Six jours
10-09-07, 10:18 PM
There was a guy here asking for a pic of my ultra-fancy alignment jig, and Bmike has asked for a few pics of my shoestring project too. So here ya go. (I'm no better with a camera than with a torch, so...)
http://i10.photobucket.com/albums/a101/Noel3006/framepics001.jpg
The above is a shot of the alignment tool. It's angle iron from Home Depot. The large bolt at the right end is for clamping the bottom bracket shell down. The seat or down tube is inserted into the shell and rests on the screw visible on the left side of the piece. The screw was carefully adjusted until the tube was level and aligned with the bb faces, as determined with a feeler gauge. (Actually just something that happened to fit the gap between the tube and the angle iron. I think it was a Phil Wood bb cartridge tool). The tube is then pinned into the shell (I tried tack brazing and it wasn't as accurate) then the tube/shell is removed from the jig and brazed in a workstand.
Once the down and seat tubes are brazed in, I assemble the head tube and lug onto the down tube, use my wife's granite countertop to ensure alignment with the seat tube and a protractor to get the head angle correct, drill and pin the head tube and lug, and again braze in the workstand. The top tube then drops into place, gets held by a single pin front and back, and brazed. This all works surprisingly well, although the wife isn't thrilled with the whole metal shavings/kitchen floor paradigm.
Rear triangles are a *******. I do the chainstays first, placing them into the shell while the front triangle is in the stand and then inserting the rear wheel. I get the wheel to line up in the chainstays, then place a single pin through the shell and into each stay. I put this pin through the sides, so the stays are sort-of held into place laterally but are free to move vertically. I then run a piece of string from the seat lug down to either end of the rear axle. Using a slipknot, I tighten the string until the chainstays are at the correct vertical angle to the downtube, as lifted from my frame drawing. This involves a great deal of fiddling to get both vertical and lateral alignment correct, but it does work.
I used a lazier method on my first frame, below:
http://i10.photobucket.com/albums/a101/Noel3006/framepics004.jpg
I used the same lateral pinning method, but didn't worry about vertical alignment. After finishing the chainstays I popped in a set of wheels and I noticed that the top tube was several degreees from horizontal. The protractor showed that the chainstays were at fault. Coldsetting them by pushing down on the top tube seemed to sort it. After the frame was finished, I noticed that the chainstays hadn't actually moved, and that I had simply pulled the BB shell into an egg shape. Yes, that's 531 and Nervex, and yes, I'm an *******.
That's pretty much the written story. Here are the rest of the pics of my newest frame in various stages of completion. It's at the paint shop now.
Down, seat, and head tubes in place.
http://i10.photobucket.com/albums/a101/Noel3006/framepics002.jpg
Mocked up with top tube and chainstays in place.
http://i10.photobucket.com/albums/a101/Noel3006/framepics003.jpg
Ready for prep and paint.
http://i10.photobucket.com/albums/a101/Noel3006/framepics006.jpg
http://i10.photobucket.com/albums/a101/Noel3006/framepics005.jpg
Questions will be cheerfully and incorrectly answered. :)
http://i10.photobucket.com/albums/a101/Noel3006/framepics001.jpg
The above is a shot of the alignment tool. It's angle iron from Home Depot. The large bolt at the right end is for clamping the bottom bracket shell down. The seat or down tube is inserted into the shell and rests on the screw visible on the left side of the piece. The screw was carefully adjusted until the tube was level and aligned with the bb faces, as determined with a feeler gauge. (Actually just something that happened to fit the gap between the tube and the angle iron. I think it was a Phil Wood bb cartridge tool). The tube is then pinned into the shell (I tried tack brazing and it wasn't as accurate) then the tube/shell is removed from the jig and brazed in a workstand.
Once the down and seat tubes are brazed in, I assemble the head tube and lug onto the down tube, use my wife's granite countertop to ensure alignment with the seat tube and a protractor to get the head angle correct, drill and pin the head tube and lug, and again braze in the workstand. The top tube then drops into place, gets held by a single pin front and back, and brazed. This all works surprisingly well, although the wife isn't thrilled with the whole metal shavings/kitchen floor paradigm.
Rear triangles are a *******. I do the chainstays first, placing them into the shell while the front triangle is in the stand and then inserting the rear wheel. I get the wheel to line up in the chainstays, then place a single pin through the shell and into each stay. I put this pin through the sides, so the stays are sort-of held into place laterally but are free to move vertically. I then run a piece of string from the seat lug down to either end of the rear axle. Using a slipknot, I tighten the string until the chainstays are at the correct vertical angle to the downtube, as lifted from my frame drawing. This involves a great deal of fiddling to get both vertical and lateral alignment correct, but it does work.
I used a lazier method on my first frame, below:
http://i10.photobucket.com/albums/a101/Noel3006/framepics004.jpg
I used the same lateral pinning method, but didn't worry about vertical alignment. After finishing the chainstays I popped in a set of wheels and I noticed that the top tube was several degreees from horizontal. The protractor showed that the chainstays were at fault. Coldsetting them by pushing down on the top tube seemed to sort it. After the frame was finished, I noticed that the chainstays hadn't actually moved, and that I had simply pulled the BB shell into an egg shape. Yes, that's 531 and Nervex, and yes, I'm an *******.
That's pretty much the written story. Here are the rest of the pics of my newest frame in various stages of completion. It's at the paint shop now.
Down, seat, and head tubes in place.
http://i10.photobucket.com/albums/a101/Noel3006/framepics002.jpg
Mocked up with top tube and chainstays in place.
http://i10.photobucket.com/albums/a101/Noel3006/framepics003.jpg
Ready for prep and paint.
http://i10.photobucket.com/albums/a101/Noel3006/framepics006.jpg
http://i10.photobucket.com/albums/a101/Noel3006/framepics005.jpg
Questions will be cheerfully and incorrectly answered. :)
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