Generic Benroy Foamie in NE Wisco

[TimC]

My son and I are starting a build which is my # 2.5 build and his first. I still have #1 which is similar to this one with more extensive mods from Mike's Generic plan here on tnttt. I started a second build but after getting halfway and storing for the winter I never was motivated enough to finish and my brother has adopted the project and will soon be road worthy. I'm excited to start a third build with Andy for he and his bride. We hope to get it on the road this fall. Wish us luck...

#1 was built on an overbuilt custom steel trailer by a local welder. Really overkill on beef. #2 was on the NT 5x8 steel version. This TD will be on the NT aluminum 5x8 which is at the local truck terminal waiting for pickup.

I want to thank George (ghcoe) and GPW for their advice on foamies and hotwire cutting.

Mike S. Generic wall profile on 2" foam.


Surforming the profile after a slow hot wire cutting session.


Laying out the rough locations for bulkhead, cabinets and door with an upgraded 13" wheelset.


Floor is two 3/4x4'x8' GC treated plywood cut to finished width of 64" for a designed two inch overhang on the left and right sides. Here is my attempt to waterproof the bottom with roofing tar. It's worked on TD #1 for years so repeated the effort here. But, talk about watching paint dry! Used a biscuit cutter and plowed a slot along the mating seam. Rather than biscuits I think I will just cut a spline to hold the joint firm.


Next up is receiving and assembly of NT trailer...

Tim

[TimC]

The NT aluminum trailer arrived so began assembly. By design the axle sits just behind the center point of the frame. We want it to be back as far as 40 percent from the rear to increase the tongue weight a bit.

This is the designed location


Moving the axle back to 38" from the rear requires a few minor modifications. Move the second from rear cross member back to the next predrilled hole and mount the rear hole of the spring retainer frame into that hole. The spring retainer move requires two holes to be drilled for the third and fourth cross members. The fourth cross member is bolted at the front of the spring retainer. Instead of the two center cross members sandwiched together they are spread about six inches apart as shown here.



This is the same axle placement I used on TD#2 except on this build I did not mount the axle slung over the springs. Andy decided the designed height was good on the floor so we installed the axle slug under the spring as it was designed. If slug over it effectively lowers the floor by about three inches.

After assembly I mounted the upgraded 13" wheels. We are going to order 14" hub spacers to bring the tire away from the spring retainer bolt head. A little too close for comfort...


Spacers will also help with a problem that just showed up. We were going to hang the floor two inches over the frame on the sides so there would be no need to trim a queen mattress width. We'll have to modify that plan a bit.


Next up...order a plate to adapt the a-frame tongue jack to the trailer from a local welding/fab shop.

Also we'll be determining whether to trim the mattress and by how much. Or modify how the wall wraps around the tires. It might be a combination of both.

Edit... A solution came to me this morning and we're going to run with it. We really want to go with a 60" interior width. That uses materials efficiently as well as not having to trim the mattress. We are going to cut the axle at the midpoint and add to it with 1" black iron pipe which should fit in the U shaped axle with very little machining.

Buttoning up a few little things to finish the trailer assembly.


Tim

[Mr. Lahey]

Looking forward to following this build. Love the classic Benroy profile.
The combination of aluminum trailer and foamie construction should finish out very light weight.
Keep up the great work.

[pchast]

It might be a combination of both.

Edit... A solution came to me this morning and we're going to run with it. We really want to go with a 60" interior width. That uses materials efficiently as well as not having to trim the mattress. We are going to cut the axle at the midpoint and add to it with 1" black iron pipe which should fit in the U shaped axle with very little machining.

Tim,

The axle normally has a bend in it to provide camber that straightens on weighting it. Please check it with a straight edge before cutting. Then be sure to brace the same into your extension repair.

[TimC]

Thanks for the warning Pete. No camber in this one. It's straight as an arrow. And my brother in law is a recently retired life long pipe fitter with awesome welding skills. I have no fears that this task will be a problem.

And as folks read through this build don't hesitate to bring up concerns. I'm confident about many of the build tasks, but, building with foam is all new to me. Especially the task of building the hatch out of mostly foam. Not sure about that, so chime in when you can.

Edit... Began the axle extension. It went well. Was 68 1/4" hub face to hub face. Now 72 7/8" face to face. And no longer a need for spacers. I've allowed for 3/4" to 7/8" clearance tire to wall.

Calcs done


1" black iron (Sch 40) pipe is about .023 wider than the Uchannel in the axle. I ground down opposite sides of the pipe a little more than half that. The pipe will fill the void in the C channel from spindle to spindle.


Cut axle in half


Fit and futz


Fitted and ready for fire




Prime and paint


As Pete warned there may be some camber to the axle. Usually good quality trailer axles have camber built in. This is a NT trailer. Not saying it is not quality, but, no camber is designed into the axle for the light use they expect it to be used for. So, as I learned today, when welding, metal moves. An experienced welder knows how to limit the movement and/or use it to their advantage. My bro-in-law is one of those experienced welders. The result of his skilled craftsmanship is the hub faces as well as the axle are now slightly cambered. I am happy that as weight is added to the trailer the toed in tires will settle into a nice flat area across the tread. I don't expect too much more than 1200# ever being loaded on this trailer so the slight camber will be perfect.

Addressing the trailer quality... this is the 5x8 Northern Tool Aluminum trailer, Ultra Tow brand I think is the correct name. I'm impressed with everything about this trailer from its aluminum gauge to its design. The only shortcomings are the fender and the turn,brake, tail light frames. Those are junk. I wasn't intending to use either so not a problem. The only other thing I would like to warn folks about is the axle and hubs. For the purpose that this trailer is intended they are all of sufficient quality. The axle just proved to be short for our TD design. When I contacted NT about getting a longer replacement I was told that the hubs/bearings would not fit the longer axle. So, rather than spending $200+ on a new axle/hub set we choose the route described above (total outlay for the axle extension was $25 for a 10' length of 1" black iron).

Bearing set is available, 30205/P6 ( https://www.amazon.com/XiKe-Bearings-30205-30x52x10mm-Bearings/dp/B01H5QP9AC and other sources. NT has no info to share about race sizes : ( I'll share other bearing/race info as I receive it. Per NT... "The bearing size is 2.05" x 1.18x 0.39". The inside diameter is .98"."

Tim

[TimC]

Trying to build some confidence in foam gluing methods. Some tests...

Front to back
Edge glued - PL Premium wet, PL Premium dry (water added or no water)
Sandwich glued - PLP wet and PLP dry
Edge glued - great stuff
Sandwich glued - great stuff


NT Trailer is mostly assembled with new extended axle. Only the tongue jack plate to pickup, paint and install. Then on to prepping the foam walls.

Hot wire jig for wall to floor cleat.


My cheapo soldering gun will only melt about half the depth in one pass, so angled the jig and did a second full depth cut after this pass.


Two walls hot wired for cleat.



Tim

[MickinOz]

The axle normally has a bend in it to provide camber that straightens on weighting it.

Exact opposite here in Oz. Trailers meant for towing behind normal cars and 4WD normally will not have a camber built in. The axles are big enough to have no noticeable flex at their rated load.
We can buy cambered axles, but usually for much heavier loads.

[TimC]

The axle normally has a bend in it to provide camber that straightens on weighting it.

Exact opposite here in Oz. Trailers meant for towing behind normal cars and 4WD normally will not have a camber built in. The axles are big enough to have no noticeable flex at their rated load.
We can buy cambered axles, but usually for much heavier loads.

I was about to post something about everything in OZ being opposite but thought that would be inappropriate Many things here are messed up, so, there's that!

[TimC]

Trailer floor is attached and now we can verify fender/wheel location and method to anchor the fenders. Walls are dry fit in these photos.





Thinking about placing a spacer of solid treated wood between the trailer frame and the end of the ply floor approximately the shape of the fender. Then bolt the fender through that and through the trailer frame front and back. Additional screws to anchor the fender into the floor/wall cleat shown on the final photo (it runs the entire eight feet). I may add additional cleat material higher up to get one more fender anchor point.

[Mr. Lahey]

Tim

I'm following along pretty close here. Kind of have a foam project in the back corner of my mind. You had welcomed questions in an earlier post so here goes.

Questions are on how you chose the method to anchor foam walls to floor. I see how you cut the center channel in foam to insert plywood center. Question is why that way instead of just a lap joint favoring either inside or out side edge of the foam panel? Just cut a 90 degree lap in foam and flush the wood to either face of the panel. Seems with wood in center there are two thin "legs" of foam straddling the wood. Leaves two thin areas where foam could break? with a 90 degree lap foam would be twice as thick where it mates with wood.

Are you going to use plywood for center spline in foam as shown? Would you be better off with a piece of solid lumber in there? I take it you plan to screw up through floor into spline to attach wall to floor? If so screws into plywood end grain are not the best way to go.

Really appreciate your post as I mull over how I might go about a foam build myself. If the day ever comes to do so.

[Pmullen503]

Once the canvas is on (make sure you wrap around the corner and glue to the bottom of the floor) that joint will be secure. Having the wood (floor) at that corner will give dent resistance to that corner.

A couple of things I wish I had done on my foamy: I wish I would have wrapped all the way over the frame rails. I stopped short (so I wouldn't have to unbolt the body from the trailer and set it above the trailer on blocks) of the frame rails and those edges of canvas are starting to fray/delaminate. Second, I should have incorporated a drip rail at that corner. Rain and dew run down the walls and crawl around the corner and hang on the underside of the floor keeping it wet. No obvious damage yet but the constant wetness can't be good. It would have been a simple matter to have added a triangular strip along to corner to create a drip edge. I plan to do this on my next build.

[TimC]

Some pics to post of today's progress, then I'll address your questions...

Andy is home for a long weekend and we hope to have the walls and bulkhead mounted in the next three days. The goal posts are moving and we may be pretty ambitious!

Andy using my ingenious soldering gun jig to cut dados in the door frame for plywood.


Andy discarding my soldering gun jig and freehanding the cuts...






Inside-out ceiling panel being glued up. Anything I had laying around for weight. And again for KC's enjoyment, the required pool noodles to assure things are held down! Remember that KC? (pg 2 of my first build)

[TimC]

Tim
Questions are on how you chose the method to anchor foam walls to floor. I see how you cut the center channel in foam to insert plywood center. Question is why that way instead of just a lap joint favoring either inside or out side edge of the foam panel? Just cut a 90 degree lap in foam and flush the wood to either face of the panel. Seems with wood in center there are two thin "legs" of foam straddling the wood. Leaves two thin areas where foam could break? with a 90 degree lap foam would be twice as thick where it mates with wood.

Are you going to use plywood for center spline in foam as shown? Would you be better off with a piece of solid lumber in there? I take it you plan to screw up through floor into spline to attach wall to floor? If so screws into plywood end grain are not the best way to go.

Really appreciate your post as I mull over how I might go about a foam build myself. If the day ever comes to do so.

Mr L, yes, you are right that solid wood would be better. And all my years of woodworking as a hobby has presented many lessons of why not to screw through the edge of plywood. Yet, here I go ignoring that lesson. I think that the trim we will add to the interior floor/wall seam will help in that matter. It will be anchored to the floor as well as to the wall inot the face of the ply with screws and glued. I intend to add trim to the outside edge as well and its anchors will go through the face of the ply as well. I hope it holds up. I've read several posts which state that glue is enough (not sure I agree, but don't have experience with foam to really say). I will be covering that outside corner with PMF as well and anchoring that under the extended floor with a trim piece with a drip edge as PMullen described. I understand the idea is that the "sock" of PMF is what gives the foamie the strength needed. The other thing I am depending on is when I built TD#1 I came to realize how much support the bulkhead, cabinets and headboard add strength to the whole package. I'm not too worried about separation as those items reinforce the walls well.

Keep the questions coming. I'm no expert, but, hope to help out anyone thinking about building a foamie. There's more expertise on tnttt to help there as well. And, maybe I will show examples of what not to do occasionally

[TimC]

Dry fitting the walls and lower bulkhead.



Scratching the foam walls to prep for PMF. An old wire brush makes fast work of perferating the foam.


Before...


After...

[TimC]

Put finish on the lauan ceiling panel and PMF'd the walls.











With temps reaching 90 today we are going to do some work in the basement shop. Drilling pilot holes to mount the fenders and possibly paint the fenders. Then pocket holes for the bulkhead attachment to floor and middle section of bulkhead. Hope to fit the walls and bulkhead pieces this evening when things cool down a bit.