1908 Schwinn Indian (schwinndian)

Ralph hop

Well-Known Member
Nov 14, 2019
180
467
63
The tank will be a cylinder with a cone on each end centered around the top tube. 5 or 6 inches diameter and as long as I can make it. I'm trying to keep the straight lines of the bike and avoid a complex curve in the down tube, could shorten it some to form a nice V but the length helps with the tank. I'll see how the pipe bends, it is a very tight bend at six inches.
 

indian22

Well-Known Member
Dec 31, 2014
3,665
3,995
113
Oklahoma
Ralph that radius makes a 12" inside diameter loop.which isn't tight at all but is difficult to bend well (without kinks) unless you use a mandrel bender, even an expensive hydraulic exhaust pipe bender with the correct dies installed kink the pipe some. I had both these in my shop as well as a common hydraulic pipe bender which really did badly kink pipe. If you must try this without good equipment pack the tube with sand and cap the ends...don't use gas or water pipe as structural material, looks strong but's quite weak.

Rick C.
 

Ralph hop

Well-Known Member
Nov 14, 2019
180
467
63
Good advice guys, I'm not offended by criticism either so don't hold back. I'll use sand and apply plenty of heat. The radius is 3 inches sorry for any confusion. The bend is six on the inside. I'm stubborn so I'll use this pipe as a test, was hoping the wall thickness would prevent kinking along with plenty of heat. I hadn't given the strength of the gas pipe much thought but the bike itself isn't made from seamless tubing or 4130 just mild steel.
 

Ralph hop

Well-Known Member
Nov 14, 2019
180
467
63
I've been reading up on pipe and tube and found some mild steel electric resistance welded seem pipe for pretty good price, 2.50 per foot. Just have to make sure the seem is on the inside of the bend. I've found there is some debate about using pipe instead of tube for roll cages in 4x4s. A guy said he likes to use schedule 40 because it bends easy... bends easy to make a roll cage lol. (Edit: I wrote "welded seem pipe" but meant to write "welded seem tube".)
 
Last edited:

indian22

Well-Known Member
Dec 31, 2014
3,665
3,995
113
Oklahoma
Water and gas pipe is way different than welded steel tube. Make sure everybody is on the same page here. Just like welded steel tube is different from D.O.M. tube. Pipe, schedule 40 or 80 are dangerous to use as structure support. While both types of tube can support structure, including motorized bicycles.

Rick C.
 

Ralph hop

Well-Known Member
Nov 14, 2019
180
467
63
I've been playing around with this plumbing pipe and now I'm not sure what the schedule is but it has some funny harmonics and flex going on, It would ruin the bike even if it never broke. I'll have to find another use for it and study some on tubing sizes and wall thickness. I have 37" of tube left over from the top tube, it slides into the stub on the head tube but I'll burn through that tube welding it to the bottom bracket. A 1.25 tube would slide over the 1.134 diameter stub left on the head tube. Might give me enough thickness for welding into the bottom bracket.
 

Ralph hop

Well-Known Member
Nov 14, 2019
180
467
63
Water and gas pipe is way different than welded steel tube. Make sure everybody is on the same page here. Just like welded steel tube is different from D.O.M. tube. Pipe, schedule 40 or 80 are dangerous to use as structure support. While both types of tube can support structure, including motorized bicycles.

Rick C.
Yes, people are using water plumbing pipes from big box stores for roll cages because they work with the HF benders. Would weigh a lot and not save much money and dangerous too.
 
Last edited:

fasteddy

Well-Known Member
Feb 13, 2009
6,433
1,981
113
British Columbia Canada
I bent some 1/8" wall 1" tubing by packing used up glass sand blasting material. Be sure to tap on the tubing repeatedly as you pour the sand into the tube in small amounts. It surprised me just how much it disappeared as it was tapped and compacted.

I used some 3/4" medium density fibre board glued together and the shaped surface sanded smooth. I nailed some small strips of wood to the sides of the MDF to keep the tubing from sliding off. I taped the ends up with duct tape. I bent it cold but if you heat it make sure that you leave a vent hole so any steam can escape.

Hope this helps.

Steve.
 

indian22

Well-Known Member
Dec 31, 2014
3,665
3,995
113
Oklahoma
Ralph is the frame marked with the type ally steel it's made from? The tube diameters you mention and this coupled with the photos and your remark about burn through lead me to think this is a chromoly frame 4130 type steel which has excellent strength and welds fine, but typically wall thickness is really thin on bicycle frames to save weight. If this is the case burn through is likely when scabbing two tubes. Your plan to insert the stub into the larger tube is fine, I'd suggest slipping a snug fit length of tube or solid steel rod into the stub first to act as a weld backer it will help prevent burn through on the thin stub and if you do burn through a bit you've welded into the backer rod and the weld is still strong mechanically. If you drill a very small hole, 3/16" will do, in the sub before inserting the backer rod: and then weld a tack through the hole onto the rod to hold it securely in place, just in case you don't burn through and then have a rod rattling around in your frame...not cool!

Normally inserting the rod is used to strengthen the butt weld of two same size frame tubes, not only as a backer but to strengthen the tube in actual use. The plug weld or Rosette weld through the drilled holes would be larger and more numerous on both sides of the tube scab.

.090" wall thickness on ERW tube would be my choice unless .120" price isn't too prohibitive.



Rick C.
 
Last edited:

Ralph hop

Well-Known Member
Nov 14, 2019
180
467
63
That's very helpful and good to know Steve. I remember reading about this on your thread awhile ago but the details weren't fresh on my mind. It helps knowing it's been done. I'll take another look at the form you made but not sure if I can match a furniture builder. Did you use a sanding drum?
 

Ralph hop

Well-Known Member
Nov 14, 2019
180
467
63
Rick, I've peeled off the sticker awhile ago but it just said tawain steel I think. It's early eighties tech. Mainly concerned with burn through because I'm using an arc welder at seventy amps with 1/16" 6013 electrodes. It does good down to 16 gauge mild steel. The method you describe with drilling and plug weld is what I have planned with the top tube except drilling a tiny bit into the backer as well and planned to braze were the tubes butt together. The wall thickness of the bike tubes are about .056
 
Last edited:

Ralph hop

Well-Known Member
Nov 14, 2019
180
467
63
There is an argument to be made that a mild steel cage is safer because it can bend and thereby absorb the impact. It's an ongoing debate. :)
Yes FOG I can see the argument there with alloyed vs mild. That's where yield strength and flex strength factor in. Tractor trailer chassis are designed to flex with the use of C channel steel. Not having some flex could break things on a vehicle. Sheldon Browns book describes yield strength as the amount of weight a tube can take before it permanently bends. Flex strength is the amount of weight it can take and still hold it's shape.
 

indian22

Well-Known Member
Dec 31, 2014
3,665
3,995
113
Oklahoma
Rick, I've peeled off the sticker awhile ago but it just said tawain steel I think. It's early eighties tech. Mainly concerned with burn through because I'm using an arc welder at seventy amps with 1/16" 6013 electrodes. It does good down to 16 gauge mild steel. The method you describe with drilling and plug weld is what I have planned with the top tube except drilling a tiny bit into the backer as well and planned to braze were the tubes butt together. The wall thickness of the bike tubes are about .056
Yes drilling a little into the backer for a plug weld is good welding practice Ralph.

The .056" wall factory tubing is about what one would suspect of typical factory steel pedal bikes. 1/16" 6013 stick should run fine. .023" 70 series wire if using a MIG...I'm TIG less at the moment & I'm needing one more and more it seems for use indoors during inclement weather and for the far superior weld appearance with zero spatter and wonderful heat control on think metals ...perfect for bike work.

I'm thinking you've got this Ralph.