You're own private block party...
just the thing you'll need when making
blocks... it's just not something that you can buy anywhere.
It's a tool that you'll need to make yourself. (ain't that
something... needing to make specialized tools)
A little background... when you go to bend your fittings, the drawing calls out for a certain radius on that bend. (Metals can only be bent to
a certain radius so that it doesn't stress the metal making it weak in that area of the fitting.) The only way you're going to make those bends with
those radii is to either buy bending blocks, with those radius or make them yourself out of steel, aluminum or hardwood.
If you're only going to made a few fittings with that radius, they say that hardwood would be fine. It does tend to distort the wood over a period of time, thus changing
the radius of that bend. Aluminum is good with metals up to around .090. Steel is good for any thickness of metal.
To make your own (I haven't found any out there for sale) you need to get a chunk of the material that you are going to use to make your bending block. A piece that is about 1/2" thick x 3" x 8" is what I used. Tony Bingelis suggests that
for most small bends a piece of steel or aluminum 1/8" or 3/8" x 3" x 8" should do the trick.
To make the bending block you'll need to grind/file down the corners of the material you have. Take a look at your plans to see what bend radius you'll need to make and then
go about grinding/filing those on the material you have. Tony Bingelis suggests 1/16 inch, 1/8 inch, 3/16 inch and 1/4 inch, unless you have some specific radius that is called out on the plans. Be sure
to mark each corner with the radius that you've ground it to.
I've decided to put only two radii on a block so that 90 degree bends can be made with them. In order to make a 90 degree bend you need to bevel the edge coming off the radius a few degrees. There is a spring-back to the metal, you'll need to bend it past
the 90 degree allowing it to spring-back to the desired bend. With that being said... only two corners can have a radius on each block.
Important schtuff:Before making any of your bends, it's imperative that you sand/file all the edges to a smooth finish. I grind my fittings down to a very close shape and then finish it off with an 80 grit then a
120 grit sandpaper. Gives it a beautiful smooth finish.
Update: April 20, 2008
I wasn't entirely happy with how my hand made bending blocks turned out so I investigated the art of routing them.