Do Dropouts really matter?
#51
Old fart



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#52
Senior Member


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You must admit that Campagnolo did an interesting thing with the verticals and the second tier road dropouts, the tooling did include some matched forming of the steel, as it shows on both sides and is not a sharp edge as found on the basic stamped dropouts seen so often, it is a neat bit of tooling.
The better builds with these I have seen include a washer brazed onto the inside (and axle way cut out) of the dropout to increase the thickness, when I first saw that on a Harry Quinn in 1974 I thought, what a good idea, but others did it too.
The better builds with these I have seen include a washer brazed onto the inside (and axle way cut out) of the dropout to increase the thickness, when I first saw that on a Harry Quinn in 1974 I thought, what a good idea, but others did it too.
#53
Trek 500 Kid

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From: Spokane WA
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The "Gran Sport" vertical dropouts were stamped:

As you note, the track dropouts were quite thick, and even Blanchard ground for smooth faces. The Gran Sport dropout is just a little thinner than a 1010 forged dropout, but thicker than the stamped dropouts on entry level bikes.

As you note, the track dropouts were quite thick, and even Blanchard ground for smooth faces. The Gran Sport dropout is just a little thinner than a 1010 forged dropout, but thicker than the stamped dropouts on entry level bikes.
Also not a milling finish or uniformity around the radius. Radiuses don't look stitched with a ball end mill either. That would be a mighty expensive way to make a stamped dropout even if it was.
I'm aware that you worked for Trek but are you sure about this one ?
Interesting thread though.
Last edited by Zinger; 12-08-13 at 08:19 PM.
#54
curmudgineer
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John are you sure that's a stamping ? I have to agree with SJX426 in that it looks to me like a forging (or maybe green sand casting?) in both what looks to me to be parting lines (on top and inside the triangular cutout) and the texture at the bottom of the dropout around the derailleur hanger where the hand grinder hasn't hacked on it.
Also not a milling finish or uniformity around the radius. Radiuses don't look stitched with a ball end mill either. That would be a mighty expensive way to make a stamped dropout even if it was.
I'm aware that you worked for Trek but are you sure about this one ?
Interesting thread though.
Also not a milling finish or uniformity around the radius. Radiuses don't look stitched with a ball end mill either. That would be a mighty expensive way to make a stamped dropout even if it was.
I'm aware that you worked for Trek but are you sure about this one ?
Interesting thread though.
#55
Trek 500 Kid

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From: Spokane WA
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That is the picture I was referring to. The pic in post #52 is a little more ambiguous-- if forgings they are pretty sleazy looking, yet if stampings, there's been some significant post-processing to create the rounded edges. On close comparison of the two photos however, there is nothing to suggest the dropouts in the two photos are actually different; only that one set has been brazed into a frame, with brazed eyelets added. So now I'm accepting JohnDThompson's assertion that they are in fact stamped, abeit with significant post stamping prep to make them look "nice". Either that, or a quasi-forging process, where the stamping die is not merely a cookie cutter, but has a female contour that creates the rounded edges that are so evident in the photos.
Last edited by Zinger; 12-09-13 at 02:49 PM.
#56
Trek 500 Kid

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Now that my old senile mind thinks about it there is some radiusing done on stamped parts where the steel is compressed by the force of the shearing.....duh.
What looks like a parting line is probably just the other side of the sheared part. If he'd taken the pictures from more of an angle you could probably see it much better as a stamping. As far as the other photos go, they probably just dressed up the sheared edges by hand on a soft wheel to pretty it up some.
What looks like a parting line is probably just the other side of the sheared part. If he'd taken the pictures from more of an angle you could probably see it much better as a stamping. As far as the other photos go, they probably just dressed up the sheared edges by hand on a soft wheel to pretty it up some.
#57
curmudgineer
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That could very well be so, in which case I would assume that they deliberately tailored their stamping process to give this [aesthetically desirable] result.
#58
Trek 500 Kid

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Well the stamping dies I've seen while programming the wire feed EDM for them were simply straight through shearing dies but they would radius the parts some just from the force of the impact of the shearing. I can just imagine that a part so small and thick would look like the four dropouts in the one photo but every time I look at the Gran Sport photo I still have to wonder.
Like I said though, I'm certainly no real diemaker and haven't, by a long shot, seen everything related to stamping dies. Never worked at all in any shop that made forging dies either although I've always been fascinated by the process.
Like I said though, I'm certainly no real diemaker and haven't, by a long shot, seen everything related to stamping dies. Never worked at all in any shop that made forging dies either although I've always been fascinated by the process.
#59
Senior Member


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From: Baltimore MD
Bikes: '72 Motobecane Grand Record, '72 Gitane tandem, '72 Raleigh Super Course, '73 Raleigh Gran Sport, '73 Colnago Super, '76 Fiorelli Coppi, '78 Raleigh SBDU Team Pro, '78 Trek 930, '81 Holdsworth Special 650B, '86 Masi GC, ’94 Bridgestone RB-T
This is all so fascinating. Someone should do an illustrated book, and maybe a poster.
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#60
Old fart



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#61
Trek 500 Kid

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From: Spokane WA
Bikes: '83 Trek 970 road --- '86 Trek 500 road
Yeah now it looks flatter. It must indeed have some forming cavity like no other stamping die I've seen before. (And I certainly haven't seen that much) That would almost make it like a cold forging though. It actually looks more than ever like a parting line there and the other side has a radius too.......????
Last edited by Zinger; 12-10-13 at 03:48 PM.






