Framebuilders - Lug prep: suggestions for mandrel?

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engo
10-31-10, 08:57 AM
Hi all,
Received tubes, lugs etc. in the mail recently, and after much reading, I'm ready to start work on my first frame. I'm interested in doing some finishing work on my lugs, and as far as I can see, using a mandrel is the best way to hold them.
I tried using a mtn bike quill stem, and it's not bad, but I'm afraid the wedge style binder will deform the lug by pushing it out-of-round.
Are my fears founded? Any other recommendations for a basement set-up? (I'm not looking to get into the business or anything, so investing in purpose made tools such as this are not in the cards.)
Looking forward to hearing some suggestions!

Neil

mudboy
10-31-10, 02:31 PM
I use a 1 1/8" steel quill stem with a couple of split shims I made from tubing scraps. I'd love to find a 1 1/4" stem for the larger tubes, but layering shims also works. This doesn't deform the lugs, but then again, I don't over-tighten.

Pete
engo
10-31-10, 07:35 PM
Many thanks for your reply, Pete. I think that the split shim is the key here.
Just before your reply, I found a clip on youtube by Tom Oswald which I believe illustrates this really well for lug cutting. I ended up doing exactly what you suggested and it works well to distribute the forces evenly around the inside of the lug.
I'm only making the one frame (so far) out of standard size road tubing, so a couple of shims and a 1" road quill should do the trick.
Again, thanks for the reply!

Neil

Live Wire
10-31-10, 08:40 PM
*sigh*
I really have been reading too many blogs these days... http://forestbikes.blogspot.com/2008/05/lug-vises.html
engo
10-31-10, 09:12 PM
Thanks for the link. This is a nice solution.

Funny....I actually got as far as cutting the scrap tubing exactly like this before I cut a shim for my quill stem, but couldn't find anything to use as an expanding plug! (I don't have a bench grinder, so I was looking for something ready-made)


*sigh*
I really have been reading too many blogs these days... http://forestbikes.blogspot.com/2008/05/lug-vises.html
tuz
11-01-10, 08:31 AM
I'm using OS quill stems and a shim for the 1-1/4 (I happened to have 1-1/4x0.058 to slip over the 1-1/8 quill).

Another trick I've heard of is to take some tubing, cut some slots like on a stem, and braze a nut on the side, so that you can thread a bolt transverse to the tube to open the slotted end.

And I would not worry too much about deforming the lug...