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Scrappers tube bending jig

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Little Scrapper

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Thought maybe someone could one day use this as an idea one day.

I realize there's people who simply grab tubing and bend it around a telephone pole out back and that certainly works. It just doesn't work for me. Everyone needs to find a way that works for them.

For me at least, I enjoy the process. I enjoy what that process teaches me. Precision is a challenge and it's the challenge itself that I find rewarding because of the person you become after you nail success.

I love my little Black and Decker laminate trim router. It's a product of the 1980's and spins at an incredibly fast RPM. It is a tough old router and has a sole plate made of Micarta and is held on by 4 little screws.

I removed the sole plate and made a aluminum jig using the sole plate as a pattern. This aluminum jig is a radius jig and the radius is adjustable by drilling holes in the right location.

The project is my fin leading edge on the Cassutt which is 1/2" tubing. The bit I used is a $5 round bit from Amazon, they are available at any Ace hardware store.

Once routed then jig saw them apart, nothing fancy.

The goal is to cut to pieces and sandwich them together. The hole in the cheap particle board is used to turn the chosen radius. The later on, that same hole and screw is used to clamp them together.

Once clamped, use a couple C clamps to really hold them. Pre drill one side, and screw the two pieces together.....on one side only.

I use my home made 12" disc sander but anything will work. Smooth the outside (optional but why not).

Then screw to table, pre drill because particle board isn't tolerant of screwing.

Hold up scrap piece of tube and use blocks to hold one end.

Shove tube in and bend.

Now you have a jig for life. This jig will bend 1/2" and if you tape the inside cove you can even bend 3/8" & 1/4".

The aluminum jig is also a life long tool that will be used for turning any diameter you like.

Photos to follow........
 

Little Scrapper

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Photos.
IMG_20171217_085814434~2.jpg

IMG_20171217_083122457_HDR~2.jpg

IMG_20171217_083627816~2.jpg

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Rough cut the pieces out with a jig saw.
IMG_20171217_084417437_HDR~2.jpg

Clamp together.
IMG_20171217_084816735~2.jpg

Sanding is optional.
IMG_20171217_085431164~2.jpg

Check your work before mounting to table.
IMG_20171217_085535878_BURST000_COVER~2.jpg

Mount jig. Mount holders.
IMG_20171217_091648804~2.jpg

Bend. The result gave me a flawless piece with absolutely zero defects. The jig cost nothing but time, about an hour.
IMG_20171217_091825859~2.jpg
 

Little Scrapper

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That's awesome, thanks for taking the time to share that!
You're very welcome. This was an experiment, I had an idea and didn't know if it would work. Really glad it did work, I enjoyed the challenge of thinking this through last night on the couch. Haha.
 

Little Scrapper

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Don't think It's luck.
What I was nervous about was getting it right the first try. If the bit depth was wrong I'd need to redo everything.

My first idea was to rout the outside is one pass (not two halves) but couldn't wrap my head around how to rout that.
 

Little Scrapper

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Any experience with how far you can bend it without kinking the tube? I presume that is a bend radius thing. Slow and steady I’m sure!
I don't know the answer to that, but I could feel as I bent the 1/2" .035" that maybe a 4" radius might be possible cold. I'm guessing, but based on feel I bet I could. Mine was a 6" radius.

If I did it hot I would coat the jig in either a black soot flame from a torch or aluminum duct tape to prevent wood burning. Black soot is best.

The problem I had with hot (Baby Ace tail) was that it stretched the outside radius of the tube and didn't transition well so I tossed it.

Cold is probably best I think.

1/4" on my Baby Lakes tail was hand bendable without kinking. Really a tight radius on 1/4". When you go to 5/8" or 3/4" things get pretty dicy because it's so stiff.

There's a photo on the "Pirate Cub" Facebook page of him bending the mail parts on a vice clamped jig. It's really difficult.
 

Little Scrapper

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The following photos are the property of Charlie Becker from the EAA and his "Pirate Cub" page on Facebook.

Everyone has a different process, his was much stiffer to work with because the tubing is 3/4" .035". That extra 1/4" diameter from mine to his is a world of difference.
FB_IMG_1513535847412.jpg

FB_IMG_1513535840551.jpg

FB_IMG_1513535829246.jpg
 

Little Scrapper

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I had 2 ideas that I decided to not pursue.

1.) Carefully cut a round circle with a jig saw and grind it perfect as possible on the disc sander. Then drill a center hole and Chuck it in the drill press. While spinning I'd use a big rat tail file and grind a cove as it rotates. This seemed risky so I abandoned it.

2.) Mount the same round wood chunk on my bench grinder and carve a cove with a home made turning tool. This seemed ludicrous and deadly so I abandoned that too.

3.) Final rendition you see in photos.

I do think there's a promise in rotating a piece in a drill press and using wood turning hand tools to carve/cut the coved radius.

The arbor you chuck in the press would need to be stiff and stable and it would need to turn at about 200 rpms maybe. Any faster and the vibration from lack of proper balance could get dicy.

If I did it I would use an arbor that passes through the disc and some sort of hole it could spin in mounted to the drill press table. Guessing that would be prudent.

This could be a fun way to make one but you'd need the right turning tool.
 
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