Author Topic: '73 500 - Subframe Fabrication (Read 142256 times)

riverfever · « **Reply #450 on:** June 22, 2016, 10:28:31 AM »

Exactly. Just needs a ball and a wall. Or....a bucket of hard boiled eggs and a bit of time.

calj737 · « **Reply #451 on:** June 22, 2016, 01:22:46 PM »

I've been substitution my head for the ball, and have an 8" solid concrete wall just off the porch with ample forehead dents. Luke had nothing on me as I've spent 25 years in this jail called Parenthood

SOHC4 Cafe Racer Fan · « **Reply #452 on:** June 22, 2016, 01:50:26 PM »

Quote from: riverfever on June 22, 2016, 10:28:31 AM

Exactly. Just needs a ball and a wall. Or....a bucket of hard boiled eggs and a bit of time.

RAFster122s · « **Reply #453 on:** January 23, 2017, 12:15:36 PM »

So, in the 6 months since this thread has been touched, anything happening on the bike?

calj737 · « **Reply #454 on:** January 23, 2017, 12:39:08 PM »

Awaiting a rear hub. Once that's done, the swingarm geometry can be completed. Then, it's off to a friends to have the main frame tubing remade from TG&P CroMo.

My son is still designing and prototyping a tail light, seat cowl, and a tank. We have been pretty busy with working on our cars, trucks, finishing the garage/shop, helping a buddy with some welding and fabrication, etc. Just life getting in the way of fun it seems.

rickmoore24 · « **Reply #455 on:** January 23, 2017, 12:54:17 PM »

Not to bring up old stuff, but I just read the bit about your son dropping your bike and I'm sorry about that but I think you handled it the best way it could have been handled. Well done.

calj737 · « **Reply #456 on:** January 23, 2017, 12:57:26 PM »

Heck, where we live, it could have been a whole lot worse. Good lesson to anyone, always wear full protective gear. Even a few miles from home.

SOHC4 Cafe Racer Fan · « **Reply #457 on:** January 23, 2017, 01:29:12 PM »

Quote from: calj737 on January 23, 2017, 12:39:08 PM

Awaiting a rear hub. Once that's done, the swingarm geometry can be completed. Then, it's off to a friends to have the main frame tubing remade from TG&P CroMo.

I'm paddling in the same boat with you as to the hub. What is TG&P?

slikwilli420 · « **Reply #458 on:** January 23, 2017, 01:37:03 PM »

Quote from: CB750 Cafe Racer Fan on January 23, 2017, 01:29:12 PM

Quote from: calj737 on January 23, 2017, 12:39:08 PM
Awaiting a rear hub. Once that's done, the swingarm geometry can be completed. Then, it's off to a friends to have the main frame tubing remade from TG&P CroMo.

I'm paddling in the same boat with you as to the hub. What is TG&P?

Curious how this applies here as well. TG&P is turned, ground and polished and usually reserved for linear shafting where tolerances are very tight and finish needs to be extremely good. Additionally, unless CroMo is stress relieved after the fact, DOM tubing is nearly as strong and much easier to work with, not to mention less expensive.

calj737 · « **Reply #459 on:** January 23, 2017, 01:38:59 PM »

Turned, Ground and Polished. It's a very high grade of CroMo. It's cold drawn steel, with an exact OD, completely true, and polished to remove any mill scale. Runs about $3.70@ft. For our frame, it looks like less than $100 of material, and I think I know someone who will bend it on their CNC bender for me

I'll just weld it to the stock neck so as to retain the VIN and title, and destroy the old frame hoops completely.

Planning to make only a couple of slight modifications to the stock frame, mostly to tie the engine hoops back to the backbone directly. Straighten and lower the backbone intersection to the neck. And increase the angle of the forward hoop, and spread the down tubes to a more perpendicular orientation as they run down and under the engine.wll certainly be adding bracing, but these small changes should improve rigidity without making the bike look non-stock.

I'll probably also see a decent weight reduction overall, greater strength, and more space. Win, win, win!

calj737 · « **Reply #460 on:** January 23, 2017, 01:43:14 PM »

Quote from: slikwilli420 on January 23, 2017, 01:37:03 PM

Curious how this applies here as well. TG&P is turned, ground and polished and usually reserved for linear shafting where tolerances are very tight and finish needs to be extremely good. Additionally, unless CroMo is stress relieved after the fact, DOM tubing is nearly as strong and much easier to work with, not to mention less expensive.

Actually, NASCAR frames are TG&P. I happen to have within my circle of friends, a premier NASCAR frame builder. So, good enough for them, good enough for me. And the fit and finish will be exceptionally tight. Not that it needs to be, but it will be.

I have a large fab table with the capacity to jig, clamp and weld this thing fully supported. That won't be an issue. And for the cost difference, a fully custom frame for less than $100 of material? It's a bargain.

slikwilli420 · « **Reply #461 on:** January 23, 2017, 01:48:24 PM »

What is the plan to have the frame stress relieved afterwards? I'm sure with those connections it won't be an issue but I was curious.

It also begs the question why a custom frame is so expensive. With todays equipment, one should be able to punch out a frame in short order with extreme precision.

calj737 · « **Reply #462 on:** January 23, 2017, 02:07:14 PM »

I'll be taking my lead from the frame bender.

I'll probably also have some good documentation when I do it so as to share the progress.

As for cost for a custom frame: material is not usually the expense; labor is. Duplicating a frame in hand, even with slight modifications, is a lot easier to replicate than to create new. Plus, the mainframe on these bikes are super simple once you eliminate the subframe (which we did with a bandsaw). So it's less material, less work, less math.

I'll be making the mounts and bracing and doing all the welding, so that expense is avoided too. Remember, it's not what you know, it's who you know.

SOHC4 Cafe Racer Fan · « **Reply #463 on:** January 23, 2017, 02:11:15 PM »

Quote from: calj737 on January 23, 2017, 01:38:59 PM

Turned, Ground and Polished. It's a very high grade of CroMo. It's cold drawn steel, with an exact OD, completely true, and polished to remove any mill scale. Runs about $3.70@ft. For our frame, it looks like less than $100 of material, and I think I know someone who will bend it on their CNC bender for me I'll just weld it to the stock neck so as to retain the VIN and title, and destroy the old frame hoops completely.

Planning to make only a couple of slight modifications to the stock frame, mostly to tie the engine hoops back to the backbone directly. Straighten and lower the backbone intersection to the neck. And increase the angle of the forward hoop, and spread the down tubes to a more perpendicular orientation as they run down and under the engine.wll certainly be adding bracing, but these small changes should improve rigidity without making the bike look non-stock.

I'll probably also see a decent weight reduction overall, greater strength, and more space. Win, win, win!

For the initiated, I presume a CNC bender has you input a 3D CAD drawing and it precision bends the tube sections to specification? Sounds like a trick piece of kit. I think my buddy used one on some girder trellis forks.

calj737 · « **Reply #464 on:** January 23, 2017, 02:20:43 PM »

Or you can use a conversational interface and "plot" the lengths, radii, and distances. Bend a single tube in multiple axises, and reproduce it exactly on a second tube. I'll notch the tubes with a annular cutter for a precise fit. They'll be TIG welded for precision.

SOHC4 Cafe Racer Fan · « **Reply #465 on:** January 23, 2017, 02:28:03 PM »

Quote from: calj737 on January 23, 2017, 02:20:43 PM

Or you can use a conversational interface and "plot" the lengths, radii, and distances. Bend a single tube in multiple axises, and reproduce it exactly on a second tube. I'll notch the tubes with a annular cutter for a precise fit. They'll be TIG welded for precision.

That combined with a STURDY jig, and you eliminate a lot of slop and asymmetry.

calj737 · « **Reply #466 on:** January 23, 2017, 02:36:22 PM »

I got the sturdy part covered...

SOHC4 Cafe Racer Fan · « **Reply #467 on:** January 23, 2017, 02:50:27 PM »

Quote from: calj737 on January 23, 2017, 02:36:22 PM

I got the sturdy part covered...

That's no joke.

calj737 · « **Reply #468 on:** January 23, 2017, 03:11:26 PM »

6'x4'x5/8" welded to a 3"x3"x1/4" tube frame. Weighs just about 1,100#. I think it will do.

calj737 · « **Reply #469 on:** January 23, 2017, 03:21:58 PM »

Wili - just as an FYI, with thin-walled TG&P, usually it's not necessary to stress relieve it. I'll either be using 0.058 or 0.063 so I'm not expecting to have to relieve it.

SOHC4 Cafe Racer Fan · « **Reply #470 on:** January 23, 2017, 03:35:25 PM »

Quote from: calj737 on January 23, 2017, 03:11:26 PM

6'x4'x5/8" welded to a 3"x3"x1/4" tube frame. Weighs just about 1,100#. I think it will do.

It took all Jeffreys on deck to move that into position.

calj737 · « **Reply #471 on:** January 23, 2017, 03:45:49 PM »

It's on leveling casters. Built the frame, installed the casters. Then brought the top home, slid it out of the bed of the truck and directly onto the frame. Rolled it over to its home, levels it, welded it. Super easy.

Drilling 130 holes took some time with a Mag Drill though

RAFster122s · « **Reply #472 on:** January 23, 2017, 04:08:41 PM »

With a frame like that you can support 2-3 ton on top? (Swag)
very nice and tidy work area...where did you learn all your skills Cal?
You are a veritable jack of all trades and master of many.

David

RAFster122s · « **Reply #473 on:** January 23, 2017, 04:11:19 PM »

Man makes plans and God laughs...
I fully understand how life gets in the way. Figured the garage, son's busy university life, and all you do helping others had slowed your efforts a lot.

SOHC4 Cafe Racer Fan · « **Reply #474 on:** January 23, 2017, 04:19:25 PM »

Quote from: RAF122S on January 23, 2017, 04:08:41 PM

With a frame like that you can support 2-3 ton on top? (Swag)
very nice and tidy work area...where did you learn all your skills Cal?
You are a veritable jack of all trades and master of many.

David

I vote that Cal opens Cal's Boot Camp for metal fabrication and electronics -- kind of like Colin Edwards' Texas Tornado Boot Camp, except for learning to fabricate frames and sheet metal, and to become a MotoGadget wiz. What you pay to stay??

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Author Topic: '73 500 - Subframe Fabrication (Read 142256 times)