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I have a Summit Freestyle that needs a new seat mast. the part simply broke off unevenly about 1/4 to 1/2 inch above the frame. I got it that way and I want it to be like it is supposed to be.

I sanded the seat post stump as even and level as possible.

I am using 4130 tubbing 1" od with .058 wall to make the replacement part.
I also got the next size up in case I decide to make a gusset for reinforcement

Next, I cut a piece to length slightly over sized.

Machining the ends to make the piece perfectly square.

Bling! Bling! · 2010-09-29 5:44pm

I tested the part on the seat post and it seems the wall is too thick and it won't slide over the post. So one more time to the lathe for machining.

So there it is, the seat mast replacement ready for the final machining and tested for fit.

Next is the slot and relief hole. I used a milling machine for this.

Tested the fit once again

And the finished part ready to be welded

nycet3 · 2010-09-29 6:14pm

awesome. I love this kind of thread.

Flatlandfox · 2010-09-29 6:37pm

WELD DONE!!!!

carbons2k · 2010-09-29 8:15pm

dam i need one done on a haro I have. The mast was broken and welded by ray charles! looks good!

mustang69250 · 2010-09-29 8:29pm

wow excellent job... the right tools sure do help on this one... great how to do post!!!!

butlerglc · 2010-09-29 8:53pm

Totally professional!!! You should give the frame doc a run for his $$$$$$$

Shodan · 2010-09-29 9:16pm

Welding it yourself too?

Bling! Bling! · 2010-09-30 4:18pm

Yes I welded it today, here are the pics.

I made an aluminum plug for a few reasons:
1. It will keep the part in place and aligned during welding.
2. Disipates heat.
3. Will catch any unwanted pass through welding without getting welded to the piece. I don't plan on doing that, but just in case.
4. It will give me a solid clamping surface.

Plug in place and how it's supposed to work inside the seat post.

The secret to a good solid weld is tight fitting parts and clean metal.

Clamped in place, it's not going anywhere.

And the welding. I am using an inverter powered TIG welder that is very good for welding aluminum and simply awesome for welding steel. I use a feature called pulse that will help me disperse the welding pool, and if the fitting is tight enough and the metal thin enough, there is really no need for filler rod. I just melted both parts together. I had to use a bit of filler rod where there were a couple of holes made by the previous owner with a hack saw. But other than that, I got a clean low profile weld.

And the final test wiht the seat post in.

kegger · 2010-09-30 5:22pm

WOAH!!
are you god, cuz that was a miracle

Last edited by kegger (2010-09-30 5:23pm)

Shodan · 2010-09-30 5:32pm

I just wanted to know if you were going to weld it yourself.

:DNice work!

That70'sGuy · 2010-09-30 6:33pm

dude youre my hero ....awesome work

Duke 01 · 2010-09-30 6:41pm

Awesome work and machining of the thin tube.
Props to you!

Duke.

Bling! Bling! · 2010-09-30 6:51pm

Thank you guys!
I got into this hobby because I like to restore stuff, and since I like freestyle bikes... perfect combination.
Now begins the real work. I am going to restore this bike. Not very popular, but I like it.

GTalltheway · 2010-09-30 6:55pm

that was one of the most amazing fixes and saves I've seen..

Jon1971 · 2010-10-01 8:25am

Very, very cool repair! Excellent job

hemi455 · 2010-10-01 8:35am

That Sir... is amazing.

Haro-83 · 2010-10-01 9:27am

would make great sticky thread.

skirkpat · 2010-10-01 10:25am

Very nice work, I have spent a few years in a machine shop, and it looks like you can get the job done. I would venture to say that there is a strong niche' market here for those types of repairs. Good luck with the bike...

Leatherman · 2010-10-01 12:22pm

Seeing this post makes me regret skipping shop class to go riding.

Great job.

joe6187 · 2010-10-01 2:02pm

Killer restore skill
Cool!
Joe

lou · 2010-10-14 4:16pm

Quetzal · 2010-10-14 4:44pm

Awesome dude!

jlewis · 2010-10-14 7:44pm

Amazing! Great stuff!

"The Shape" · 2010-10-16 3:23am

where would i get stock 4130 tubing. I have a Free Agent Freeflight that needs all platforms replaced, since I cut them all off as a kid? I also want to lengthen a KHE frame. Had thought about just hacking up an old frame for tubing.

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Repairing a broken seat mast

Repairing a broken seat mast

#2 2010-09-29 5:44pm

Re: Repairing a broken seat mast

#3 2010-09-29 6:14pm

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#4 2010-09-29 6:37pm

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#5 2010-09-29 8:15pm

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#8 2010-09-29 9:16pm

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#25 2010-10-16 3:23am

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