CNC Build: The Bed and Breakfast at 4 years and 40,000 miles

[capnTelescope]

Contents
Plywood jigsaw joint video
First vacuum bag glue up
Vacuum bag setup explained
Cutting insulation panels video
Wiring the left wall
Starting the right wall
Vacuum bag the inside wall
First CNC cuts on the left wall + video
More CNC cuts on the left wall + video
CNC machine runs amok!
Left wall front end finished
First CNC cuts on the right wall
Video of finish cuts on right wall
Video -- Inspecting the walls
Beginning work on the galley
Floor
Dry fit assembly
First stab at hatch
Second stab at hatch
Hatch 3.0
Field trip!
Hatch 4.0
Hatch 4.1
Hatch 4.x fatal flaw
Hatch 4.x fatal flaw + Hatch 3.1
Hatch 3.1 + DXF of drawing
Hatch 3.1 Corner Tinkering
Annotated Hatch 3.1 pix
Hatch 3.1 Corner block hammered
A little progress with more tomorrow
Hatch Spar router dust
Building the hatch
Cutting aluminum spar stiffeners
Cutting aluminum spar stiffeners + video
SawStop talk
More welding practice
Assembling the hatch
Explanation: fitting the hatch
More fitting and now the trailer
Small parts of the trailer frame and more
Router Bit Dies in Collision
Headboard
Trailer welding begins
Odds and ends
Assembly begins
Assembly continues
Cabinet face frames
Galley under counter design/build 1
Galley under counter design/build 2
Galley under counter design/build 3
Ecuadorian Conspiracy
Ecuadorian Conspiracy II
Galley oven/stove semi-final
Galley hatch and TV report
a little bit of hatch work
Hatch frame installed
Connecting wiring
Rain gutter and ceiling
Splicing the ceiling
Ceiling, spars and half a skin
Research result -- Poly on bent ply
Tongue box and A/C
Right side AL success, hatch, more
Hatch gutters
Hatch bottom seal and Ecuador conspiracy
More hatch, more electrical
preparing to skin the roof and hatch
Finally, skinning the roof
...aaaand the hatch is skinned
finishing touches on the hatch
Hmmm--Fenders
Fenders 2
Fenders 3 -- Fenders!
Weigh-in
Registration Day (one)
Registration Day (two)
Galley odds and ends, Hatch Gasket
Reg day 3 & 4 It's legal (for LCG)
Maiden voyage to LCG IX
Maiden voyage catching up
Hydro Testing
Registration Day (five)
Reg Day (six) - Stamping the VIN
Reg Day (seven) - Victory!
Easy Table Saw Box joint
Tambour doors for the galley - First look
Look what came in the mail!
Making the tambours
(SawStop talk)
Making the tambours 2
Making the tambours 3 + ADD strikes!
Making the tambours 4 -- Final steps
Tambours 5 -- Install
Tambours 6 -- Galley Install finished
Tambours in the Cabin
Plumbing & shtuff
Plumbing for cooking, capnT goes steampunk
Camp oven cookie test--Graphic images!
CNC Video Action--Tambour lifters!
Hydrotest II
Second Outing Trip Report
Finishing work in the galley
Finishing work in the galley II Trash Can Holder
Finishing work in the galley III
Tongue Box
Charging While Towing
Charging While Towing Schematic
Finishing out the galley -- Countertop
Hatch Prop 3.0
Right Galley Trim Panel
Right Galley Trim Panel and Left
The Bed and Breakfast at 4 years and 40,000 miles

Original post
It's about time to start a build journal.

Made a lot of router dust and wasted some glue this weekend. Didn't make anything usable.

One thing about CNC: If the design is not right, CNC will faithfully make it wrong. If you have just the least little doubt, try it on a piece of scrap. If you don't, you'll make a piece of scrap you can practice on until you get it right!

The gozen goes into the gozinta. Due to a design error, the gozen didn't go into the gozinta. I'll get it right and report on the whole tale of woe.

I'm learning CAD drawing, how to operate my CNC machine, graphical NC programming and CNC woodworking all at the same time. And some rusty old wheels don't turn as fast as they used to.

Anyway, I figgered out what went wrong, and improved a design detail. In the early days of the space program, this was called a successful failure. Tomorrow's goal: 10 foot plywood panels from 8 foot sheets. That's even been done before.

[jarrell]

Why not make my first post a reply to something I know a little about....CNC. You are so right if it's programmed wrong it isn't going to cut anything but just what you ask for. I program and operate a 5x10 machine daily. CNC I know about, tear drops I'm wanting to learn. Build process is just a dream at the moment but getting a serious itch.
Are there CNC files available for plans?

[capnTelescope]

Hi Jarrel, welcome to the group. I know about the itch. I've had the teardrop itch about ten years and I'm just now getting started. The CNC itch goes back even farther. About 35 years ago, I made my living programming 2-axis lathes and 4 axis vertical mills. Considering what those babies cost, I never thought I'd ever have one of my own. I'm building a 5x10 Tear on a 4x8 machine.

Are there CNC files available for plans?

Not yet.

I plan to make drawings, CamBam files and g-code available as they happen.

BTW, stop by the Newbie forum and introduce yourself. http://www.tnttt.com/viewforum.php?f=40 We have some semi-official greeters, and we can get to know you better. This is a great bunch of folks here.

[jarrell]

You can do longer work on a short table no doubt about it, just make index and move part and run additional program. I've done 16' work on a 10' table...It's the wider than 4' that will limit you the most IMO. I've been meaning to drop by and introduce myself, Thanks for the reminder!

[KCStudly]

This is going to be good! I like your comic style.

That said, it's not too late to build lighter. Paraphrasing the quote, "no one has ever complained that they should have built heavier." Don't let your doors dictate your wall panels. Route out spacer frames at the doors to build that area up, and make the wall skins thinner.

Here is how I made spacers for my inner door flange, to give you an idea.

[capnTelescope]

Hi, KC. Thanks for chiming in.

I checked out your door frame link. That's how I'd have to do it. When 1/8 ply came up, I thought about doing it that way. At the time I decided to go ahead with 1/4", I didn't have a source for 1/8" ply. Now I do, of course, now that I have bought quarter inch. Since the doors are long since bought and I have about $250 in plywood ready to go, I'll stay the course.

I also noticed the weatherstrip you got. That's what I'm going to need for my hatch design. Thanks for the sources.

Progress report coming right up.

[capnTelescope]

Finally, progress!

As you might have guessed from my first post, things didn't get off to a glorious start. I'm trying to join plywood sheets to make my 4x10 outside walls by using a tricky joint I saw somewhere. This video shows what I'm talking about.



Here's some real CNC action, cutting half of the joint.


Clearances are close, and very critical. Too tight and it doesn't go together. too loose and it won't hold still until the glue dries. I'd done it before on 1/2" material, and beginner's luck made it work on the first try. Not this time. The first try was so tight, I couldn't begin to dry fit it. I had left enough meat on the mating piece for one more try. I fiddled with the numbers and gave it a rip. Better. I figured my 2# dead blow hammer would make up for any tightness. I put a nice radiused 2x4 caul clamp (made on my cnc, of course) across it and crossed my fingers. Some time later, the result was such a disgrace I couldn't bear to take a pic.

So I took a deep breath and went back to the drawing board, programmed a few test pieces, got nowhere until I realized I had things bass-ackwards and was making things worse. Once I got that straightened out, I programmed a few more test pieces. A .005 clearance wouldn't fit up, a .010 fit very tightly, and .015 clearance was somewhere between just right and almost too loose. So the next try gets the .015 treatment. Along the way, I had a small eureka moment and found a better way to get these things drawn.

Since I ruined my "cheap" plywood, I got to go shopping at a real lumber yard and got my first exposure to marine plywood. That's some nice stuff! 5 plies in a quarter inch panel that lays (lies?) flat on the router table. Really nice mahogany outer layers on both sides. The Big Box cheap sheathing was pretty curly, and wouldn't lay flat on the router table. Only 3 plies, too. And ugly. The marine ply must be at least twice as good, because that's about what it costs. Ow.

The first try on the marine plywood went smoothly until the part where you fit the two pieces together. Then it was tight as a drum, again. I don't know what went wrong, but more R&D before I cut the second wall (I'm going to do one wall complete before I go on to the second). Using "gentle persuasion," I got the two pieces together with only slight darnage. I now have a 10'1" x 48" piece of 1/4 marine ply

Here's the join:


A vast expanse of plywood:


This pic shows the excess length hanging off the back end of the table. It will take two operations to finish one complete wall. I will slide the ply to the right about 3 feet for the second op.



The gantry is all the way to its left end of travel, so it can't reach to the left from where the magic marker is.

Next is to draw the wall framing on the ply, so I don't have to measure for each piece during glue up. This will give me a chance to practice lining up the two operations.

[AlgoDan]

Great build you have going on. The CNC part I love as I run CNC Lazer, so you building by CNC is cool to watch. Also your videos are great and to learn from. Will be following your build.

[mikeschn]

I'm jealous. My cnc machine doesn't have the accuracy that yours does, and I don't know why. It's repeatable, but it's not accurate.

I thought maybe there was some deflection in the gantry as I was cutting, but I can't verify that. Makes me wonder if a laser cutter would be a better option, AlgoDan?

Mike...

[AlgoDan]

I'm jealous. My cnc machine doesn't have the accuracy that yours does, and I don't know why. It's repeatable, but it's not accurate.

I thought maybe there was some deflection in the gantry as I was cutting, but I can't verify that. Makes me wonder if a laser cutter would be a better option, AlgoDan?

Mike...

Hi Mike, yes a CNC Lazer would be sweet, but for a price of course..

[capnTelescope]

Algodan -- welcome aboard. It's good to have another CNCer watching. A CNC laser? Sometimes the boss provides the very best toys, you just have to play by his rules.

I'm open to suggestions, better ways to do something, or whatever else I can save for "next time." I've probably forgotten more than I ever knew about this, and I'm making it up as I go along.

Mike -- Don't be too jealous -- I have some of the same problems, too. Repeatable, but not always accurate. For example, I had to get out the BFH to get this joint to go together, but the one in the video was just about right. It might be one of those stepper motor things. Or backlash, or deflection, or tool wear, or... Together we'll figure this out.

[jarrell]

I really like your Jigsaw joint, it's a great idea I might have to play with that one myself.

[capnTelescope]

I might have to play with that one myself.

Enjoy!

I've tried two versions of this. The first version uses the same tape (g-code program) (I'm old school. Back then, we really used punched paper tape.) to cut both ends. You make the male part of the contour slightly smaller and the female part slightly bigger.

The second version requires 2 tapes. In the first one, the radii are the same. 3/8 in the video. The second side runs 2 parallel arcs to the originals so that you get the same smaller male/bigger female. Version 2 leaves equal space between the ... I don't know what they are called. The Gozin and the Gozinta.

In either version, you cut the joint the same way. Same (good/bad, top/bottom, left/right) side up, same orientation in the machine (joint left/part right or vice versa). When you're finished cutting, rotate one of the parts 180 and they fit up. With version 1, you can even cut them both at the same time, if you can clamp them together accurately.

I'll attach a DXF of version 2.

0375 jigsaw joint A-B.dxf

.375 jigsaw joint study

(85.06 KiB) Downloaded 933 times

Do they still call a g-code program a "tape?"

[capnTelescope]

Finally, progress to show. I'm taking the same excuse as WitsRUs (http://www.tnttt.com/viewtopic.php?f=50&t=57566), and claiming the weather was too cold to work in an unheated shop last week. That's my story and I'm sticking with it. I'm sure you folks up north where it's really cold are laughing at us Texans for thinking it's cold in the 30's. No problem, we're laughing at you for living in a deep freeze.

I spent the cold days as productively as possible, checking my drawings and making sure everything is in order. I moved the headboard aft 2 inches, and everything went aft with it. I also lowered the door an inch. Then drawing checking and drawing the framing, outline and roofline details on the plywood. If someone wants to see it, I'll post the video, but it's the same kind of stuff I posted before.Video editing is a bit of a PITA.

I also got my vacuum press modified and in order, because I want to use it for gluing up the wall framing. Got the last Tee fitting I needed this morning, and it's good to go. So today I got to try out my 5 x 12 vacuum bag. It works!

I made two practice runs before I popped the top on the glue jug. First one was after I got the 5 platen boards (2 x 4' MDF. HEAVY!) into the bag. Then a dry run with no glue to verify I could manage to get the wall in and out of the bag without mishap. A half-inch splinter in my finger, and I added leather gloves to the kit. It only bled a little. On the second run, it took forever for the little vacuum pump to evacuate the bag. That's when I added the shop vac. That's the ticket for getting most of the air out of the bag.

Here's everything ready to start glueing:

I thought I was going to be smart and use a paint roller to spread glue. Ha! That didn't work well at all. Used an old credit card with notches cut in one edge. Pour the glue from the jug, spread it with the card, place the part and shoot a few nails to try to hold it in place long enough to go into the bag. Lather, rinse and repeat. Then staple the breather mesh (that's the white sheet of stuff in the upper left of the photo) on top of the assemblage so it stays in place all the way to the bottom of the bag. Stuff it all into the bag, suck out excess air with the shopvac and turn on the vacuum pump. Have a smoke/beer/lemonade/snack or whatever you reward yourself with. Come back in an hour.

Here's what it looks like bagged and the vacuum running:

I only attached the end pieces and baseboard in this operation, since I hadn't tried something this large before -- trying to keep the tree destruction to a minimum.

Here's a different view:

The baseboard is on the left, front end piece nearest the camera, and the aft end piece waaaay in the back. The bag is 40 mil EPDM pond liner. To give you an idea of how well the vacuum bag clamps, the line you see on the end piece is the edge of the breather mesh, which is only 60 mils thick (That's .060" or about a 1/16"). Ditto the line running vertical from the end of the end piece, on the right. Then you see the 1/4" plywood with the platen board under that.

Here's the gear:

Right to left: Air compressor for the brad nailer, green monster blower from an A/C unit to blow into the bag to open it up for sliding the wall in. Blue tarp to put the wall plywood on so it doesn't get all scratched. 2 PVC pipe vacuum reserve tanks in cardboard box shrapnel guard. Vacuum control board has a pressure switch that cycles the vacuum pump as pressure rises/falls. Shop Vac to remove excess air from the bag after loading. Small Harbor Freight vacuum pump to do the really hard sucking. Duct tape. Orange air hose suction line to the vac bag. Bungees hanging from the garage door to hold the mouth of the bag open. Vac bag, clamped shut. The yellow bucket did not participate.

Shrapnel guard? Yes. Homemade pressure vessels scare me. Like the absent-minded skydiver once said, "So far, so good."

http://VeneerSupplies.com has a ton of good info on building vacuum presses and related stuff for sale, of course. They get the capnTelescope seal of approval.

The vacuum setup cycles from -15 to -18 inches of mercury every minute or so. I need to do some leak fixing to slow down the cycling. First I need to do some leak finding.


Tomorrow, more glue-up. then some router dust!

[Junkboy999]

I have yet to vacuum bag anything yet, beside home made vacuum holding down claps, and a few attempts at Vacforuming RC aircraft canopies.

That looks fun, you need a neighbor close by to help you get it into the bag.