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Can I safely drill through Chromoplastic?



 
 
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  #1  
Old December 21st 05, 09:32 PM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?

I got some lovely SKS fenders for my tour/commute rig recently and
discovered a compatibility problem with my frame. Since it's set up for
cantilever brakes, the seatstay bridge is not an actual brake bridge:
its hole, instead of being roughly horizontally oriented, faces the
dropouts and is threaded for a 5mm bolt, to allow fenders to attach
directly to it.

Problem is, the fenders don't have a hole in this region, instead
coming with an angled bracket that's supposed to attach to the brake
hole. For right now, I have this bracket bent around the bridge, but
since the bracket's not very long, it sometimes pops off, giving the
fender room to wiggle and occasionally lean on the tire.

Hence, the question in the subject line. I believe the "Chromoplastic
is simply metal with a plastic laminate on each side. So is the
laminate prone to some sort of horrible cracking/shattering requiring
some ultra-specific drilling technique, or can I just have a go at it?

-------
Yoni Mazuz
(there isn't actually poop in my e-mail address)

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  #2  
Old December 21st 05, 09:46 PM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?

It's just a metal/plastic sandwich.

It's similar, but a bit stronger, than the zefal's I've got on my road
bike.

The Zefal's are very brittle, and mine are held together by a couple
mending plates and screws. Drilling is not a problem.

http://static.flickr.com/39/76033586_dd0763ba92_o.jpg

A regular wood bit works fine.

  #3  
Old December 21st 05, 11:34 PM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?

plastic can be penetrated with a hot nail held with vice grips-heated
on stove or torch

  #4  
Old December 22nd 05, 12:09 AM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?

Yonatan Mazuz wrote:

Hence, the question in the subject line. I believe the "Chromoplastic is
simply metal with a plastic laminate on each side. So is the laminate
prone to some sort of horrible cracking/shattering requiring some
ultra-specific drilling technique, or can I just have a go at it?


The technique is to start with a very small bit, i.e. 1/16", and work
your way up, 3/32", 1/8", 5/32", 3/16", etc. until you get to the hole
size you want. If you start with the bit for the hole size you want, it
can be dangerous, as it can snag the plastic and crack it. Use a high
speed drill, and don't put a lot of pressure on the bit.
  #5  
Old December 22nd 05, 12:32 AM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?


SMS wrote:
Yonatan Mazuz wrote:

Hence, the question in the subject line. I believe the "Chromoplastic is
simply metal with a plastic laminate on each side. So is the laminate
prone to some sort of horrible cracking/shattering requiring some
ultra-specific drilling technique, or can I just have a go at it?


The technique is to start with a very small bit, i.e. 1/16", and work
your way up, 3/32", 1/8", 5/32", 3/16", etc. until you get to the hole
size you want. If you start with the bit for the hole size you want, it
can be dangerous, as it can snag the plastic and crack it. Use a high
speed drill, and don't put a lot of pressure on the bit.


Don't bother. Just drill through it. I just drill through mine to
atttach them and as I sit here I'm looking at 4 pairs mounted without a
problem.
Phil Brown

  #6  
Old December 22nd 05, 01:22 AM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?

"Yonatan Mazuz" wrote
Hence, the question in the subject line. I believe the "Chromoplastic is
simply metal with a plastic laminate on each side. So is the laminate
prone to some sort of horrible cracking/shattering requiring some
ultra-specific drilling technique, or can I just have a go at it?

I drilled holes in mine to install mudflaps, no problem.
--
mark


  #7  
Old December 22nd 05, 02:06 AM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?

Yonatan Mazuz wrote:
I got some lovely SKS fenders for my tour/commute rig recently and
discovered a compatibility problem with my frame. Since it's set up for
cantilever brakes, the seatstay bridge is not an actual brake bridge:
its hole, instead of being roughly horizontally oriented, faces the
dropouts and is threaded for a 5mm bolt, to allow fenders to attach
directly to it.

Problem is, the fenders don't have a hole in this region, instead coming
with an angled bracket that's supposed to attach to the brake hole. For
right now, I have this bracket bent around the bridge, but since the
bracket's not very long, it sometimes pops off, giving the fender room
to wiggle and occasionally lean on the tire.

Hence, the question in the subject line. I believe the "Chromoplastic is
simply metal with a plastic laminate on each side. So is the laminate
prone to some sort of horrible cracking/shattering requiring some
ultra-specific drilling technique, or can I just have a go at it?


As someone else noted, just be careful. If you start with a big drill
bit at low speeds, the bit can dig in deep very quickly and rip rather
than cut - or tear the piece out of your hands, or cause other problems
- the result can be a nasty crack. Keep the drill RPMs high and use low
pressure and all will be well.

BTW, I've drilled many a chromoplast fender, to install mud flaps. I
think I only had a problem once when I foolishly rushed things.

Mark

  #8  
Old December 22nd 05, 11:42 AM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?


Yonatan Mazuz wrote:
Hence, the question in the subject line. I believe the "Chromoplastic
is simply metal with a plastic laminate on each side. So is the
laminate prone to some sort of horrible cracking/shattering requiring
some ultra-specific drilling technique, or can I just have a go at it?


I drilled mine to rivet on a mudflap:
http://delap.org/images/mudflap2.gif

I used a regular drill bit hand held and drilled the guards in situ.
It didn't take very long

bestw ishes
james

  #9  
Old December 22nd 05, 05:46 PM posted to rec.bicycles.tech
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Default Can I safely drill through Chromoplastic?

Drill all you want, but know that any large hole may become a crack
propagation point. I drilled my SKS in a couple places to put in a
metal span across the brake bridge. A pop-rivet seems to be the best
solution I've found since it's doesn't un-thread with vibration like
even self-locking nuts can.

  #10  
Old January 9th 06, 12:12 AM posted to rec.bicycles.tech
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Posts: n/a
Default Can I safely drill through Chromoplastic?

Yonatan Mazuz wrote:
I got some lovely SKS fenders for my tour/commute rig recently and
discovered a compatibility problem with my frame. Since it's set up
for cantilever brakes, the seatstay bridge is not an actual brake
bridge: its hole, instead of being roughly horizontally oriented,
faces the dropouts and is threaded for a 5mm bolt, to allow fenders
to attach directly to it.

Problem is, the fenders don't have a hole in this region, instead
coming with an angled bracket that's supposed to attach to the brake
hole. For right now, I have this bracket bent around the bridge, but
since the bracket's not very long, it sometimes pops off, giving the
fender room to wiggle and occasionally lean on the tire.

Hence, the question in the subject line. I believe the "Chromoplastic
is simply metal with a plastic laminate on each side. So is the
laminate prone to some sort of horrible cracking/shattering requiring
some ultra-specific drilling technique, or can I just have a go at it?

-------
Yoni Mazuz
(there isn't actually poop in my e-mail address)


I just shoved a screwdriver thru and waggled it about untill the hole was
roundish.

Hasn't messed up yet after a couple of winters.


--
Andy Morris

AndyAtJinkasDotFreeserve.Co.UK

Love this:
Put an end to Outlook Express's messy quotes
http://home.in.tum.de/~jain/software/oe-quotefix/


 




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