fix it? sporty rick

The Slims · 08-28-2006, 02:12 PM

Quote:

Originally Posted by sportyrick

newer truck frames are heat treated steel (to make them lighter and stronger) and should never be welded on. use your head and make clever brackets/mounts and just drill holes and bolt whatever you need to to them. You will find that even drilling them will be a chore because of the hardness and alloying elements that were added to them to make them heat treatable (chrome, molly etc). Look at them, do you see a weld anywhere on them, they are all bolted and rivetted together, no welding allowed or you will have a crack later on, then how do you fix it? sporty rick

This feels like the safest route to go and all of the welding/fabrication can be done on the bench in the shop. Plus, bolted on brackets/mounts provide an measure of flexibility in the event of future design/component changes. Thanks for the input!!!

Elliot Naess · 10-25-2006, 01:41 AM

From memory, and 24 years of noodling around with 18-wheelers; I think you will
find that the label that says "Do not drill holes..." goes on to say "...in the frame
flanges". That is, the top and bottom horizontal parts of the frame rail.
It should be fine to drill holes in the "web" of the frame -- that is, the vertical part.
That's how we mount equipment on the 18-wheelers. Fabricate on the bench;
bolt to the frame web.
An other way to mount stuff to the frame is to use U bolts around the frame rail.
Good luck with your project!

GoneCamping · 10-25-2006, 09:21 PM

Quote:

An other way to mount stuff to the frame is to use U bolts around the frame rail

I'm glad you posted that! I had been looking for a way to mount someting to the bottom of my frame without having to drill holes... The thought of U-bolts never even crossed my mind....and it is the perfect answer for my needs. Thanks for the idea!!

oldog12 · 10-27-2006, 01:12 AM

Dotto "Gone Camping"

oldog12 · 10-27-2006, 01:12 AM

I mean Ditto...

paul iossi · 12-12-2006, 10:38 AM

the sticker says do not weld or drill frame rail flanges if my memory is not totally gone. To drill the verticle part of a framerail you can rent a magnetic base drill (magdrill) or wrap a chain around the rail and have a helper use a lever to apply pressure to the back of the drill while you control the angle and speed, perpindicular and slow. also it helps to drill a pilot hole, I use 1/8 or 3/16 bits buy nthem in 10 pack bulk packs, they are consumable shop msupplies like sand paper.

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