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Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

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Old 05-07-10, 11:57 AM   #1
schnee
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Finishing fillets - want some advice and examples

I took Yamaguchi's class, and as fantastic as it was and as much as I learned, I didn't get to do the final prep on many fillets.

Part of it was me (I'd never brazed or worked with metal before), part of it was my choice of bike (lugless except the fork crown and seat clamp, a lot more work), but... I have to admit... I was 'that slow guy'. I basically got the frame all done and together late Friday, and didn't get to see him demonstrate much finishing work.

Now I'm on the more difficult places and at a bit of a loss, and don't want to spin my wheels with bad techniques. So, I'd appreciate some advice:
  • Smoothing out between the chainstays & seat tube on the bottom bracket - how do you get in there? What specific techniques do you use? Tools?
  • Rear dropouts: when I clean up around the slots in the stays (where the dropout tongues insert), should I clean them up a lot - i.e. steel visible except for the thin line where the braze is, squared off - or should I leave a slight curve there as well?
  • Rear dropouts: how do you do to clean up the 'scalloped' cutouts on the stays where they meet the dropout? I did well on most of them - a slight concave shape - but a couple have big blobs that I want to carve in a bit, not sure what tools to use.
  • Pits: I've found a few here and there. Do you fill them in with silver, or just tell the painter and have them fill them in?

Thanks!
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Old 05-08-10, 06:46 AM   #2
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I was told by a well known Canadian builder that Chris DeKerf uses a mini hand held belt sander to clean up those areas. You can buy one with a very slim belt that will fit in those hard to reach areas.
You can also buy abrasive emery "cord" that can be very useful for this.
A set of small specialty metal files always helps if you are worried about power tools getting away from you.
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Old 05-08-10, 11:53 AM   #3
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I was told by a well known Canadian builder that Chris DeKerf uses a mini hand held belt sander to clean up those areas. You can buy one with a very slim belt that will fit in those hard to reach areas.
Probably a "Dynafile:"


These are extensively used by framebuilders, but are expensive and hard to justify unless you build a lot of frames. They are also capable of rapid destruction of frames if not wielded competently.

Quote:
You can also buy abrasive emery "cord" that can be very useful for this.
Rolls of emery cloth of various grits are also useful. You can wrap them around pencils and such to get into tight radiuses.
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Old 05-08-10, 02:16 PM   #4
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Thanks!
Yeah, I saw him use the Dynafile, too rich for my blood right now.
I have rolls of 80, 100, 120 grit shop cloth in 1" strips. I've been tearing them down to 1/2" width for some tighter places. The pencil idea is a great trick!
My set of small metal files should be here in a day or two, I'll use those for the dropout details.

Thanks!
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Old 05-08-10, 04:41 PM   #5
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Files, fingers and shop cloth. Remember to feather the edges- don't just start in the middle and cut a groove. Be careful (especially at the edges) to not cut into the tubing. Play with file/ sanding direction.

Pay attention to what is difficult to clean up and work on that the next time you braze a frame. Hard clean up makes you a better brazer, and better brazing makes for easier clean up. All of those are just practice things as you develop a personal method.

Dynafiles are great tools, but they can kill a frame in seconds if you don't have the fundamentals down. I'd get a feel for doing these by hand first.
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Old 05-08-10, 04:55 PM   #6
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Pay attention to what is difficult to clean up and work on that the next time you braze a frame. Hard clean up makes you a better brazer, and better brazing makes for easier clean up. All of those are just practice things as you develop a personal method,
Oh yes, Koichi stressed that as well. Believe me, the first brazes I laid down are a lot harder to clean up than the last ones, lol.

Those pics of the dropouts are exactly what I was looking for. Thanks.

Those fillets on your BB look pretty small...at what point are you reducing the structural integrity of the fillet?
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Old 05-08-10, 06:44 PM   #7
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On a small fillet its fairly easy to file away an entire thing if the initial depth is inconstant (cold and hot highs and lows, or chasing a pin hole). The 3x wall thickness rule is a good one- deeper in the age of thin butted ends. Err on the thick side if the fillet is inconsistent or you have any doubt about an internal fillet forming.
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Old 05-08-10, 08:22 PM   #8
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Here's where I am on the BB.
Evening out the whole bike before I go back and make that area balanced.

The pit and creases aren't as deep than they look here.
The creases should even out no problem... the pit I'm leaving alone.

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Old 05-09-10, 06:58 AM   #9
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Here's where I am on the BB.
Evening out the whole bike before I go back and make that area balanced.

The pit and creases aren't as deep than they look here.
The creases should even out no problem... the pit I'm leaving alone.

Melt a little lead solder into them to smooth them out before you paint it.
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Old 05-09-10, 07:20 AM   #10
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Lee Valley tools sells a hand held non-powered equivalent of that electric sander.
BTW you put your BB on the wrong way...







Just kidding.
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Old 05-09-10, 10:36 AM   #11
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Old 05-10-10, 06:32 AM   #12
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if that is your first frame i would say those fillets are finished good enough. you could spend days filing them down to nothing to make them look good.
like others have said, when your torch skills get better, fillets become pretty easy to finish, bc you wont have to remove gobs and gobs of brass!

get that thing built up, and start thinking about your next frame.

the more time you have with a torch in your hand is time spent improving that skill.....
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Old 05-10-10, 09:41 AM   #13
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From a fellow newb:
I`m currently going through a lot of the same issues on my first build, Schnee. For the dropouts, I really like how scallops look, and that`s what Paterek uses as his example of the "normal" way to do them. But when I did a few practice runs I couldn`t get them to come out clean and, like you noticed, it`s really tough to get in there and clean them up after the fact. What I ended up doing was filing my bevels flat rather than scalloped- about the same when it comes to filling the gap, but by really heaping on the filler it isn`t too hard to file clean after soaking. That might be an option for you on Number Two, or you might still be able to file your scalloped drops flat. Here`s a thread with lots of dropout pics, including mine:
http://www.bikeforums.net/showthread...15459-dropouts

About your fillets, I`m glad the word was to just leave them alone. Mine looked a lot like yours. For a few joints, I went back over them after cleaning with a second brass fillet over the first, but later decided not to bother. When the whole frame is bronzed I`ll go back and hit the uglies with a little bit of silver. Hey, you got any overall pics of the whole frame? What kind of bike are you doing?
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Old 05-10-10, 12:52 PM   #14
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Progress. Very happy with this. I know I won't get them all like this, but it's good that I could do one.

I'll take all your advice on the rest. I'll sand the high spots down fairly smooth, then leave them alone for paint.

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Old 05-11-10, 12:32 PM   #15
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i have found the easiest way to get a dropout scallop to look good enough and not be a time suck to clean up is to scallop the end of the tube prior to brazing. then when you are brazing in the drop the filler takes on the scallop shape. pile up the brass a little above the open end of the tube, then its really quick to knock off the excess with a file or emery to be flush with the scalloped tube.
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Old 05-11-10, 03:32 PM   #16
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If you are painting, bondo it, or use epoxy. Obviously one strives for work that looks as beautiful naked as painted. Always strive for the best work, but when you reach the end of the road, you can still fill it, and try again the next time. This is different than doing sloppy work and then covering it with bondo, and never getting any better at it. And anyway, high build epoxy primer is just a thin coat of filler sprayed everywhere. I prefer to fill with epoxy than heavy metals, though I have both on the property. I don't really want to have to sand lead.
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Old 05-11-10, 04:08 PM   #17
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legalize_it: the dropout tube is scalloped. I was a little overboard with braze on this one, and I'm coming back to it once the rest of the bike is done.

Well, I'm taking it to Joe Bell to paint, because he's local and I love awesome paint jobs. He talked with me on the phone a bit, and when I told him I fillet brazed my first frame he laughed and said 'yeah, don't be embarrassed, everyone's first brazed frame has all sorts of cosmetic issues. Just bring it in and we'll go from there, I'll bondo out all the ugly spots'. SUPER cool guy.
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Old 05-11-10, 06:43 PM   #18
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Files, fingers and shop cloth. Remember to feather the edges- don't just start in the middle and cut a groove. Be careful (especially at the edges) to not cut into the tubing. Play with file/ sanding direction.

Pay attention to what is difficult to clean up and work on that the next time you braze a frame. Hard clean up makes you a better brazer, and better brazing makes for easier clean up. All of those are just practice things as you develop a personal method.

Dynafiles are great tools, but they can kill a frame in seconds if you don't have the fundamentals down. I'd get a feel for doing these by hand first.
I really like this answer. The OP's fillets are far larger than necessary, I'd take them down until they are smooth. My pet peeve as far as finishing fillets is are edges with depth. It seems like it takes forever to get rid of the edge while not cutting into the tube.

I've seen more damage to frames from Dynafiles than any other tool.
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Old 05-11-10, 11:57 PM   #19
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Yeah, the fillets are OMG HUGE. I erred on the side of too much, rather than too little, intentionally.

Question though... when I hear things about fillets like 'optimal structural size is 3x or 4x thickness of the tube'... does that mean that's the depth of the fillet at the most concave portion of the curve?

Another thing, I'm a big dude. 260 in shape. 280 now. Basically an ex-bodybuilder ten years past my prime. So, if leaving them bigger is a good idea for strength, I will.
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Old 05-12-10, 11:33 AM   #20
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I think it's far more likely that you will get a crack from any sharp edges you leave in the fillet than that they rupture due to lack of strength. I believe the "structurally optimal" thickness refers to the notion that you want some compliance in the fillet so it doesn't break the tube at the edge of the fillet. Never seen this happen though.
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Old 05-14-10, 07:13 AM   #21
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it has been shown (i think tom ritchey and some others did the experiment) that fillets larger than the minimum size (3 or 4x i guess?) doesnt increase strength. its the time heated that will really make a difference. so if you take an extra 5 minutes building up really big fillets, that is actually weakening the joint. its been discussed before on the framebuilders list. so i think the consensus is "get in and get out as quick as possible."
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Old 05-16-10, 01:37 PM   #22
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Thanks for the info.

Dunno how much this matters, but when I was brazing, the flux was clear and smooth, and the regions 2-3" out from the are being brazed showed no blackening or overheating. I also had bright gold brazes and little to no carbon or dark spots. Compared to what I've seen on many brazed frames from first-timers posted on Flickr, my temps were pretty good.

Also, Yamaguchi was watchful of one student who was overheating and kept reinforcing how I had good temperatures (and pointed out details to me like how the flux should look).

So, I *hope* I'm fine with this bike. Time will tell.

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Old 05-16-10, 02:04 PM   #23
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Not sure what I said that needs challenging. Your brazing looks good, you left some large defects because of inexperience. It must be nice to hear praise from your teacher. He must be happy to have a student that grasped things so quickly.

The pit is ok, I'd fill with silver because that's what I know how to do.
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Old 05-16-10, 02:04 PM   #24
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