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-   -   Practice tubes NAHBS (http://www.bikeforums.net/framebuilders/800668-practice-tubes-nahbs.html)

veryredbike 02-24-12 04:04 AM

Practice tubes NAHBS
 
Anyone going to NAHBS have some steel tubes or lugs that aren't suitable for building? I could use some practice materials and would love to free up your shelf space ;-) Let me know what you'd want for it, I can't spare a ton, but I can spare a bit.

Jim

jimn 02-28-12 03:35 PM

I'm in Brooklyn and have a ton of tube scraps. Didn't this forum used to post location?

Cynikal 02-28-12 10:23 PM

I'd also be interested in some scrap to play with. PM me and let me know what you are wanting for some.

veryredbike 02-29-12 12:56 AM

I'm in San Francisco, what would you want for them?

Jim

unterhausen 02-29-12 06:48 AM

Quote:

Originally Posted by jimn (Post 13910150)
Didn't this forum used to post location?

you have to add it to your profile or it doesn't show anything

Andrew R Stewart 02-29-12 10:36 AM

The practice tubes and sleeves that me and my student are using are sourced from Aircraft Spruce. $66 is getting us 18' of differing diameters. We make practice fillets and "lugs" from these. At a few inches per piece you can do the math and see that there's a lot of practice for the price. Once my student shows comfort with the practice stuff he'll go to actual lugs. But by then it will really only be to get comfy with the fit up and shoreline differences and not heat control or flow through. So only an actual lug or two will be needed for his practice. Andy.

jimn 02-29-12 02:22 PM

When I'm in my shop next I'll put together some bundles of scrap and figure out what shipping will be. I'd just charge for shipping, because I like the idea of this stuff going to use.

I end up using a lot of scraps for bridges, for making temporary fixturing, for practice, and for all sorts of little things, but at this point it's gotten a bit out of hand.

brazen 02-29-12 09:43 PM

Andy, I recently purchased some 1" and 1.125" 4130 from Spruce on a recommendation for practice that I found in another thread. I've cut the 1.125" down for some "lugs", but after sanding the interior and exterior for prep, the "lugs" are too wide and slide around. What diameters have you been using for practice for your student?

On a related note, did you just pick and choose and come up with $66, or was there a cheap bundle that you got?

veryredbike 03-01-12 04:06 AM

Andy: I've been using some sleeves (per your suggestion), and still have a bit of scrap left, but I'm running out. I live right near NAHBS and thought I might snag extra stuff, since I keep hearing that builders have piles of scraps lying around ;-)

Jimn: That'd be amazing. I'll make sure it goes to good use. I've got a lot of ideas for little non-structural things to make while I practice. My fake bicycle company is Curmudgeon Bicycles, so maybe I'll make some fancy fillet brazed cane-handles with decorative cutouts.

Andrew R Stewart 03-01-12 08:24 AM

1 Attachment(s)
http://bikeforums.net/attachment.php...hmentid=239559http://bikeforums.net/attachment.php...hmentid=239559http://bikeforums.net/attachment.php...hmentid=239559http://bikeforums.net/attachment.php...hmentid=239559Sizes to make practice lugs. The outer tube (the "lug") needs to be .125" larger in diameter then the inner tube and have a .058 wall. So a 1.250" tube with a .058" wall slips over a 1.125" tube. The fit is a slide fit. After light sanding or dremelling to clean i find the fit is just about perfect for brass/bronze. My sleeves are cut to resemble a head lug with one end square and the other cut at a diagonal. I hold it all together with a nail/pin. See attached photo.

squirtdad 03-01-12 01:15 PM

Quote:

Originally Posted by veryredbike (Post 13917081)
snip I live right near NAHBS and thought I might snag extra stuff, since I keep hearing that builders have piles of scraps lying around ;-)

snip .

as builders have to for the most part pack up and ship from some place else.... i would hazard a guess that they won't be bringing extra pounds of old tubing and lugs :)

here is an example from kirk http://www.kirkframeworks.com/blog/2...with-the-show/ He looks to have some really nice bikes there

I wish could go...family comittments preclude

brazen 03-01-12 03:41 PM

Andy, is the brazer pulling the filler through those lugs or brazing both sides?

Andrew R Stewart 03-01-12 06:56 PM

brazen- The brazer is I. I work the joint, with the torch, as I see the heat levels needing attention. I tend to raze with a smaller tip and heat content then more experienced so only portions of the joint are up to brazing temp at any one time. For the practice joint pictured (too many times, getting the hang of this forum's processes) that means I heat overall as best possible then focus on the long side of the sleeve. I draw the filler through this long side first and move on to either side sometimes adding more filler, sometimes flowing excess filler from the shore line. I try to work around the sleeve alternating from side to side to even out the heat between each side. I end up on the short side and flow whatever filler is still hanging out along the shoreline or add the least amount of filler I can to flow the band fully.

In an actual lug brazing this sequence is still followed but modified to have the flow through occur between the two tubes, across the tube contact point. But the lug's long axis is still the first section I try to flow through then go the the sides and end up on the band in front of the head tube. Andy.

jimn 03-12-12 12:51 PM

Pm me your address, anyone who wants this assortment of scraps. All pieces are about 8-10" long, and range from 7/8 to 1.5". It includes some .058 which will slip-fit over the next 1/8" size smaller. That is, 1-1/8 will slip over 1". I would just ask that you pay for shipping. If you are in Brooklyn you can pick it up (and more!) Thursday or Friday.

http://farm8.staticflickr.com/7068/6...d7805669a0.jpg
Cromoly tubes by jimn, on Flickr

http://farm8.staticflickr.com/7187/6...d07b0d3ce2.jpg
cromoly tubes of different thicknesses and diameters by jimn, on Flickr

unterhausen 03-12-12 03:19 PM

Quote:

Originally Posted by Andrew R Stewart (Post 13920128)
brazen- The brazer is I. I work the joint, with the torch, as I see the heat levels needing attention. I tend to raze with a smaller tip and heat content then more experienced so only portions of the joint are up to brazing temp at any one time. For the practice joint pictured (too many times, getting the hang of this forum's processes) that means I heat overall as best possible then focus on the long side of the sleeve. I draw the filler through this long side first and move on to either side sometimes adding more filler, sometimes flowing excess filler from the shore line. I try to work around the sleeve alternating from side to side to even out the heat between each side. I end up on the short side and flow whatever filler is still hanging out along the shoreline or add the least amount of filler I can to flow the band fully.

In an actual lug brazing this sequence is still followed but modified to have the flow through occur between the two tubes, across the tube contact point. But the lug's long axis is still the first section I try to flow through then go the the sides and end up on the band in front of the head tube. Andy.

You should have started out with the short answer :) I assume I'm reading right and you are pulling the filler through from one side.


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