Drill Carbon Frame (for internally cabled dropper) Yay or Nay?

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Drill Carbon Frame (for internally cabled dropper) Yay or Nay?
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O+
Posted: Nov 28, 2020 at 5:13 Quote
Is it "safe" to drill into my 2012 Santa Cruz XC's carbon-fibre seat-tube to permit the installation of an internally cabled dropper seat-post?

Time is of the essence to take advantage of Black Friday discounts. Thanks.

O+
Posted: Nov 28, 2020 at 16:49 Quote
Oh man, that’s a loaded question. So many variables that I doubt anyone’s going to say sure as nobody wants your blood on their hands.... I will say that I successfully drilled two holes and filled them with rivnuts on a carbon tribike top tube to install a bento box and have 1000’s of miles on the frame after the mod. But.... different situation all together. The hole was filled, in a different spot, with much less stress on the bike, and I’ve worked with composites and close tolerance delicate projects more than a few times and had access to high quality equipment. Can you? Maybe. Would I? Probably. If you do go for the gusto be careful, take your time, measure 42 times, and let us know how it goes!

Posted: Nov 28, 2020 at 19:55 Quote
I would have no hesitation. Other carbon frames have dropper holes so why should it matter who drills it. I would use a new drill bit and drill the final size in one go. If possible drill on an angle to accommodate the direction of the cable housing for ease of insertion. Assuming you won't be using a grommet in the hole you should probably seal the edges of the hole with something like resin or flex seal to prevent fraying.

O+
Posted: Nov 30, 2020 at 9:21 Quote
PupPuck wrote:
Is it "safe" to drill into my 2012 Santa Cruz XC's carbon-fibre seat-tube to permit the installation of an internally cabled dropper seat-post?

Time is of the essence to take advantage of Black Friday discounts. Thanks.

Can you, sure, its your bike.
But be aware that you instantly VOID your frame warranty.
also depending how aggressive with the drill you are you may (although not likely) crack/damage the frame.
Finally it will be much harder to sell you bike with a questionably modified frame, nobody I know would buy it.
There are several externally routed dropper posts on the market I would consider first before drilling carbon.

Posted: Dec 25, 2020 at 18:51 Quote
Cover the area with masking tape first.

Drill at a near perpendicular angle with a very sharp and small drill at high speed with light pressure, stepping up a size at a time until you get the diameter you need.

Use a rat tail jeweler's file to adjust the angle of the hole as needed.

I've done this multiple times with no problems. Takes patience and a steady hand, but it's not rocket surgery.

O+
Posted: Dec 27, 2020 at 6:51 Quote
RunsWithScissors wrote:
Cover the area with masking tape first.

Drill at a near perpendicular angle with a very sharp and small drill at high speed with light pressure, stepping up a size at a time until you get the diameter you need.

Use a rat tail jeweler's file to adjust the angle of the hole as needed.

I've done this multiple times with no problems. Takes patience and a steady hand, but it's not rocket surgery.

Well you got one part correct, drilling a hole in a seat tube is definitely not rocket science.

If you stop and put a few more minutes of thought into this project you would realize it’s probably not a good idea. Drilling a hole in a seat tube is not OK just because other bikes have a hole in the seat tube. Those other bikes also have a reinforced seat tube to account for the hole, a thicker seat tube, different carbon fiber layup, or all of the above.

The hole required for a cable and housing is quite large. It may work out, or you may completely trash your frame and end up with a CF enema. External routed droppers exist for a reason and that the best route to go.

Posted: Dec 28, 2020 at 2:09 Quote
I'm usually the one person on here with the '0-F***'s" attitude, so it's rare that I'll be the one to say 'naw'.

Unfortunately, in the nature of things, drilling carbon isn't a great solution, since the resin provides a lot of the initial strength of the material. Exposing the base material as a raw deal leaves the area susceptible to a LOT of issues with vibration, cracking, or otherwise.

If it were me, I'd avoid it. Can't tell ya what to do - I'm all for finding out what the limits are, but on the coattails of some serious bucks......yikes......There HAS to be a better solution which allows you to maintain warranty while keeping things neat and professional.

Posted: Dec 28, 2020 at 5:00 Quote
dood wrote:
I'm usually the one person on here with the '0-F***'s" attitude, so it's rare that I'll be the one to say 'naw'.

Unfortunately, in the nature of things, drilling carbon isn't a great solution, since the resin provides a lot of the initial strength of the material. Exposing the base material as a raw deal leaves the area susceptible to a LOT of issues with vibration, cracking, or otherwise.

If it were me, I'd avoid it. Can't tell ya what to do - I'm all for finding out what the limits are, but on the coattails of some serious bucks......yikes......There HAS to be a better solution which allows you to maintain warranty while keeping things neat and professional.

You're know that a shit ton of carbon rims have a shit ton of holes drilled in them AFTER coming out of the mold, right...?

Posted: Dec 28, 2020 at 5:25 Quote
RunsWithScissors wrote:
dood wrote:
I'm usually the one person on here with the '0-F***'s" attitude, so it's rare that I'll be the one to say 'naw'.

Unfortunately, in the nature of things, drilling carbon isn't a great solution, since the resin provides a lot of the initial strength of the material. Exposing the base material as a raw deal leaves the area susceptible to a LOT of issues with vibration, cracking, or otherwise.

If it were me, I'd avoid it. Can't tell ya what to do - I'm all for finding out what the limits are, but on the coattails of some serious bucks......yikes......There HAS to be a better solution which allows you to maintain warranty while keeping things neat and professional.

You're know that a shit ton of carbon rims have a shit ton of holes drilled in them AFTER coming out of the mold, right...?

But those rims are designed to have holes drilled in them.....if you drill a hole in a frame you may weaken it. Although it would depend on the frame and where you drill.

Posted: Dec 29, 2020 at 4:28 Quote
RunsWithScissors wrote:
dood wrote:
I'm usually the one person on here with the '0-F***'s" attitude, so it's rare that I'll be the one to say 'naw'.

Unfortunately, in the nature of things, drilling carbon isn't a great solution, since the resin provides a lot of the initial strength of the material. Exposing the base material as a raw deal leaves the area susceptible to a LOT of issues with vibration, cracking, or otherwise.

If it were me, I'd avoid it. Can't tell ya what to do - I'm all for finding out what the limits are, but on the coattails of some serious bucks......yikes......There HAS to be a better solution which allows you to maintain warranty while keeping things neat and professional.

You're know that a shit ton of carbon rims have a shit ton of holes drilled in them AFTER coming out of the mold, right...?

Which rims? Any post-treatment? Documentation? Word from the manufacturer that they leave a raw hole in the rim? Proof of testing? Very curious to see the results, if someone could provide a link or something....Would help tremendously with my education......

Posted: Dec 29, 2020 at 7:29 Quote
Do a little poking around online with carbon manufacturers in Asia and you can get all those questions answered first hand by the people doing the work. It's not hard to do. They want to talk to you or anyone else who's interested in buying product. Just get on Alibaba and start emailing companies. I used to work for an American startup in the carbon business that never could get their funding together. In the process I came in contact with Asian suppliers like Carbon Speed, for instance. Look at their website. You can order carbon rims with different types of carbon, different layups, different spoke hole drilling, ask questions of the supplier, have your own logo placed on the product. Workswell Bicycles is another one you could look into. Their website is a trainwreck, but they've been around for quite awhile and they make good stuff. Stuck Bikes (what a name!) is another manufacturer that seems pretty transparent about what they do.

I can't speak for every manufacturer out there, but I've built wheels on carbon rims from several different suppliers and I've never seen a rim that I can recall that DIDN'T have mechanically drilled holes. Little bits of leftover carbon from the spoke hole drilling process falling out of a carbon rim when you take it out of the packaging isn't uncommon at all.

Carbon is amazing stuff, it has very different structural properties from metal, but there's nothing supernatural about it. The commonly held belief seems to be that carbon is brutally strong unless you scratch it, then it flies apart like an exploding car in a 1970's action movie. If carbon was really that delicate you couldn't make even half of the things out of it that people do. Manufactures also build large safety margins into their product designs in order to avoid product liability lawsuits. Do you really think that a major manufacturer would sell a frame that is so wimpy that it's just one 6mm hole away from cracking and falling apart...?

Posted: Dec 29, 2020 at 21:47 Quote
A pnw external works nicely for me. Coulda used the hole for the front derailleur if i enlarged it. I opted to keep mine unmolested. Couple zip ties. Done.

Posted: Dec 30, 2020 at 3:52 Quote
RunsWithScissors wrote:
Do a little poking around online with carbon manufacturers in Asia and you can get all those questions answered first hand by the people doing the work. It's not hard to do. They want to talk to you or anyone else who's interested in buying product. Just get on Alibaba and start emailing companies. I used to work for an American startup in the carbon business that never could get their funding together. In the process I came in contact with Asian suppliers like Carbon Speed, for instance. Look at their website. You can order carbon rims with different types of carbon, different layups, different spoke hole drilling, ask questions of the supplier, have your own logo placed on the product. Workswell Bicycles is another one you could look into. Their website is a trainwreck, but they've been around for quite awhile and they make good stuff. Stuck Bikes (what a name!) is another manufacturer that seems pretty transparent about what they do.

I can't speak for every manufacturer out there, but I've built wheels on carbon rims from several different suppliers and I've never seen a rim that I can recall that DIDN'T have mechanically drilled holes. Little bits of leftover carbon from the spoke hole drilling process falling out of a carbon rim when you take it out of the packaging isn't uncommon at all.

Carbon is amazing stuff, it has very different structural properties from metal, but there's nothing supernatural about it. The commonly held belief seems to be that carbon is brutally strong unless you scratch it, then it flies apart like an exploding car in a 1970's action movie. If carbon was really that delicate you couldn't make even half of the things out of it that people do. Manufactures also build large safety margins into their product designs in order to avoid product liability lawsuits. Do you really think that a major manufacturer would sell a frame that is so wimpy that it's just one 6mm hole away from cracking and falling apart...?

Cool! So, how does everyone get around leaving raw, unchecked carbon strands hanging out in open space? Can we just throw a twist-bit at 'er and assume it'll be fine?

How do you get around geometric and non-geometric defects? Fiber pullout, delam, and matrix cracking? What about hole taper, alignment, and surface profile? This junk is way too expensive for my wheelhouse, so anything is appreciated!

Posted: Dec 30, 2020 at 5:24 Quote
dood wrote:
RunsWithScissors wrote:
Do a little poking around online with carbon manufacturers in Asia and you can get all those questions answered first hand by the people doing the work. It's not hard to do. They want to talk to you or anyone else who's interested in buying product. Just get on Alibaba and start emailing companies. I used to work for an American startup in the carbon business that never could get their funding together. In the process I came in contact with Asian suppliers like Carbon Speed, for instance. Look at their website. You can order carbon rims with different types of carbon, different layups, different spoke hole drilling, ask questions of the supplier, have your own logo placed on the product. Workswell Bicycles is another one you could look into. Their website is a trainwreck, but they've been around for quite awhile and they make good stuff. Stuck Bikes (what a name!) is another manufacturer that seems pretty transparent about what they do.

I can't speak for every manufacturer out there, but I've built wheels on carbon rims from several different suppliers and I've never seen a rim that I can recall that DIDN'T have mechanically drilled holes. Little bits of leftover carbon from the spoke hole drilling process falling out of a carbon rim when you take it out of the packaging isn't uncommon at all.

Carbon is amazing stuff, it has very different structural properties from metal, but there's nothing supernatural about it. The commonly held belief seems to be that carbon is brutally strong unless you scratch it, then it flies apart like an exploding car in a 1970's action movie. If carbon was really that delicate you couldn't make even half of the things out of it that people do. Manufactures also build large safety margins into their product designs in order to avoid product liability lawsuits. Do you really think that a major manufacturer would sell a frame that is so wimpy that it's just one 6mm hole away from cracking and falling apart...?

Cool! So, how does everyone get around leaving raw, unchecked carbon strands hanging out in open space? Can we just throw a twist-bit at 'er and assume it'll be fine?

How do you get around geometric and non-geometric defects? Fiber pullout, delam, and matrix cracking? What about hole taper, alignment, and surface profile? This junk is way too expensive for my wheelhouse, so anything is appreciated!

Sounds like you're eating a bowl of word salad instead of actually working with the product. Not everything that you can imagine is realistically likely to happen. Keep worrying. I'll keep making a living at this stuff the way I have for years and we'll both have great lives Smile

Posted: Dec 30, 2020 at 6:21 Quote
RunsWithScissors wrote:
dood wrote:
RunsWithScissors wrote:
Do a little poking around online with carbon manufacturers in Asia and you can get all those questions answered first hand by the people doing the work. It's not hard to do. They want to talk to you or anyone else who's interested in buying product. Just get on Alibaba and start emailing companies. I used to work for an American startup in the carbon business that never could get their funding together. In the process I came in contact with Asian suppliers like Carbon Speed, for instance. Look at their website. You can order carbon rims with different types of carbon, different layups, different spoke hole drilling, ask questions of the supplier, have your own logo placed on the product. Workswell Bicycles is another one you could look into. Their website is a trainwreck, but they've been around for quite awhile and they make good stuff. Stuck Bikes (what a name!) is another manufacturer that seems pretty transparent about what they do.

I can't speak for every manufacturer out there, but I've built wheels on carbon rims from several different suppliers and I've never seen a rim that I can recall that DIDN'T have mechanically drilled holes. Little bits of leftover carbon from the spoke hole drilling process falling out of a carbon rim when you take it out of the packaging isn't uncommon at all.

Carbon is amazing stuff, it has very different structural properties from metal, but there's nothing supernatural about it. The commonly held belief seems to be that carbon is brutally strong unless you scratch it, then it flies apart like an exploding car in a 1970's action movie. If carbon was really that delicate you couldn't make even half of the things out of it that people do. Manufactures also build large safety margins into their product designs in order to avoid product liability lawsuits. Do you really think that a major manufacturer would sell a frame that is so wimpy that it's just one 6mm hole away from cracking and falling apart...?

Cool! So, how does everyone get around leaving raw, unchecked carbon strands hanging out in open space? Can we just throw a twist-bit at 'er and assume it'll be fine?

How do you get around geometric and non-geometric defects? Fiber pullout, delam, and matrix cracking? What about hole taper, alignment, and surface profile? This junk is way too expensive for my wheelhouse, so anything is appreciated!

Sounds like you're eating a bowl of word salad instead of actually working with the product. Not everything that you can imagine is realistically likely to happen. Keep worrying. I'll keep making a living at this stuff the way I have for years and we'll both have great lives Smile

NoNo!...I really want to know more! Making a living on coatings, materials, and all the great things we deal with daily is awesome! Just looking for the absolute basics. Not a big expert on carbon whatnots..........Would love some of the engi-bits on stress concentration, or whatever else is available - this is really cool stuff!

Ignore this - it's irrelevant:

From Specialized:
Drilling holes in a down tube is a bad idea. The holes will create stress concentrations where cracks could form, compromising the structural integrity of his frame. If we meant for holes to be drilled in those locations we would have reinforced the tube walls in those area. (Needless to say this would void the bike’s warranty). Most of the holes in our frames are drilled, but we have specific reinforcements in those areas to prevent structural issues and the drilling process is very controlled and repeatable.
— Luc Callahan
Engineering Manager- Road
Specialized Bicycle Components

From Trek:
There is no circumstance where a hole can/should be drilled in a carbon frame by anyone other than the manufacturer. The reason we can drill holes in frames is that we specifically design areas with reinforcement for post-molding machining processes. We make intricate and exact fixtures that can take advantage of those areas with the appropriate cutting tools. There is absolutely no circumstance where we would feel comfortable with anyone outside of Trek drilling a hole in a carbon frame.
— Ben Coates
Trek Road Product Manager

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