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

[tony.latham]

Brad:

I'm still stalking your hatch thread and noticed this: "I'm shying away from wood due to my experience with the crappy 1/4 ply I cut out for the inner gutter walls. Both pieces have broken."

Yes, the reality of today's plywood. My local yard, all-but-in the middle of nowhere (three hours from a Lowe's/Home Depot), stocks 1/4" plywood subfloor. He stocks it 'cause it's about $5 cheaper than 1/4" AC. I use it because it's much better. It's got a solid core. Both sides are sanded, and one side is something that I've been told is "Russian Birch." I don't know about the latter but it isn't Douglas Fir. It's made to survive moist environments, so the glue is exterior and my water bucket tests agree with that.

You might ask around, it's nice stuff. Here it is on the interior wall:


Tony

[Heifer Boy]

Oops! Double post!!

[Heifer Boy]

After seeing what Jeff is doing, my conclusion is that I want to save this for the "Next Build." I will probably learn to make the molded gutter first, then start the "Next build." Plus, molded fiberglass has many applications in the hatch area, including the hatch itself.

In the highly unlikely (IMHO) event that Hatch 3.x is unworkable, I want to get in there and find out sooner rather than later after learning a whole new skill.

Thanks for the tip, Heifer Boy.

No worries mate... (I'm not an Aussie but it's what we say down here)

Jeff does do some great work and I wish I had his skills. How he presents his ideas is fantastic too. But, as you say it is another skill to learn and probably for another day.

Good luck with your continuing project. Love the cnc work and hopefully your hatch hinge idea works out. I can't see why not as every car boot and hatch uses the same method. Could you imagine a current day hatchback or suv with a hurricane hinge on the back!! Things have moved on from 1934 so I can't see why teardrops can't move up to date too. Have fun and I'll be watching.

HB

[capnTelescope]

Good luck with your continuing project. Love the cnc work ...

Thanks, HB. I like it when someone new speaks up. Hope you're enjoying this as much as I am.

... and hopefully your hatch hinge idea works out. I can't see why not as every car boot and hatch uses the same method. Could you imagine a current day hatchback or suv with a hurricane hinge on the back!!

Things have moved on from 1934 so I can't see why teardrops can't move up to date too. Have fun and I'll be watching.

Amen. Glad to have you aboard, HB. Y'all stay tuned. (I'm a 50% Real Southerner, so we say Y'all 'round here.)

My local yard, all-but-in the middle of nowhere (three hours from a Lowe's/Home Depot), stocks 1/4" plywood subfloor.

HD & L both stock "sheathing" grade. Must be one step above OSB/chipboard.

He stocks it 'cause it's about $5 cheaper than 1/4" AC.

I can't even hardly find graded ply around here, unless I go to a real lumber yard. Once in a while BC. The subfloor looks good on your walls. HD sells a 1/4" that they call "underlayment," that looks like it may be pretty good. It's 5 ply, 3 thin and 2 thick. The 3 thin plies look like luan, the 2 thick look like some Chinese whitewood. And I'm on the outskirts of Somewhere!

[KCStudly]

Hey capn, where'd you go?

Any updates, or have you been distracted?

[capnTelescope]

Any updates, or have you been distracted?

Thanks for asking, KC.

I'm still here. I'm back on it now, but not much to report. In the two weeks since my last post, I've devoted my time to getting some yard projects done before the weather gets hot, and FIVE DAYS, in one way or another, devoted to income tax. The latter included converting from Single Shoebox Accounting to Multiple Shoebox Accounting, so next year isn't so bad. What a colossal waste of my life.

Meanwhile, back at the drawing board, all was not work with no play. Now that I've settled on a hinge design, I've been working on the hatch design, to the point where it's almost g-code ready. Expect updates with video soon.

[KCStudly]

Awesome! ...and thanks for reminding me that I haven't wasted any time on my taxes yet.

[vtx1029]

I've cut a bunch of 2024 t3 aluminum with my router. Feeds and speeds really come into play here.

First off I've used wd40 as a lube and it works pretty well, I also always now use an air blast. Single O-Flute up cut spriral bits are what you want to get. Personally I've tried Amana but I tend to snap the tips off even ramping them in. I've had great luck with the Magnate spirals from amazon. Down cut spirals suck and clog up. Build yourself a little vacuum table to hold the sheet. You can look up my build thread on the CNCzone under the same screen name. I have pics of my vac table and cutting aluminum.

You really also need to be using O temper aluminum for this to make that inside curve. Also put a radius on the forms your bending around. 2X the material thickness should be a good radius for your form.

[capnTelescope]

Howdy, VTX1029. Thank you for speaking up.

I've cut a bunch of 2024 t3 aluminum with my router. Feeds and speeds really come into play here.

Hooray! Someone who's done it.

I was wondering if WD might work. I ass-ume one wants to keep their router RPMs and cutting speed down as low as the router can go.

What diameter cutter did you use? I've been thinking 1/8" to keep cutting speed low.

What approx feedrate/chipload? Depth of cut?

I will want to cut out several pieces from 1/8" stock, alloy TBA, but NOT dead soft.

It's surprisingly hard to find specific info for this. I did find out about O-flutes, but no one had any brand recommendations, so you've already got me another step further.

Thanks again for rescuing me from another R&D project!

[vtx1029]

Here is what I was running for both 1/8 and 1/4 bits. FYI I had a better finish with the 1/4

ImageUploadedByTapatalk1396922025.742736.jpg (241.32 KiB) Viewed 4638 times

ImageUploadedByTapatalk1396922039.391142.jpg (239.54 KiB) Viewed 4638 times

[capnTelescope]

Here is what I was running ...

Thanks for the info, VTX.

I would have guessed a lower spindle speed, but nothing succeeds like success. What little I was able to find before suggested light depths of cut, which you are taking. About .003"/rev for the 1/4" and .002"/rev for the 1/8 ". This gives me a good starting point. Can't thank you enough!

I took a peek at your photo album. You do some very nice carving. Is that your CNC in a couple of pix? Looks like a sibling to mine! Is it a CNC Router Parts?

Thanks yet again!

[capnTelescope]

The last few days, I put the walls back up on the CNC for some finish cuts in the galley area. I didn't do this the last time up, because I didn't have a firm design for the hatch and needed to do some R&D. So I left some meat on the walls, pending a final decision on the hatch.

So I got the Left wall up on the table and started a dry run of the g-code. The laser pointer said the machine wanted to take about an inch off the end. Too much! This should be about 1/8". So I took a look at the drawing, and it agreed with the router. But how did I get the profile that got actually cut? It's still a mystery to me, but I went and got the Right wall out of the garage and took measurements The Right wall is about an inch shorter that the left. Now I felt confident enough to make the cut on the Left wall, so I did.

Next, I put the Right wall up, mirrored the g-code for the Left wall, as usual, ... and cut air. This is the end that has to be *right* if the hatch is to seal. Well, the only explanation I can think of is that I usually find out what doesn't work on the left wall, and fix it for the Right wall, and the two don't always agree. .

These two pictures show the offcut hunk from the Left, and clamps holding my first ever bent wood project on the Right.



I have g-code for the Hatch Spars. Tune in tomorrow for another exciting episode.

[vtx1029]

Here is what I was running ...

Thanks for the info, VTX.

I would have guessed a lower spindle speed, but nothing succeeds like success. What little I was able to find before suggested light depths of cut, which you are taking. About .003"/rev for the 1/4" and .002"/rev for the 1/8 ". This gives me a good starting point. Can't thank you enough!

I took a peek at your photo album. You do some very nice carving. Is that your CNC in a couple of pix? Looks like a sibling to mine! Is it a CNC Router Parts?

Thanks yet again!

oops I just saw a problem. I had my pass depth too high on that 1/8 bit. limit your DOC on the 1/8 to .025

Yep its a CNC router parts 48x48. I really wanted to go with the 8' Y but I don't have the garage space to spare for it. I'm hoping to put some profile linear rail and ballscrews on it some day.

Here are some more pictures. top one is of how I made my vacuum table. It uses 2 shop vacs. It works pretty good until you start making small parts.


Cutting out wing ribs for the aircraft I'm building.

Typical edge finish. I think with profile rail I could get a much better edge. (I think my bearings are a little too loose now as well)

More rib parts

Cutting 2024 t3 1/8 plate

[KCStudly]

Ooh la la!

[capnTelescope]

Wow, that's impressive. This makes building a Tear look like child's play.

Are you journaling your aircraft build anywhere? There's at least 2 people here (KC & me) that would like to look over your shoulder.

limit your DOC on the 1/8 to .025

10-4. You caught that in plenty of time.

Again, many thanks!