Whats your best technique for filing / smoothing fillet brazed welds.
 

So I am filing away today trying to get my fillet brazed welds to look smooth and thinking this is taking ages and I wonder what tools, techniques other people use. Do people use power files or recommend me any certain sizes of file to make things easier? Any good techniques?

Thanks in advance

You'll find fans of both curved hand files and power files or flexible belt sanders. Probably most people use both according to the specific need. Hand filing offers excellent precision and control, but is slow as ... The flexible belt sanders are excellent and very fast, but can be too fast if you're not used to them.

The one thing you want to keep in mind is that you want to shape or remove brass down to the steel tube, without undercutting or removing steel at the edge. If you're not careful it's very easy to thin the tube where the brass ends which unfortunately is the place of highest stress.

If you're new to power sanding, consider brazing up a few joints out of some scrap and practicing until you develop touch and control.

I use a Dynafile.

Actually the nicest fillets that you see in photos on line are often needing the least finish work. With much practice one can have a fillet that needs little filing or sanding to be REAL NICE. I have had this result only a few times, I don't practice enough. Andy.

I know this isn't really an answer to the OP's question but the way to end up with a clean looking finished fillet is to start with a very clean and well shaped fillet in the first place........so I agree with Andy in a big way.

A poorly laid fillet can be shaped into a nice looking finished fillet if one has the time and energy but you'll need a lot of both to pull it off. I say all of the above because I've taught a lot of folks how to fillet braze and most want to know how to shape them after the fact when in reality the time needs to be spent on the front side so that the finish work is simple and easy.

All that said - I rarely use any power tools when finishing a fillet. If I've done my best work I can finish things up nicely with just emery cloth..........if it's my average work I will use a the largest size round file that will fit into the space to give it the shape I want and then it's on to emery cloth. A simple joint, like a head tube or top tube/seat tube joint, will take about 10 minutes in total to clean up and be ready for paint.............bottom brackets of course take longer as there are concave sections that are harder to work that the convex shapes of the simple joints.

So practice, practice, practice on the brazing itself and you'll end up having little finish work to do.

Make sense?

dave

As true for lugged brazing as it is for fillet brazing.

I was going to say the most important tool is the torch.

The biggest emphasis for me while brazing is making sure there isn't a sharp edge of filler. Getting rid of the edge while simultaneously not removing tube material is not an easy chore. Of course, if the lumps are big enough you might have to take off a lot of material, so it's better not to have lumps at all.

A tapered spiral abrasive roll mounted on a Foredom Tool is really useful and fairly safe for fillet clean up, especially around the BB.
-Ryan

BONDO! Ha, ha, ha... ;)

verktyg :50:

Chas.

Yea, with enough Bondo one can make a Huffy look like a Klein:) Andy.

It's funny........I've seen just that. I once saw a crashed fillet brazed bike that was whacked hard enough to make the big round bondo fillets pop right off of the crappy tig beads buried under them. It happens.

dave

I also use the tapered rolls on a dremel at low speed. Filing is difficult... and harder to describe. Basically the file moves mostly parallel to the tubes but with a slight forward motion, from one edge of the fillet to the other. Repeat with a starting position slightly forward of the previous stroke. Of course having a even fillet to begin with greatly helps and is something I'm struggling with. Even slight "stack of dimes" ripples can be hard to remove without filing out a fair amount of filler.

I certainly agree with what my colleagues have said and will add just a couple more thoughts. I know a few of my framebuilding students will not have the ability and/or patience to lay down a really good fillet. We are not all created with equal talents and for some of them 20 practices (or even 100) would not be enough to get a don’t-need-to-file-much result (while others can do a really nice job right away). What this less talented group can do is still blob on enough brass without overcooking the tubes. Then they can file the bumpy mess into some kind of decent shape to still get a good final result which is all that matters.

Just like what Dave said I suggest starting with the biggest round file to rough out the basic shape. What I might add is the filing stroke Tuz was talking about. I'll just use different words. It is the possibility of using smaller round files with a specific filing pattern to get things even nicer after roughing it out with bigger files. This pattern is a stroke that slides to the right (or to the left) as the round file is moving forward as well as twisting. In other words the file pattern remaining on the fillet is really going just left to right (or right to left) and NOT forward. It is only the file moving forward at about a 45º angle (and twisting too) so its teeth can cut. The result is a line going to the right. After that file stroke is taken you move the file every so slightly forward of the last stroke and stroke again. These strokes are combined incrementally so that in maybe 10 strokes you might have covered 4mm (give or take obviously). There shouldn’t be any space between these strokes or you have moved (rotated forward) too much. The advantage of this kind of sliding motion is that it helps from digging the file into the brass or tube and making a unsightly (and potentially damaging) groove. It is particularly useful at the edge of the brass tube transition.

To practice this filing method (which is the basis of all good filing) you can use a round rusty or discolored tube (it can also be colored with a sharpie or layout die) held horizontally. Filing away the rust (or surface color) leaves clear marks so you can analyze your stroke pattern. As your file is moving forward at a 45º angle, it is actually sliding only to the right and will leave a straight left to right line on top of the tube (if you are right handed). This line will probably be less than a millimeter wide (depending on how hard you push). Then ever so slightly rotate your file a wee bit forward so it is cutting new territory just above your last stroke (but leaving no space in-between) and file again. This is done multiple times until you run out of space on your joint or you have to move the work so filing is comfortable again. Rookies tend to just slide the file right without moving it forward at the same time and/or leaving too much space between strokes. Some students catch on to this immediately while for others it takes much practice and many demonstrations. Don’t confuse this stroke with a forward rotating motion like filing around the tube.

The sound of your file can be your indicator of how much pressure to use. Too light of a stroke that only polishes and doesn’t remove metal has a higher sound than one doing work.

For those unfamiliar with "tapered rolls" (tapered cartridge rolls is the proper description), they're made of abrasive coated cloth, rolled and glued into a tapered cylinder. They easily screw onto a mandrel and are used in a power tool. As the grit wears off the roll, the backing cloth breaks down exposing fresh grit.

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verktyg :50:

Chas.

What ever the tool a steady hand is crucial!

Not necessarily....

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Campagnolo Tool #1


:lol:


verktyg :50:

Chas.