Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Framebuilders (https://www.bikeforums.net/framebuilders/)
-   -   Best abrasives to clean up brass from brazed frame (https://www.bikeforums.net/framebuilders/1001204-best-abrasives-clean-up-brass-brazed-frame.html)

wrq1103 04-01-15 06:25 PM

Best abrasives to clean up brass from brazed frame
 
As a new frame builder, I am looking for the best way to clean my brazed joints. I have tried metal die cutting tool, and spiral wound sandpaper. Any suggestions?

Andrew R Stewart 04-01-15 06:56 PM

Hand files (medium cut then fine) then production cloth (80 grit is enough), with media blasting just before paint. Millions of frames have been done this way and many more will be in the future. Why reinvent the wheel? Andy.

unterhausen 04-02-15 05:44 AM

Andy is right. The only shortcut is to get closer to final shape with the torch. I know that's easier said than done

kylecycler 04-03-15 09:06 PM

Dave Kirk takes you through the whole process on the Framebuilders' Collective site, in four parts:

The Framebuilders' Collective | Kirk Fillet Brazing

He covers cleaning up the joints in Part 1:

The first stage is roughing the shape with a hand file. If Iíve done my brazing job well there is little to do here and this goes very quickly. Next is Ďfile backed emeryí which is just like what it sounds like. I use an old worn out file to support 80 grit emery cloth to further refine the shape of the fillet. Next comes the use of the Ď3[SUP]rd[/SUP] thumbí tool. Yes itís a high tech device consisting of some rubber tubing shoved over an old round file. Itís soft and allows for a smooth contouring of the fillet. This is now more a polishing act and less of a shaping one. The next to last step is to use narrow strips of emery cloth to further polish and blend the joint and the final step is to use a rotary brush in a drill to give the joint some shine. Frankly I donít really care about it being shiny but the shine makes any defects really stand out so I can go back and work them some more. The various joints take different amounts of time to finish. A simple head tube joint takes about 12 minutes from start to finish. There is lots of room to work on these and easy access so it goes really fast if the brazing is clean. The bottom bracket can take a solid 40 minutes or so because some of the areas are harder to get at and are concave in nature.

That whole 'masterclass' by Dave Kirk is like gold dust. I've never cut a tube or lit a torch, but I hope to learn to build frames some day; until then I'll just have to learn what I can. I've learned a lot from reading the likes of Andy, unterhausen and the rest of the builders on this forum (no point in asking questions and I can't venture any answers until I've tried it myself!), but there's no substitute for experience, so well done for trying.

Dave Kirk hardly uses any power tools (I don't think he needs to!) but this got good reports from some of the builders on VSalon just last week:

The PRR 250 ES Sanding Roller - the versatile sanding tool from Bosch.

I know framebuilders have been using Dynafiles for years but they're seriously expensive and I don't know how that ^ would compare.

JohnDThompson 04-04-15 01:17 PM


Originally Posted by kylecycler (Post 17688757)
I know framebuilders have been using Dynafiles for years but they're seriously expensive and I don't know how that ^ would compare.

Dynafiles (and die grinders) in untrained hands are a recipe for trouble. If you're in a (semi-)production environment, by all means invest in a Dynafile or die grinder. For one-off or hobbyist building, stay with the manual methods described above, and concentrate on your prep and brazing technique to minimize the need for post-braze filing.

duanedr 04-05-15 01:25 AM


Originally Posted by JohnDThompson (Post 17690131)
Dynafiles (and die grinders) in untrained hands are a recipe for trouble.

Agreed! Undercutting the tube is what you're trying to avoid and with power tools, that can happen very fast. I'm nowhere near as fast finishing my fillets as Dave is (for a couple reasons) but, it doesn't take that long by hand and for me that's all quality time in the garage alone so, why rush it?

Andrew R Stewart 04-05-15 09:11 AM

When I file down my fillets (and they need some, not being done by a master) I concentrate on the mid sections of the fillet first to avoid the edges for as long as possible. It's during the edge filing that undercutting the tube is most likely to happen. Andy.


All times are GMT -6. The time now is 09:59 PM.


Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.