Hindsight is [almost] always 20/20...

 As I've said before, this trailer has been a very agile project.  There have been more than a few compromises, changes, and adjustments on the fly, and hey - in my defense, I've never done this before, and some of the 'rules of thumb' are an opportunity to insert your thumb between the board and the hammer!

In this case, I'd designed the trailer frame with a standard hitch receiver mounted on the tongue.  If I'd thought about this just a little more carefully, I _might_ have calculated the weight of the rack, and the bikes and factored that extra 125lb into the calculation for axle placement - and moved the darn thing a few inches forward.  As it was, my tongue weight was closer to 230lb with the trailer loaded, so 300 would be very much too much.

But that's all water under the bridge.  Fast forward 10 months to now, and I realized that in order to bring bikes they'd either have to go on the roof of the car, or on the back of the trailer.  I opted for the latter.  Having acquired fairly decent CAD skills, I sat down and whipped out a very elegant folded piece of 1/4" steel, and sent that off to Send-Cut-Send.  Nope, the drawing was not something they could work with, and from the sketch, the price would easily buy enough steel to rebuild the whole darn frame...

So back to the drawing board.  I started looking at hitch bits on the internet, and realized that all I really needed was a simple plate that could be replicated 3 times, and a steel tube for the receiver.  Twenty five minutes later, I sent the new drawing off to Send-Cut-Send and received a quote that was *much* more reasonable (and in line with my target.  

A week later, I received my 3 plates in a plain brown wrapper - FedEx guy commented that he didn't think the dog could carry it (she loves to handle the 'last mile' for FedEx), and he was correct.  A quick trip to CoreMark for a 36" chunk of 'receiver tube (2.5" sq tube, .25 wall), and I was on my way to the shop for the evening.  A little filing to open up the hole in the plate, a fair bit of time with the flap wheel to clean everything, and then a quick trip to the MIG welder, and I was on my way.  The welds look horrid if I judge them fairly, but there's more than enough to keep the plates from ever breaking loose - and all three plates would have to break loose before the tube could move. A little cleanup with the flap wheel, a good wash down with acetone, and a couple of coats of primer and it's ready to finish coat.

A signature of mine is that any major project I do contains one red component.  I started this years ago building bike wheels, with one red spoke nipple, and even before that on sailboat repairs, using red nail polish to cover a screw head (usually in a bilge).

In this case, I went slightly overboard...

It's bolted to the frame with 4 grade 8 bolts, across both the rear and next cross tubes, and it's definitely solid. I need to re-check the tongue weight, but I think it took about 50lb off the tongue.  It does make the trailer a little more 'lively' to pull - it was so dead solid, but still less so than many boats I've pulled over the years on factory trailers.  

It'll probably be spring before I have a picture of everything - the trailer is in the garage, most likely for the winter, but I promise I'll post more pics to "Life in the Swamp" next spring, and any additional construction details here as they get done this winter.  Yes, there are still at least 10 projects to be finished on the build before it hits my definition of 'done'.

What's that over head? Roof, Roof? No...

 It's the ceiling you stupid dog...

Alright, I know - it's one of the worst dad jokes, but that's where we are today.  The ceiling is in, and I'm working on things like wiring, blocking, and poking holes in the side of the trailer (truly an essay in courage, or my lack thereof).

First-up, I added all the blocking on the sides. I made use of the leftover bits of 3/4" ACX to CNC arcs of plywood that matched the arc of the wall.  Hey, once in a while even the blind squirrel gets the nut!  

A couple of pocket holes, a couple of screws, and a little sculpting with the jigsaw, and they were in.  I had intentionally left them a little proud, and once installed, I cleaned them down to the wall line with a pattern bit.

Next up, wiring for all the lights, MaxxFan, and I'm still not sure what else.  Some sort of little command center up front, but I still don't know quite what - so I'll run a bit of flex conduit and a messenger line in it - just in case I figure it out.  With the exception of the 3-way switches for the cabin lights, I'm home running most all of the lights, and using Wago connectors anywhere I have to join two wires.  No wire nuts or crimps to fail.

I'm not particularly proud of these, nor the reason they exist...  In my jumbled planning, I neglected to consider letting in wireways during the build.  As a result, I had to find a way to get wire down to the light switches in the cabin, and surface molding was not a consideration!

So I chose to make a template and hog out a wireway and switch box.  I CNC'd the templates out of MDF (a really bad idea, BTW).  It's really easy to cut MDF, and if you touch it with a router it will make a 1/4" dip.  Since hogging the wireways took a couple of passes, I had a couple of extra opportunities to inflict non-straight lines as I went along.   I also made a second template to cut in a cover plate on the outside so no weak spot in the aluminum right next to the door.

My porch lights are corner mounted, with  a pigtail.  I used a 1 1/2" Forstner bit to cut a pocket in the wall (a little less than 3/4" deep, and then came down from the top with my trusty Kreg pocket bit (it's just about 5 1/4") to provide a dropper.

Same bit chucked up from the inside of the roof, I cut another hole into that top down hole to get the wire to feed thru.

Obviously a little out of sequence, but it looks pretty good up there.

Finally, to fill in the wireways that I hogged out, I 3D printed a set of covers that snuggle in pretty well around the bundle of wires going down the wall.  Printed in 6" sections, and trimmed as necessary.

Yet another excuse to pull out the printer and tell my wife how much I 'saved' by printing my parts!

Wireway covers deployed (well - sort of).  I'll need to move them, trim to fit, and add a little dab of glue, but you get the idea.

Next up - more wiring, wiring the electrical panel, insulating the ceiling and installing the *roof*, and then starting on the dreaded galley hatch and lower front.  

Weekend Update

 This was supposed to be a post about the first wall was standing and here's the video.  Didn't quite get there for a number of reasons, but I did:

• 
  Get the right side wall (left has been ready for a week) pocket drilled, grooves cleaned out, and a couple of little annoyances fixed.  Rounded corners cleaned up too!
• Varnished back wall, ceiling panels
• Accumulated a little more hardware in prep for final assembly. 

Fridge and stove shelves going together.  It took a little more time and a couple of false starts to get the clearance right so that things fit together properly.  

Hint: 40 thousandths seems about right.  Teeth are 1.98 and notches are 2.02 inches.  

Glued together with Titebond II.  They seem to be plenty strong.  

I got this task out of the way mostly on timing, and to ensure I could size the back partitions correctly. 

Roof spars bundled up to cut wireways.  Yes, I certainly could've done it on the table saw with a sled and a dado blade, but it would take me longer to set that up than it took to draw it in CAD and cut it with CNC.

These started out as an 11' plank of basswood that was pretty straight, dry and pretty good grain structure.  A few passes on the table saw and we have 1 1/4x 2¨ spars.  And I still have a nice bit of basswood in reserve (probably for the hatch!)

The sides came home.   You can see the cladding aluminum standing behind them waiting its turn.  The right side (shown here) will probably get bolted to the floor on Wednesday.

   

Last but not least, the trailer chassis finally got out of the garage, and the floor got checked for fit.  I always assumed it would fit properly - and it did.  

Walls 'done'!

 Well, ok.  Not 'done-done', but nearly done.  The final coat of epoxy is hardening on the bottom right now, and I'm taking the afternoon mostly off to go ride my bike.  

Things I learned from these - 

Baltic birch soaks up Titebond 3 (varnish too!) like a sponge.  It takes a lot more glue than I expected, so I'm glad I bought a gallon!

When planning to cut the top layer rabbet using the core layer as a guide, make sure the core rabbet is deep enough for your router bit stack height (I had to grind off most of the screw holding the bearing in place to get it to fit.)

The use of some staples is almost unavoidable.

Don't forget to plan and clean a pocket for your door side switches, and the cable next to them.  (I did on the first wall - will go in from the back, mill out a path, and then cover it.  Oops - lotta extra work!

One can never have too many clamps!

The first task tonight was to machine 3/4 inch foam to match 3/4 inch plywood!  (hint: it's not really 3/4 inch foam or plywood!)

Pink 3/4 inch foam is actually about 1/16 inch thicker than the plywood.  Too much to force fit.  Instead, I used the spoil board facing program for our CNC to remove an even 1/16 (.065¨) from a panel of foam insulation.  15 minutes well spent!

Glue.  Lots of glue - the panels for the interior of one side took over a quart!  I had a glue spreading partner tonight, and we were able to knock it out pretty quickly - but that's a lot of glue to spread with a 10 minute pot life!

And finally, there's no substitute for lots of clamps.  Except maybe buckets of water to weight down the panels!

Unlike the outer panels that have tons of narrow crown staples, the interior is mostly relying on glue.  There are a few well placed pin nails, but I'm hoping that the bond will suffice for most of this job.

Varnish - step one

 Step one is really sand the heck out of everything, but we'll pretend that's step 0.8 and 0.9...

A bit of a hairy dog story, but Friday, on what was a brutally cold and windy day, I made my last big 'wood run'.  Not having a pickup or van, I hooked up the trusty utility trailer to the Volvo, and headed off to Forest Products for a stack of plywood.  Several dollars later, and I was on my way to the shop to rack and stack everything, and make a couple of re-cuts that were necessary due to my screwups in properly placing panels on the CNC - (which really stands for 'create new compostables'...)

On my way home, the trailer got hit by someone trying to drop in right behind me on the cloverleaf!  The trailer lost a clearance light, their car didn't fare so well.   They were nice about it, the young guy in the Smokey Bear was nice about it, so I just headed home.  I can replace a clearance light.

When I got back home, I had a great UPS 'present' waiting for me.  As I'd mentioned in the last post, I have become increasingly nervous about delivery times on components. So as I have finalized my choices, I'm ordering 'stuff'.  The ICECo VL45 cooler seems like a solid choice.  I knew I wanted a plug-in cooler, and after a fair amount of research, I decided on the VL45.  It'll be plenty big for a weekend's beverages and a steak or two :)

Tonight was spent laying down the first coat of varnish on the interior walls.  Mostly because of past experience with the vendor, I chose to go with TotalBoat light amber gloss varnish for the interior.  It's a couple of bucks more than some of the other products, but the quality is excellent, plus Jamestown and Totalboat stand behind their product.  

I chose to roll on the base coat with a 1/4¨ nap 6" roller, and then tip it with a 3¨ polyester/nylon brush.  I can still feel a little roughness in the surface, which will get knocked down by the next sanding pass (320/400) and we'll see whether it needs 3 or 4 coats!

Panels drying in the finish room

Outer wall laminations

 The outer wall sections are now laminated to the core!  This was kind of a milestone for me - getting the core bonded, and the outers on - Now I can actually visualize the dimensions of the full trailer.  There were a few little gotchas - like the edge at the back of the main outside panel where I was obviously a 1/4"inch closer to y=0 than I thought, and cut the panel just a tad short.  No big deal, but I will need to fill that void where the two outer panels should join up  

I used Titebond III to give myself a bit more work time.  And I learned it takes 16 oz to cover the entire side.  I happened to be in Rockler the other day, and they had this cool 5¨ glue roller that just seemed too good to pass up.  A touch spendy, but boy howdy, it's a lot better than trying to use a 3¨ roller!  The first panel I did I tried making a zigzag pattern with the glue and rolling it out.  Too much work.  Pour on a good puddle and use the roller to spread it out.  Much easier, faster and complete.  Then used a crown stapler to really secure the panels.

I splined the core panels together - 1/4¨ Freud slot cutter on a Bosch 12 Amp router made fast work of it, and a large pile of sawdust to boot.  

I used the ´caul & clamp´ method to pull the panels together, supplemented by bars across the back to keep the panel straight.  And the whole thing was clamped to the bench - again to keep it straight. 

Thankfully the shop has plenty of clamps - long clamps, pipe clamps, pretty much everything but speed clamps.  In a number of spots, I used a clamp across the piece to serve as a holding spot for a longitudinal clamp.  

The next couple of days will be mostly spent doing piddly stuff - making sure my inside wall CNC code is spot on, doing a little finish sanding on the outside in prep for a coat of penetrating epoxy, cutting insulation to fit, and cutting the inside walls.  

Hopefully by next weekend I'm ready to laminate those!

The Jigsaw puzzle - Part 2

 Tonight's puzzle was brought to you by the letters A, C and X, and the numbers 3 and 4...

I got on the CNC tonight to cut the sidewall cores.  I must be learning something along the way, I didn't make a total hash of it, which is good.  
I don't have a good picture of it, but the CNC manager built an experimental vacuum hold down out of a couple of sheets of 1.5¨ pink foam, hollowed, perforated and glued up.  That and a shop vac makes a perfectly adequate full table clamp. It made aligning the sheet a little tricky, and I did let it slip over a little bit on the last panel - it still worked, but it was a little tight to the edge.  Aside from that, it worked great.

The other little gotcha from this episode is that I learned that the version of FreeCAD I'm using has a bug in the pocket routine.  I was still able to cut the rabbets for shelving and dividers by using a profile command, setting the depth by hand, and making a couple of passes to clear the middle of the groove.  If I'd thought a little longer, I could have offset the cutter by a little more and it would've saved me the clearing pass.

At the end of the day, I wound up with two sidewall cores that will spline together, and they match up with the outer wall.  I left the rear section solid since I haven't finalized the galley build (and may not before I start using it.  As you can see from the rabbets, there is a headboard and two shelves in the cabin, and a 'dead space' that will be the heater on one side, and electrical bay on the other. 

CNC Art

 If you look really closely at the image to the right, you may be able to pick out a few features, or just wonder what in the heck...

This is a composite of the cut jobs for the side wall cores.  The walls are made up of three layers - 1/4" Baltic birch on the outside, 3/4" fir plywood in the middle, and 1/4" Baltic birch on the inside.  Baltic birch is great - better laminations, consistent veneers, no voids.  Fir plywood is, well, plywood.  But it's reasonably solid, straight and inexpensive.  Splurge on the show, cheap on the no-show.

The three cut jobs shown here represent about 10 hours of work on the computer, and will probably take 2 hours of setup/cutting/cleanup.  From some old school boat building I've done, it would probably have taken nearly 40 hours to loft this using an offset table and batten marking, plus another 5-10 hours to cut and then clean up the cuts.  

Now in truth, it's probably a wash to this point.  I've spent an inordinate amount of time learning CAD/CAM, and figuring out some of the 'opportunities for improvement' in FreeCAD.  But the payoff is that now that I *have* figured things out, things like ceiling blocking are a matter of taking a sketch, sectioning a piece of it, and cutting multiple pieces to match.  And since with my design, there's quite a bit of blocking to be done...  That in itself will be a big payoff!

Next up - more CNC fun.  I will try to set up a camera for the whole operation and condense.  Should be interesting.

More CNC fun

We have panels!!!  At the end of the day it all went pretty good - mostly.  I got in the shop tonight, loaded up the first panel, loaded the program, and carved away.  A couple of learnings from tonight.  

1.  Just because the feed chart *says* you can run at 'x' inches/minute doesn't mean you _have_ to run there.  A little slower is an advantage, particularly on smaller tools.  Yep, snapped a mill.

2.  Dealing with warped plywood makes having a partner who can act as a dynamic clamp a real help.  

I'm sure I will have to refine this joint a bit, but for right now - it's zero clearance between the hatch and the back end.

Next up - epoxy on the trailer floor (underside, and maybe some bedliner? (suggestions welcome).  

CNC time

 After more than a little frustration with FreeCAD over the weekend, I was finally able to pin my woes down to a couple of things:  

1. My drawing had a defect that was not noticeable until you tried to to run the CNC.
2. FreeCAD didn't handle the Tag dressup very well.  This may be a bug, or yet another artifact of #3 
3. I still don't know what I'm doing.

The latter is definitely an issue - generally, I suggest people pick something small and simple when learning new technology - like "Hello World".  Not me - I dove in and started with a complex layout that wouldn't fit on a single sheet of plywood, which necessitated splitting up the drawing in ways that are not normally done.  "That's not generally something I'd contemplate" - advice from someone who is supposed to be a CAD guru...

And at the end of the day, I generated sawdust.  You can see the outline on the right - that's the top of the side panel at the rear hatch.  Wait... why does it drop 1" at the end of the curve?? (It shouldn't).  

Fortunately, or irrelevantly, it didn't matter.  Somehow the depth was incorrect, so it only cut the first layer of veneer.  (never commit gcode on a Saturdayy night at 2300 after working on the problem for 12 hours.  I really, really should know better...)

So back to the debug tree, and I *still* don't know why it thinks one of the panels is .4 inches tall, but I learned how to enforce the boundaries, and it's now all on the correct plane - and Yep, I read the gcode itself to verify that!

Off to the shop now to try again.  Hopefully the next post is a set of panels instead of more expensive sawdust!!!

Making dogbones on CNC

 Here's hoping everyone has a healthy and successful 2022!!! 

Obviously this blog is about my teardrop trailer build, so I won't delve into opinions on beer, people, politics, life, etc - you can catch that over in ¨Life in the swamp¨ if you are interested.  Progress has been kinda slow for the past week.  I have actually had to pull some extra hours at my day job, and that's been enough to occupy most of my time.  In my free time, I've been clearing out the build space, and working on learning how to use the Path workbench in FreeCAD. 

Let's talk a little bit about FreeCAD.  There are other packages that are probably easier to use for generating gcode, like Fusion360 and V-Carve in particular.  Our makerspace/shop has a license for both, and I was starting to learn F-360 when the pandemic hit. At that point, I lost direct access to the machines (makerspace was closed down tight), and the F-360 personal use license was becoming 'difficult'.  Oh, and I built a CAD workstation using Linux, and F-360 only runs under Windows, so - not gonna happen.  Looking at the options, I started investigating FreeCAD, and found it was a)very similar to F-360 in capabilities (and difficulties), b)runs great on Ubuntu Linux, and c)it's really and truly free!  Not a demo license or one that allows you to create but not save, etc.  This is really free, is moderately well documented (good, not great) and has a very active user community, and numerous Youtube communities.

FreeCAD is a 3 dimensional parametric modeling application, with multiple workbenches supporting things like architecture, sheet metal, metal tubing, and 3D printing/CAM/CNC.  

OK, now the bad news.  It's a pain in the ass to learn, crashes occasionally, and many of the videos make assumptions about your existing skills that may or may not be appropriate.  And, while the documentation is often marginal.  If your last drafting experience was paper, ruler, t-square and a compass, it's a complete and total mind warp.  And if you are an 'experiential learner', your brain _will_ hurt - often.  If I paid myself $10/hour for watching FreeCAD youtube videos, I could probably afford a nice windows machine and full pro license for FreeCAD or V Carve!!!

But, I've gotten pretty proficient, made enough 3D widgets and sketches that learning one more bench wasn't that tough.  Even if that one drives a 10K spindle and can destroy 160 bucks worth of plywood in the blink of an eye.  

After a couple of false starts, today was the first day I've cut anything meaningful on the CNC.  It doesn't look like much, but these are the major components of a CNC job - perimeter profiles, grooves and pockets.  The 'dogbone' cutout was the most interesting challenge.  If you work in wood, you've doubtless learned that you can't put a 1/2¨ board in a 1/2¨ rabbet.  It won't fit (without some sanding/chiseling anyway).  Getting a shape like the dogbone to fit is even more of a challenge.  

To make it work, I used a .250 (1/4¨) end mill on the slot, and used the same mill on the tab - but told the program that it was a .240.  This positioned it just a little closer to the edge line, and allowed it to fit very snugly.  I am not sure I could get 10 of these in a row to fit like this though! Nor would the joint contain much glue. For the wall and ceiling seams, I will (after more experimentation) use the same technique, but make it .220 or .230.

And why am I so wrapped up on this particular feature?  Aside from the mechanics of making it work, I think it will be a nice feature on the inner sidewalls of the trailer, and the ceiling.  Having two pieces of plywood simply butt against each other is not the most attractive, and they tend to 'work' against each other over time. You can cover it with trim, or use a scarf joint to make it blend better.  Using puzzle joint means that the two pieces can't move freely, there's more glue seam, and glass tape with epoxy on the back will lock it in for good.  Note: in thicker wood, biscuits, shims or dominos will make a strong mechanical joint.

At the end of the day, I'm a definite fan of FreeCAD, and strongly support the direction that it seems to be going.  It is probably a lot more difficult to work with than a program like SketchUp, but the price is right, and the end result is spot on.  

Ready for powder coating!

 It was a boring day.  Boring holes in the frame, that is :)

My buddy Kris came down and helped me get the frame down on the blocks, double check alignment, clamp the suspension,  mark the holes, check the alignment again, and then drill the holes.  And I have to confess that I can't drill a straight thru hole to save my life.  I'm going to find a way to get at least a couple of them a little off center.  But at the end of the day, I thin we are 'close enough'.  Triangulating spindle to tongue is within 1/32 of an inch.  I'll get it professionally aligned once everything is together, and the body weight is on the frame, but this will do for now - especially when it will be taken apart again.

Assembled Timbren suspension units in place!  These are definitely heavy duty!  Grade 8 bolts thru the  frame.   i had a little sticker shock when I bought nuts, bolts, and washers.

The Timbren specd reinforcement plates fit well.  Only a little nudging was needed to get them properly aligned.  

One 'sticker shock' item for me was the bill for Grade 8 hardware!  Bolts for both the suspension and the receiver were nearly $100.  That's the price for doing it right.

Final inspection tomorrow, and off to the powder coaters on Monday!