Re: [CR] Sending for repaint (lug thinning prep)

(Example: Bike Shops)

Date: Wed, 05 Sep 2007 11:46:58 -0400
From: "George Allen" <jgallen@lexairinc.com>
To: "'Classic Rendevous'" <classicrendezvous@bikelist.org>
Subject: Re: [CR] Sending for repaint (lug thinning prep)
References: <C303DF84.9232%fatticbicycles@qtm.net>
In-Reply-To:


Garth,

Since Doug gives you a one in ten shot of not trashing your San Rensho I'd be happy to send down my 1971 Raleigh International frame brazed up in a 10th grade English shop class. The lugs have never had a file touch them and brazing has oozed all over everything. In other words, it's a real mess and there is no way you could make the frame worse. It would make a great practice frame. If all goes well I'll send down my Carlsbad twin-plate. I've always thought its lugs could use some touching up too. :-)

George Allen Lexington, Ky 40511

Doug Fattic wrote:
>From: Bianca Pratorius <biankita@comcast.net>
>
>I have decided I really like my mid 80's 3Rensho. The shifting is good,
>a nice mix of campy, Suntour parts etc. I absolutely hate the fade
>paint on it because it is impossible to touch up and ends up looking
>very dirty all the time. I am sending it out to my local painter but
>before I settle on which decals to use ... original or repro, I need to
>thin those lugs. (my 3rensho is lacking in that department). I feel I'm
>up to the task but I don't want to reinvent the wheel. What's the best
>way to go about it. ie.. file, sandpaper grit, methodology....?
>
>Garth Libre in Miami Fl USA
>
>Garth,
>
>One of my day jobs is teaching framebuilding classes (besides building and
>painting) so I've outlined for you a 4 step process to follow when you want
>to go to your workshop and play with your SanRensho (San being the Japanese
>word for 3). Keep in mind that I believe filing is more difficult to get
>right than brazing although our instinct might suggest otherwise. I'm also
>going to assume you haven't been frightened away from doing this after
>hearing the startled, fearful gasps of your CR "friends". I personally see
>no beauty in a lug that hasn't had some work to at least even the thickness
>all around and I have no affection for one that hasn't been thinned.
>Otherwise they look just like production frames with different decals. I'm
>also going to assume you have the basic equipment to do this work that
>includes wood blocks to hold the frame and file handles on the files.
>Right? If not you can order very nice wood blocks from Dave Bohm.
>
>Step 1. Rough out the shape using as large a bastard cut file as you are
>comfortable with. Start on the sides and work toward the tips using short
>strokes until - as you move towards the center - you can lake longer ones a
>s
>you clear the interference from the side. When you can take longer stokes,
>be sure and rotate the file around the tube some with each motion so you
>don't create flat spots. Keep an eye on the edge to know the depth you are
>removing and don't let the file touch the tubes in order to guard the lug
>edge which can get destroyed if the file slips off the lug.
>
>Step 2. Smooth out the roughness from hogging off the lug material with a
>smaller and/or smoother cut file. I typically use #1 Swiss pattern file to
>do this. The file motion will be clocklike from the lug crease to the edge
>being careful to advance each stroke just enough so that it is not cutting
>where the last stroke did but just next to it. You want to remove and not
>create flat spots. After you have reached the end of one area that doesn't
>require you to adjust the frame being held by your wood blocks, shift the
>file stroke direction and file back with this motion to where you started.
>Your goal is to have a consistent look throughout the area you just worked
>on. When necessary, move the frame position and then do the next section.
>
>Step 3. Remove file marks with a smooth cut file. I typically use a round
>or half round #2 or 3 cut Swiss pattern file. This motion is the same as i
>n
>step 2. However because the file cut is smoother, you can't shape with
>these files, only remove file marks. Your goal again is getting a
>consistent look throughout the area being filed.
>
>Step 4. Polish with 80 grit emery cloth without yucking up the lug edges.
>
>I've measured the outside thickness of various builders lugs (on 1² tubes)
>with my calipers. A typical lug will start around 1.090². Depending on th
>e
>era I built a frame, my lugs ended up to be 1.060" in my thinner early year
>s
>to 1.070² when I liked more definition. Tom Sanders has a Chris Kvale from
>Minneapolis frame. He is an extremely fine builder that is known for havin
>g
>very thin lugs. They varied a bit from 1.060² to 1.070². I also repainted
>a frame from another very fine American builder Peter Mooney. He learned
>from Ron Cooper who was a better builder than were some places other
>Americans went to learn in England. He makes sure the lug surfaces are fla
>t
>and filed but not as thin nor as consistent in thickness. His lugs were
>around 1.080² give a take a few (maybe up to 10) thousandths depending on
>where you measured. The difference between 1.090² and 1.060² doesn¹t seem
>like much but to my eye it really is a lot. I can easily tell .010²
>difference when I¹m looking at them. I¹m pretty efficient with filing but
>it still takes me a number of hours to do each lug. I think the production
>guys like Curt Goodrich use the belt sanders for prethinning before brazing
>and Dynafiles afterwards a lot more than me.
>
>That 4 step list is nowhere near exhaustive (it's just a starter guide) and
>if you decide to really give it a go, I'll send you my written out filing
>tips (including common rookie mistakes) from my framebuilding class in an
>attachment. Don't expect instant success. I'd estimate about 1 out of 10
>do a really decent job filing lugs on their first frame. It takes a
>tremendous amount of hand control and it is easy to have the file slip just
>a bit and ruin the lug edge. If you are really good, the frame tubes
>themselves will show no marks of from either the file or emery cloth.
>
>Good Luck and you're welcome,
>Doug Fattic
>Niles, Michigan USA
>
>
>_______________________________________________
>
>
>

--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.