Super thin titanium rudder blades.

[Terry Keeley]

A little shaky but I was crankin' a handle at the same time!

 

[Jim Allen]

Terry,

I use fixtures to cut the wedge angles on Titanium, steel & aluminum rudder blanks. The rudder blanks are clamped to the fixtures at both ends making the entire setup very rigid for machining. What ever angle is necessary for the width of the rudder blade is computed with trigonometry & that angle is set up with a sine bar on the heavy aluminum fixture. The fixture is easy to set up with it's base sitting on precision parallels in the milling machine's vise. By flipping the blank around & re-clamping, both angles on the rudder blade must be exactly the same since the fixture has not moved.

JA

 

[Terry Keeley]

Well I only had one of them break through, was one of the 3/64" holes I did on the mill, otherwise no scrap. Might be able to patch it with a little JB weld and use as a backup.

I figured I only had about 0.015" clearance on a couple sizes and they're all good, I'm happy.

 

[timothy johnson]

Really nice stuff Terry!! Will they be for sale or are you just taunting us?

 

[Terry Keeley]

Really nice stuff Terry!! Will they be for sale or are you just taunting us?

Sorry, just for personal consumption. Here's some real taunting!

 

[BobHorowitz]

Terry,

Nice job. Keeping it nice and simple. I would have thought you would use some kind of special fixture like Jim is talking about. That's hanging alot out in the air, but it seems to work fine. Do you do some post milling polishing.

Bob

 

[Terry Keeley]

Terry,

Nice job. Keeping it nice and simple. I would have thought you would use some kind of special fixture like Jim is talking about. That's hanging alot out in the air, but it seems to work fine. Do you do some post milling polishing.

Bob

Nope, that's the finish right from the cutter.

It's a setup my toolmaker buddy Rudy came up with, works very well. I take the 1st 0.100" with a cobalt roughing end mill and finish up the last 0.020" with carbide. LE left is 0.010" to be hand sharpened.

 

[Charles Perdue]

Terry,

I use fixtures to cut the wedge angles on Titanium, steel & aluminum rudder blanks. The rudder blanks are clamped to the fixtures at both ends making the entire setup very rigid for machining. What ever angle is necessary for the width of the rudder blade is computed with trigonometry & that angle is set up with a sine bar on the heavy aluminum fixture. The fixture is easy to set up with it's base sitting on precision parallels in the milling machine's vise. By flipping the blank around & re-clamping, both angles on the rudder blade must be exactly the same since the fixture has not moved.

JA

I do the same. The only difference is I bought a bar of 7075 T6 aluminum the same size material as the jaws in my mill vise, just a little taller. I machine my holding fixtures right into the jaws in the vise. This makes a VERY sturdy, accurate and simple fixture. I do this for my Zoom carb fixtures also. To replace the fixture just replace the soft jaws.

I like soft jaws and I like simple

Charles

 

[David Ashcroft]

Terry Great work.. I would pay top dollar for a super fine 60/80rudder. ;-)

 

[Jim Allen]

Good job Terry, You can save yourself a great deal of material with the fixtures shown. They sit on a pair of precision parallels & they are extremely rigid. The fixtures also make the time consuming tilting of the milling machines head & re-tramming unnecessary. Sometimes rudder blanks are screwed to the fixtures which saves even more material. Water inlet holes in the side of blades are drilled before the wedge is cut. The same type fixtures are used for 1/8" thick steel rudder blades & 1/16" thick steel skid fins. Steel parts are hardened & tempered after machining.

JA

 

[Terry Keeley]

Yup, I do end up cutting off 3/4" of material so there is a bit of waste. Use a sine vise tho for the angles so don't move the head.

I'm not quite "seeing" your fixture Jim, is it adjustable? Or do you make a different fixture for different wedge angles?

 

[Jim Allen]

Terry,

The fixtures are not adjustable. When I need a smaller width rudder blade, I reduce it's width while it is still in blank form on both ends. All of my blades have tapered back edges which are done in blank form & I drill the water passage way last. Locating the water passage way is easy because the blank it still a rectangle on both ends & it can be easily mounted on a precision angle plate. I also press a hardened steel piece in the hole where the shear pin is to be mounted. Different width wedges, on identical blade shapes, will produce different amounts of lift to the rear of the boat when the speed is constant. This is also true for wedges of same width & different lengths.

JA

 

[BobHorowitz]

Terry,

How do you hold the blade when you cut all the excess off the back of the blade?

Bob

 

[Terry Keeley]

Terry,

The fixtures are not adjustable. When I need a smaller width rudder blade, I reduce it's width while it is still in blank form on both ends. All of my blades have tapered back edges which are done in blank form & I drill the water passage way last. Locating the water passage way is easy because the blank it still a rectangle on both ends & it can be easily mounted on a precision angle plate. I also press a hardened steel piece in the hole where the shear pin is to be mounted. Different width wedges, on identical blade shapes, will produce different amounts of lift to the rear of the boat when the speed is constant. This is also true for wedges of same width & different lengths.

JA

Thanks Jim! You touched on a subject no one else has mentioned, that is lift caused by different rudder shapes and profiles.

Years ago I was having a high speed lifting type "flutter" with my 40 boat, tracked it down to the tapered LE/TE rudder I was using. Went to a straight blade and it went away.

Terry,

How do you hold the blade when you cut all the excess off the back of the blade?

Bob

I cut most of it off with my little 4 x 6 bandsaw then finish it up in the mill, aluminum shims help hold the wedged section.

 

[steve wood]

These are my fixtures for rudder blades.

1. Fixture for drilling side hole on correct angle

2. Fixture for drilling long water hole

3. Special jaws to hold 7075 blank solid, so it won't chatter. Works perfect

4. Fixture to hold rudder to mill off excess material from back of blade, no chatter at 4500 rpm and about 20 inches a minute

5. Custom ground tapered end mills from the conical tool co. For different blade widths.

 

[steve wood]

Pics are out of sequence. Far right one is #1,then left to right

 

[Terry Keeley]

These are my fixtures for rudder blades.

1. Fixture for drilling side hole on correct angle

2. Fixture for drilling long water hole

3. Special jaws to hold 7075 blank solid, so it won't chatter. Works perfect

4. Fixture to hold rudder to mill off excess material from back of blade, no chatter at 4500 rpm and about 20 inches a minute

5. Custom ground tapered end mills from the conical tool co. For different blade widths.

Very cool!

Neat to see how others get the job done.

How are you drilling the long hole? ie: stub, taper aircraft length? Parabolic flute in one shot?

 

[steve wood]

Spot drill,standard length drill, then long titex parabolic flute drill(in a da collet) to depth, with copious amounts of wd-40, peck drill on a 5 to 7 count

 

[BobHorowitz]

Steve,

Nice fixtures. You obviously spent some time and thought on them. I like the way you're doing the tapers with tapered end mills instead of angled fixtures. Much simpler. Sweet setup. I always say 95% of the job is how to hold the part. Rigid, rigid, rigid.

Bob Horowitz

 

[Terry Keeley]

Finally got back to these and finished them up, pretty happy with the way they came out.

The 90 rudder is 0.150" thick down to the 20 size which is only 0.100". Looking forward to see how this translates on the water!