How to drill out the rivets of the Shimano 9070 rear derailleur?

Discuss light weight issues concerning road bikes & parts.
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2old4this
Posts: 308
Joined: Mon Jan 13, 2014 7:26 am

by 2old4this

I've been shaving off some excess weight on the rear derailleur (please let's not get into "is it safe?" discussion. Dremel is your best friend...)

I want to powder coat the parts l "update". The problem is each part is riveted/pined to each other. I've tried using a dremel press drill. The pins are made from a much stronger metal than the derailleur arm parts. So during the drilling, the bit goes the easy way (obviously not through the pin.) I.e. Dremel is not a good press drill...

I need a solid press drill that can handle 2-3 mm drill bits. Any recomendations?

nvroadie
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by nvroadie

I use a Ryobi drill press with 1mm bits every day. It works great and I highly recommend it.


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PinaF8
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by PinaF8

What will you use when you are putting them back together? Do they sell these rivets or is there aftermarket parts available?
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Klaster1
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by Klaster1

2old4this wrote:I've been shaving off some excess weight on the rear derailleur

Do you mind sharing details on this? I had similar in mind (dremel-out faceplate of RD-9000, paint it black), but lack of tools and experience has stopped me. Drilling out pins and then assembling everything together are a major concern. I'm sure other people would be interested too.

2old4this
Posts: 308
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by 2old4this

nvroadie wrote:I use a Ryobi drill press with 1mm bits every day. It works great and I highly recommend it.


Thanks for the quick reply. Home Depot it is then...

Klaster1 wrote:Do you mind sharing details on this? I had similar in mind (dremel-out faceplate of RD-9000, paint it black), but lack of tools and experience has stopped me. Drilling out pins and then assembling everything together are a major concern. I'm sure other people would be interested too.


Largely experimenting on a 9070 used RD I bought from fleebay, for the time being.
Disassembling the servo and pulley cage out were simple. Taking out the inner spring is not a big deal either. That leaves a few pieces of small(er) metal pieces connected in a loop. Three of those parts (one connecting to the rear hanger, one middle piece, and one where the servo is) are over built, IMO. Well, I guess they are build to take impact in crashes. But there are a lot of excess weight on those three.

I simply disconnected them from the smaller looping parts (I'll post some pictures tomorrow) and started experimenting. The body of the parts are easily grindable with a dremel. I think I can easily get 40-50 grams out from them.

The issue is how to paint them. For powder coating, I have to separate them. Unfortunately they are hold together with pins/rivets (actually there are 4 of those...) I've tried a dremel router. The bit goes through the softer material of the body of RD, not the pins (I am glad I got the RD from fleebay.)

So I definitely need a much much more stable platform than a dremel router. This week I'll try with a press drill and see how it goes.

nvroadie
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Joined: Tue Mar 31, 2015 11:11 pm

by nvroadie

Also, make sure that you have new drill bits. It will make it a lot easier.


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Benno
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by Benno

I did this a few years back with an xtr derailleur. Just opened up a hole on one side and tapped the pin out through the hole. Replaced with some screws and bushings. Never did try it on a bike, was just for fun.

Image
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2old4this
Posts: 308
Joined: Mon Jan 13, 2014 7:26 am

by 2old4this

i thought of that too. I can easily take out three of the pins that way. The problem is the pin next to the servo. There is no way I can go from one side and punch the pin out from the other. The screw of the derailleur connecting it to the hanger is in the way (yep, I should take some pictures...)
If nothing else works, I think I'll cut the back of the assembly in which the pin goes through, cut the pin into two, and remove each piece separately (got it, I am definitely taking some pictures...)

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WonderSausage
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Joined: Fri Mar 29, 2013 10:51 pm

by WonderSausage

Related -- 6770 derailleur teardown on milling machine: https://www.youtube.com/watch?v=hAW5DvLSkak

2old4this
Posts: 308
Joined: Mon Jan 13, 2014 7:26 am

by 2old4this

I think I may need to buy a milling machine :-( Couldn't make the press drill work ...

https://1drv.ms/i/s!AmELerXy0Rtoh9dZOAV1YUBEgD3Tzw

Drilling the aluminum is like a hot knife through butter. So, I took two of the pins out by drilling on the closed side and tapping the pins out. The third pin, however, has to be drilled out from the side where the head is visible. All I managed to do is to scratch them (yeah, new bits and all that...) They are either of some very very hardened steel, or titanium. Pressing the drill causes the bit (2.4 mm) to go to one side or another (yes, the parts were secured well) only minutely. But it is enough for the bit to start going through the aluminum body. Using a thicker bit (3.6mm) is more stable but then the hole is too big.

The alternatives are
- I get a milling machine (not very likely)
- Cut the shaft I marked in yellow and push/pull the pin inside (I think worth trying)
- Give up, and simply shave off the part I marked with red and call it a day (at the expense of not painting the final product...)

Before I go with the option 2, any other suggestions are very welcome.

beanbiken
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by beanbiken

Can you give it to a local who has a milling machine to have him do it for you?
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joejack951
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Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

If the head of the rivet is not square it can be very difficult to get a drill bit to start accurately in the center. You can try center-punching the rivet but that may be just as difficult to do, and you still may have issues getting the bit started.

What I would recommend is to get a hand-held rotary tool (i.e. Dremel) and some carbide burr bits to fit it. You can then carefully remove just enough material from the rivets in order to be able to push them out. Have the derailleur clamped somehow to enable you to use both hands on the rotary tool so that it doesn't slip (been there, done that several times!).

2old4this
Posts: 308
Joined: Mon Jan 13, 2014 7:26 am

by 2old4this

I took the pin out :-)
I simply could not drill it out. Period. I think the pins are made of titanium, even making a small dent took a glass drill bit out...
So I ended up cleaning out the aluminum surrounding the pin (option 2 above). Make a small dent on it with a dremel, and gently (hah!) tap it out. It came out surprisingly easy...

The parts I can "lighten" are a total of 102.6 gr. Looking at them, I am guesstimating I can shave of ~30-35 gr. That obviously is not enough. Since modifying the servo is out of question, I have to do something with the derailleur cage (it is 26.4 gr) I am guessing I'll end up building a custom one, unless you guys know something 10-12 gr range (excluding pulleys.)

TheKaiser
Posts: 482
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

Benno wrote:I did this a few years back with an xtr derailleur. Just opened up a hole on one side and tapped the pin out through the hole. Replaced with some screws and bushings. Never did try it on a bike, was just for fun.

Image


I am normally more of a function over form sort of guy, but damn that derailleur is gorgeous! And yes, I am aware that I included the photo in the quote above...I thought it merited replication.

2old4this
Posts: 308
Joined: Mon Jan 13, 2014 7:26 am

by 2old4this

Exactly. I know, I'll be making the derailleur more susceptible to crashes. It'll undoubtedly be less fragile. But after painting, it'll be unique and will look much better than unpainted aluminum pieces.
The downside is It'll just take a very long time to complete the project...


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