PithyBikes

Well, technically not my first. I did build a mtb frame in a class. It was roughly a 60 hour course but too short to cover everything. It was a great class none the less and opened my eyes to all the new stuff I needed to learn. I had two great instructors and they crammed a lot of info into those 60 hours. The course was at The Crucible in Oakland CA. The Crucible | Industrial Art Classes & Workshops in The Bay Area If you're in the area I highly recommend the course.

Now on to my build! I plan to build a fixed gear hybrid between a freestyle and track frame. The frame I'm building is a bit weird and already I see future problems I may run into with getting a larger tire on a track crank set. In addition to the build, I'm also shooting video of the whole thing. Another first for me.

About my setup; I'm in a tiny garage which means that all my equipment needs to be compact. I put everything on wheels so I can wheel it around and out of the way when it's not needed. I don't own a jig and decided to built one. I don't own any fixtures for that matter. I've got a long road ahead of me. I'm trying to spend as little as possible on this since I'm a beginner.

On to the fun stuff!
You can see my videos here:
https://www.youtube.com/channel/UCqQ...Cgviyj_E0VEy9Q

My most recent progress is attached. It's a tube press that I built with left over steel. The last pic is of the router jig I built to create my tube die. I'm very close to the point where I'll bend my first chain stays. It's very likely I'll mess that up
-Steve

Andrew R Stewart 

Do keep us informed. Not many will build a chainstay form with which to control the bending (if that's what your router is for). Andy.

Live Wire 

Nice welds on the press handle!

PithyBikes

Haha Thanks! The pic is making them look way better than in real life Today I was messing around with low frequency pulse. Man is it tricky. I was curious about it because most vids I see of pro frame welders are using this technique. Anyway, tried it today but it will take some getting used to. I'll post some pics later on this when I get closer to the welding stage.
-Steve

PithyBikes

Ok, some more progress. I routed the tube form and built pivoting angle blocks for the other side that pushes the tube. You'll also see a pic of a little widget I machined. I made this widget so that when I machined the angle blocks I could machine one side, flip it and then machine the other side at exactly the same angle. Also, you'll see that I reinforced the wood form. Here's the video of it. But pics attached if you'd rather not sit through that.

PithyBikes

Hi folks
Here are some pics of the tubes I bent with the press. I ran into some problems. First, the wood form split. Most likely because I cut a V angle rather than a circular cut. And then I ended up with a wrinkle/dent in my first bend. On the second bend I used a trick that I read on MTBR about filling the tube with water and freezing it. That ended up working great. If you'd like to see the tube being bent, here is the video.

duanedr 

Filling the tube with sand will help as well. The second one looks pretty good!

Andrew R Stewart 

The grain of the wood form should cross the groove, not run with it. Andy.

PithyBikes

Ah, that makes perfect sense! I guess that means 2x4's are a bad choice for wood I was trying to go cheap but I paid in the end.

duanedr, yes I read about that trick too. I think for that one I would have to weld on end caps? I also read that some people use brass rod inside.

duanedr 

You could probably finish off a couple bottles of wine and use the corks cut to the right sizes to plug the tubes but, yes, probably have to find some way to keep the sand in. I've never tried it so, I'm no expert on the technique. For that matter, at this point, I'm no expert on any technique other can cutting up mistakes and replacing saw blades! I'm having fun though and that counts for something.

Live Wire 

Grooves in the bending shoes need to match the desired profile of the chainstays.
The sand won't help on a tight bend, the bender just needs to be better...cerrobend is really the only filler that works reliably.

PithyBikes

duanedr - Wine corks is a cool idea. It is indeed all about the fun, mistakes and all!

Live Wire - I never heard about cerrobend until now. That stuff is off the hook. I wonder if it would leave any residue inside the tube?

TiHabanero

Can small tubes be bent using a mandrel type set up with heat applied to the tube "coaxing" it to follow the heat? I saw this done by a guy building roll cages and the bends were beautiful.

PithyBikes

TiHabanero - That is a good question that I don't know the answer to. I have never seen a small mandrel bender down to the size of say a chain stay. I don't think I've ever seen heat used to bend chainstays either.

Here's some more progress on the jig. The very beginnings. Pics attached. And video here
https://www.youtube.com/watch?v=eo81PJC0Jgk

unterhausen

I'm sure there is some nasty stuff left behind from cerrobend. There may be ways to get rid of it, info is probably out there.

I suspect bending with heat is a skill that requires some practice. I have tried it and wasn't really happy about it. I suspect there is a good reason none of the framebuilders that I am aware of bend with heat

dhwes87

This is great to follow! Really enjoying the videos.

ksisler

PB; I have best luck with rock maple for any jigging that is going to be put under a bit of pressure. Check around shops that install butcher block counter-tops for kitchens...very likely they will have bins full of scraps and cutoff bits of maple more than adequate for your purposes.

Hope that helps.
/K

ksisler

[QUOTE=....duanedr, yes I read about that trick too. I think for that one I would have to weld on end caps? I also read that some people use brass rod inside.[/QUOTE]

duanedr; If use sand filler to ease the bending (best method imho), you can just plug the ends with wooden plugs leaving about an inch extra plug sticking out the ends. Then put a piece of scrap tubing spanning the end of the stay and the wood extension. If you saw a 1/2" slot on each end of the sleeve, then a couple of well tightened hose clamps will keep the plug and thus the sand in place. After making a set of these, they will likely be re-usable for future projects.

Hope that helps
/K

PithyBikes

Loving these tips.
unterhausen, For other things though, I really want to get an acetylene torch. I can't believe I still don't own one @_@
Ksisler, I'll try the wood plug and sand for my next round of bending. I'm too impatient to wait for water to freeze haha. And I'll look for counter top shops for sure.
dhwes87, Thanks for watching! I just uploaded a new one yesterday. https://www.youtube.com/watch?v=wNUDSW1OPkg
I'll upload close up pics hopefully tonight. It's been a really busy week at work.

unterhausen

I used to use a friend's fork raking fixture that was made from a 2x6. Worked really well.

MassiveD

My fork bending jig is a 2x10 that I cut a curve on. I also ran a groove in it with a hand plane. I took a piece of metal strap, drilled a hole through it that was just the size of the fork end. Since I have some trim, I run a tap in a little, and that holds it in the strap with a bolt. The strap runs down the side of the wood, and there are several screws holding it to the wood. The more difficult issue is stopping ovalized forks from rolling, but it is doable.

If you have trim, a screw is a better way to hold back sand than a cork, there is a lot of pressure when the walls go in. I would probably tack the other end with a plate. I have trim there also. Those tacks can hold the handle on and stop rotation. The old fashioned way of bending with a cheater bar is better than a press, unless you have great tooling. The bend creeps along the blade with each degree of bend, no localization to flatten the bend.