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Xyphota's bicycle related projects

Xyphota

Ultra Member
Thanks! I did have two small blow-throughs which were on the non-mitered tube, heatsink backed, so that was a bit surprising lol. The tacks on my head tube made a small riser on the backside of the tube. I tried filing them down a bit before welding, but maybe they were still proud enough that they prevented the heatsink from getting contact with the rest of the tube.
 

PeterT

Ultra Member
Premium Member
Nice. Remind us what welder you have. Looks like a CK torch in the background? Did you get this specific one for this kind of metal gauge, or same with it & its just suitable?
 

Xyphota

Ultra Member
This is a #9 air-cooled torch with a flex head and superflex cable/hose. When you make cylindrical welds, you have to rotate the torch as you move around your circumference, and the superflex hose and smaller (lighter) #9 torch body make this a bit easier todo while keeping the torch steady. If the torch is heavy or if the hose is stiff, my fingers get tired very quickly and they start spasming a bit so its really hard to keep the tungsten close to the puddle without dipping. Any tig welder will work, but pulse functionality will make it easier on thin walled stuff.

I'm also using a CK 'gas saver' kit which lets you stick the tungsten out a bit farther so everything is a bit easier to see.
 

Rauce

Ultra Member
I use a 17 since I do aluminum too and need the extra amperage range. Flex neck is ideal, same with pulse but you could manage without.

A gas lens to get extra stick out is pretty important on some joints where you need access.

@Xyphota what pulse settings do you use? I only recently got the hang of the low frequency pulse technique a lot of framebuilders use. 1-2pps and the almost 0 background current.
 

Xyphota

Ultra Member
I’m mostly copying Don Ferris’ settings. He uses a 2Hz pulse which is a bit quicker than my skills, so I’ve dialed it back to 1.3 hz

 

Xyphota

Ultra Member
Remounted the frame in the v-blocks and spent probably an hour trying to get it realigned while compensating for the warp in my table top. Finished up my dummy axles. The notch is to keep the slot in the bicycle dropouts aligned. I hand filed the radius around the thread hole because I didn't have a good way to mount it to my rotary table. Perhaps a dividing head is in order...

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The post-in-a-plate that located the bottom bracket previously is now paired with this block thingy which holds the dummy axle. The dropouts I'm using are in the BikeCAD library, so again its pretty easy to line the parts up over top of the drawing with the right angle to get everything positioned. Next step is to miter the chainstays and then weld/braze them in.
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Xyphota

Ultra Member
I was hoping to spend like 16 hours in the shop this weekend, and then I ended up getting like 2. That's how every weekend goes it seems haha.

Small update today; Here is more functionality I built into my mitering jig. I wanted to make it as modular as possible to keep the space requirements down. Here it is configured to hold the chain stays for cutting the bottom bracket miter. These additions are mostly a straight rip-off of this tool: https://farrframeworks.com/farr-tools/chainstay-miter-fixture which would be $1200+ CAD shipped to Canada.

This was my first time using it in this configuration, and I mostly liked it. There are a few things I'd like to tweak to make it easier to use. But one feature I really like is that at the mitering end, there is a 3D printed black triangle piece (eventually to be made out of steel) that is used to keep the tube grippers centered about the centerplane of the tool. You can slide the triangle forwards and backwards to adjust the spacing and as long as the cylindrical stand-offs below the gripper touch the triangle when tightened down, you know they are equi-distant from the centerline. I left all the wing-nut screws full length as I didn't know what to trim them too before using them.

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Xyphota

Ultra Member
Wow that website is incredible! Thank you so much for sharing, there are some amazing visuals in there. The more I scrolled the more impressed I was by how many topics they covered. The reaction forces visual about the spokes in a bicycle wheel is the best I've seen, I'll reference that the next time I hear an argument about whether or not a bicycle wheel hangs or stands on its spokes >:^).
 

StevSmar

(Steven)
Premium Member
These welds wont be winning any awards, but I think they'll do lol.
Your welds look great to me.

Building a bicycle would be a fun project- but I’d need to get back into riding before considering it… I dream of making a knock-off of a Ice Trike recumbent…
 

Xyphota

Ultra Member
thats quite the jig, is that something you made? or bought from someplace?
I bought the actuator bits from here, but everything else is shop made!

The chainstay cutting configuration of this jig was mostly inspired by these guys:
 

phaxtris

(Ryan)
Premium Member
Premium Member
I bought the actuator bits from here, but everything else is shop made!

The chainstay cutting configuration of this jig was mostly inspired by these guys:

Nice work, and edgenuity! Save your self some bucks and ended up with a nice tool
 

Xyphota

Ultra Member
I was hoping to have this frame done by now, but I finally caught covid for the first time so that put me on my ass for a week (I've never napped so much in my life LOL). I finished up the chain stays and welded them to the frame. I am pretty proud of the welds that came out of the left chainstay. The right chain stay was a total ***** though and I blew 4 holes through it. Probably should have just cut it off and restarted. The photo below only shows the flattering angles :). The dropouts are tacked only, as they will be brazed in instead of welded.

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Next step is the seat stays. The seat stays I purchased are straight out of the box (as opposed to the pre-bent chain stays) and I needed to put a 4 degree bend in them. My tube bender has a 5" radius die and a 11" radius die for 3/4" tubing, and this tubing is ~5/8". The person I bought the bender from said he had no problem shimming 5/8" tubing with some cardboard. I did some practice bends on some dummy 5/8" x 0.028" chromoly tubing on the 5"R die and was not too happy with the results so I tried filling them with water and freezing them. The filled & frozen tubes made a near perfect bend so I felt good about trying the filling and freezing method on the proper seat stays.

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But alas the seat stays (which are also ~5/8" x 0.028") decided they did not like being cold and rather becoming part of a beautiful bicycle, they would instead prefer to live in the scrap bin. Fortunately I purchased two bicycles worth of tubing when I made my tubing order, so I restarted with the second set, and elected to use the 11"R die instead with no water/freezing. The bend only needed to be 4 degrees so the radius of the die ended up being almost entirely inconsequential for this bend. Shimming the tube with cardboard only on the 11"R die worked out just fine.

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After bending both seat stays, I put them in my mitering jig and cut in the seat tube miter. This setup was a bit janky as the mitering jig is mostly unsupported, so I will address this for the next frame build.

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However, it seems today was just an unlucky day because one of the seat stays was not secure enough and ended up rotating on me mid-cut, resulting in a pretty nasty gouge.

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This is not the end of the world as I can make it shorter with another cut and just reposition where the seat tube will end up meeting the seat tube. Functionally this makes no difference, but it means my frame will look a bit different than what I was hoping for.

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The cope came out pretty much bang on, so at least the mitering setup works pretty well lol.

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Six O Two

(Marco)
The welds as pictured look awesome - I'd certainly be happy with that result. Bike tube bending seems like such a black art to me. It's very hard to find good information on how to accomplish it, and it seems to take a lot of trial and error! I'm only on bike #2, and I think I'll be using pre-bent tubes for a little bit...
 
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