Author Topic: '73 500 - Subframe Fabrication (Read 142332 times)

calj737 · « **Reply #375 on:** August 19, 2015, 07:05:47 PM »

Actually, the shock angle will be almost dead-on stock. I am delaying the shock gussets until the swing arm is mocked-up so that we can insure the angle and alignment to stock geometry. The overall length of the shock may change slightly because the seat hoop is just slightly above parallel and the stock hoop "droops" (which is a big reason we made this unit).

By the way, thanks for the kind words everyone

slikwilli420 · « **Reply #376 on:** August 19, 2015, 07:06:35 PM »

Quote from: calj737 on August 19, 2015, 06:57:15 PM

Correct, 0.375 wall. Just because .093 was used, doesn't mean I am. There's virtually no weight detriment but theres huge strength and rigidity benefits to it.

Ok now I see. I didn't realize you were using aluminum tubing. That thick wall steel would be unnecessary and EXTREMELY heavy. The seeley arms were 093 wall steel.

Bootsey · « **Reply #377 on:** August 19, 2015, 09:10:25 PM »

That's some interesting & impressive work Cal - nearly as impressive as the safety footwear.

calj737 · « **Reply #378 on:** August 20, 2015, 04:20:04 AM »

Leather shoes, Bootsey. One benefit of TIG welding is no slag or splatter. U.S. Southern boys are a tough lot; maybe not the most safety-minded, but tough nonetheless.

70CB750 · « **Reply #379 on:** August 20, 2015, 05:08:09 AM »

Ha, welding in crocs teaches interesting dance steps

Nice and inspiring , Cal!

calj737 · « **Reply #380 on:** August 20, 2015, 05:13:28 AM »

Thanks, 70CB. Need all the control with my toes on the pedal. If I MIG or Stick, it's full gear. But when it's about 90* inside and you're cranking out about 2,500* of arc, safety shoes are out the window -

MessnerMoto · « **Reply #381 on:** August 20, 2015, 05:49:47 AM »

Quote from: calj737 on August 19, 2015, 05:45:06 PM

And the pieces ready for fitment to the frame. The "tenons" we're milled from cold rolled steel and will be welded to stock frame. A rough mock up-

This is very impressive work! Did you maybe do some kind of calculations FEA to now what tubing to choose ?

calj737 · « **Reply #382 on:** August 20, 2015, 06:00:36 AM »

just the standard materials specs of material v material. Since I am not altering the supporting geometry, the analysis wasn't really mandated, unlike another of my projects.

knowsnothing · « **Reply #383 on:** August 20, 2015, 07:26:34 AM »

Impressive work Cal! Curious (you might have mentioned this and i missed it, i like pictures more than words

), why did you make the subframe removable instead of welding it in?

calj737 · « **Reply #384 on:** August 20, 2015, 07:52:37 AM »

A couple of reasons:
1. We wanted the hoop to be fully parallel to the ground, and slightly upswept at the rear.
2. We reshaped the seating area with a taper to narrow the position and bring the knees closer together
3. Weight/Strength benefits of aluminum over the thin walled steel
4. Aluminum is much easier to work in terms of bending than steel
5. Wanted a "modern" approach to the connection technique. Almost all modern bikes have a bolted subframe now

Because the seat hoop bends in 4 directions, and I'm a backyard/shade tree builder, its easier to rely on aluminum to heat, bend, torque, heat, tweak until you get it right. After it cools, it sticks where you put it very well. I don't have a CNC bender so creativity, muscle and old-fashioned leverage were the primary tools. And, its over 4 pounds lighter and much, much stronger than stock. And I like to be a tad "different" on some things, truth be told.

MessnerMoto · « **Reply #385 on:** August 20, 2015, 08:18:52 AM »

Interesting. And when tubing is heated does material loose some structural strength?

knowsnothing · « **Reply #386 on:** August 20, 2015, 08:20:38 AM »

Quote from: calj737 on August 20, 2015, 07:52:37 AM

A couple of reasons:
1. We wanted the hoop to be fully parallel to the ground, and slightly upswept at the rear.
2. We reshaped the seating area with a taper to narrow the position and bring the knees closer together
3. Weight/Strength benefits of aluminum over the thin walled steel
4. Aluminum is much easier to work in terms of bending than steel
5. Wanted a "modern" approach to the connection technique. Almost all modern bikes have a bolted subframe now

Because the seat hoop bends in 4 directions, and I'm a backyard/shade tree builder, its easier to rely on aluminum to heat, bend, torque, heat, tweak until you get it right. After it cools, it sticks where you put it very well. I don't have a CNC bender so creativity, muscle and old-fashioned leverage were the primary tools. And, its over 4 pounds lighter and much, much stronger than stock. And I like to be a tad "different" on some things, truth be told.

Works for me

calj737 · « **Reply #387 on:** August 20, 2015, 09:42:49 AM »

Quote from: MessnerMoto on August 20, 2015, 08:18:52 AM

Interesting. And when tubing is heated does material loose some structural strength?

Not aluminum. It's being annealed to make it workable, not heated enough to melt. When you TIG aluminum, it's reverse polarity and takes a lot more heat to weld it. The swing arm planned for this bike is 0.375" wall and I'll probably either pre-heat it with a torch if I can't borrow a water-cooled MIG fixture. Else, it will be almost too hot to work on (I'll have to wear boots that day).

SOHC4 Cafe Racer Fan · « **Reply #388 on:** August 20, 2015, 10:04:39 AM »

This swingarm will be not only lighter but stronger than the stock mild steel tube-based swingarm.

Cal, is there any need to heat or cryo treat the aluminum swingarm after assembly? I hear that the MGP milled swingarms are cryo treated for hardness, but wasn't sure about yours.

calj737 · « **Reply #389 on:** August 20, 2015, 10:11:05 AM »

I would fully expect that Cryo is a great step for a high stress/rave application. Mine is not considering that. It may also have to do with the method the extrusion is made under for the MGP.

The legs on my arm will be much heartier, and there will be a boxed structure behind the pivot tube to provide lateral strength and reinforce the independent legs.

Let's not forget, this bike is being conveyed to a solo rider only, so some manufacturer liabilities can be abandoned and other considerations don't apply.

70CB750 · « **Reply #390 on:** August 20, 2015, 10:16:22 AM »

Quote from: MessnerMoto on August 20, 2015, 08:18:52 AM

Interesting. And when tubing is heated does material loose some structural strength?

The funny thing with aluminum is that heat makes it soft to bend and it stays soft for short time but in few days it goes back to original strength.

SOHC4 Cafe Racer Fan · « **Reply #391 on:** August 20, 2015, 10:21:48 AM »

Looking forward to more updates. The latest ones were definitely worth jonesing for!

754 · « **Reply #392 on:** August 20, 2015, 10:29:51 AM »

Not all aluminum age hardens. Your welds and bend areas are probably. In 0 temper now, so at around 1/2 strength of T6 hardness.
The swingarm if aluminum..you do plan on heat treating it, correct.?
The subframe should look cool polished..

calj737 · « **Reply #393 on:** August 20, 2015, 10:45:37 AM »

A polished finish definitely under consideration

scottly · « **Reply #394 on:** August 20, 2015, 09:38:22 PM »

Quote from: calj737 on August 19, 2015, 05:34:54 PM

Used some heat and a tubing bender to hand shape the tubes

Came out pretty close. TIG welded the rear closed with a miter cut piece, then heat bent the "kick" into the rails.

While you don't have to worry about slag dropping onto your feet while Tig welding, you DO need to be concerned about exposure to intense UV rays, especially when welding aluminum. The first time I welded aluminum, I was wearing a white long sleeve linen dress shirt. I only did a 4" long filet weld on some 1/4" thick stock. The next evening, my torso felt irritated, and when I looked, I was beet red from a distinct horizontal line just above my belly button, where I was bellied up to the steel table, to just below my chin where the bottom of the helmet ended.

70CB750 · « **Reply #395 on:** August 21, 2015, 04:09:13 AM »

I worked with a guy who never wore gloves for welding or plasma cutting. His hands looked accordingly.

calj737 · « **Reply #396 on:** August 21, 2015, 04:10:30 AM »

Quote from: 70CB750 on August 21, 2015, 04:09:13 AM

I worked with a guy who never wore gloves for welding or plasma cutting. His hands looked accordingly.

Probably like my feet!

Stev-o · « **Reply #397 on:** August 22, 2015, 08:54:20 AM »

Quote from: Tews19 on August 19, 2015, 06:17:43 PM

UMMM, when do I move in ?

Do I sense a Bromance?

Impressive work, Cal....can kinda understand why Tews wants to live with you!

calj737 · « **Reply #398 on:** August 22, 2015, 08:59:11 AM »

He just wants me to be his Daddy and build him a bike like this. I've offered him the "Son of Mine" package, but he balked at the workload!

Restoration Fan · « **Reply #399 on:** August 23, 2015, 05:25:23 PM »

Quote from: calj737 on August 22, 2015, 08:59:11 AM

He just wants me to be his Daddy and build him a bike like this. I've offered him the "Son of Mine" package, but he balked at the workload!

Hold on, I called dibs on that deal a while ago. I'm a hell of a hard worker; especially when it means someone else pays for the stuff I usually have to pay for.

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Author Topic: '73 500 - Subframe Fabrication (Read 142332 times)