Re: Wandering First Build - Finally Going Again

[dales133]

Havnt realy read your build thread in real detail and ive got to say kudos for thinking outside the box and doing things outside the box... failures part of the process my friend.
I noticed your concern earlier with the profile but i realy like that sleek profile.
I played with my profile a bit and althogh my radius isnt as big as your i prefer this take on the benroy lines.
At the risk of sounding like a sika salesman i love this product and for sealants and specialised adhesives in my opinion they have no comparison.
I think its called 252 but its a specialised assembly adhesive made for rv and truck assembly.
I warn you its pricey but ive seen demonstrations of this with stupendous flexibility and strenth.
I just picked up 10 tubes of sika 11fc for 5 bucks a tube just over thier use bay dates.
Ive sadly used most of what i need of it on this build and i paid 20 plus for it

[tony.latham]

I think you're doing a great job. It's an interesting build.

My first task was to trim the edge of the aluminum skin with a router. I had 2 flush edge trim bits, a small old one , and one larger better one. I tried the dull one first and it it just got clogged with globs of aluminum after a pass of less than a foot along the edge! I cleaned it off and it just kept getting worse each try. It finally would not cut any longer and I became afraid of damaging the skin. I tried the better bigger bit ...

Are those bits carbide tipped? The one photo looks like it's a straight tool steel bit.

I have not had galling problems using a new carbide trim bit on .040 aluminum.

Tony

[Prototear]

KC, Great questions about the seals.

I have the trim seal in hand and have dry-fitted it successfully around the small radius corners on the small doors. It took some muscle to get it there but it just fit on one side and I noticed that it wanted to creep off the metal if I didn't securely jam it down. I think I got lucky since I got my trim seal long before I changed from a simple radius to the jeep fender shape. I might add some adhesive or add some friction under it to keep it from wanting to back off. I am using this one http://www.zoro.com/trim-lok-inc-trim-seal-alum-clip-026-in-w-25-ft-3100b3x332a-25/i/G4062003/. I'll get a picture of it and post it here soon.

The above trim is for the sides and top of the door, and I will use a garage door seal on the bottom like this http://www.homedepot.com/p/MD-Building-Products-2-in-x-16-ft-Rubber-Replacement-for-Garage-Door-Bottom-03749/100353454. My plan is to place the crease of the garage door seal into the small ~0.625" step at the door threshold so that half sticks out and under the door and the upper half is attached to the bottom inside edge of the door so that it is compressed along both the bottom of the door core and also between the exterior door skin and trailer frame. I'll get a picture of a dry fit of that too and post it soon too. I am hoping to use this method on the bottom edge of the galley hatch too, although the side galley seals will be like that on Frank Bear's trailers using trim and seals I got from him.

[Prototear]

I think you're doing a great job. It's an interesting build.

Are those bits carbide tipped? The one photo looks like it's a straight tool steel bit.

I have not had galling problems using a new carbide trim bit on .040 aluminum.

Tony

Thanks for the complement Tony!

Yes they were carbide tipped bits. Since I had that problem and used my aluminum machinist friend's advice it has been working smoothly for me most of the time. I used 1/2" Diablo bits and recently got the same bit by Freud (coincidentally almost the same model number, but they are the same company) and mainly when doing finish trimming after rough cutting in another means (e.g. shears). I have had some bits fail, however, with bearings coming off so I've had to make sure the tiny screw on the bearing is tight. I also used a bit with the bearing on the shaft before the blade rather than after the blade then the bearing seems to hold better since it is not on the tip, but only when I can arrange the material to do it that way. Some, but not all, of the bearing failure may be my doing however if I don't hold the router just right as I move it forward.

[Prototear]

Havnt realy read your build thread in real detail and ive got to say kudos for thinking outside the box and doing things outside the box... failures part of the process my friend.
I noticed your concern earlier with the profile but i realy like that sleek profile.
I played with my profile a bit and althogh my radius isnt as big as your i prefer this take on the benroy lines.
At the risk of sounding like a sika salesman i love this product and for sealants and specialised adhesives in my opinion they have no comparison.
I think its called 252 but its a specialised assembly adhesive made for rv and truck assembly.
I warn you its pricey but ive seen demonstrations of this with stupendous flexibility and strenth.

Thanks for the suggestion, Dales133. I have been considering the Sika 252 and the 291 but was able to get the first Sika product easily on my way home and thought I'd try that.

I peeled off the skins from the honeycomb door cores and cleaned them off. The first one came off the rest of the way easily but the second one was more difficult although it would have failed eventually without my "help" to get it off. I noticed that the epoxy failed more in the middle of the panel and not as much near the perimeter, probably because that is where the clamps were applying the most pressure. It peeled off the anodized surface more cleanly than from the bare aluminum of the skin side of the joint. Given the difficulty scraping it off in certain areas, I think there might be hope for the epoxy to work if I knew better what variables are working against me.

I tried some of the Sika with samples on a scrap of the honeycomb panel to see if it would work before committing to a whole door (even a small one). The scrap honeycomb panel is the one where I had tried to remove the anodized finish so I had different places to try. After sanding and cleaning all surfaces with denatured alcohol, I adhered 4 aluminum skin scraps on different surfaces with different clamps (partly because I own only 2 face clamps but suspect that a stronger clamping force may help)).
1 - un-anodized with face clamp and a overhang for later peel test
2 - un-anodized with spring clamp
3 - anodized with spring clamp
4 - anodized with face clamp



After sitting for a day, they seemed OK, then I put it in the freezer overnight. After sitting all day I tried to pull the skin samples off the panel and they all seemed to have about the same strength. #1 peeled easier because of the overhang and probably a smaller surface area actually adhered. #2 was able to pry up a little, but it had little overhang. #3 and #4 are holding better but maybe because of slightly larger area and less free edge to pry up, or maybe the anodized surface underneath helped. The first impression is that the relative strength might about the same for all of them when considering their area and ease/difficulty of grabbing an edge to peel but maybe those on the anodized surface is stronger. The adhesive is elastic where exposed and can probably take a straight pull force quite well, but maybe the the vulnerability will from peeling loads and in this regard is not much different than the epoxy that failed. Since this is to hold an overlaying door skin, I'd be concerned about it getting caught on something that would put a peel force on it and start the failure. This Sika Universal (from Lowes) seems like very strong adhesive for the right use, but I'm not sure yet whether I'll use it here. I wonder if the Sika Aktivator 205 would have helped here.

I may try the Sika 252 next, and from what I've read should use the Sika Aktivator 205 first (apparently used to be called Sika cleaner 226). The best prices I'm finding for this so far is on http://www.EMIsupply.com Stay tuned....

I also found a handy tool online for deciding what adhesive to use on different surfaces here http://www.adhesivestoolkit.com/Docu-Data/SurfacePreTreatment.xtp although it is gives general types and not specifics.

[Prototear]

I have continued experimenting with the adhesives to see what holds the aluminum together well. Here is a closer look at the failed samples:



1 - peeled using only my hands. Some of the adhesive is left on both surfaces
2 - could pry somewhat with screwdriver under a free edge but would have had to get more leverage to actually peel it back.
3 - pried off with screwdriver. hardly any adhesive remains on the back of the sample and almost all is stuck to the anodized surface.
4 - could not pry back with a screwdriver. I think the biggest factor is that this is 0.063" thick compared to the rest that were 0.040" but there was also less of an exposed edge to get the screwdriver into.

What I've learned from this is 1) I'm glad I'm using the thicker 0.063" thick aluminum for the door overlay since it will be stiffer and harder to peel, 2) adhering the outer edge will make it more resistant to peel, 3) both the epoxy and Sika Universal work well on the anodized surface but don't work well on the bare aluminum. It seem that better prep of the bare aluminum surface will be important.

With more research I found out the surface needs cleaning, abrading, degreaser then a condition it with acetone or 99% isopropyl alcohol. There are other more complex methods with chemical etching but I would rather not get into the complexity and expense of those. I figured my next step would be to do a thorough prep using easily available materials. Using multiple samples of the same 0.063" thickness and prepared the same way, I figured I'd try to see if what I had available could work. I was out of acetone so I bought some and also saw another affordable high strength polyurethane product to try http://www.homedepot.com/p/Loctite-PL-Premium-10-fl-oz-Advanced-Polyurethane-Construction-Adhesive-1417170/202192562

I sanded all surfaces with 220 sandpaper, cleaned it with citrus degreaser (normally used on my bike chain) and conditioned them with acetone and let it evaporate off for 6 samples and another scrap of the honeycomb panel.

1 & 2: Loctite 2-part epoxy
3 & 4: Sika Universal polyurethane
5 & 6: Loctite 8X polyurethane

The surface area of each one was similar (although slightly different) and I left an overhang similar to what the door skin will have so I can do a peel test later. Here is the initial setup from Wednesday night:



Thursday evening I took off the clamps to check the holding power of each one:


I tried peeling each one by holding the sample set down on a table with my left hand and prying as follows:
Peel test with just right hand: Samples 5 and 6 readily peeled off but samples 1 through 4 held strong. Most adhesive remained on anodized surface but some remained on the bare samples.
Peel test using pliers for better grip and leverage: Samples 1 & 2 popped off with moderately high force. Back of bare aluminum samples were clean with no visible epoxy remaining, all epoxy remained on anodized surface.

Samples 3 & 4 held with pliers test with at least as much force was applied to pop off samples 1 & 2 but I felt a very slight give on sample 4 - it might have started to peel if I were to apply much more force. I stopped there so I could retest them again later since the label on the Sika product says it can take 5-8 days to fully cure so there probably more strength to come.



If I had to make a decision right now I think I can make the Sika Universal work with good surface prep and making sure the adhesive flows out to the edge so that it is difficult to get a peel starting. I'll see how samples 3 & 4 are doing this weekend after curing longer. In case the completed door starts to peel in the future my fallback plan can be to include just a few rivets in the door away from other fasteners that will hold the hinges, latches, and trim to the door. I'll think more about it but will want to get back to actual assembly of the trailer soon....

[Prototear]

I decided to try skinning one of the small doors (left side) with the Sika Universal adhesive with good surface treatment. I set it up with lots of clamps on Saturday. It seemed solid so I started the right side door on Sunday and I'll let it cure overnight. This is the left door:



After wrapping the Trim-Lok seal around the top and sides then carefully placing the hinges, Here is the dry fit in the side of the trailer.



I cleaned about 1/3 of the door skin with Mother's aluminum cleaner before mounting the hinges on the door. This was the first time trying this stuff and it cleaned it very well - that took only about 2 minutes and the whole door would have taken another 4 minutes or so. The cleaning can wait for later.

I expected the hinges needing a spacer underneath them as described in Dave's Atma Travelear but was surprised that I will need a much thicker spacer. The combination of the way I mounted the skin overlay plus the Trim-Lok brings it out to 5/16" rather than just 1/8".



I had started to make the 1/8" spacers but will need to either stack up multiple spacers or just get some thicker stock to make a single thicker spacer. This door is almost done, but it has taken a long time just for this simple door. The time and effort makes the price of the pre-made doors seem like a bargain, but this way I'm getting what I wanted.

[Prototear]

I was surprised to see that it's been a couple months since my last entry, but I had lots of distractions and my garage got messy again. I spent a few hours this holiday weekend cleaning the garage and moved my larger sheet goods under the trailer (plywood, aluminum, insulation) so I can work more easily around the trailer since I will likely keep it in the garage all winter. When the weather was nice I had pushed it out into the driveway for easy access.

I got back to the rear left side door to get it to fully close - the clearance on the forward inside honeycomb panel hit the door jam frame before it closed all the way so it needed to be trimmed just a little bit to close. Up to this point I had cut and included the 1/4" aluminum spacers behind the hinges successfully, but the door didn't quite close. It can be forced to close but that starts to bend the door and strain the hinge attachments.



I figured I'd use the router set to a precise depth to remove the 1/2" honeycomb from the recently glued-on exterior skin. Since it just needed a little trim of slightly over 1/8" wide and 1/2" deep, I figured I'd make the cut with the door in place. On prior trims before installing the door I had used the table saw with a few passes to control the depth but my table saw was still buried and wanted to keep my mess contained in one area. Gee - what could go wrong.......

Looking down above almost-fully open door with 1" oak plank for straight edge to guide the router:


I made the trim successfully part way down then started to trim upward to finish it. On the upward motion the bit must have migrated outward from the router and cut about 1/16" deeper and cut a slot into the exterior skin behind the hinge!

This shows the areas trimmed with the unplanned slot. The green line on the edge shows what I had intended to trim.




I removed the door to confirm my worst fears and had to figure out want to do next. I didn't want to rebuild a new door (it took too much effort to get this far, but that is an option I could explore later) and I didn't want an ugly patch either. I came up with a patch idea that would minimize unsightly out-of-place lines and prevent extra fasteners yet put a watertight patch over the hole. Most of the patch edge lines will be parallel to the hinge contour so hopefully won't be too distracting.

I first made a template of the patch, then cut it out of scrap aluminum sheet with a trim router bit. Here it is dry-fitted to see how it looks.


Here it is after being placed and glued with some leftover Sika Universal with clamps to keep the edges flat.


My little shortcut to trim the inside door edge in place cost me over 4 hours work to recover with a little worse outcome (with a patch). My next step will be to removed the clamps and clean up the door skin and try to install it and hope I solved the door closure problem, then move to the other rear side door.

[KCStudly]

Nice recovery.

Hopefully you won't have to shim the fixed side of the hinge by an equal amount.

[tony.latham]

Thanks for sharing the adhesive tests. I'll have to find the source of the Sika stuff.

tony

[Prototear]

I got the Sika at Lowe's.

[tony.latham]

I got the Sika at Lowe's.

And the nearest Lowe's ––or any other real box store–– is three hours away... That's what defines Salmon, Idaho.

I'll just have to grab a couple of tubes next time I'm in the city.

Tony

[Vedette]

Way to hang in there Steve!
What a project! I bet you have learned a lot more then you anticipated in the last couple of years??
Have a great winter!
Hope to see you out and about around the PNW in 2016!
Good Roads
Brian & Sandi

[Prototear]

Upon installing the door I found that my costly fix only fixed it slightly and there was still a gap in the door closing flat. Despite using a 1/4" spacer under the hinges there was still a gap. I pulled off the edge seal to get a good look at the edge and confirmed it.


The the Trim Lok edge seal was fully compressed near the hinge so it became clear that I needed a little more spacer under the hinges. Even with one more 1/8" spacer under the hinge since it STILL wasn't laying flat but at least the seal was no longer fully compressed near the hinge. Here is a view with a flashlight shining from inside to show the gap, first with little seal compression then even with seal compression there was still light leaking out in the upper corner.




I began to think my door was warped but it didn't make sense that the super flat honeycomb core would have warped unless it was due to having a bulge of adhesive under its outer skin. I checked it with a straight edge and it was pretty good so this left only the trailer itself. Using a straight edge along the inside of the frame we can see that the frame is about 1/8" out of flatness (most evident due to a gap on middle of 3 vertical frames near the 470mm mark). This was more evident at the top of the door but almost nonexistent at the bottom of the door.


I didn't want to shim the space between the frame and skin as it is applied with VHB tape and I don't have any left (it is almost $1/foot and I'd have to make a minimum purchase with a delay to have it delivered). I thought of bending the outside of the door skin slightly but would prefer that it stay flat - this could be done but I wanted a better solution.

I rigged some leftover 2x1" steel channel to help carefully bend out the frame slightly at the upper aft corner of the door frame. I welded a little T piece at one end with a 11 degree angle to surround the vertical frame member and put another little T at the other end to accommodate a jack. A beveled scrap of 4x4" fence post was used under the jack to spread the load at the bottom of the opposite wall. Even with applying the force slowly, it took less than 5 minutes to bend it but about 2 hours to find materials and set it up. The frame creaked a little as pressure was applied and there was no sign of other collateral damage from the alignment.
This is looking from the right aft corner of the trailer toward the left aft corner.


I made some spacers to fill the whole 3/8" instead of the multiple stacked spacers and installed the door and it almost completely fixed the gap! There was still just a hair of a gap remaining so I used some sheet metal bending pliers and just slightly bent the upper corner of the door skin inward and this finally resolved it. In the end, there were 4 things done to get the door to lay flat to get a reasonable seal:

1. Binding on inboard edge of door hitting frame (not doing this trimming carefully enough led to the collateral damage (hole) that had to be patched in the door skin).
2. Extra spacer beyond initially planned 1/8" (eventually ending on 3/8")
3. Aligning the trailer wall frame with a purpose-made rig
4. Fine tuning with very slight bending of door skin with sheet metal pliers.

This is how big my spacers are (as seen on the drill press). Trying to make these fit precisely enough and look fairly decent takes time.


I wish I had been able to get the outer door skin to lay almost on the exterior wall skin but the thickness of the seal I found to work for me lead to pushing it further out with the thicker spacers. If there is ever a chance to use a thinner seal that can also look reasonable I can always change the spacers with thinner ones. For now I will stay with this so that I can get on with the rest of the project and finish someday.

Next I am ready to install the other small door on the opposite side. I hope this will go more smoothly now that I have worked my way up the leaning curve on this. Once these smaller doors are OK I can move on to the 2 main doors.

[noseoil]

Steve, good job working out the kinks on your door. None of us were born knowing this stuff & education can be expensive! The next door will be easier & the last one will be "Heck, this isn't too bad after all." When everything is in place, it will be worth it.

That's why the moaning chair was invented many centuries ago in a boat-building shed. It usually had a nice shiny seat area....