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    Apr 2012

    Default Frame & bracket tech

    Below is a pic of one style of clamps that I make, followed by a drawing with dimensions of those same clamps. They're not really difficult to make but they are pretty time consuming. I use these particular clamps to run 3/8” ID (5/8” OD) hoses along the 1-1/8” frame rails on touring bikes in order to remote mount the oil filters because the factory location is one of the bigger pains in the ass that H-D ever came up with. They also work well with cables if you sleeve the 5/8” holes in the clamps with 1/2” long pieces of hose.

    I’m going to write this as if you were going to make these exact same clamps so that the dimensions I list here will make sense to you as you look at the pic and the drawing. As for instructions on how to make them, the short version is: “Drill the right size holes in the aluminum and then cut it in half.” The more in-depth version goes like this:

    1. Scribe a center line across the width of the piece of aluminum that you’ll be working with so that all holes will stay on the same centerline. You’ll want it 1/2” thick and 6061-T6 is your best bet as far as alloy goes. It’s inexpensive, readily available, and easy to machine. Contrary to popular belief, not all aluminum alloys are as easy to machine as others.

    2. Drill or hole-saw the 1-1/8” hole and the two 5/8” holes. You want to drill the holes at the same size as the OD of the frame tube and the OD of whatever hoses or cables you want to clamp onto. When you make the cut it will change the hole dimensions in one plane only, meaning that the clamp will still easily fit the tube & the hoses, yet still give a good, solid “interference fit” when the clamps are tightened down.

    3. Using a #7 drill bit (.201” diameter) drill 1.4375” deep, 1/4” from the end of the aluminum and 1/4” from the side (this will be the center as far side-to-side goes). You want to drill this hole before you cut so that the holes in the top half and the bottom half of the clamp will line up perfectly after you make the cut. You could drill all the way through and make it easier to tap the top halves but that’s pretty cheesy. As far as that goes, you could drill all the way through at 17/64” and use nuts & bolts instead of tapping them at all, but that would be so cheesy that people would laugh at you.

    4. Cut it in half just like in the pic. If necessary, you can cut slightly off center so that you end up with a deep half and a shallow half, but if you cut too far off center the deep half won’t fit over the frame tube.

    5. Using a 1/4”-20 “bottoming” tap, or “modified bottoming” tap, tap the holes in the top half of the clamp. I personally use (and really like) spiral flute taps for hand tapping aluminum. Instead of filling the hole with chips a spiral flute tap will pull the chips up and out of the hole in long, continuous pieces. For only a few holes, WD-40 or light machine oil will be okay to lubricate the tap. If doing more than a few, or if you anticipate tapping more aluminum in the future, “Tap Magic For Aluminum” is excellent. Pic of spiral flute tap is at the bottom.

    6. On the bottom half of the clamp, enlarge the .201” though-holes to 17/64”.

    7. On the bottom side of the bottom half (the straight side) add a 3/8” counterbore, 1/4” deep, to the holes you enlarged in the previous step.. This allows the screw heads to recess into the clamp as shown in the pic.

    8. Slightly radius the top 2 corners of the top half of the clamp as shown in the pic.

    9. Use 1/4”-20 x 1-1/4” long, 18-8 stainless steel socket head cap screws (allen heads). Do not install the screws dry. Stainless into aluminum, installed dry, can easily “gall” and seize. Many people use anti-seize. I use blue Loctite as it still creates a barrier between the dissimilar metals and prevents galling, as well as keeps things from rattling apart.

    10. Finish accordingly. I use these underneath bikes so the sanded finish shown (80 grit belt) is satisfactory. Another nice thing about 6061-T6 is that it polishes out nicely if used in an exposed area.
    I’m pretty sure that’s all of it. It’s late and I’m old & tired, so if something here doesn't make sense to you, please don’t be afraid to question me on it.

    Last edited by Nottso; 04-02-2013 at 10:38 AM.

  2. #2

    Default Frame & bracket tech

    Konging a Frame

    Building a frame or rigid, bolting or welding on a hard tail? Changing rake or otherwise modding a frame? Post the process up.

    Brackets / Pivot, mounts etc.:

    Brake Rod Extending

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