Repair question - removing damaged top and down tubes

[cudak888]

I'm repairing a lugged steel Basso with bent/kinked/damaged top and down tubes (front end accident, from what I can deduce).

Anyway, I had heard that it is advised NOT to torch out damaged tubes if they were originally brazed with brass, mainly due to the the weakining of the tubes from multiple re-heating, and that it is better to cut the tube off close to the lug, and grind the excess metal off.

Well, my dremel proves that grinding with improper tools can be a royal pain in the neck - and frankly, I can't see how someone can grind out the entirety of the tube far back in the corners without damaging the lug.

My question is if should continue this nonsense and grind the tube reminants out, or if I should just heat the damn piece and do it the easy way.

All suggestions appreciated - I'm new to framebuilding, but have been reading up on the subject - lugged steel construction, primarily (or exclusively, you could say).

Take care,

-Kurt

(P.S.: Looking for some replacement 531/SL tubing; 1" top-t., 1-1/8" down-t.; to replace the damaged tubes currently on the frame)

[ultraman6970]

Heat it and take it off... be carefull anyways because if you apply too much heat the lugs will be ovearheated (duh) and youl get something called crystalization (not so sure of the word ok?) in the lugs.

Once the Bass turned to liquid (or is softed) u have to pull the tube out. what U can do to play safe is to replace the lugs also (because of what I said before.) and since you are re doing half of the bike, replace the front also heheh after all u have to bass it again right? :)

My next solution is to bend the tubes again untill you get the bike right, and how the tubes have a dents for sure, put some brass in the dent and u are done (all depends of the damage anyways).


UM.

[Nessism]

Maybe one of the pros will chime in here but I've had poor results trying to get the tubes apart on repairs - particularly with brass. The main problem is that it's very difficult to get the entire area up to temp at the same time without overheating the crap out of the whole mess. My suggestion is to stay the course and keep grinding, a cheap air type die grinder works okay and the bits are way cheaper than dremmel type since the arbor is 1/4". Or, cut grooves into the tube stub and peal it out in pieces after heating up each area.

Good luck. BTW, it's almost easier to build a complete front triangle than repair a damaged one - my opinion of course.

[Dave Moulton]

If you don’t have a frame jig you may want to replace one tube at a time. Cut the down tube in two places leaving about eight inches of tube sticking out of the BB and head tube.

Use a large soft oxyacetylene flame, a rose bud tip is ideal. Heat the lug area uniformly; you will have to keep the flame moving constantly from one side to the other or as you heat one side the other will cool.

When the whole area is glowing a bright orange red, twist the tube out using a pair of pliers. When the temperature is right the tube will slide out easily so don’t force it or you will break the lug.

Allow to cool then correct the head angle by bending the old top tube. Miter the down tube and spring the frame apart to get it into place. You will probably need to clean the inside of the lug and BB with a Dremel or similar tool to get the tube to slide in easily.

Check the head angle and head tube seat tube alignment; then fully braze. Next remove and replace the top tube in exactly the same way.

If you have a frame jig then it is often easier to replace the top and down tubes along with a new head tube and two new head lugs.

[cudak888]

Hello fellows,

I appriciate all the replies. Looks like I'll go back to grinding the tube out - see how far I get with that. Wish me luck, I'll need it.

Incedentally though, would a case of the lugs being pinned to the tubing during the frame's construction hamper the removal of the tubes? With the help of some fellows at one of the local machine shops, we heated the downtube-headtube joint pretty much as Dave suggested (and a few ways Dave would NOT suggest :o ), with absolutely no luck - the tubes refused to seperate, even though they were heated properly (and perhaps, too much).

Again, thanks for all your help.

-Kurt

P.S.: Empathetic thanks to Dave, who, in one post, explained and answered a good many additional questions of mine that I have attempted, without luck, to locate online.

[potus]

My suggestion is to stay the course and keep grinding, a cheap air type die grinder works okay and the bits are way cheaper than dremmel type since the arbor is 1/4".

I agree, my $10 harbor freight die grinder works way better than it's price tag suggests. and get some of these: http://www.grizzly.com/products/h6100 they work better and last longer than your standard dremel bits.