Muzi/Frame builders: Modifying vertical to horizontal dropouts

Squid-in-Training said:

Before I start, I would like to say that my following idea is foolish,
because that's probably what everyone's reaction is going to be. Okay, now
I'll start.

I want to convert the dropouts on my aluminum frame from vertical to
horizontal. It's a Giant XTC frame with 4.35mm dropouts that get to 6.5mm
thick just at the locknuts.

First of all, I know that frames are heat-treated to enhance their strength.
I also know that welding something on will screw up the grain structure and
locally kill off the heat treatment in the area, producing the heat-affected
zone. And yes, messing with dropouts is also risky business. My reasons
for doing this are that the frame was free (and cracked previously, but more
on that later). I've also been doing some machine shop work that allows me
to work on these projects, so it's kind of a matter of pride and exercising
the limited amount of engineering skill I've learned since starting
undergrad.

Here's a picture of my plan:
http://plaza.ufl.edu/phillee/stuff/dropout.jpg

Okay so in the picture above I want to cut out the yellow portion of the
dropout, and then weld on the green highlighted area. I figure that since
the frame takes the weight of the bike and person on the axle of the wheel,
the upper portion of the dropout is really the only part that takes the
load. I'm also thinking that the bottom portion of the dropout, load-wise,
is there almost exclusively to retain the wheel in the dropout and to
balance the upper half of the clamping skewer face. Therefore, it should be
okay to just weld on a bottom plate of the same thickness so as to offer the
skewer some biting surface.

Am I totally off-base here?

The cutouts on the chainstay portion of the dropout make me nervous, as it
will be close to the heat-affected zone, and may pose a problem if a bottom
part of a horizontal dropout is welded on.

I will be using v-brakes in this application, not disc brakes.

I welcome any constructive thoughts that further progress on this topic. If
you want to tell me to buy a new frame or that I'm crazy, you're probably
right, but I want to try this, even if it does fail after a while.

Hi Phil, how's the squid training?

Me not an engineer and don't even play one on TV. And I know TIG can do all
sorts of cool stuff, but I'd have more trust in a fabricated aluminum dropout
that was cut to fit and then installed at the ends of the stays.

It just looks like a lot of fill while welding and will require all the cutting
and shaping work is done in an awkward location, on the bike at the end of the
whippy stays. If you fabricate dropouts all your cutting and shaping work is
off the bike and the wheel gets clamped to a single homogenous piece of metal.
Cutting the old drops off the stays means that you won't be reheating the
previously heat affected area.

Just seems cleaner to me.

That said, I've got no doubt your proposal will work and that with your craft
and patience will turn out sound and looking good. I'm pretty sure it won't have
the same ultimate strength, but am also pretty sure it won't try to kill you
either.

Ron

Phil said:

Before I start, I would like to say that my following idea is foolish,
because that's probably what everyone's reaction is going to be. Okay, now
I'll start.

I want to convert the dropouts on my aluminum frame from vertical to
horizontal. It's a Giant XTC frame with 4.35mm dropouts that get to 6.5mm
thick just at the locknuts.

First of all, I know that frames are heat-treated to enhance their strength.
I also know that welding something on will screw up the grain structure and
locally kill off the heat treatment in the area, producing the heat-affected
zone. And yes, messing with dropouts is also risky business. My reasons
for doing this are that the frame was free (and cracked previously, but more
on that later). I've also been doing some machine shop work that allows me
to work on these projects, so it's kind of a matter of pride and exercising
the limited amount of engineering skill I've learned since starting
undergrad.

Here's a picture of my plan:
http://plaza.ufl.edu/phillee/stuff/dropout.jpg

there's some very important design features on that existing dropout
that you need to pay attention to.

1. apart from the hanger socket, it's massively thick. that is to buy
time against fatigue.

2. *everything is radiused*, even the root of the hanger socket cutout.
again, that's to buy time against fatigue.

3. note that they are not straight butt welds, but the face with both
tubes is angled. again, fatigue, buy time, etc.

now, having noted the above and taken them to heart, and overlooking the
heat treating & welding issues for the time being, i think your best
choice is to machine whole new dropouts that replicate as best as
possible all the above features but with your new horizontal slot
incorporated. you're going to need a fairly sophisticated machining
program to do that, so i guess it depends on what you have access to.
when you have the new parts, cut off the old dropouts through the center
of the existing welds, prep & weld.

you'll need to figure out what alloy the frame is, select dropout
material accordingly and do yourself an appropriate new heat treatment,
but if you do all that, are a good clean welder & have a good design,
there's no reason why you can't have fatigue properties for the modified
frame very close to that of the original.

i think that if you just try to weld a bit onto the existing dropout,
results will be unsatisfactory because excess material has already been
machined away so you'll be welding to something too small for the job.

Quoted message said:

Okay so in the picture above I want to cut out the yellow portion of the
dropout, and then weld on the green highlighted area. I figure that since
the frame takes the weight of the bike and person on the axle of the wheel,
the upper portion of the dropout is really the only part that takes the
load. I'm also thinking that the bottom portion of the dropout, load-wise,
is there almost exclusively to retain the wheel in the dropout and to
balance the upper half of the clamping skewer face. Therefore, it should be
okay to just weld on a bottom plate of the same thickness so as to offer the
skewer some biting surface.

Am I totally off-base here?

if you have access to a good machine facility & heat treatment facility
- maybe even outsourcing that bit - no, it's definitely do-able. i'm
more worried that you're contemplating using a frame that's already
cracked. how do you propose repairing that bit? much better to get
another uncracked frame as a starting point.

Quoted message said:

The cutouts on the chainstay portion of the dropout make me nervous, as it
will be close to the heat-affected zone, and may pose a problem if a bottom
part of a horizontal dropout is welded on.

I will be using v-brakes in this application, not disc brakes.

I welcome any constructive thoughts that further progress on this topic. If
you want to tell me to buy a new frame or that I'm crazy, you're probably
right, but I want to try this, even if it does fail after a while.

jim beam said:

Phil said:

Before I start, I would like to say that my following idea is foolish,
because that's probably what everyone's reaction is going to be. Okay, now
I'll start.

I want to convert the dropouts on my aluminum frame from vertical to
horizontal. It's a Giant XTC frame with 4.35mm dropouts that get to 6.5mm
thick just at the locknuts.

First of all, I know that frames are heat-treated to enhance their strength.
I also know that welding something on will screw up the grain structure and
locally kill off the heat treatment in the area, producing the heat-affected
zone. And yes, messing with dropouts is also risky business. My reasons
for doing this are that the frame was free (and cracked previously, but more
on that later). I've also been doing some machine shop work that allows me
to work on these projects, so it's kind of a matter of pride and exercising
the limited amount of engineering skill I've learned since starting
undergrad.

Here's a picture of my plan:
http://plaza.ufl.edu/phillee/stuff/dropout.jpg

My news service bit the dust... using Google Groups currently.

Quoted message said:

there's some very important design features on that existing dropout
that you need to pay attention to.

1. apart from the hanger socket, it's massively thick. that is to buy
time against fatigue.

2. *everything is radiused*, even the root of the hanger socket cutout.
again, that's to buy time against fatigue.

3. note that they are not straight butt welds, but the face with both
tubes is angled. again, fatigue, buy time, etc.

now, having noted the above and taken them to heart, and overlooking the
heat treating & welding issues for the time being, i think your best
choice is to machine whole new dropouts that replicate as best as
possible all the above features but with your new horizontal slot
incorporated. you're going to need a fairly sophisticated machining
program to do that, so i guess it depends on what you have access to.
when you have the new parts, cut off the old dropouts through the center
of the existing welds, prep & weld.

you'll need to figure out what alloy the frame is, select dropout
material accordingly and do yourself an appropriate new heat treatment,
but if you do all that, are a good clean welder & have a good design,
there's no reason why you can't have fatigue properties for the modified
frame very close to that of the original.

I won't be doing any heat treatment to this modification.

Quoted message said:

i think that if you just try to weld a bit onto the existing dropout,
results will be unsatisfactory because excess material has already been
machined away so you'll be welding to something too small for the job.

Yes - I spoke to the machine shop student and he suggested cutting out
the yellow section as I thought before, but then placing a horizontal
dropout inset that is shaped almost identically to the derailleur
hanger with the radii and everything, which would then be welded in
place far away from the tubing, isolating the heat-affected zone in the
thick beefy aluminum dropout portion. A similar process would be done
for the non-drive-side dropout, too.

Quoted message said:

Quoted message said:

Okay so in the picture above I want to cut out the yellow portion of the
dropout, and then weld on the green highlighted area. I figure that since
the frame takes the weight of the bike and person on the axle of the wheel,
the upper portion of the dropout is really the only part that takes the
load. I'm also thinking that the bottom portion of the dropout, load-wise,
is there almost exclusively to retain the wheel in the dropout and to
balance the upper half of the clamping skewer face. Therefore, it should be
okay to just weld on a bottom plate of the same thickness so as to offer the
skewer some biting surface.

Am I totally off-base here?

if you have access to a good machine facility & heat treatment facility
- maybe even outsourcing that bit - no, it's definitely do-able. i'm
more worried that you're contemplating using a frame that's already
cracked. how do you propose repairing that bit? much better to get
another uncracked frame as a starting point.

There was a crack in the chainstay near the BB and right at the brace
that holds the two chainstays together. Here is a picture:

http://plaza.ufl.edu/phillee/stuff/cs1.jpg
http://plaza.ufl.edu/phillee/stuff/cs2.jpg
http://plaza.ufl.edu/phillee/stuff/cs3.jpg

Yes, the welds are contaminated and are amateurish... I didn't weld it
myself but the person who did has had some experience already but
nothing expert.

Phil

In message <[email hidden]>,
[email hidden] writes

Quoted message said:

Quoted message said:

Quoted message said:

Before I start, I would like to say that my following idea is foolish,
because that's probably what everyone's reaction is going to be. Okay, now
I'll start.

I want to convert the dropouts on my aluminum frame from vertical to
horizontal. It's a Giant XTC frame with 4.35mm dropouts that get to 6.5mm
thick just at the locknuts.

First of all, I know that frames are heat-treated to enhance their
strength.
I also know that welding something on will screw up the grain structure and
locally kill off the heat treatment in the area, producing the
heat-affected
zone. And yes, messing with dropouts is also risky business. My reasons
for doing this are that the frame was free (and cracked previously,
but more
on that later). I've also been doing some machine shop work that allows me
to work on these projects, so it's kind of a matter of pride

The metal does not care about our financial circumstances, motivations
or feelings of pride. It will behave very much as the text books says
for you, for me, or for the most expert frame builder working for a
celebrity customer.

Quoted message said:

Quoted message said:

cracked. how do you propose repairing that bit? much better to get
another uncracked frame as a starting point.

There was a crack in the chainstay near the BB and right at the brace
that holds the two chainstays together. Here is a picture:

http://plaza.ufl.edu/phillee/stuff/cs1.jpg
http://plaza.ufl.edu/phillee/stuff/cs2.jpg
http://plaza.ufl.edu/phillee/stuff/cs3.jpg

Yes, the welds are contaminated and are amateurish... I didn't weld it
myself but the person who did has had some experience already but
nothing expert.

It does look like there are some bubbles in there but depending on the
choice of filler alloy and just how poor the weld is inside you may find
the frame fails in the weakened metal around the fused joint (the
heat-affected zone) and not in the weld.

Do you know what alloy the frame is made from, what temper it was at and
the filler alloy used in this attempt to fix the cracks?

Have you used the frame much since the attempted repair? I would not
trust a frame that was designed for post fabrication heat treatment
after a casual weld repair and no heat treatment.

If you want a frame for single speed, how about finding a scratched but
sound steel frame from the period before vertical dropouts became
general?

--

Martyn Aldis, e-mail [email hidden]
==============================================================================

Quoted message said:

jim beam said:

Phil said:

Before I start, I would like to say that my following idea is foolish,
because that's probably what everyone's reaction is going to be. Okay, now
I'll start.

I want to convert the dropouts on my aluminum frame from vertical to
horizontal. It's a Giant XTC frame with 4.35mm dropouts that get to 6.5mm
thick just at the locknuts.

First of all, I know that frames are heat-treated to enhance their strength.
I also know that welding something on will screw up the grain structure and
locally kill off the heat treatment in the area, producing the heat-affected
zone. And yes, messing with dropouts is also risky business. My reasons
for doing this are that the frame was free (and cracked previously, but more
on that later). I've also been doing some machine shop work that allows me
to work on these projects, so it's kind of a matter of pride and exercising
the limited amount of engineering skill I've learned since starting
undergrad.

Here's a picture of my plan:
http://plaza.ufl.edu/phillee/stuff/dropout.jpg

My news service bit the dust... using Google Groups currently.

Quoted message said:

there's some very important design features on that existing dropout
that you need to pay attention to.

1. apart from the hanger socket, it's massively thick. that is to buy
time against fatigue.

2. *everything is radiused*, even the root of the hanger socket cutout.
again, that's to buy time against fatigue.

3. note that they are not straight butt welds, but the face with both
tubes is angled. again, fatigue, buy time, etc.

now, having noted the above and taken them to heart, and overlooking the
heat treating & welding issues for the time being, i think your best
choice is to machine whole new dropouts that replicate as best as
possible all the above features but with your new horizontal slot
incorporated. you're going to need a fairly sophisticated machining
program to do that, so i guess it depends on what you have access to.
when you have the new parts, cut off the old dropouts through the center
of the existing welds, prep & weld.

you'll need to figure out what alloy the frame is, select dropout
material accordingly and do yourself an appropriate new heat treatment,
but if you do all that, are a good clean welder & have a good design,
there's no reason why you can't have fatigue properties for the modified
frame very close to that of the original.

I won't be doing any heat treatment to this modification.

Quoted message said:

i think that if you just try to weld a bit onto the existing dropout,
results will be unsatisfactory because excess material has already been
machined away so you'll be welding to something too small for the job.

Yes - I spoke to the machine shop student and he suggested cutting out
the yellow section as I thought before, but then placing a horizontal
dropout inset that is shaped almost identically to the derailleur
hanger with the radii and everything, which would then be welded in
place far away from the tubing, isolating the heat-affected zone in the
thick beefy aluminum dropout portion. A similar process would be done
for the non-drive-side dropout, too.

Quoted message said:

Quoted message said:

Okay so in the picture above I want to cut out the yellow portion of the
dropout, and then weld on the green highlighted area. I figure that since
the frame takes the weight of the bike and person on the axle of the wheel,
the upper portion of the dropout is really the only part that takes the
load. I'm also thinking that the bottom portion of the dropout, load-wise,
is there almost exclusively to retain the wheel in the dropout and to
balance the upper half of the clamping skewer face. Therefore, it should be
okay to just weld on a bottom plate of the same thickness so as to offer the
skewer some biting surface.

Am I totally off-base here?

if you have access to a good machine facility & heat treatment facility
- maybe even outsourcing that bit - no, it's definitely do-able. i'm
more worried that you're contemplating using a frame that's already
cracked. how do you propose repairing that bit? much better to get
another uncracked frame as a starting point.

There was a crack in the chainstay near the BB and right at the brace
that holds the two chainstays together. Here is a picture:

http://plaza.ufl.edu/phillee/stuff/cs1.jpg
http://plaza.ufl.edu/phillee/stuff/cs2.jpg
http://plaza.ufl.edu/phillee/stuff/cs3.jpg

Yes, the welds are contaminated and are amateurish... I didn't weld it
myself but the person who did has had some experience already but
nothing expert.

Phil

cringe. phil, it you want to ride that thing, you're a braver man than
me. if i were lookng for a cheapo ride, i'd get one of these:

http://www.nashbar.com/profile_moreimages.cfm?category=130&subcategory=1176&sku=14905&brand=

or

http://www.supergo.com/profile.cfm?LPROD_ID=26065&lsubcat_id=1818&lcat_id=7604&referpage=

and an eno hub.

seriously, some things are worth repairing, some aren't. your frame is
definitely a case of the latter. if you want to learn how to weld
aluminum frames, cut your frame up & weld back together, but don't ride
it and expect it to hold very long. when you have your welding down,
extend to heat treatment. then tube sets. you could build your own
frame with the right tube set.