Bending a short stuffing tube?

[rickwess]

Knowing that I'll have maybe 2" of stuffing tube in my mono, while I'm waiting for parts I thought I'd practice bending the

After a few attempts, this is what seemed to work best:

• Cut a piece of brass tube about 4" long.
• Anneal the brass tube.
• Insert a K&S bending spring inside the tube.
• Insert the tube into the hole in the transom.
• Using the exposed part of the spring, I pulled up and the tube bent as I pulled up
• Remove the tube from the boat, remove the spring and dremel the tube to the right length.
• Deburred the tube and put it back into the transom hole.
• Line up the motor and tweaked the tube to align it perfect.

Does that sound about right or is there a simpler way?

Also, I see an advantage of not rehardening the brass tube so to make any final adjustments easier. If I plan on using a teflon liner, how important is it to reharden the brass tube.

Thanks in advance.

[rickwess]

BTW, it's this very step that I worry about the most. Lining up the stuffing tube with the motor is the most intimidating part about the build to me. Never have done it before and learned tons over the last hour.

[srislash]

Good for you Rick. It is not so bad. I usually try a couple test pieces till I'm happy with it. It can b hard making it form that imaginary line.

[tlandauer]

I find that by leaving a bit of leeway on both ends of the curve, I don't immediately cut the tube to the correct length, come times with the curve pretty much right on one still needs to fiddle abit to line up with the motor perfectly, having that extra bit helps. I realize of course that is how I do my builds.
I use a solid shaft ( rod) of the correct dia. to line up the tube. For 1/4" tube I get .187 rod and cut to a length that will give me a good indication of how the angle should be.
just my $.02

[tlandauer]

It's always interesting to see that how many ways one can bend a brass tube. Since I mostly use 1/4" tube (.150 with liners and .187 w/o). I have used a .187 flex cable covered with a .150 silicone liner as my tool. ( yes, it is a struggle to pull/push that line over a cable that it wasn't designed to go over, but entirely possible) This goes into the 1/4" very snug, and I bend without concern of pinching the tube, there is no way that this will happen---the .187 cable with that liner outside have no gap whatsoever once it is inserted to the tube. I don't anil as that is beyond me...lol
I thought the K&S bending spring go over the tube, not inside it?

[rickwess]

The challenge of course is the short length of tube. I found I could only bend it when it was at least 4" long and while in place. That way I could be certain that the first 1/2" remained straight.

I didn't have a bending spring large enough to fit over a 9/32" tube so I made due. Going to try to find a larger one.

[mattmak]

The K+S springs go inside.

You can use a tube bender. I've had good luck with the one Darin suggested and he used for the Sitletto oiler mod. You can make many slight bends to get the shape you want. Princess Auto $13 - Tubing Bender SKU: 2910677

I've also toyed with the idea of making my own tube bender with the exact radius I need. Cut a perfect circle out of 3/4" MDF, put that circle on a drill press to carve out a channel on its edge appropriate for the tube, then build the handle/bender part and bolt it to the MDF circle. Actually can re-use the purchased bender's handle with a custom pivot arm.

[rickwess]

The K+S springs go inside.

You can use a tube bender. I've had good luck with the one Darin suggested and he used for the Sitletto oiler mod. You can make many slight bends to get the shape you want. Princess Auto $13 - Tubing Bender SKU: 2910677

I've also toyed with the idea of making my own tube bender with the exact radius I need. Cut a perfect circle out of 3/4" MDF, put that circle on a drill press to carve out a channel on its edge appropriate for the tube, then build the handle/bender part and bolt it to the MDF circle. Actually can re-use the purchased bender's handle with a custom pivot arm.

LOL. I guessed right then on the springs.

I have that tubing bending on my list of things to get today. The brass gets pretty soft once annealed so I had hoped it would work well. I'm also hoping that gradual bends can be accomplished, knowing full well it will all depend on my patience level at the time.

The radius of the stuffing tube bends we're using are pretty large, or at least that's what I think they are without actually measuring one. I'm guessing a 6-8" radius for what I need right now. That's a big jig.

[mattmak]

6 to 8" is big but not impossible. I guess it depends on if it is worth the effort of building a jig vs trial and error. If you only need one good one, then multiple attempts of practicing sculpting it without a jig might be a better way.

I was bending a larger length, then cutting out the segment that worked best. That way I can get a bit of straight portion on one end of the curve.

It does get soft so you can bend it over anything probably even without the tube bender tool. Go to the wreckers and get a 14 to 16" honda civic rim :)

[tlandauer]

I certanily am glad that you guys think the springs should go inside---I read the instruction and several other tutorials and came with the impression that is other wise.

http://www.youtube.com/watch?v=-gxqBIN-Awg

Here is from Tower:

NOTES FROM OUR TECH DEPARTMENT



This is a Tubing Bender Kit from K&S Engineering.

FEATURES: Handles 1/16" to 3/16" Brass, Aluminum and Copper tubing
Supports the tubing and creates a kinkless bend
Insert tubing into the bender, then bend around a dowel or bar stock
Includes four different sizes of benders
Carded packaging


My point is not to argue with you, I am gleefully happy that one can put the spring inside for I believe it is the supurior way of achieving the correct bend. The only thing is that IMO even with the correct dia. spring, it is still not snug eough for my taste. The spring inside is loose in comparison, for that matter if you choose to use it outside, same thing. ( now the spring is too loose outside). I have observed an ever so slight deform around the bend. My method had not produced any kinks , the inner curve will have rinkles where as the bend with the K&S spring does not---there is lateral room inside or outside the spring , depending your choice of method. but I can only have this on 1/4'' tube as I have not found the necessary "tools' for the larger tube that you are bending.
I am glad to have read your findings. I am only hoping this will encourage more input to this great thread you started.

[rickwess]

I read that as well on the packaging. I did always think you needed internal support on the tube to prevent pinches from occurring. For me anyway, it's a moot point given they don't have a piece that fit over a 9/32" tube. One of the springs however fit very tight inside the tube.

For bending a Cat or Hydro stuffing tube, you'd have no choice but use the spring on the outside. A flex shaft of the appropriate size would work the same.....1/4" for 9/32" for example.

I see HomeDepot has Brasscraft bending springs. That could be my fall-back if the tub bender doesn't work out

[tlandauer]

Thanks, good to know, glad to learn that spring fits inside the 9/32" tube. I know there are different thoughts here but I prefer a liner and if this works out my next tube would be this size with a liner using .187 cable!

[mattmak]

Well, I never read the instructions. I assumed they were support for inside the tube as others describe using flex cable or sand etc to support the inside. To me the "bender" is not the K+S spring, but the tube bender like this. Also, it made sense to me, in the case of a flex stuffing tube, that you want the inside of the brass tube to remain its original diam; the outside can change based on how the metal stretches, but the inside will stay the same as the K+S spring that was used to support it from the inside.

However, I recently used the Dubro 5/32 tube bender kit and its included tubes and it doesn't use support inside the tube to be bent. The one thing it has going for it is that its support structure is solid, whereas a spring could expand if something inside it was pushing on its insides.? Maybe not. I dunno.

I'd like to add a detail - I did sand down the sharp end of the K+S spring and greased it up.

[RaceMechaniX]

I have several tricks for this: Don't anneal the tubing I have always found it better not to. Find some fine wire solder and fold it end over end and twsit to build it up make a rope that just barely fits on the inside. Start with a much longer piece like 12" and bend in the middle. You should have ample leverage on either end to bend it. Pull the solder out and trim the ends to fit your boat.

TG

[rickwess]

I found the non annealed tube unpredictable. By that I mean difficult to put a little bend into. Just when you thought you have just enough force being applied, it kinks. I'm just going to have to buy more tubes and experiment.

My particular complication on this build is I want to solder a short (1/2") piece of 1/4" tube into the 9/32" tube so the 1/4" tube will insert into the stinger. I was planning on joining the two pieces first since it will be much more difficult if the 9/32" tube isn't perfectly straight on one end. That would mean bending from one end of the rod.

I see I have lots of experimenting to do.