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

[Louisd75]

I'm in the process of building my trailer. No build thread started yet, I'll get one going eventually. In the vein of "it's a small world afterall" I just took a tour of the RoundRock Tech Shop while visiting family out in Pflugerville. My old man is a member and wanted me to check it out. It's a pretty nice facility. I liked the Lowe's tie in... material is never more than a short walk away. As it is, I'd have to drive two states away to get to my closest one. Oh well.

Anyhow, on the welding, do you own your own helmet? The bigger manufacturers usually have magnifying replacement lenses. I've seen some out there that go from .75 to 2.75 in .25 increments. Might be worth looking into, they may even have a stash of them at TechShop for the helmets they have. I didn't look too closely to see whether they provide the auto darkening or fixed shade style. Both the fixed and auto darkening have their pluses and minuses. Besides the ear protection recommendation, I'd also add a hat of some sort to wear under the helmet, burning hair isn't much fun. Don't wear synthetic socks either. Dropping slag into your boot isn't much fun as it is, but it's a whole different level when it melts your sock to your foot Another recommendation is to pick up a copy of "How To Weld" by Todd Bridigum. I found my copy at Barnes & Noble, but you could probably find it cheaper online. I think he does one of the better jobs breaking down the techniques with clear pictures and drawings.

I'm back to lurking

[capnTelescope]

I bet there is a way to replace the motor on the cnc with a welding rod.

That would be ultimately cool!

I just took a tour of the RoundRock Tech Shop while visiting family out in Pflugerville. ... I'd have to drive two states away to get to my closest one. Oh well.

They'll build more. Maybe near you. If you have some money to burn, they are looking for lenders and investors.

do you own your own helmet? The bigger manufacturers usually have magnifying replacement lenses.

It's a Harbor Fright. I didn't want to get other peoples cooties. I don't think they have the magnifying lenses. Maybe it's a standard size?

I'd also add a hat of some sort to wear under the helmet

Everyone I've seen wears a do-rag. A backward ball cap sounds good to me, Don't want splatter down my neck!

I'm back to lurking

I'm honored to be your first post. Don't be a ten-year lurker like me.

[capnTelescope]

All right! R&D is R'ed and D'ed and it''s time to get on with the build. Yesterday, I went to Fine Lumber and Hardwoods and got the 1/8 ply for ceiling and roof. Today I dusted off the table saw and got busy making the 4 cross-ribs for the hatch. Each of the ribs gets a dado in the center and a rabbet on each end to fit up with the notches CNC machined in the 3 spars.

After cutting the ribs to length, the next step was to cut a dado in the center. Here's pop quiz #1 for this post: Try to figure this out in your head. No cheating by using pencil and paper. Each rib is 56 inches long, and the center dado is 3/4", nominal. The ruler on the saw fence measures from the right side of the normal thin kerf saw blade. What reading on the saw ruler will locate the fence to the right of the dado blade, and center the dado close enough for the girls we go out with(CEFTGWGOW)? I tried about 4 times and finally just used the tape measure, but you don't get any credit for that answer.

After that ordeal, I quickly dispatched the dado cuts:



Tested for fit:

The cross rib fits snug in the spar notch, the spar fits snug in the rib dado and the top of the rib is flush with the top of the spar.

Onward to the rabbets! If things are going to fit up nicely, you have to use the right datum for your measurements. In this case, we want the edge of the rabbets to be consistently the same distance from the nearest edge of the dado. Remember, the dado is centered CEFTGWGOW. Using clamps and wood scraps, I rigged up a stop that fit in the dado so I could cut the rabbets at the same distance from the dado:



It was pretty shaky, but worked out well. Here I fit a piece of ply in the dado to line up the 4 ribs.:

CEFTG! Actually, it turned out even better than I expected.

One more detail to take care of on the rib at the bottom edge of the hatch:

This picture isn't one of photography's finest moments. What it's trying to show is that the bottom of the hatch spars come to a point, and there's excess material sticking out where there should be roofing. You can see a short saw kerf to the right of the spar end. That is what has to come off, plus a little.

After the cut:

There is still a little material to remove, which I'll get later with a hand plane.

With all that done, I did a dry assemble:

It all fitted up square and parallel without any drama.

Then it was back to the drawing board. I want to glue and pocket screw this whole thing together, but there's a little problem. Using the standard Kreg settings will result in the screw meeting the spar right at the corner of the notch cutout, which practically guarantees a poor result. Picture worth $1.98:

The upper drill centerline illustrates the standard settings. I want the screw to emerge farther down the dado wall, shown by the lower CL. I made the drawing to solve the problem, but I thought it might be worth sharing.

Made a test run with the dado setup piece:

With First Article Inspection passed, I was off to drill pocket screw holes.

Pop Quiz #2: Q: What's wrong with this picture?

A: The opposing pockets could interfere with each other. This side doesn't show, so I went back and drilled a pocket between the holes on one side. That was the original plan, it just got lost in all the excitement of drilling pocket holes.

Answer to Pop Quiz #1: 28-3/16"

Thanks for stopping by!

[capnTelescope]

With many thanks to VTX1029 , and a package from Amazon, I was able to boldly go forth and cut out my aluminum hatch spar stiffeners. Everything went surprisingly smoothly. Knowing what you're doing can sure make a difference.

I used an Onsrud 1/8" single "O" flute cutter running at 23,000 RPM, .015 depth of cut and 50 inches per minute feedrate. The lubricant was WD-40 . Material is 1/8" 5052 aluminum. It cut like I knew what I was doing.




I even tried my luck at using holding tabs. It turned out better than doing it in wood.


The result was a big dustpan full of aluminum chips...


... and 3 really good looking spars:

I never once considered how the spars would look when finished, but IMHO they look really good.

This is a messy process. Even after careful vacuuming, there's still chips everywhere. On the table, the machine, the floor, and even getting tracked into the house.

One unexpected result I had was the finish on the edge of the parts. The edges had vertical ridges like the edge of a freshly minted quarter. It won't show, so no biggie, but I can't explain it.

Video is on its way. Stay tuned.

[KCStudly]

Tool flex maybe caused the ridges?

I second your opinion, they look marvelous!

Seeing them laid out there, I wonder if you had you given any thought to continuing the aluminum inlay all the way up and around to encircle the hinge pin.

[RandyG]

Looks very nice. Kc has a good point, maybe adding another inlay into the hinge and through the thinner piece. I really like the inlays, have you thought about installing it in select parts throughout the whole trailer?

[capnTelescope]

Video is posted, and should be available tonight after 9:20 CDT.

I second your opinion, they look marvelous!

and

Looks very nice.

Thank you. Thankyouverymuch!

I wonder if you had you given any thought to continuing the aluminum inlay all the way up and around to encircle the hinge pin.

and

Kc has a good point, maybe adding another inlay into the hinge and through the thinner piece.

I thunk of it but didn't think it was that important. That was probably before I ended up with a 5x5' piece of Al. It wouldn't add much stiffness to the curved part of the hatch, but might look pretty snazzy. Maybe an all-aluminum hatch frame! Where's the info on that TIG welding class?

Tool flex maybe caused the ridges?

You'll get to see the ridges in the video. They're much too pronounced to be the tool flexing. Maybe slop in the router spindle or even more likely cumulative play in the 3 axes. It's puzzling to me because the ridges are vertical the full height of the cut. The spiral on the tool should have taken care of it. Maybe something to do with stepper motor tuning. Oh well, If the need arises, I can use the edge as a saw.

have you thought about installing it in select parts throughout the whole trailer?

Hmmmm. Not until just now. I've got plenty of Al. Hmmmmm.

I'll get back to you on that.

Thanks for stopping by!

[vtx1029]

Yea the edge finish isn't going to be as good as you would expect to see from a milling machine. If you want a better finish you could cut over size on the outside cut and then come back and take a full depth finish pass say cutting .010 and it should turn out better. The other thing I see is you only held it at the 4 corners. Next time screw it down to your table every 6 or so inches. I use sheet rock screws. The material is flexing/vibrating while your cutting it. congrats on your first aluminum cutting. I'm glad to help people save $ from making some of the same mistakes I did. Cutters get expensive

[tony.latham]

Good gawd. The only way those spars could look better if you would have filled the stiffener slots with molten pewter and I'm not sure that would have raised the beauty bar.

I've got all my fingers and that same table saw BTW.

Tony

[capnTelescope]

you could cut over size on the outside cut and then come back and take a full depth finish pass

I will try that on the weatherstrip mounts.

Next time screw it down to your table every 6 or so inches.

Doh! I knew to do that, too. The walls got held down with screws in a few places where clamps wouldn't reach.

congrats on your first aluminum cutting.

Thanks, vtx. You were a big help.

Cutters get expensive...

Knowing how short life can be for a cutter on my machine(not the machines fault ), I ordered an extra, thinking best case scenario. Now I have an new unused extra bit. It'll get used some day.

The only way those spars could look better ...

Thank you. Like so many other great discoveries, purely by accident.

I've got all my fingers and that same table saw BTW.

Twins again!

I did this...

...and made one of these :

$150 penalty for having your head in a place devoid of sunshine.

I made the SawStop decision partly because a friend, in an absent-minded moment, reached over a saw blade and cut off three fingers. One of which was never found.
Absent-minded moment... Who does that? Sawstop... Yes!

So far, no finger-related incidents (Knock on wood. ) That would have taken out a big enough chunk of skin to make you think about it for a few days.

[tony.latham]

Bro:

I've heard that noise. I was cutting a dado slot for a T-track in my old router table and found a pin nail and you know the rest of the story. I'd built that table and shoulda known better. Since then I bought a metal detector on eBay that woulda detected it. Any suspicious wood is going to get a once over.

Here's what your Tacoma will look like by fall:


That's from last week. It was a good trip.

TL

[vtx1029]

Ouch on the saw stop oops. Looks like its time to measure up the replacement part you get and make a spare or 2 on your cnc

[lthomas987]

I too have gotten my finger in a table saw. I was tired and hungry and making poor decisions. Fortunately early in the day I had made my good decision and set the cut height of the blade only a tiny fraction of an inch over the the wood height. We were installing flooring so everything were were cutting was all the same thickness all day long. I got away with only a handful of stitches and a very sore trigger finger that never quite came back nerve-wise.

[capnTelescope]

Here's what your Tacoma will look like by fall:

Must... finish... teardrop.

its time to measure up the replacement part you get and make a spare or 2 on your cnc

It's the electronic innards that have me stumped.

I too have gotten my finger in a table saw. I was tired and hungry and making poor decisions. Fortunately early in the day I had made my good decision and set the cut height of the blade only a tiny fraction of an inch over the the wood height. We were installing flooring so everything were were cutting was all the same thickness all day long. I got away with only a handful of stitches and a very sore trigger finger that never quite came back nerve-wise.

Just gives me the shivers to think about it. It's hard to imagine you were lucky and got off easy, but you made your good luck with that blade setting. Glad it didn't turn out worse. Whew!

[capnTelescope]

I stopped by Metals4U and scrounged through their drop off pile for some proper practice pieces. Got a nice chunk of 10ga, headed for Techshop, cut some coupons and fired up MIG #2. 10ga is .100 thick, and the tubing for the trailer chassis is .125, so that's close. Good enough for now.

After laying down a couple of beads, I took the resulting piece to the bandsaw, grinding wheel and disc sander, and polished the cuts as good as 120 grit would let me. Dipped in white vinegar to attempt a met-lab specimen. This first pic shows a gap where the edge of one piece meets the side of the other.


Obviously no penetration at the intersection. I ground a chamfer on the edge of a new piece and tried again. here's the result:

Big void where the chamfer is. On the left side, you can see/imagine the line where the weld meets the base metal (heading north/up) Is that OK or non=penetration?

Another angle:


(EDIT) I got a better do on the polish & etch:

(/EDIT)

Questions:
Bigger weld prep? is 45deg OK?
In the 2nd pic, which is closer to the preferred shape of the bead? Left? Right?

Suggestions?

Thanks for stopping by!