Sawtooth XL Build

[DanCooper]

The Pictures Speak For Themselves

BOOM!





















Then the wind started blowing and we had to shut down for the day. The forecast is for rain and strong winds.

We did get a late start, about 10:00, and closed it down at 3:00. Spent about two and a half hours of that trimming the roof panels to an exact fit to the width of the floor. Everything fit with a minimum of persuasion, which I think is remarkable given that the humidity today varied between 43% and 79% at the shop's location.

 

[indiedog]

Now you are talking!

 

[DanCooper]

Instead of sealing them with JB, weld a nut to the bottom under the hole, so you can thread a bolt into it and have a drain in case you do get water in there. Other alternative might be to use something like this: http://www.grateseal.com.au/ though I've seen them in motive power applications, so you may find something more suitable. They do seal against slight submersion.

Both of those are good ideas. I never think of the welding solution, and the second idea really appeals to me. Thanks!

 

[stomperxj]

Awesome!!

 

[Taylor1982]

Been looking at these for awhile now, mostly why I joined this forum. Wondering what you will be using for final outside material? As stomperxj had said he was going with something composite for his next one? Great job so far. Enjoy looking at all these trailer build journeys.

 

[compactcamping]

BOOM!
View attachment 354022

Coming along great, always nice when it "starts" looking like the planned finished product

 

[DanCooper]

Been looking at these for awhile now, mostly why I joined this forum. Wondering what you will be using for final outside material? As stomperxj had said he was going with something composite for his next one? Great job so far. Enjoy looking at all these trailer build journeys.

This will be all plywood, and the top coating will be MonstaLiner, a bed liner type product. Hope to be doing that next week if the weather holds.

 

[DanCooper]

Who knew it would take most of a day to install ten little pieces of curved wood?







Looking forward with trepidation to the kerfing of the inner and the outer skins to fasten to those pieces. Here is where I really wish I had my track saw with me! We spent the rest of the day noodling the rear/galley hatch and the rear roofline. We've mocked up a couple of different versions, but I'm still not quite happy with the way it looks. I will keep playing with it until I am happy.

 

[DanCooper]

A Few Frustrating Days

Spent Saturday doing final conceptualization of the rear galley hatch, and odds and ends. I heard a loud crash followed by yelling, and ran inside to find my brother under a pile of plywood and parts. He slipped, fell to his knees, and some panels that had been leaning while awaiting their turn to become sawdust fell on him. He banged up his knees pretty badly and squashed one fender pretty flat. Thankfully, he was not immobilized.

I spent the rest of the day cutting some 1/4 inch panels for skinning the exterior and interior. I cut them overlength so they can be trimmed to exact fit once glued and stapled into place.

Sunday I started kerfing the rearmost roof panel. First, I experimented on some scrap material. Before that, I used Mr. Google to try and find a formula or schedule for kerfing different thicknesses of material. I did find one formula, but it was just flat wrong. But it did occupy my time. At my age, I don't buy green bananas, so I need very few time wasters.

I corresponded with Jess and reviewed his build thread on the original Sawtooth XL. At post 186, he describes kerfing about 2/3 of the way through the material, at 1/4 inch spacing. The photos there corroborate that. He had no apparent problems, and his curves are well faired.

I tried twice to cut kerfs that would allow the plywood to bend around that 7 in radius and was unsuccessful. Spectacularly unsuccessful. The first time I cut the kerfs too deep, I think. The second time I got out the digital caliper and measured the plywood. It was 13/64 thick, made of three plies: Two outer plies of 3/64 and an inner ply of 7/64. So I calculated a kerf of 1/8 inch would be a little less than 2/3 of the total thickness. To compensate for that .67/64, I made the cuts on 1/4 inch centers.

No Bueno. It seemed to do well while test fitting but failed at several points while installing it. This was after several hours of measuring, laying it out, setting up the cuts, cutting, and test fitting. To say I'm bummed is an understatement.

Anyway, I think I will go get some door skins tomorrow, and try them. I tried a piece of scrap door skin, and it made the curve without kerfing. If I glue and staple one down, let the glue set, and then laminate another skin on top of that, I should have the strength and thickness I need.

However, if anyone has any suggestions, I'm open to reading them.

 

[stomperxj]

I corresponded with Jess and reviewed his build thread on the original Sawtooth XL. At post 186, he describes kerfing about 2/3 of the way through the material, at 1/4 inch spacing. The photos there corroborate that. He had no apparent problems, and his curves are well faired.

However, if anyone has any suggestions, I'm open to reading them.

Dan I think I remember that when I made my test pieces they were only about 6-8" wide and it seemed to bend fine but the full width sheet was a lot harder to bend. I think I ended up boiling some water and using rags to soak the kerfed area. Sorry I didn't mention that before but it just popped into my head reading your update. The radii on your trailer are larger than the original too just for that reason. The original was 6" to the outside of the skin.

 

[indiedog]

Hey Dan. Sorry to hear about your kerfing issues. Couple of questions/suggestions.

1. Do you guys have access to "bendy" ply there? Boat building companies will sell it and it's made for such applications where it bends in one direction only. Might be worth taking a look.

2. For the 3ply you are using, do you have the outside plies running across the trailer so that the grain direction best suits the desired bend?

3. Is the wood species used in the ply suitable for bending? Some are, some aren't.

4. Can you just kerf and sheet a small section so there's less chance of handling breakage?

I'd chase up a plywood manufacturer or boat materials supplier locally who knows their stuff and tell them what you are wanting to do and see what they suggest. Materials differ depending on your location and supplier so what you are using may have totally different characteristics to what Jess got.

Anyway, good luck with it.

EDIT; I see Jess suggested wetting the ply. I avoided saying that as some of it can develop mold depending on if it's exterior grade or not.

 

[DanCooper]

Hey Dan. Sorry to hear about your kerfing issues. Couple of questions/suggestions.

1. Do you guys have access to "bendy" ply there? Boat building companies will sell it and it's made for such applications where it bends in one direction only. Might be worth taking a look.

2. For the 3ply you are using, do you have the outside plies running across the trailer so that the grain direction best suits the desired bend?

3. Is the wood species used in the ply suitable for bending? Some are, some aren't.

4. Can you just kerf and sheet a small section so there's less chance of handling breakage?

I'd chase up a plywood manufacturer or boat materials supplier locally who knows their stuff and tell them what you are wanting to do and see what they suggest. Materials differ depending on your location and supplier so what you are using may have totally different characteristics to what Jess got.

Anyway, good luck with it.

EDIT; I see Jess suggested wetting the ply. I avoided saying that as some of it can develop mold depending on if it's exterior grade or not.

Thank you for your suggestions. I am going to run up to Edensaw Wood in Port Townsend this morning and talk to them. They have some 6mm poplar in 4x8 sheets that they describe on their web-site as "bending-ply." And it looks like they sell it in two versions for bending in different directions.

I am using 1/4 inch birch plywood with only one veneer of birch. I am bending on the long axis because I am spanning approx. 63 inches. The outer veneer grain runs on the long axis, so directionally it is good. I don't have a moisture meter with me, so I can't tell the current moisture content, and a guess is worse than useless here. But I agree that the problems bending it may be because I am using the wrong type of plywood.

As a note to future builders, there are many applications in a build like this for a track saw. This is one of them. With the track saw system, you can get very precise depths of cut. Moreover, the track system will keep the sole plate of the saw from lifting. When using a circular saw like I did, you have to visually inspect each kerf to make sure it is of uniform depth (discovered that in the testing and experimenting phase). The sticky track bottom also makes it much easier to line up for each cut. I've been using a Bora straight edge that requires clamping. Since I didn't bring my track saw with me, I'm going to stop at the tool rental store and see if I can rent one. Finally, this is most easily done as a two-person job. That way you will have someone with whom to share the experience, and also someone to move the other end of the track/straight-edge to the next little tick mark in the seemingly endless succession of little tick marks.

 

[DanCooper]

Dan I think I remember that when I made my test pieces they were only about 6-8" wide and it seemed to bend fine but the full width sheet was a lot harder to bend. I think I ended up boiling some water and using rags to soak the kerfed area. Sorry I didn't mention that before but it just popped into my head reading your update. The radii on your trailer are larger than the original too just for that reason. The original was 6" to the outside of the skin.

Thank you, Jess. We briefly considered that, but moved on. We will give it a try in the next iteration of this step. My brother, a carpenter by trade, is particularly frustrated because you could do this (and did it!) and he can't figure out how to do it too. He has done a lot of kerfed wood work, for staircases and the like, and has used steam boxes, etc. but this one has him stumped.

Did you put the rags on the wood and pour the boiling water over them as you bent it, or just soak the rags, place them on the plywood for a few minutes and then bend the wood? Any further description will be appreciated.

Dan

 

[stomperxj]

Thank you, Jess. We briefly considered that, but moved on. We will give it a try in the next iteration of this step. My brother, a carpenter by trade, is particularly frustrated because you could do this (and did it!) and he can't figure out how to do it too. He has done a lot of kerfed wood work, for staircases and the like, and has used steam boxes, etc. but this one has him stumped.

Did you put the rags on the wood and pour the boiling water over them as you bent it, or just soak the rags, place them on the plywood for a few minutes and then bend the wood? Any further description will be appreciated.

Dan

Tapping into the memory banks I think I set up a camp stove in the shop, boiled the water and laid rags/small towels out across the kerfed area and poured the water onto the rags, let it soak several minutes. I spread glue out while the rags were sitting on the wood and then quickly dumped the rags off, threw the ply on the roof, lined up the back edge on the top and started stapling. I do remember it being a huge pain in the *** and I may have used ratchet straps and 1x2's across for support. I cut my skin about 1" wider than the body so I didn't have to worry about lining up the edges while trying to go around the bends and then used a flush trim bit afterwards. I actually ended up using a roundover bit on the top edge for aesthetics.

 

[DanCooper]

A Mere Modicum of Success

I took a drive up to Port Townsend yesterday morning to visit Edensaw Wood. It wasn't too busy yet, so I was able to talk about the problem I was trying to solve with both the counter guy and the plywood guy in the warehouse. After looking at various options, I agreed with the plywood guy that the best option for this application was some 8 mm (3/8 inch) Falcata Albizzia bender ply short grain, a type of meranti grown on plantations. It is very bendy. I bought 3 sheets, loaded it on the Subaru, and headed back to Lofall.



Once back at the shop, I built some jigs to hold clamps to help hold the panel on the front while the glue set. This really makes a difference. Trying to use the door frame alone as the clamp anchor will cause even a devout man or woman to raise their voice. And even mutter imprecations sotto voce.



After giving a few flying lessons to certain clamping devices that tended to fail in their intended purpose, we got the thing skinned. There is, of course, a transition issue between the 3/8 inch nose and front,and the 1/4 inch rear roof panel. I will laminate a 1/8 inch door skin on top of the 1/4 inch panel to even it up.



Over the weekend I was also able to mock up the galley hatch hinge. Yes, it looks rough on that corner, but I will learn how to patch plywood on those corners. I have a pound or two of clean sawdust and almost a gallon of resin, so something ought to work out here.



And here are some miscellaneous shots of the wiring for the ceiling fan and light. Nothing special.



Finally, an example of the kerfing. These cuts are 1/8 inch deep in 13/64 inch material, cut on 1/4 inch centers. It takes a while to do this.



Today's work plan is to finish installing the skin on the roof, and then start filling holes. Earlier in this build, I had some idea that I was going to build this with minimal penetrations into or through the outer skin. That was very, very, very foolish. I have staples and screw holes all over. So today will be fill and sand, and if I'm lucky, laying down a coat of CPES. I don't expect to be lucky.