Deck build questions..

[Slixter]

20 hours ago, trimster said:

Spent some time with a fabricator today. Tossed around some great ideas. I hope to document the process for all here.

Here's where we stand:

- extension on the frame will be 25'ish inches. (the wheelbase is 210). We're allowing for a 57" wide trike and the 60" radius for the trailer. The trike will be loaded via a loader instead of ramps.

- we ARE leaving the rear axles as they are. Tandem tires and both axles.

All the input and thoughts have been really helpful. Big thanks all.

Construction basics (so far):

- Capping the frame rails with hard wood. Wonder if Trex decking would work?

- Using 2"x3" channel on top of that. Tied to the frame with angle iron bolting it down. Kept the commercial hitch mount rails to tie too. Will add front and read connection points as well.

- 2"x2" square tube cross members.

- I hope to make the the center frame deck panels removable .

   That's where we stand.

Bob

What gauge 2x2 are you using?

[GlennWest]

My bed is boxed out with 2X4X1/4". 

[trimster]

12 minutes ago, Slixter said:

What gauge 2x2 are you using?

Not sure yet. I'd like it to be strong. .25" is  , maybe overkill. Maybe not.

Bob

[rickeieio]

Beemergary..... the only thing wrong with your bed is that it's not on my truck.

Bob, it appears you've got this pretty well sorted.  Sounds great so far.

[Alie&Jim's Carrilite]

3 hours ago, trimster said:

Not sure yet. I'd like it to be strong. .25" is  , maybe overkill. Maybe not.

Bob

.25 is fine.  Since you're leaving it tandem, the extra weight will not hurt.

As far as using the Trex decking between the frame and bed, I probably wouldn't as the material is slick.  and over time it might move on you.  I have... or had oak slats between mine.  I say had because sometime recently they finally disintegrated... its only 18yrs old.  The company called "Browns" that build truck boxes uses Hickory between their boxes and frames.

[Moresmoke]

When I did the figuring for my deck, I came up with 1/8 on 12” center crossmembers. I was planning for a 10000 lb farm tractor as the load.

So far so good.

[house]

call me crazy but it went with .120 wall with quarter inch plate and It is plenty stout enough.  to me .25 cross members would be a bit over kill that said I went with 2x8x.120 rails and 8 inch channel setting on the frame I just could not see adding more weight from the cross members 

[RoamingRanger]

I'm not sure if this is helpful for selecting your bed frame tubing size or not but if you want to compare the different tubing sizes from an engineering perspective, I ran a few quick calculations. The first column is the weight per foot of different square tubing options. I know many aren't concerned with weight since it's a HDT but I've come from a racing background so I couldn't help myself. The second column is the "Section Modulus" which determines the strength of the member relative to a bending load. For both calculations I've used 2" x .120" wall square tubing as a baseline so you can compare both the weight and strength of other sizes to a 2" x .120" wall square tubing baseline. As an example- 2" x .25" is 71% stronger compared to 2" x .120" but weighs nearly twice as much per foot whereas 2.5" x .120" is only 27% heavier per foot compared to 2" x .120" but is still 62% stronger.

I think the big takeaway is that if you're interested in increasing strength, you're always better off increasing the height of the member (or outer diameter for tubing) than you are increasing the wall thickness.

Edited August 22, 2020 by RoamingRanger

[RoamingRanger]

19 hours ago, beemergary said:

Trimster  Got from National Recreation Products-planks cut to order and bolt on clips was $950.00 shipped from In. to mi. Everything in pic is bolted + trailer hitch/light assembly.

Beemergary- A very creative solution, I like it! Question- How did you minimize the gap between where the two planks butted up to one another at the angled portion of the bed (plank two and three counting from the rear of the bed)? Did you have to miter them? Also, what size did you use? 12" x 2"?

[HERO Maker]

2 hours ago, RoamingRanger said:

I'm not sure if this is helpful for selecting your bed frame tubing size or not but if you want to compare the different tubing sizes from an engineering perspective, I ran a few quick calculations. The first column is the weight per foot of different square tubing options. I know many aren't concerned with weight since it's a HDT but I've come from a racing background so I couldn't help myself. The second column is the "Section Modulus" which determines the strength of the member relative to a bending load. For both calculations I've used 2" x .120" wall square tubing as a baseline so you can compare both the weight and strength of other sizes to a 2" x .120" wall square tubing baseline. As an example- 2" x .25" is 71% stronger compared to 2" x .120" but weighs nearly twice as much per foot whereas 2.5" x .120" is only 27% heavier per foot compared to 2" x .120" but is still 62% stronger.

I think the big takeaway is that if you're interested in increasing strength, you're always better off increasing the height of the member (or outer diameter for tubing) than you are increasing the wall thickness.

Interesting Chart!  Thanks!  Wish I knew how to put it into the Resource Guide.

[phoenix2013]

2 x 3 x 3/16 wall tubing and 3/16 deck is all you need, more than enough strength for whatever you put on it. You can go even thinner if you put stiffeners in between, 1 x 1s or 1.5 x 1.5s. Here's an example.

2 x 3s were laid flat on the rails (2 inch height), then the deck framing was done with 2 x 3s vertical (3 inch height). Between the two you have 5 inches total which you need to allow the tires to rise (4 to 4.5 inches typical) when the suspension airs down to hard stops. Note the position of the two tubes on either side of the tire, even though they are in over the tire they are far enough apart to work with the radius of the tire when the suspension is down. 

Note that as I started building it I changed my mind and lost the tubing on the back side of the tire and just ran stiffeners forward and back between the tires, more than enough strength there, particularly that nothing heavy like a car never ends up there.

3/16 plate deck on top.

 

Plate was smaller by about 3/8 all around, solid heavy fill weld all around and stitch welded underneath only, not too much to not "encourage" warping. That extra thick perimeter weld was then ground down with grinder flapper wheels to create new radius between the deck plate and the the perimeter tubing. It goes pretty quick one you get the "touch"

Note tire basket holders and weldnuts under the plate for mounting the drom. Also weldnuts in an angle welded to the vertical tubing bottoms, makes mounting tool boxes a cinch.

Custom tool boxes to attach to those bottom weldnuts

Drom box attached to to those through the deck weldnuts, a cinch, don't need under the truck guy with a wrench, attaching is done on the top.

Winch system also bolted inside the tool box to weldnuts

Engineering "musing" and the thought process

Finished product

Wonna pick my brains, give me a call

 

 

Edited August 22, 2020 by phoenix2013

[phoenix2013]

Post is all screwed up, I guess there is limit how many pictures you can attach to the a single post.

[HERO Maker]

Yeah! I think I've seen that picture before!!!!

 

 

 

[SuiteSuccess]

Just for completeness realize that wood slats or any separating material has been debated on this forum often.  Some very good fabricators say it is not necessary while others routinely do it.  Henry’s above sits steel on steel as does mine.  No problems in mine in over 10 years and I discussed with my builder the debate.  He has done a lot of steel and convinced me it would be okay.  Our discussion centered around (like Jim’s) what happens when the material disintegrates or wears?  Will the bed start shifting?  Maybe someone has experience with that.

Edited August 22, 2020 by SuiteSuccess

[HERO Maker]

4 minutes ago, SuiteSuccess said:

Just for completeness realize that wood slats or any separating material has been debated on this forum often.  Some very good fabricators say it is not necessary while others routinely do it.  Henry’s above sits steel on steel as does mine.  No problems in mine in over 10 years.

Same with mine Carl.

[GlennWest]

Mine steel on steel. No problems

[phoenix2013]

I fixed the above post, duplicates replaced with the "right pictures". I think the server had a momentary constipation, needed time for the digital enema to do the purge.

[RoamingRanger]

Nice work Henry! Did you model the bed in Solidworks? 

[phoenix2013]

2 hours ago, RoamingRanger said:

Nice work Henry! Did you model the bed in Solidworks? 

That would be yes. Solidworks is the King, everything else is a court jester, or the fool.

But Solidworks is only a quarter of the "fun", turning what you come up with in Solidworks into real thing is the remaining 3/4 of fun.

[phoenix2013]

By the way for all you deck builder, strength does not necessarily come from massive or from bulk. See this "mini deck"

The two horizontal members holding the six roller wheels is a C-channel, 5 inches tall. The vertical tubing and perimeter tubing was 3/4" square tubing, the thickest wall available in that size. Everything covered in 3/16 decking. Strong enough to hold Smart like that.

[Alie&Jim's Carrilite]

8 hours ago, SuiteSuccess said:

Just for completeness realize that wood slats or any separating material has been debated on this forum often.  Some very good fabricators say it is not necessary while others routinely do it.  Henry’s above sits steel on steel as does mine.  No problems in mine in over 10 years and I discussed with my builder the debate.  He has done a lot of steel and convinced me it would be okay.  Our discussion centered around (like Jim’s) what happens when the material disintegrates or wears?  Will the bed start shifting?  Maybe someone has experience with that.

My bed is "Shifting".  As it is 18 yrs old its past time to be pulled off and cleaned up. Just gotta decide if we want to replace the truck with the bed, or ?????

[noteven]

My '98 KW dually has a body that is installed steel on steel.  The interface between the top of the rails and the deck sills bitches and squeaks and chirps.  The Kenworth Body Builder Manual advises an isolation material. It would be just that easy to protect the frame from corrosion. 

 

Edited August 24, 2020 by noteven

[lockmup68]

steel on steel. Charlie will steer you right. 

[RoamingRanger]

I don't want to interject myself into the debate  but perhaps a thin strip of an engineered plastic such as acetal/delrin would be a good compromise. It would prevent corrosion between the two metal layers, minimize squeaking and should not break down or change shape over time.

[trimster]

I'm thinking about Beutithane (sp?).

The thick rubbery membrane used to frost/freeze guard eves on house roofs. Adheasive on one side. 2 layers of that would stop squeaks and allow for a bit of movement.  It's tough stuff. 

Bob