PDA

View Full Version : Cutting metal


Taywood
July 12th 03, 10:09 PM
I'm about to do surgery on my Kona Lavadome.
The seat tube has a single bolt thru two brazedon lugs and I
need to replace this with a new Seat Clamp.
I've bought a new rear brake cable guide, new seat clamp and
a shim before I cut metal.

My question to you is How do I cut two brazed lugs off a
cromoly seat tube? I've no experience of this.
Should I borrow a dremel tool, a B+D hammer drill or an angle
grinder and having severed the lugs what tool should I use to
grind off protruding metal. I'd appreciate any advice.

The new seat clamp is a two bolt deep job to disguise my
handiwork.
Mike

Tony Raven
July 12th 03, 10:53 PM
In ,
Taywood > typed:
> I'm about to do surgery on my Kona Lavadome.
> The seat tube has a single bolt thru two brazedon lugs and I
> need to replace this with a new Seat Clamp.
> I've bought a new rear brake cable guide, new seat clamp and
> a shim before I cut metal.
>
> My question to you is How do I cut two brazed lugs off a
> cromoly seat tube? I've no experience of this.
> Should I borrow a dremel tool, a B+D hammer drill or an angle
> grinder and having severed the lugs what tool should I use to
> grind off protruding metal. I'd appreciate any advice.
>
> The new seat clamp is a two bolt deep job to disguise my
> handiwork.

Why do you want to change from the lugs? Are you really really sure you
want to do this?

Tony

--
http://www.raven-family.com

"All truth goes through three steps: First, it is ridiculed. Second, it is
violently opposed. Finally, it is accepted as self-evident."
Arthur Schopenhauer

Jim Price
July 13th 03, 03:14 AM
Tony Raven wrote:
>>My question to you is How do I cut two brazed lugs off a
>>cromoly seat tube? I've no experience of this.
>>Should I borrow a dremel tool, a B+D hammer drill or an angle
>>grinder and having severed the lugs what tool should I use to
>>grind off protruding metal. I'd appreciate any advice.
>>
>>The new seat clamp is a two bolt deep job to disguise my
>>handiwork.
>
> Why do you want to change from the lugs? Are you really really sure you
> want to do this?

Listen to Tony, think carefully before you abandon any ideas which don't
involve major surgery. If the lugs still work, use them with a new bolt.
If they don't (oh no!), then Screwfix do a cheap angle grinder, but it
may be considered sacrilege to take it to a viable and working steel
frame. And if you do, bear in mind that you need to seal the inevitable
damage against rust before covering it with a double bolt seat clamp...

--
Jim Price

http://www.jimprice.dsl.pipex.com

Conscientious objection is hard work in an economic war.

Aye!.

Ivor Cave
July 13th 03, 09:34 AM
Taywood wrote:
> professionals not me, in the same way I dont have Aheadset.
> Keith Bontrager said in one of his rants that a well maintained
> canti is as good as a V brake in all conditions except for continual
> hard braking as in the racing scene.
> So thats the background to the surgery.
> Mike
>
>
>
>

If you upgrade you bike to V-Brakes you would know this is not true.
After riding a friends bike that he had put Vees on I upgraded mine the
difference is substantial.
And in your case could be cheaper than a new bike if your not experienced with
metal cutting tools. One slip and you have a very weak frame.

Ivor Cave

Tony Raven
July 13th 03, 10:21 AM
In ,
Taywood > typed:
>
> There is a rear brake cable guide which takes the cable behind the
> seat tube and centres it over the canti cable hanger.
> Its plastic, its old and weathered and it split. Its held together
> with Araldite. I bought the new metal Kona cable guide called a Dog
> Collar, then found that as its a solid ring it wont slide down the
> seat tube because of the lugs. They have to go.
>

You can get hangers that hang off the seat bolt and fit in between the lugs.
Understand your wishes to stick with cantis but what you are proposing to do
could leave you with no choice as new frames are now inevitably v-brakes and
that's the way you are probably heading. If you know enough to do the frame
mods competently you wouldn't have needed to ask the question of how to do
it.

Other options:

Get a frame builder to do the mods properly
Get a frame builder to braze on a hanger
Get a seat tube clamp adapter for a bolt on front derailler and modify it to
act as a cable guide (probably the easiest and cheapest option)
Get a clamp on cable stop from Ison (they open out to go round the seat
post)

Tony

--
http://www.raven-family.com

"All truth goes through three steps: First, it is ridiculed. Second, it is
violently opposed. Finally, it is accepted as self-evident."
Arthur Schopenhauer

W K
July 13th 03, 12:54 PM
"Taywood" > wrote in message
...

> I like canti breaks, I keep them well maintained and cleaned and
> I have the time to tweak them plus a boxful of canti brake parts,

well, if you like fiddling.
....
> I DO NOT WANT V BRAKES.
....
> Its new technology to me, its major expense,

I haven't got the prices off hand, but what ... 40 quid?

> the servicing benefits
> professionals not me
....
Eh? the non-servicing of V-brakes makes them very good for people who are
not professionals and who aren't very good at fiddling or maintenance.

> Keith Bontrager said in one of his rants that a well maintained
> canti is as good as a V brake

Even if that is true, its only "as good as", and then only if looked after
rather well.

I'm not raging against canti's, but V's are good, simple, technology that
work - so why butcher the frame?

Cicero
July 13th 03, 01:03 PM
"Taywood" > wrote in message
...
> I'm about to do surgery on my Kona Lavadome.
> The seat tube has a single bolt thru two brazedon lugs and I
> need to replace this with a new Seat Clamp.
> I've bought a new rear brake cable guide, new seat clamp and
> a shim before I cut metal.
>
> My question to you is How do I cut two brazed lugs off a
> cromoly seat tube? I've no experience of this.
> Should I borrow a dremel tool, a B+D hammer drill or an angle
> grinder and having severed the lugs what tool should I use to
> grind off protruding metal. I'd appreciate any advice.
>
> The new seat clamp is a two bolt deep job to disguise my
> handiwork.
> Mike
>
>
=========
If you're determined to remove the brazed lugs take your frame to a local
garage. Almost all garages have gas welding / brazing equipment. They will
simply melt the brazing metal away from the lugs and leave you with a little
easy filing / sanding to clean up the job.


Cic.

Mutz
July 13th 03, 05:13 PM
On Sat, 12 Jul 2003 22:09:44 +0100, "Taywood" >
wrote:

>I'm about to do surgery on my Kona Lavadome.

Forget using an angle grinder unless you have a REALLY REALLY steady
hand. One slip and you are going to make a real mess.
If you are still sure you want to remove the lugs then use a hacksaw
to get most of the material off and then use a file and emery cloth to
finish off, it'll take longer but you are not going to graunch a hunk
out of your frame in a millisecond like you will with a grinder. Slow
and steady is the way to go.

Eatmorepies
July 13th 03, 09:40 PM
>
> I like canti breaks, I keep them well maintained and cleaned and
> I have the time to tweak them plus a boxful of canti brake parts,
> cables and salmon brake pads which are new or partly used.
> As this is probably the last bike I shall own
> I DO NOT WANT V BRAKES.
>

1. Paying a frame builder to do it will cost loads more than V brakes.
2. If you do do it - use hand tools only. If you're not skilled with a
hacksaw, find someone who is.
3. Try V brakes first.

If you live in Mid Wales come to my house. I have some spare V brakes
(having gone hydraulic). You are welcome to try them - I think you will be
pleasantly suprised at their power and simplicity.

John

Taywood
July 14th 03, 08:40 AM
Thanks for the responses, some are very helpful and give me
lots to think about.

I do not want V brakes, having said that in capital letters to avoid
any discussion on the subject, why have people gone on about it.
Perhaps I dont understand people or perhaps I've not expressed
myself clearly.

I've passed on my road bike, I've passed on the Orange dream
(with V's, fully sussed) and all the bits and bobs for those bikes
I've collected over the years which might come in sometime!

Much to my wifes delight I only have the one old basic bike now.
Sure its got threaded forks but I've got two suss forks and one
Project Two all in good nick. Same with tyres, I'm left with
Avocet wide slicks, Velociraptors and Panaracer Fire Pro's.
Next seasons 'must have' forks or tyres with all their doodahs
will most likely be incompatible with this seasons stuff and its
my decision to drop out of this new technology and stick to
basics as long as I can.
I can still look thru the shop window at all the shiny new bike
parts, as I did years ago when my offroad bike had rod brakes
and balloon tyres and I fancied drop bars and narrow wheels.

Having said I'm old and this will be the last bike I shall own it
should be obvious I'm on a pension and the WK estimate of
£40 for basic bike parts is something hard to justify. Even
worse when I'd be wanting 2004XTR with Ti levers or such!
So thanks again
Mike

Dave
July 17th 03, 02:14 PM
"Taywood" > wrote in message
...
>
> > On Sat, 12 Jul 2003 22:09:44 +0100, "Taywood" >
> > wrote:
> >
> > >I'm about to do surgery on my Kona Lavadome.
>
> Job now completed, Bill Nickson Cycles at Leyland agreed to do the
> cutting off the lugs.
> Thanks for all your responses, everything went well, ermm almost!
>
> Back home I treated the bare metal then put Hammerite on it.
> Whilst it dried in the sun I uncoupled the rear brake, removed the
> old cable guide and found they had accidentally severed some cable
> strands, fortunately I had a new cable in 'the box'.
>
> Fitting the new cable guide needed two alu shims, I accidentally
> dropped one down the seat tube and it jammed at the bottom.
> Off came the cranks and the bottom bracket, I cleared the shim by
> pushing a coat hanger up thru the vent hole into the seat tube.
> Then I noticed the outer ring is worn and the centre ring is
> missing one tooth. More expense to come.
>
> Fitting the new seat tube clamp was more difficult than I expected.
> I never thought the seat tube upstand would be slightly flared from
> the top tube junction to the top where the seat post goes in.
> I expected it to be a constant diameter and had bought a clamp
> accordingly. With a bit of shaving metal and brute force it now fits.
>
> Having got the cranks on I tested the brakes - OK
> On impulse I tested the gears - it wouldnt jump to big ring.
> Off with the cranks again and with just a half turn on the drive
> side cup, tried again - OK
>
>
> Bike reassembled and then tested with a road ride in the sun.
> As always, nothing is ever straightforward is it?
> Thanks again Mike
>
Yeah, but if it was, how boring would life be ?? <sigh!>
Well done sir!!
Dave.

Google

Home - Home - Home - Home - Home