Drilling Titanium Chainstay

Discuss light weight issues concerning road bikes & parts.
PyreofFyre
Posts: 17
Joined: Thu Apr 12, 2018 6:43 am

by PyreofFyre

Hi all,

Seeking the collective wisdom of all the experts here.

First time poster, long time lurker here.

Am currently in possession of a titanium frame, that's lacking a drive-side chainstay port for a Di2 cable (for the rear derailleur).

I've noticed that the dropout uses hooded style Paragon one, with a tiny breather hole at the rear of the chainstay.

Assuming the necessary tools are available, would there be any issues to the frame if I were to enlarge this whole to 6mm in diameter to fit the cable (along with the Shimano SM-GM01 grommet)?

Would there be any impact on durability, reliability, etc?

Thanks and very much appreciate the inputs.
PoF

by Weenie


jfranci3
Posts: 354
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

I'd take it to a local bike builder for the best placement and size of the hole. If you're talking about the capped area at the end of the tube, it should be fine. Do you have pics of the chainstay?

Also, look up particulars of drilling Ti. You need some oil, a sharp & hard bit, and some pressure. Material is grabby.

Marin
Posts: 3069
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

Wouldn't it be easier to splice a thinner cable into the Di wiring loom?

kode54
Posts: 1325
Joined: Tue May 23, 2006 9:39 pm

by kode54

i think its fine. i have an older Guru Ti frame that has a Di2 port in that area.

you just need to make the breather hole larger, yes? to 6mm, correct?
- AX Lightness Vial EVO D + DA9150 + Enve SES 4.5 carbon hubs
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- Guru Praemio R Titanium + DA9150 + Enve 3.4 CK hubs

numberSix
Posts: 76
Joined: Sun Sep 23, 2012 1:53 pm

by numberSix

don't let the frame get hot while drilling. Oxygen embrittlement seems to happen very easily with titanium

Theologian
Posts: 41
Joined: Sat Jun 23, 2018 3:34 am

by Theologian

I have the same problem looking to upgrade my volagi Ti to di2. There're di2 holes on the downtube and seat tube for front derailleur, but nothing for the rear exacept the breather hole. I think I'm going to splice the etube, becuse the etube wire fits in the hole without the plugs.

PyreofFyre
Posts: 17
Joined: Thu Apr 12, 2018 6:43 am

by PyreofFyre

kode54 wrote:
Mon Jun 25, 2018 3:46 pm
i think its fine. i have an older Guru Ti frame that has a Di2 port in that area.

you just need to make the breather hole larger, yes? to 6mm, correct?
Hi Kode54, yup, that's the idea. I didn't want to risk my chances with an external job, where the drill bit might slip and mar the finish of the frame.

Thanks for the feedback.

PyreofFyre
Posts: 17
Joined: Thu Apr 12, 2018 6:43 am

by PyreofFyre

jfranci3 wrote:
Mon Jun 25, 2018 2:27 pm
I'd take it to a local bike builder for the best placement and size of the hole. If you're talking about the capped area at the end of the tube, it should be fine. Do you have pics of the chainstay?

Also, look up particulars of drilling Ti. You need some oil, a sharp & hard bit, and some pressure. Material is grabby.

Thanks Jfranci3, I've got a 6mm cobalt bit that I could use for this, and was going to go with some chain lubricant (also as a coolant). Just more worried about stuff like embrittlement like Theologian said.

Appreciate the inputs though.

jfranci3
Posts: 354
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

PyreofFyre wrote:
Mon Jun 25, 2018 11:21 pm
jfranci3 wrote:
Mon Jun 25, 2018 2:27 pm
I'd take it to a local bike builder for the best placement and size of the hole. If you're talking about the capped area at the end of the tube, it should be fine. Do you have pics of the chainstay?

Also, look up particulars of drilling Ti. You need some oil, a sharp & hard bit, and some pressure. Material is grabby.

Thanks Jfranci3, I've got a 6mm cobalt bit that I could use for this, and was going to go with some chain lubricant (also as a coolant). Just more worried about stuff like embrittlement like Theologian said.

Appreciate the inputs though.
That coolant needs to be run through continuously. Chain lube as coolant is too low temp.

PyreofFyre
Posts: 17
Joined: Thu Apr 12, 2018 6:43 am

by PyreofFyre

jfranci3 wrote:
Tue Jun 26, 2018 1:45 am
PyreofFyre wrote:
Mon Jun 25, 2018 11:21 pm
jfranci3 wrote:
Mon Jun 25, 2018 2:27 pm
I'd take it to a local bike builder for the best placement and size of the hole. If you're talking about the capped area at the end of the tube, it should be fine. Do you have pics of the chainstay?

Also, look up particulars of drilling Ti. You need some oil, a sharp & hard bit, and some pressure. Material is grabby.

Thanks Jfranci3, I've got a 6mm cobalt bit that I could use for this, and was going to go with some chain lubricant (also as a coolant). Just more worried about stuff like embrittlement like Theologian said.

Appreciate the inputs though.
That coolant needs to be run through continuously. Chain lube as coolant is too low temp.
Thanks for the heads up. What would you use for coolant then?

NickJHP
Posts: 124
Joined: Wed Feb 14, 2018 2:22 am

by NickJHP

Some discussion of cutting/coolant oil here: https://www.practicalmachinist.com/vb/g ... um-315381/.

jfranci3
Posts: 354
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

That's a bit too much for a shallow wall 6mm hole. Maybe motor or olive oil. Ideally you want something that can pull the heat away as TI does not conduct heat, it'd rather heat the tool and bond with it.
Ti will also work harden, no tap tap tap tap rather than light constant pressure.

Orbital
Posts: 62
Joined: Wed Feb 14, 2018 12:52 am
Location: Pitt Meadows, BC

by Orbital

If you’re enlarging a drain hole a reamer would be more appropriate and much quicker. The quicker work you can make of it, the less heat. But you would want to use a cutting fluid like Rapid Tap as opposed to coolant.

PyreofFyre
Posts: 17
Joined: Thu Apr 12, 2018 6:43 am

by PyreofFyre

Wow, thanks guys for all the info! Much appreciated.

=)

pdlpsher1
Posts: 1717
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

My Di2 cable comes out of the Paragon dropout. Use a grommet. This is the best place for a hole for a very clean look.


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by Weenie


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