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

[RandyG]

+1 here on the aircraft eye candy!

[mikeschn]

vtx,

I can't make out your cnc table. Just wondered what you were using for the x axis? chain? rack and pinion? ball screws?

How about your Y and Z axis?

Mike...

[capnTelescope]

Ahhh. It was good to get back in the shop and make a bunch of router dust today. Three hatch spars got cut out. Without drama! Okay, just a little drama. The router got a little too cozy with one of my clamps:


Here they are stacked up, as alike as peas in a pod.


and laid out together:


different view:


The light colored zone in the center is a pocket for an aluminum stiffener, to be cut later. The odd one has the pocket underneath. These turned out very much to my satisfaction. They're as close to the same as you can get with wood. The rectangular pockets you see are for cross stringers to fit into. Rather than scab in a bunch of short pieces, the stringers will be dadoed to provide spacing and enforce squareness. The stiffeners are an idea I got from the teardrops.net Facebook page, and a build Grant Whipp is journaling there. He's been doing Teardrop builds long enough that I think he probably knows what he's doing.

Lots of video to edit. Stay tuned!

[KCStudly]

Those are fairly complex, even with a CNC router and CAD. Nice.

[vtx1029]

vtx,

I can't make out your cnc table. Just wondered what you were using for the x axis? chain? rack and pinion? ball screws?

How about your Y and Z axis?

Mike...

My X and Y are rack and pinion (stock CNC router parts stuff). The z is acme driven (its a K2 Z axis assy) . I uploaded some more pictures of my cnc in my gallery. I don't want to bogart this thread.

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.

I don't have anything online right now. There's a build log program that seems pretty good that has an online section but from my understanding the program has changed owners a couple of times and they don't respond to emails so I'm keeping my $ for now. The plane I'm building is a Bearhawk Patrol http://bearhawkaircraft.com/index.php/bearhawkpatrol I figure I'm on a 10 year build plan with 8.9 years to go.

+1 here on the aircraft eye candy!

Thanks I saw your handywork on your trailer frame build. I was really tempted to build an aluminum tear to pull behind my motorcycle but I have to many long term projects right now so...

[capnTelescope]

Video of cutting the hatch spars is up. About 15 minutes


I also managed to cut out my hinge blocks, stain the blocks and spars, and get a first coat of varnish on.


Enjoy!

[capnTelescope]

Those are fairly complex, even with a CNC router and CAD. Nice.

Thanks, KC. You shoulda been there.

Every feature on the spar, except 90% of the bottom edge, is critical for fit to the body and not leaking. Everything has to be just the right distance from the hinge hole. Plus getting the exact vertical location of the hinge blocks.

No wonder it took a while to design. (Besides that I don't work that fast.) I'm not sure I got it right yet, but I think it's close. It concerns me that I don't have any means of adjustment. Maybe some adjustment of the gasket? I'm going to build it out and see.

[vtx1029]

No worries on the clamp. Been there done that. Did you know that you can cut thru drywall screws

Question for you. Was there a reason why you didn't connect your vectors while cutting the outside profile on those parts and just run it as a single toolpath? It would have saved you a bunch of time. What bit are you running there a compression spiral?

[capnTelescope]

No worries on the clamp. Been there done that.

My guess is that anyone that hasn't, hasn't used clamps. Several of my clamps have hickeys on them. I always do a dry run an inch high with the laser on to check for that kind of thing, but the laser won't tell you where the collet is going.

Did you know that you can cut thru drywall screws

I know that a dado blade will. I also know that if you try to rout thru a washer, the washer wins.

Was there a reason why you didn't connect your vectors while cutting the outside profile on those parts and just run it as a single toolpath? It would have saved you a bunch of time.

Ummm. I've run into this situation where I did that and disconnected the part from all clamping before I got all the way around. I don't quite have CamBam under control yet. Since the CNC is my personal toy, I don't worry too much about optimizing g-code for cycle time. Plus, I'm only making onesie-twosies most of the time, so it takes less time overall (programming + cutting) to not stress over optimization. OTOH, it is much more fun to watch a well-optimized program run.

What bit are you running there a compression spiral?

It's a Bosch downcut, available at Lowe's for cheap. It works better than the Freud (available at HD), IMHO. I haven't tried a compression bit, yet. For one thing, bit longevity was pretty short at first. (See routing thru a washer, above.) And they're not available locally. And they're a little more spendy. Excuses, excuses. Next trip to Woodcraft, I'm putting one on the shopping list.

Thanks for stopping by!

[vtx1029]

No worries on the clamp. Been there done that.

My guess is that anyone that hasn't, hasn't used clamps. Several of my clamps have hickeys on them. I always do a dry run an inch high with the laser on to check for that kind of thing, but the laser won't tell you where the collet is going.

Did you know that you can cut thru drywall screws

I know that a dado blade will. I also know that if you try to rout thru a washer, the washer wins.

Was there a reason why you didn't connect your vectors while cutting the outside profile on those parts and just run it as a single toolpath? It would have saved you a bunch of time.

Ummm. I've run into this situation where I did that and disconnected the part from all clamping before I got all the way around. I don't quite have CamBam under control yet. Since the CNC is my personal toy, I don't worry too much about optimizing g-code for cycle time. Plus, I'm only making onesie-twosies most of the time, so it takes less time overall (programming + cutting) to not stress over optimization. OTOH, it is much more fun to watch a well-optimized program run.

What bit are you running there a compression spiral?

It's a Bosch downcut, available at Lowe's for cheap. It works better than the Freud (available at HD), IMHO. I haven't tried a compression bit, yet. For one thing, bit longevity was pretty short at first. (See routing thru a washer, above.) And they're not available locally. And they're a little more spendy. Excuses, excuses. Next trip to Woodcraft, I'm putting one on the shopping list.

Thanks for stopping by!

Can cam bam do tabs? I only tried cambam for 20 minutes and gave up and bought v-carve pro. Work holding sucks no matter how you cut it. I find my vacuum table is the most flexible when it comes to plywood work. Keep up the good work.

[capnTelescope]

Can cam bam do tabs?

Technically, yes. Can I do tabs with CamBam? Many tries, fewer successes. They either don't leave enough material to hold the part, or they leave so much it's a PITA to get the part free. Could it be... operator error?

Score! I went down to Metals 4 U today to get some 1/8 aluminum 4x4 ft. for my needs. The price was good enough. Then he asked me if I could use a 5x5 sheet for the same price. Someone made a mistake cutting the sheets. My first thought was "No, my table is 4 ft. wide. Drat." Then I remembered I inherited a jigsaw from my Dad. So I said "Yes." I got a square yard for free. (5x5=25) - (4x4 = 16) = 9 sqft = 1 square yard. Woo-hoo! Had to tie it down on the TV roof, it wouldn't go under the camper shell. BFD.

I also went by Woodcraft today, and inquired about compression bits for the router. All they had was a 1/2" bit for $85. I didn't want one that bad. I did find a tungsten carbide sanding block that will take care of the splinters on the "bad" side for 12 bucks.

[capnTelescope]

After being taken aback by the quote I got for welding up a simple trailer frame, I resurrected the the idea of doing it myself. I've been around welders quite a bit in my manufacturing career, but never once laid down a bead. Zero. Zip. Nada inch. Welding is something I've wanted to learn. I've looked at community college courses, but they're way down by downtown Austin, 25 miles at rush hour times. So that went nowhere.

But, not 5 easy miles from the house is a [url=techshop.com]TechShop[/url]! They offer a 2-hour intro class in MIG welding that teaches you the basics of turning the machine on, and a chance to make sparks. In 2 hours, I went from zero to this:

First try at the top, last pass in the middle.

On the back, final last pass:

I really wasn't drunk. I just couldn't see the seam I was supposed to follow.

I signed up for a 3-month membership to get some practice. We'll see if I can get good enough to think I'm capable of doing the trailer myself.

[KCStudly]

It's a start! I recommend that you practice on the same stock, and attempt to weld the same configuration of joints that you intend to use on your frame. Also, it is a good idea to cross cut a few of your practice welds (band saw) to confirm the depth of penetration you are getting matches the outward appearance and what you thought you were seeing when you were watching the puddle form.

Sometimes if there is back lighting it can reflect off the inside of your lens or glasses and make it harder to see. If this is the case you can try to reposition yourself, turn the offending light off, or shade it. Also, despite it being a safety no-no, when I am TIG welding and there is little to no threat of splatter, I will remove my prescription safety glasses (since I am wearing a full hood anyway) to eliminate the extra reflections (with my face down close enough to see the weld well, I can see better without my glasses anyway). I wouldn't do that with MIG, tho; too much chance of splatter (good reason to wear foam ear plugs, too).

Another trick is to focus your eyes out in front on the leading edge of the puddle, and use your peripheral vision to see that you are getting a good melt in. If you stare right at the arc you can lose the line. If you tack weld the parts in a few locations you may find that the tacks are more visible and can also be a guide. A slight bevel or root prep on thicker material will make it a lot easier to follow the seam, but you don't always want to do that with thinner materials as it can make them harder to weld without blowing thru. With experience, the correct heat settings/wire feed rate/torch motion
and travel speeds you should be able to put at least some bevel on anything 1/8 inch or thicker.

Don't forget to factor in the fact that you will need to flip your frame several times so that you are mostly welding down. I had the advantage of working in a production shop with overhead trolley hoists, so I didn't have to think that hard about it; I could flip my frame at will by myself. Without that luxury, I would have had to plan much better to optimize my work with fewer maneuvers, and enlist more help for each move. Just saying, it's something to consider.

[capnTelescope]

It's a start! ...

This was the easy part. Just needs practice, practice, practice. Torch (gun?) handling is really a lot like some of the exercises we used to do in Penmanship. Keeping the chassis "square" and "flat" strikes me as being a little bit tricky.

I'm not convinced yet that I can do this. At least they have a barrel full of practice scrap. For now, I'm counting the TechShop costs as tuition. I've been wanting to learn basic welding for a long time. They have nice equipment, plus the wire and gas is included.

The instructor suggested wearing cheaters rather than trying to adjust my head position for bifocals.

If you stare right at the arc you can lose the line.

That's no doubt what happened. He didn't really mention where to look.

... the tacks are more visible and can also be a guide.

Check.

Don't forget to factor in the fact that you will need to flip your frame several times...

I'm thinking maybe something made of 2x4's and steel pipe that would allow me to spin it around. Overhead welding is definitely out. Ain't even gonna try. Probably also vertical uphill/downhill.

[RandyG]

I bet there is a way to replace the motor on the cnc with a welding rod. Keep with it, like you said "practice".