With welding the ST and DT to each other before attaching the BB, there's gonna be that area inside that joint that not welded to the BB... Seems to be a potential to start cracks, to me.
Some are born to move the world to live their fantasies...
"the fun outweighs the suck, and the suck hasn't killed me yet." -- chasea
"Sometimes, as good as it feels to speak out, silence is the only way to rise above the morass. The high road is generally a quiet route." -- echelon_john
That's the difference between someone who does or doesn't have experience with doing it right. Anyone can build a frame, takes experience to learn to do it well.
After seeing the video, I would not definetly recommend it as a way of building a frame, but being fair I think it was not either the author's main idea, but more about showing some of the TIG welding techniques and kind of promo of their working table possibilities.
And leaving behind the specific things on framebuilding, for sure there might be interesting things to anyone with curiosity on tig welding, specially with the scenes on the puddle and rod feeding, you can always learn something from everywhere and I guess that was the idea.
Apart from that, for sure BB and ST should be welded first alone, then check alignment, face bb, and then add the DT/HT/ST, although I've seen some people as modikoso (great guy with loads of open info on his site to learn as well) who prefer adding first the rear triangle rather than the front one. Some things are pretty much "closed" and "highly recommended" to do in a very specific way, but others are up to each one.
Another thing I do not like much is the usual destructive test, as this might prove welds are really not bad ones, but would definetly say nothing about "geometrical" problems on the bead or contaminations or many other things that will only show their bills with fatigue cicles. Is a cool and very dramatic test to show, sure, but not too realistic as mechanical properties are not the key, but fatigue, and here are other things wich will ask their part. Well, just my opinion.
but, again, good you shared it as I think has interesting close-up scenes on the welding puddle and thoughts on pulse, rods, etc.
I don't think his point is to produce a how-to weld a bike frame video. Seems like he's more focused on talking about how the two rods weld.
That's how I took it, at least.
Really interesting video. Thank you for posting it Proparc.
I've been wondering about pulsing DC and what most people use.
At about 6:20 This guy is saying he has a 33% on time, 33% background time, @ 33 pulses per second...
Whats happening the other 33% of the time?
He then (8:40) mentions that he either uses an extremely low pulse rate ( 1 per second) or over 30, and nothing in between.
I just have a small Miller Diversion 180 which doesn't do pulsing DC, but I was thinking of hacking together an Arduino based digital potentiometer foot switch interface to allow me to do so.
To any of you who do use Pulsing DC, please let me know your settings, and what the foot switch controls (on your particular welder) when you are using it.
ie Does the foot switch change the duty cycle, the max amperage during ON or the amperage during the low part of the cycle?
About pulsing settings, it all depends on each one likes, material, rod, etc. In my case I do weld steel tubing in the 0,5-0,7mm range with a 1mm stainless steel rod and I have a pulse setting of 70amp peak, 22 background, 48% peak-52% background, 0,9 hz. Then with the foot pedal I control the instant amperage depending on what the welding pot asks for, etc.
Normally, the foot pedal allows you to adjust the peak amp as if it was a car's gas throttle pedal, keeping the rest of values constant (%, hz). It's pretty useful as you can control the heat to the very needs of each moment leaving your torch-hand free to hold and control it best
Those figures can be absolutely different with other people (and they'll be), including higher amps, higher hz, etc.
When the video speaks about using only very low or very high pulse HZ values, I think it's mostly due to how this affects to the puddle feeding, for example if you're going with the 1hz-ish pulse, you'll be able to feed the puddle with this "speed" having some kind of 1 feed per second, and you can use this as a metronome or the like. When using 30% or higher HZ values, then the feeding will pretty much be the same as it was no pulse at all, as the arc will have a very similar consistency as if it was "normal", then you just feed the puddle as if you're weldign with a non-pulsed arc. Probably this is more natural to oldschool welders used to the non-pulsed arc, so they'll have no changes on the procedure, but will benefit of the lower total heat input produced by the pulsed ard. If you decided to use some pulse in between, for example 10hz, the situation would be kind of annoying as the pulse would be too fast to be used as metronome, not being able to keep this rhythm (too fast for your hands) and neither being the same as a "constant" arc for "oldschool" feed, so this "inbetween" pulse speeds are more likely to disturb your puddleing rather than the slow ones (use the pulse as your puddle feeding rhytm) or the "fast" ones (just weld and puddle as if non-pulsed). I've weld both ways, with high and low HZ and only difference I could see is just how confortable are you on the feeding, as the weld result was pretty much the same in both cases (of course keeping speeds, etc, similar), just play around with different settings and choose the one you're more confortable with.
Finally, the remote pedal control can be also used as a "fake" pulse generator, when machine does not have pulse settings, you can use the pedal to create this kind of pulse, obviously only the "slow" one (1hz-ish), so you can keep lower heat input.
In the end total heat input is about amp+speed+time, and probably a very experienced welder in easy position can weld at very fast speed with higher amp, wich can create less total heat input than lower amp at lower speed. The pulse can help to keep the total heat input low with slower speeds (wich allow for better control on difficult positions, or make nicer looking beads).
well, just my 2 cents...
When I was looking at buying a welder I asked a few builders about features and Zank encouraged me to get one with a pulser. I practiced for a long time with no pulse to get get the mechanics of speed, heat control and using the filler hand before I threw other variables in. I'm regularly now using 60 pulses per second and 90 amps with the background current set pretty low(I keep it all written down in the shop.) I find the pulse agitates the puddle and I get a little better flow especially at the toe. The pulse also helps control the heat, which is especially important on the thin tube ends. My least accurate miter is usually the second miter on the DT, with pulse I have no problems putting fill across that joint. I think the extra heat control of pulse also helps joining a thicker BB or HT to a thin tube. I tried using the pulse at 1 per second and to me that was just about keeping time. I didn't get any better welds once I had worked on the basic mechanics. It's no so natural to have to use your eyes, right hand, left hand and foot at the same time. The slow pulse gave the left hand some rhythm, but with practice you should have that anyway. The old timers will tell you you should be able to weld without the features and I agree with that. Understanding what's going on has allowed me to use the features more effectively than I otherwise could have. Pulse doesn't solve any problems, you can still melt edges and burn holes pretty easily.
Im no expert, those are just the observations of somebody relatively new at welding who struggled like everyone else does until the aha moments hit.
Ps, the best gadget for me wrt to welding has been a $2.99 pair of reading glasses. Seeing is believing.
I don't wear glasses for anything else, but being able to see the fine details of the puddle with the extra magnification that the reading glasses give is a big help.
To that end, the gold tinted lenses that have been discussed here before are an excellent compliment to a cheater lens/reading glasses in obtaining the clearest view of the puddle that you can get.
What can I say, as a beginner, I can use all the help I can get...
I just want to comment that Jody's intention wasn't to make a how-to video on making a bicycle frame. The frame was simply a prop to demonstrate some thin wall welding. Bill, I understand your point of view though too. Ultimately, I'd hope that anyone looking to make a frame will do a lot more research. One thing to keep in mind though is there are a lot of mass produced bikes that do not have a full weld on the tube making full contact with the BB, whether that's the seat tube or down tube.
And +2.50 reading glasses for the win.
Thank you for the detailed replies guys.
That is exactly what I was hoping to hear. I know I should be focused on controlling the puddle, not making gadgets. I am just curious. I've been trying to smooth out my foot's pulse, but I'm no drummer, so the hand/eye/foot coordination does not come easy. Even when trying to keep it consistent and even, I'll accidentally blast it too hot on one pulse, then not enough the next, making for a bead that runs big small big small etc. Every awesome tig bike I see has robot like perfectly spaced beads, so I assume that they're being done with pulsing DC.
As far as reading glasses go, maybe I'll try that out. I've gotten pretty good results out of adjusting the lighting in my welding area so that I can see my start/stop up close (and not trigger the tint on my cheapo auto mask by reflection), so I can see how better vision would help.
If I do end up making an interface box to go between my foot switch and welder, I will post up the schematics/code. It may be a very economical upgrade to emulate a higher end welder.
PDF of the schematic of a footswitch meant for lower end Miller welders
Miller foot switch documentation (looks like the internals are all the same, just the connector differs)
Analog Devices digital potentiometer data sheet
Sorry for the total derailment, this is the only active TIG thread, even if it is suppose to be about how sweet that buildpro table is...
I've never tried a really nice auto darkening helmet myself, but I have tried a cheap one which I found to be pretty bloody awful. Since it sounds like that's what you're using currently, you might consider trying flip down passive lens helmet.
For me, it was the one variable I changed that yielded the biggest improvement (combined with 1.75 reading glasses and a #9 tinted gold lens).
You may already have read this info elsewhere, but I thought I'd throw it out there anyway.