# First frame build. Seat tube to BB shell is kicking my butt.



## qwkswede (Nov 13, 2012)

*First frame build. Welding failures. And pushing through to the end.*

I'm working through my first frame build. I am assembling a 29er with a 17.5" seat tube, "medium" frame. The tube set I bought from Nova Cycles, and I'm tig welding everything. I'm an OK welder, but don't have much experience with tubing under 1mm thickness. So this is a challenge.

I bought a larger diameter double butted seat tube so that I could run a dropper post. And to make the length work for my smaller size, I needed to trim down the butted sections at both ends. I trimmed so much that I'm working with a thinner part of the seat tube against the bottom bracket shell. Even at 20 amps and pulsing 33% I'm having trouble burning holes through the thin seat tube sections. My mitering and welding on other joints are coming out OK for a first attempt. But this uber thin to thick union is kicking my butt.

Any suggestions? Did I choose the wrong seat tube?


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## Eric Malcolm (Dec 18, 2011)

Hi

Firstly, welcome, and its good to hear from you.

Nova supplies a Columbus 31.6 mm dropper stem in 560 length with 200mm of BB end able to be cut. This will give you plenty of meat at this end @ 0.9 wall.

You may need to start over and use your example above for practise welding.

Eric


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## TrailMaker (Sep 16, 2007)

Indeed;

That is a critical joint in terms of getting a straight frame. Strength is an issue as well, and you'd rather have plenty of wall thickness there. In order to use that tube for your purpose, you should have cut the top butt short and done an externally silvered sleeve. But no matter, as Eric has given you a direction. There are guys that are really good at finding/cataloging tubes for purposes in their heads. I'm definitely not one of them, but Eric is!

Have fun!


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## Walt (Jan 23, 2004)

Yep, wrong tube, start over. Never never weld to anything but the thick portions of a butted tube unless you are reinforcing somehow (ie a sleeve/lug/etc).

-Walt


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## qwkswede (Nov 13, 2012)

Thanks for the info guys. I have been readin here over the last year as I rounded up the gear and courage to finally start my own project. Great resource.

I did manage to get the seat tube welded to the BB, but when I dropped the down tube in place, and started the weld the overlap area 1/2" up the length of the seat tube I was hitting the very thin portion. Pow, instant hole... I think I'll finish welding up the front triangle on this one, get some more practice, and hang it up on the wall for decoration. I have been learning alot already... 

Tell me more about the sleeve. Can I buy these sleeves? Or do I make my own from straight gauge chromoly? I might need to give this some thought for frame #1.5.

I don't want to fix the BB strength issue and end up welding into the thin tubing at the top tube junction.


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## qwkswede (Nov 13, 2012)

Is this the seat tube we are talking about?

LIFE OVER SIZED ROAD SEAT TUBE for Dropper or OS Road

Dia bottom x Dia Top x Wall W1/W2/W3xL = 32.7mm/33.5mm x 0.9/0.5/0.9 x 560mm

Butts: B1/B2 = 80mm/300mm

Tapers: T1/T2 =40mm/40mm

Columbus PN# ZON113560001

----------------
So with the large end pointing down to the BB, then I use a 30.9 post. With the large end pointing up the I.D. is 31.7mm . Is that close enough for a 31.6 post O.D.? 

And what happens i the post needs to insert farther down the tube than the 80mm large end taper? It gets stuck I imagine?

I had the original Nova post with the small end up, to avoid the bind with a seatpost sliding down the narrowing taper.


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## Walt (Jan 23, 2004)

Just get the True Temper 31.6 tube. It's perfect for beginners and impossible to screw up with. Part number is VERUSSTMAG.

True Temper 34.9 mm (1.375") Seat Tubes for Bicycle Frame Building : Henry James Custom Made Parts For Bicycle Frame Builders and Bike Enthusiasts

-Walt


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## qwkswede (Nov 13, 2012)

Does that size need a shim on the I.D. to accept the 31.6 post? Or do you use the thick 1.6mm butted section pointed up to accept the post. That would give 31.7 ID. That sounds pretty close for a 31.6 post diameter.


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## Walt (Jan 23, 2004)

Thick portion takes 31.6 post.

-W


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## TrailMaker (Sep 16, 2007)

Hey;

I've been a hammerhead and always just used straight gauge tube for my frames. Yeh... bought too much the first time! ST shims work, but they suck butt after a while, aesthetically and... spiritually. I just did a collar on my latest frame. Fun project, lathe work and all, but... I think next time even I may punt and buy an ST that is already sized so that one of the zillion sizes of post fits it with no more screwing around.


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## Eric Malcolm (Dec 18, 2011)

Walt has given a better option for you.

For you to understand tubing, if you use an External Butt Seat Tube, the outer Dia is enlarged at the external section, the centre ID remains constant, so no problems with how far you can slide the seat stem down the tube. Do not cut any length off this end. To fit for size, you cut from the BB end, so in choosing your seat tube, select a tube that has a long butt as it will allow for a lot of shortening, like the example I gave. I used this example because you are purchasing from Nova, and yes the tube you describe is correct. But Walt does offer the better solution if you're OK with going to another supplier.

Eric

Oh, and I forgot to add, Sleeving is done only at the TT Joint, not off the BB end. You sleeve only to increase wall thickness for clamping the seat stem and as a multiple joint area, adds strength to a stressed area if the tube wall is to thin.


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## qwkswede (Nov 13, 2012)

*The frame that never was.*

I spent another 80 bucks and ordered some new tubes for the front triangle including the Truetemper tube Walt showed for the seat tube. But in the meantime I finished welding on this one to get a feel for the difficult spots. I already knew about the cluster at the bottom bracket. But I might make some other adjustments after this exercise. Please critique. I know I have some learning to do here, I'm not entirely happy with the outcome.

Downtube to bottom bracket. . .








Problem area around the seat tube. Including some piled up hole repairs and actual holes.








Top tube/seat tube...









And had a little trouble at the head tube too. Might have been a bit too close to the edge, or just need to back way down on the heat here.


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## Walt (Jan 23, 2004)

Great start!

I would do some more practice on the TIG and maybe play with your shielding/flow/settings. What you have there is not going to last very long.

-Walt


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## life behind bars (May 24, 2014)

Are you welding in quadrants? Moving around, making short welds to limit the heat introduced into each fitment?


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## qwkswede (Nov 13, 2012)

Nothing too planned for the weld order. But I was welding 1/4 the way around a joint in one shot then allowing time to cool and reposition. But I didn't move to another joint. I typically just flipped the frame 180 and welded the other side of the same joint. Then I would concentrate on the leftover gaps at the top and bottom of the same joint with similar pause between. 

The weld color doesn't seem as shiny as I would expect. Certainly not like welding stainless. But maybe that is just the nature of 4130. I'm using ER70S2 filler, and trying a mix of regular cups and gas lenses and the outcome seems about the same.


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## Walt (Jan 23, 2004)

You definitely have oxidization happening, and plenty of it. You may need to work on technique or play more with cup size/flow/etc. Regardless, all sort of gray oxidized crud is not a good thing.

-Walt


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## thedudeman (Nov 10, 2006)

Don't know if you saw this thread, but my welds started off at about the same place. The generous folks in this forum helped me make a lifelong dream (frame build) a reality and I can't thank them enough! 
There are a lot of valuable tips from them in here helping me to improve my welds as I put in the practice time:
http://forums.mtbr.com/frame-buildi...d-cad-drawing-would-love-feedback-900417.html


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## qwkswede (Nov 13, 2012)

Hey dudeman, 
I have read parts of that thread a while ago. Its long! But I just read the first couple pages again and it was a good review the welding parst with some context of doing my own now. 

I have some more scraps here now. I'll be doing some bench time before my next tube set arrives. I have to say that seeing the tight positions at the seat tube/down tube area and underneath side of the downtube at the head tube was valuable. I noticed you were struggling there too. Those tight inside corners are tough to get right, and something I didn't practice when I was welding scraps on my bench. I'll do some simulations before I get back to the frame.


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## qwkswede (Nov 13, 2012)

*Practice practice practice.*

I bought some 1" x .035" wall chromoly to practice on. My practice tee is much easier to work around than some of the tight joints on the real frame. I'll make some sharper angles in the coming days too.

But here is tonight's practice.

Just a quick freehand job on the mitering. I had tighter fit on my real ones. But I figured some small gaps might teach me something. This tubing had mill scale that I sanded off at the joints.









I welded in very short stretches, lots of starts and stops to allow cooling. I think there are 8 segments in this joint. 









I'm not sure what happend on this side, some black specs and pits.









This looks a bit nasty inside: 









I tried a new pulse rate at 2hz, and max amps about 90. I was trying to use a bit more heat and move faster this time. Trying to find a rythm with the pulse.

And reflow of the ugly pitted weld:


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## TrailMaker (Sep 16, 2007)

Hey;

You have contamination there, causing the cratering. I can't tell if the inside of the tubes was similarly prepped as the outside. You may be pulling impurities from inside the tube into the weld puddle. This can also happen from too much heat cooking the materials and "blowing them out", but that is speculation since it appears you have brushed the joint after welding, before taking these pics. I do note that the outer edge of the HAZ is quite a ways up the ST. I've also found that fusing two pieces together without filler can do this, but stops when filler is added. Some fillers are also more prone to this than others. 

You can definitely waste a lot of time prepping/cleaning too much, but the right amount is indeed necessary. It's a process.


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## qwkswede (Nov 13, 2012)

Thanks for the feedback, 
I didn't touch the welds after welding. I was trying to leave them pristine for inspection. I prepped the tubes by sanding the exterior to remove the gray mill scale. However I did NOT grind the internal mill scale, just gave the interior a cleaning before welding to remove some internal greasiness. This was not a cycling tube set, just some standard .035" CrMo. I'll try to get a sanding roll on the interior for the next one. I wonder if i was sucking something from the inside.

About the HAZ being so far away, I assume that's from too much heat into the joint? Either amperage too high, or taking too much time to complete the joint. I was trying to minimize that by stopping to cool things frequently, not sure that is really helping though. I'll weld the next one with some more continuous longer segments and see how that goes.


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## Walt (Jan 23, 2004)

Turn the pulser off for now and run ~50-60 amps. Start with just a tack. If that's not shiny and nice, you have some kind of contamination problem. If the tack is shiny/good, then weld some short runs and see what you get. You are certainly using too much heat but you should still be able to get shiny/non oxidized welds.

I'd also swap to the biggest cup that will fit your torch and stick your tungsten out more. 

-Walt


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## qwkswede (Nov 13, 2012)

I have never used the pulser before this project. But it seems to help on the thin material. I will go back to standard DCEN tonight and see what I get.

That's the biggest cup I have for now. #10 and a large gas lens. I stepped up to that just for this practice session. Previously using a smaller "medium" lens with #8 cup when I welded on the bicycle parts above. I'll see if I can round up something even larger.


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## qwkswede (Nov 13, 2012)

Should I try something like this?


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## Evil4bc (Apr 13, 2004)

Toxic cup !
ToxicFab - ToxicFab #14 cup kit


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## afwalker (Apr 26, 2012)

Nice monster/toxic cups May only need a 10/12 gas lens, flow the argon 15. You have too much heat it looks like, wide HAZ, gray/haze weld/dreaded burn through. Use a sharp point on the tungstun, consider argon back-purge and heatsinks to help control heat. short cycles and lower amps.
And really this is a good start! Welds look as good as my first ones, you can only get better 
andy walker
www.flickr.com/photos/afwalker50
Walker Bicycle Company | | Walker Bicycle Company


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## adarn (Aug 11, 2009)

What are you doing to clean the tubes? sand(mill scale)/scotchbrite and then dish soap + water with scotch brite and then denatured alcohol to finish is good. Also just miter up like 50 practice joints and weld away! good luck.


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## qwkswede (Nov 13, 2012)

I prepped the outside like you said but probably left the inside too dirty. I wiped it, but didn't send or brush the coating inside. After welding I noticed there was some interior mill scale too, and maybe even extrusion grease stuff. The butted bicycle tubing is so much cleaner than raw 4130.

More practice coming up.



adarn said:


> What are you doing to clean the tubes? sand(mill scale)/scotchbrite and then dish soap + water with scotch brite and then denatured alcohol to finish is good. Also just miter up like 50 practice joints and weld away! good luck.


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## shlammed (May 19, 2015)

practice is key.


IMO, since your hand feeding the weld (not on a turntable) turn pulser off and use constant heat.
You will need a lot less of it than 90A! for 0.035" tubing your probably in the 30a-35amp range under the pedal.

What size filler are you using?

Are you trying to "weave" the weld? (Don't do that) If your not, just a little more torch time and you will steady up big time.


This whole steel welding thing works better with clean tubes, but with what you just posted you should be getting better results. its definitely just practice you need.


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## shlammed (May 19, 2015)

Noticing here that your tungsten has turned a nice shade of blue too... You don't have enough post flow going on. your tungsten should be shielded until its cool enough not to majorly change color.

While its post flowing, leave the torch over what you just welded until the post stops.... its a bit annoying to do if your starting and stopping a lot, but you shouldn't need to start and stop that often.

In the next welding bits, get your fitup as good as you can. it makes all the difference and practicing on joints different than what you want good results on wont help.

Matt

Check my instagram for my progress over the last year or 2.
www.instagram.com/hellafabrication


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## qwkswede (Nov 13, 2012)

*More practice. No pulsing.*

I mitered 2 joints, and did some more practice tonight.

Not sure if these are better, but slightly less grey with the extra argon flow maybe?

# Changes: No pulsing, set the max amps at 55, and was running about 1/2 pedal after the start. I also cranked up the argon flow a bit.

I am noticing that welding two tubes of the same diameter, the edges (long part of the tube) that wrap around are very sensitive to burning off and keyholing. I didn't notice this when the butt is a smaller tube against a larger tube like the head tube or BB. But the more the fishmouth wraps around the other tube, the tougher that area is to weld. So I got these welded, but I had to do some weaving and circling to fill a small keyhole on one or two of those longer lips with tonight's practice.

Pictures from the album.

Cleaned thoroughly









Welded









Old pulse welded joint on the left. Tonights weld with no pulsing. No wire brushing or cleaning here either.









Practice joint #2 With an angle for practice.


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## shlammed (May 19, 2015)

getting better! good work.

Im not sure how other framebuilders deal with the wings of the mitre being thin... but what you need to do is take a file and grind them back just a little so that your welding into something at least a little substantial and when you get to welding them, angle your torch more into the solid tube that isn't mitred.

it takes some practice because too much angle into the thicker tube and your weld will just be a bead on top of the larger tube and not enough torch angle and you will keep blowing through the mitres. I might also suggest putting a small tack weld with as little filler as possible at 10 and 2 (oclock) of the longest part of the mitre before wrapping in weld. this puts more of the heat into the larger tube-in my experience. be careful because too big of a tack and it will show through your top weld.

*

1. what do you have your POST FLOW set at on your welder/do you have that option?

2. What size of filler rod are you using? 0.035", 0.045" or 1/16"?
*


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## qwkswede (Nov 13, 2012)

I'll get a look at my postflow timer this weekend when I get back to it. I would guess 3-5 second range right now. I do hold the torch there until it clicks off. Normally. Sometime I forget. What sounds reasonable? 10 seconds?

Filler is .035" er70s2. With a copper coating on the outside. I haven't been scrubbing that, just using it as is.


----edit---
My shipment with new seat tube showed up today, I also got some weldmold 880 .045" diameter from Henry James. I'll give that a try this weekend.


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## TrailMaker (Sep 16, 2007)

Hey;

Use the lowest voltage that gives you the heat penetration and ductility in the puddle that you need. The lower the voltage setting, the more sensitive the control is because you are pedaling less voltage over a wider range of pedal motion. In other words, at low voltage the pedal travel is longer for less voltage change, -vs a high voltage hair trigger that goes from zero to stupid in no pedal travel at all.

You will like the 880 a lot more than the generic S2. I was using Harris S2, and far too thick at that (3/32"). The Weldmold flows in nice and soft, and matching the rod gauge to the tube is very helpful.

The "ears' of the nested tube are indeed tricky. You need to roll your torch angle away from them a bit, more toward perpendiculr to the joint, and try to put more heat into the parent tube. Practice.


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## qwkswede (Nov 13, 2012)

I'm taking some advice and trying things. 
- bumped up my post flow timer to 7 seconds. The tungsten is staying shiny now. 
- This round I used miter templates and ended up with really tight fit up, especially on the "wings" of the joint.
- still using er70-s2 for now.
- I still make an occaisional mistake. I dipped the tungsten once on this one and stuck it to the joint. And I made a small keyhole when trying to get a tack installed in an area I couldn't see very well. I'd like to be a bit more confident that I won't do that on the real tubing. I think a couple more joints and I'll be mentally ready to get back to building the bike. The tubing is here and tempting me.

Bottom weld is the new one here.


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## qwkswede (Nov 13, 2012)

I do have a Tee and extra hose from my argon tank. Should I set up some back purge to keep the back side of the joints from looking so crispy?


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## Walt (Jan 23, 2004)

Leave the actual bike tubing in the box for another month. You need another 50 practice joints if you want it to last. 

Yes, backpurge it. It won't dramatically improve anything but it'll save you a bunch of hassle when you go to ream/face/chase things on an actual frame.

-Walt


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## qwkswede (Nov 13, 2012)

Alright. Patience. . . Advice taken.

Maybe I should work on a setup to cut miters with my drill press and hole saws so I can get faster and nicer fitting joints. I'm doing OK by hand, but it takes an hour per miter the way I'm doing it.



Walt said:


> Leave the actual bike tubing in the box for another month. You need another 50 practice joints if you want it to last.
> 
> Yes, backpurge it. It won't dramatically improve anything but it'll save you a bunch of hassle when you go to ream/face/chase things on an actual frame.
> 
> -Walt


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## TrailMaker (Sep 16, 2007)

Hey;

Getting better. Always focus your heat more to the parent tube and you will have less trouble with blowouts. I wouldn't be in a big hurry to mechanize everything. I think that people that do miss out on many of the foundational lessons that rudimentary procedures teach one in spades. Mechanization is for those who enjoy that style for its own sake, who are in a hurry, or making their living and increasing profits. Working the old way satisfies more in many instances.


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## dr.welby (Jan 6, 2004)

qwkswede said:


> I'm doing OK by hand, but it takes an hour per miter the way I'm doing it.


Half-round files cut to common fractional sizes. Since you don't need to hit an exact miter angle for practice, you should be able to file a joint in under 5 minutes.


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## qwkswede (Nov 13, 2012)

dr.welby said:


> Half-round files cut to common fractional sizes. Since you don't need to hit an exact miter angle for practice, you should be able to file a joint in under 5 minutes.


Hah. Obviously I need more practice. I don't see how you could file a joint in 5 minutes at this point in my skills development.

I am taking advice here and trying things. I appreciate the comments. I put down the dremel tool for final fitting last night and used an 8" half-round file I picked up at Homedepot for $10. It was slow going, but the control is nice. I think I was ready to weld after about 30-40 minutes work on that joint. It isn't a race, i don't feel I need to move fast at this point. But I do want to put wheels on this machine sometime soon and take it for a spin.

--Question--
Should I be drilling vent holes somewhere in the tube joints? 
I ask because last night I was welding on a sealed chamber and making my best welds yet. And suddenly I got a crazy unexpected blowout with the puddle spraying outward that I could only explain by pressure inside the tube. It is possibe that it was some contaminant on the inside that I didn't get clean enough, but seemed like pressure buildup. Maybe my miters are getting tight enough now that I'm having a problem where I didn't before.

I ride a custom steel CX bike that is TIG welded. It doesn't have any holes into the BB area from the main or rear triangle tubes. The builder told me he likes that because of the harsh wet conditions we race in and he is trying to keep water out of the inside of the tubes.


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## dr.welby (Jan 6, 2004)

qwkswede said:


> Hah. Obviously I need more practice. I don't see how you could file a joint in 5 minutes at this point in my skills development.... I put down the dremel tool for final fitting last night and used an 8" half-round file I picked up at Homedepot for $10.


The 8" is too small a radius so you have to manually get the shape right.

Get a 10" 2nd cut half-round file. It cuts a 1 1/8" diameter, so you get an instant miter for that size tubing. The file doesn't cut over a full 180 degrees so you'll have to learn how to twist the file to get deeper miters, but the shape of the file will be doing most of the work for you.

12" files cut 1 1/4" diameter

14" files cut 1 1/2"


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## qwkswede (Nov 13, 2012)

I'll have to place an order from somewhere online. 8" was all I could find locally.



dr.welby said:


> The 8" is too small a radius so you have to manually get the shape right.
> 
> Get a 10" 2nd cut half-round file. It cuts a 1 1/8" diameter, so you get an instant miter for that size tubing. The file doesn't cut over a full 180 degrees so you'll have to learn how to twist the file to get deeper miters, but the shape of the file will be doing most of the work for you.
> 
> ...


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## dr.welby (Jan 6, 2004)

Also, If you rough cut the miter with a hacksaw or aircraft snips before you file you can do it even faster.


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## afwalker (Apr 26, 2012)

I vent the main triangle but not the cs/st. With slotted dropouts there is less blowout from sealed gasses, if you do hooded drops you might try a vent hole, maybe someone can comment. Good pickup on noting the differences in the joint, the sides are a T joint and the "feathers" are a lap joint. Just being aware of the difference and use a bit less heat on the lap joint. Keep up the practice, there will be breakthroughs, plateaus and setbacks but keep at it. I made a pile of practice joints before trying a frame, it is time well spent. With just the perfect amount of heat the weld will be bright, not dull gray, you may even hear the puddle sing to you
wax on, wax off


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## qwkswede (Nov 13, 2012)

*More practice, keeping the nice tubing in the box.*

- I bought a 10" half-round to add to my 8". It work *****en on my 1.25"(31.9mm) practice tubing. My sanding roll on the Dremel was faster. But this does make nice smooth curves, and the gaps are smaller than ever now.

- The Monster-Nozzle showed up too. After playing with different gas flow rates I think I have this thing dialed in. I'm running just about 20cfh on my regulator/orifice style flow control. I never measured at the torch, so that might not be accurate. Regardless, I love the longer tungsten stick out. I have never tig welded with the point so far out. Probably 1" now. I have some stainless car headers I need to fab soon too. And the collectors will be SWEET with a torch setup like this, if I can remember how to weld schedule 10 after messing with so much thin tubing.

I still need more days of practice, but i'm getting comfortable and i'm not blatantly destroying nice tubing now.

Pictures:
*Mitered tubing, clean and ready. Old crummy weld on left.*









*Tacked in 4 spots.*









*Welded er70-s2. You can see a gray spot where I knocked the part over and had to set the torch down in a hurry.*









*Practice joint 2. First bead with weldmold 880. Interesting colors.*


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## shlammed (May 19, 2015)

Looking good! tight fitup will help for sure.


For practice, it might make sense to do like the welding tips guy on youtube says and do some practice passes without actually lighting the torch.... like to move the torch over the path you want to weld while maintaining the torch angle. I still do this on occasion if there is something hard to reach or if its in a really acute angled part.


With small tubes like bike tubing your not really moving horizontally ever, your more rotating your wrist to keep the weld going with proper torch angle. once you get this totally dialed, it will click.

M


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## qwkswede (Nov 13, 2012)

*Practice near edges.*

I have been doing some practice torch motions. But I'm really uncoordinated with my fingers. You should see my lousy hand writing. I can't write, draw, or weld a straight line.

Here is tonights practice with weldmold 880. I have a question and some thoughts about the gray areas near the open tube edges. I intentionally cut the T section of the joint short this time to simulate welding the top tube to the head tube with only 5-10mm to the edge of the head tube. l obviously overheated here and did not have any back purge to help cover the back side. I was originally using 95mm for the head tube. How much room should I leave between the weld and tube edge?


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## qwkswede (Nov 13, 2012)

*Brazing bits.*

I'm still working on my miter shaping and welding, buut realized I should plan ahead for adding brazed on bits.

What is the easy way to add water bottle bosses? Should I drill and braze those before assembling the downtube and seat tube into the frame fixture?

I have some brazing rod and flux on hand. And I should probably do some practice on my scrap pile before bringing a flame near my precious butted tubing.

Should I buy a bit of silver solder to work at lower temperature for installing these items?


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## dr.welby (Jan 6, 2004)

You'll want to drill them before you tack the frame since there's some locations a drill won't fit inside the triangle.

As for brazing, it's easier to do finish work on a single tube. One could argue that the heating of the tube for the bosses will change it's alignment by some small amount and you're better off getting that out of the way earlier in the process. But realistically it's not going to make a big difference.

Silver is nice for the small stuff but with the price difference you might as well try the brass you have and see how it goes.


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## Walt (Jan 23, 2004)

I'd just get an ounce of 56% from Henry James along with a little flux. For a $35-40 investment you'll be set for brazeons for a LONG time, and being able to silver braze is going to be a useful skill in the future.

Agree with Welby - you can drill and install the bosses first, or you can drill first and then install after the frame is done. The amount of heat is not going to have any meaningful effect on alignment but in general why not just get the bosses on first and be done with it? I guess if you have a 90 degree drill attachment you could also do everything at the end but why?

-Walt


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## qwkswede (Nov 13, 2012)

Drilled and brazed some threaded bosses on the downtube










Then put that tube into my jig and proceeded to weld up a front triangle.










The welding went OK, but still a struggle in a few places. That downtube - seattube tight angle is tough to weld down into the throat. All my practice helped somewhat. But only for the easy welds. The tight places were tough. I welded with alot of tungsten stickout and just went for it.

----------------------------------
Now for the rear triangle. I suspect this will be tougher than the front triangle.


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## qwkswede (Nov 13, 2012)

Slow Progress. I finally figured out a basic rear triangle fixture and that got me moving again.

_Rear dummy axle holder_









_I had some trouble making the drawings match the Nova 29W chain stays, and it looked too tight, so I made my best measurements and started cutting tubing. I am not using the Cad tool correctly I'm sure. Problem is related to the shape of the animated crankset in the picture. It is not the same as my XT crank._









_Chain Stays In!_









_Bottom bracket convergence._


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## qwkswede (Nov 13, 2012)

*Back to the build..*

I had to do some other projects in the garage this last month. And racing CX every week too. The fall is busy. But I got the rear triangle assembled and tacked this week. I installed a wheel and everything looks straight. But I really don't like the looks of the wise chain stays. I have a crank coming. I need to assemble and see how it looks with parts. Otherwise I'm cutting these out and getting some chain stays with milder bends.


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## qwkswede (Nov 13, 2012)

*Summarizing...*

This is how bike #1 ended up. I'm waiting for some good dry weather to really ride it. I'd like to make sure I'm done with metal work before I send it to the powder coat shop. Open questions are about more bracing in the rear triangle, and maybe more cable/hose holders on the tubes so that I can run a rear derailleur.

I have lots to learn still. But the process was enjoyable. I'm already looking forward to #2. I'll start a thread for that. I need some suggestions.

The biggest mistake, that I used some brute force to make work. The chain stays were way too wide, and don't match the seat stay width at all. I had to do some serious dimpling with a clamp and round object to get chain ring clearance. I have an idea about how to model that better before cutting tubing next time. 








Parts installed, ready for riding. 23lbs finished weight. Surprisingly light feeling.








The snowy maiden voyage! It rides like a bike!


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## dr.welby (Jan 6, 2004)

There's a saying around here - "your frame's not finished until you tighten your last crankarm bolt."


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