Welding SOON. Right now it is metal massage with a tube bender. One bend is 3" centerline radius on 0.058" wall 3/4" OD tube. Too tight unless inside support so tubes are bent after filling with Woods metal, an alloy of bismuth, lead, tin and cadmium that melts at 158 °F. It bends like tin, minus the cry. Yes, taking precaution against lead and cadmium by melting under water with a drop of vinegar to keep pH below 7. No fumes and no oxides. Just have to dispose of that water carefully. Only a few ounces.
The tubes also needed normalizing to bend so I made a tube furnace with 6" stainless chimney liner, ceramic wool and a few plate scraps. Heated the ID with a torch and monitored the exhaust temp with a thermocouple. Then plugged both ends and let it cool for two hours. Tubes had slight warpage which was easy to remove with the tube roll machine.
I have one butt joint and then it is miter time. I work 4-10s so three days off is all the time I can devote the unless I take time off. No pressure though..it will be done by April.
Coped tube welding is one heck of a complex weld.
The change in angle is so marked as you weld.
I'm no expert by any stretch but one thing that helped me was to think about the joint in distinct parts.
The right angle side is a fillet weld. The flat side is a lap weld. Subtle differences in where you direct the heat and how much filler you add.
The change in angle is so marked as you weld.
I'm no expert by any stretch but one thing that helped me was to think about the joint in distinct parts.
The right angle side is a fillet weld. The flat side is a lap weld. Subtle differences in where you direct the heat and how much filler you add.
Great tip! Only a few joints not at right angles. Gas lens plus huge stick out. I'm planning every weld since first view of the drawings.
The welding will be the easiest part. Bending tubes is the worst.
The welding will be the easiest part. Bending tubes is the worst.
Listen to this guy. He is the tube welding master!zank wrote:I think it looks great. Repetition will get you far!
I hope he doesn't mind...
https://www.flickr.com/photos/zanconato ... 560833492/
I am not worthy of his praise..forgive me for I am but an unclean welding dilettante.
I have lots of scrap to practice with as the bending is done and only the copes on bent sections need to be done. The students got the straights coped by the machine shop on the milling machine using end mills.
I have lots of scrap to practice with as the bending is done and only the copes on bent sections need to be done. The students got the straights coped by the machine shop on the milling machine using end mills.
Here is a crude drawing of frame subassy. Also welded would be steering knuckle- kingpins and minor attachment points.
Here is the roll hoop. I made plywood templates for bends to preserve sanity. They worked great in bending.
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One other thing..these tubes (4130 a normalized) are highly magnetic. When deburring, all the swarf stays on the end. Will this pose a problem? If so, I can degauss with an alternating current in a coil of wire..a contraption I made to get my bicycle chain cleaner as the Polar power meter uses a strong magnet to determine chain tension and speed..power is simply the product of chain tension and chain speed. Anyhow, wear products would stay in the magnetic chain. Degauss and the swarf washes off in solvent.
Since Jody admitted buying from this chain. .Harbor Freight 
Yes, their roll bender. The dies were all wrong but a guy in of all places, Bend OR, makes custom dies for it.
This is a three roll with only the top roll turned by a two foot diameter wheel, the bottom two are on bearings. In addition, I moved the bottom two axles closer and higher to tighten the bend radius.
Tubes are degreased with acetone, then coated in rosin for grip. The top roll is fed down by a healthy sized Acme thread feed screw. I can measure the travel with calipers for repeatability. No visible wrinkles or deformation
Yes, their roll bender. The dies were all wrong but a guy in of all places, Bend OR, makes custom dies for it. This is a three roll with only the top roll turned by a two foot diameter wheel, the bottom two are on bearings. In addition, I moved the bottom two axles closer and higher to tighten the bend radius.
Tubes are degreased with acetone, then coated in rosin for grip. The top roll is fed down by a healthy sized Acme thread feed screw. I can measure the travel with calipers for repeatability. No visible wrinkles or deformation
There have been issues with spring back after removal of the Woods metal filling but another tripthrough the bender fixes it. Out of plane issues are tweaked on the work bench via brute force..slip some 3/4" PVC over the end and use a long tube over that to cold set both bends in plane.
This roller works slowly and only material directly under the middle roller is worked. Not for high volume work but its working fine on this project if only at a near geologic rate
This roller works slowly and only material directly under the middle roller is worked. Not for high volume work but its working fine on this project if only at a near geologic rate
Ever have an "oh CRAP" moment? Yep, scratched cornea. All better now. Bends and copes done, just down to fitting, tacking and welding. Great news is new hole saws at correct speed do a wonderful job at cope miters in the drill press with Harbor Freight tube notcher. 1600 RPM on a 1" Milwaukee bimetallic is golden. Blue chips are the goal so watch feed. No cleanup other than debur.
Have to say Blue Ox Lenox hole saws seem to cut better but are more fragile. But WTH do I know as this is my first CrMo rodeo. I do know when feed and speed are right, it cuts great and fast.
When chips turn blue, all is good. Put heat in swarf and the tool will stay cool.
Have to say Blue Ox Lenox hole saws seem to cut better but are more fragile. But WTH do I know as this is my first CrMo rodeo. I do know when feed and speed are right, it cuts great and fast.
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Last edited by Keith_J on Tue Mar 28, 2017 2:13 am, edited 1 time in total.
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We have a bicycle!!
Only have one front axle as these purchased parts are 416 stainless and required a redesign as I won't weld such a part due to stress and material. Sure, it could be done but the part is designed and purchased so use it as intended. I did one steering knuckle and it worked so the team will use the university machine shop to replicate.
I also fabricated the knuckles from A36 1/4" plate. Fun welds for a change.
The hardest was the rear triangle. Laid it out, jigged the dropouts and tacked it up. After welding, the wheel dropped in with NO cold setting of the spacing. 135mm on the money.
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I also fabricated the knuckles from A36 1/4" plate. Fun welds for a change.
The hardest was the rear triangle. Laid it out, jigged the dropouts and tacked it up. After welding, the wheel dropped in with NO cold setting of the spacing. 135mm on the money.