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Thread: Tig Steel from zero

  1. #21
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    Default Re: Tig Steel from zero

    Quote Originally Posted by cfrisia View Post
    sorry for hijacking...
    No sorry at all!! Thanks for sharing your techniques.

    In fact I hope anyone would feel free to give their word about anything, either about different ways of ding same things, or as happened with the rods, suggestions or pointing out things that might be wrong. The idea is trying to make the post as some kind of complete guide to build a steel frame with a tig welding perspective, step by step.

    Cheers
    Aimar Fraga Angoitia
    www.amarobikes.com

  2. #22
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    Default Re: Tig Steel from zero

    Quote Originally Posted by sebaudet View Post
    It's very interesting, many thanks, but I don't see how you make that with precision (perhaps a pic ?) :
    I think both cfrisia and Steve has explained good ways of finding those centerlines (probably much better than mines), but just in case, here is a couple o pictures of how I've been doing that so far:
    Once a first "random" line is marked, I take the "half-circumference-paper" of the corresponding measure (42mm diameter in this case) and mark the opposite centerline:
    5papel.jpg
    5papel2.jpg
    Then, just locate the tube on the flat surface, tight it and mark with the scraber.
    6linea2.jpg

    Quote Originally Posted by steve garro View Post
    Take a set of 1/2 blocks on the table & rest the tube on them - draw a line on either side using the blocks as guides.
    Hold the tube down, rotate one block 90*, mark, repeat with the other one.
    - Garro.
    Steve, this wold be definetly the best way, but all tube blocks I have are not exactly half diameter, so they'll be able to make full "tight" once attached. At least the paragon ones are this way, kind of missing 1mm height in the middle so to catch the tube properly, so the mid lines of the tube blocks are not exactly the middle of the tube, just 1mm "below". Anyway, what they're helpful for is to be used as line to follow with the scraber once you've located the starting points, probably much better and easy than using directly the flat surface as I've shown in the pictures.
    Just for the record, what tube blocks do you actually have? any suggestions?

    Cheers
    Aimar Fraga Angoitia
    www.amarobikes.com

  3. #23
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    Default Re: Tig Steel from zero

    Does you have an easy, reliable way of finding the centerline of a bent tube? I've been having issues with keeping s-bent stays in phase with each other. I can get them pretty close, however it's rather time consuming. Just curious if you have any tips.

    Sorry for the hijack, but I'm watching this thread with great interest as I'm now just learning to tig frames.
     

  4. #24
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    Default Re: Tig Steel from zero

    I guess you'd need machined blocks like Garro suggested. My method is for people without equipment like that. If you plan to do a lot of frames, I'd suggest to have blocks with oval settings machined.

    regards
    Cheap, durable, light: choose two.

  5. #25
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    Default Re: Tig Steel from zero

    Well, here we go with another "chapter".

    But more than chapter II this more likely be chapter 0, why? well, Yesterday I realized I did not show the previous work of checking and tube preparation, wich should be done before any "real" work with the tubes. Also, I'll try to show some things that can make the process a bit easier.

    First of all, we should make sure our tubes are straight. Yes, might sound strange but things are not always as they should... it's pretty uncommon, but you should always be aware and make sure things are perfect or then all the centerlines and the like would be an useless thing as tube will then take it's own decissions (if it's disaligned, then will take this disalignment to the frame). Sometimes, this disalignment is not too big and you can then decide to make the centerline in a specific face of the tube were will not take the disalignment into the frame, for example if tube is disaligned in one way, we can keep this way on the "longitudinal" axis, and leave the lateral alignmend sound. As I'm really bad explaining things, here is a picture of what could happen (It's a pretty extreme case I keep as a "souvenir" from the first time I had this issue, really clarifying):
    1disalign2.jpg

    Ok, once we have checked all out tubes are sound enough, the chainstays/seatstays are symmetric, etc, then we can proceed to mark the butted areas and manufacturer cutting sections, etc, so we know how to place the tube properly and avoid weak points. You can use your own signs, I just draw three lines, a spoted one for the cutting area limit, a long continuous line for the end of "thick" butt and a shorter continuous line for the beginning of thin butted area. Something like that:
    2marcar.jpg

    After all this, we have pretty much our tubes checked and ready for working on them.

    Then, as useful things to have at your workbench, I do keep a set of "dummy" tubes for checking the saw/file process while mitering the tubes, so you can leave quiet and relaxed the actual tubes you'll use on the frame. The dummy tubes you'll need are basically one for each measure of HT and ST you're using on yuor frames, and also a BB shell. In my case that's not too much as I always use 31,7mm seat tube and just two different HT types, 46,3mm OD for semi-integrated and 37mm OD for the standard one. Then I always use same BB shell (sylva 39,1mm OD). So, all in one it's just 4 tubes and the usual dummy axles (120-130-135). Here is the actual set (the 135mm dummy axle is being used at this point in a mtb frame, so not at the picture ;)
    3dummies.jpg

    Also, for all those "dummy" tubes, good to mark clearly centerlines on them, so you'll check all the phasing on the mitering process. HT and ST is pretty easy, you just need one random straight line (longitudinal). And then for the BB you need a cross, one line each direction, so you'll be able to check perfect phase on all situations. Normally would be enough with just the longitudinal one, but the other line can help doing things a bit more accurate. I've marked in this picture the non-longitudinal line, as it's not very visible...
    4bb.jpg

    I think that's pretty much all, but please feel all free to say your own words. I've not gone about heatsinks as this will be later seen once we get welding. And even some old skool guys will not even use them, so can even be considered as "extra" (although I think it's quite a good and recommended extra).

    About Tools, that's what I use (Osrry I did not take pictures, as I've thought of that once writing this new chapter..):
    -Files (1 big half round, 1 big round, 1 medium half round, 1 small half round, 1 small round)
    -Saw (I recommend highest tpi as possible for smoother cut, mine is 24tpi and goes nicely)
    -Sandpaper (1 fine grain and 1 medium grain)
    -Alcohol for cleaning tubes, rod, etc
    -Cotton rags for cleaning tubes, etc
    -Tube blocks (Paragon for 28,6 31,7 35 44 tubes and home made wood ones for 38 and 42 tubes)
    -A radio! you need a good and faithful company...

    Sure, many more things (jig, tig machine, alignment table, etc), but those would need pictures and detailed explanations wich will be better seen further on the process.

    That's all for today, will try to make next chapter as soon as possible, but can't promise anything too fast. I'll try to find some spare times here and there so to do it properly with pictures and so on.

    Cheers
    Aimar Fraga Angoitia
    www.amarobikes.com

  6. #26
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    Default Re: Tig Steel from zero

    Just a fast comment on the 309-312-316 tig rod discussed previously, I've been today with someone who's really known on this questions and basically told me few things I think might be useful to complete the already said.

    As a first statement (probably to make me feel a bit less worried), he guaranteed me there's no problem at all with the 316L rods, because the possible ferrite on the bead due to the different nickel proportions on 316-309 and 312, it's deffinetly an issue with thick base materials welded outdoors, but not so with such thin base material as bicycle tubes and welded inside of a "climate controled" workshop. Also, about the better mechanic properties of 312 against 316, it's not so critical in a weld as it's fatigue or stress free shape, so failures will arrive due to lack of penetration, weld bead stressfull shape, overheat, etc. It's like the classic beginner test of trying to break a weld and always being the tube wich breaks first, almost never the weld, and sure it can be very dramatic and cool to show on a blog/flickr, but this is not at all a reliable way of seeing if this weld is sound, as failure will not come due to the mechanical properties of the weld, but due to fatigue.

    Other part of the question, about using stainless or mild-steel rods, again not much differences in "figures", but as stainless rods are somehow "easier" to flow (at least for me and some others), this implies the bead will be a bit better for leaving the bead free from stress. Some welders feel more confortable with mild-steel rods, in wich case that question would not apply. As happens with the machine/pulse settings, each person is a different world.

    Once all this is said, and even if he told me 316L is fine, I think I would be pretty dumb if not taking in consideration many other builders thought on that and going to the 312L rod as it costs almost the same and even if it's more theoretical than practical, there're serious figures and numbers explained so to think it would be a better option. I say this just to make clear I'm not trying to say anything about someone being right or wrong, just to give some more light on something I did not have perfectly clear and might be of any help to anyone.


    Finally, and that's soemthing really surprised me and made me rethink many previously stated questions and procedures, we had a long talk about heat imput. till now I always had the "rule" of never doing second passes on steel as to keep material as free from heat as possible, but the thing is heat is not acumulative, so if that possible second pass is done once the material is cold, it would not have any added heat. Keeping this in mind, gives a chance to go later on over some weld you're not happy about (maybe not enough penetration, sharp edge, etc), without adding absolute value of heat, instead of maybe staying and extra second in the first pass, wich will increase the absolute heat input. I don't know if I'm explaining more or less the question, I hope it makes some sense.

    Well, the talk has been quite long hours and pretty interesting and clarifying aspects, I just wanted to share some of the general ideas I thought might be of interest as in some cases are not what I thought before.

    Cheers

    (Next chapter will be downtube mitering, hopefully some pictures ready on monday)
    Aimar Fraga Angoitia
    www.amarobikes.com

  7. #27
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    Default Re: Tig Steel from zero

    Hola,

    Here is another mini chapter, monday I managed to cover some parts till camera went off again (yes, you can imagine how good it's!)

    Again, before going into the chapet, I would like to remind that this is not some kind of "how things should be done" tutorial, but just "how things can be done". Anyone will have their own tricks and ways to do same tasks, this is just a sample on how it ended up working for me, although always learning from both own experience and other builders shared experiences. Anyone feel free to give their words on this post, sure.

    As a general overview, we'll first do all the miterings, then weld st-bb, then all braze ons, then weld front triangle, then chain stays, then seat stays and finally bridges and brake mounts (if applied). Of course with the respective alignment checks and facing/reamer as needed.

    Ok, so once we've done the st-bb, it's time for mitering the dt-tt. Pretty much all said about mitering the ST applies for rest of miterings, although each tube has their own ways. In case someone has never gone through mitering and every step would be needed, I will include some more shots on the cuts&file.
    We'll do the same procedure as previously explained by marking our tube sections (butted areas, cut section limit, etc) and center lines. Once all ready, we place the tube on the vise and make two raw cuts with the saw, keeping always in mind all our frame measures and being VERY conservative, leaving pretty longer than needed so to have material to play with (you can work on a longer tube but there's no return from a too short cut tube). The more experience you get with the files, the more close to final length you can go for, but if you're still not sure on the process and need essay/errors, much better to go long. I do usually cut about 20mm longer and begin with the files from there. TRy to make the cuts with the center line references so the final cut will be as centered and close to desired "fishmouth" as possible, if in doubts, always check durign the cut in case you're going out of phase. Here are some pictures of the sawing raw cuts:
    Attachment 52553
    Attachment 52554
    Attachment 52555
    I do like to begin with the DT-BB sompound miter area, and first of all just make a simple miter of DT-BB wihtout the ST interference. So all you need to do is an easy square match as did before with the st-bb. So final result should look something like:
    Attachment 52557
    And we check align and phase as we did in first chapter (centerlines, square, etc), as it's ending in the BB shell, better if check the 4 centerlines at our dummy bb shell:
    Attachment 52558
    Attachment 52559
    Once the "simple" miter is done, we go for the compound one, just using the centerline as reference for your file and begin taking material off till it matches according to the frame drawing, for doing so you can use the wonderful and simple tool of an angle protractor, so it would be something like this (don't worry about the already welded st-bb on the picture, we'll do it later on other chapter, so think of it as if it was not welded yet, it was weld when the battery was dead):
    Attachment 52560
    Attachment 52561
    Attachment 52562
    Just in case, about angles/measures and how to decide cuts and lengths, etc, I do use a frame drawing where apart from usual geometries figures, I use as reference the miter-to-miter distances (both top and bottom) and angles between tubes. It looks like.
    Attachment 52563
    Ok, once bottom part of DT is done, time for the DT-HT area, wich will be just same procedure as all miters we have done so far, first saw cut, then file and reach the final point where tube meets all our needs on align, phase, angle, etc, just a couple of views:
    Attachment 52566
    Attachment 52567
    So there we go with the dt finished.
    Attachment 52568
    It's pretty important that all tubes seats easy and without any forces or the like, not just dt but all of them. Any force or unnatural position will later show up once we weld it, so if you can see any gaps on the miters, or you need to "push" with yoru hands so the tube fits properly, it means something is wrong, maybe phase, or anyother detail, so if this happens would be time to measure all again and check where have we missed up something. If centerlines are properly marked, should be pretty easy to make a sound miter, but never give anything for sure, triple check is good help.

    Ok, time for the TT. Again, usual process as before, centerlines, etc. I do like to mark the top front face of the tube as once the miters are done, it can help quite a lot not to get confused on what goes where. Normally is visually obvious, but sometimes, like non sloping top tubes with similar ht-st tube diameters, can get a bit more time to find out. So marking this front-top face of the tube will make things easier to find. Here is marked as "TT":
    Attachment 52569
    Will not go again on the centerlines and phases, etc, but will show something that could be wrongly done even if you check the centerlines with your dummy tubes. I've done it too dramatic so it's easy to see the mistake in the picture, but idea is to check it even if "visually" does seem to be symmetric, sometimes it's not, wich would mean that the tube would not be straightly phased once located on the jig. How could this be possibel if we check centerlines? because it could happen that your dummy tube's centerline is aligned with your mitered tube centerline, yes, but dummy tube might not be perfectly "vertical" on it, I mean it could be rotated a little bit, so it's centerline is a bit out of the 0º. I'm pretty bad on the explanation, I know... I hope it makes a bit of sense. Anyway, with this pictures is very easy to see the possibel problem:
    Attachment 52570
    And how it should actually be:
    Attachment 52571
    And here is front triangle tubes presented:
    19ft.jpg
    About tube preparation, making them as clean and smooth as possible will help out for good welding, and also making it much easier. Apart from chapters one cleaning pictures, I think might be good to show some general preparation once the miter is good. First of all with a small file pass over the edges, both out and inside, gently, so to make all smooth and avoiding sharp edges or pointed curves. Also the inside must be clean from grease or even paint (some tube manufacturers do have paint at some areas).
    15lim1.jpg
    16lim2.jpg
    Once the gentle small file is done, just finish it with sandpaper, again both outside and inside:
    17lij1.jpg
    18lij2.jpg

    Ok, that's all for today. I've done some pictures of the chainstay process but camera went off batteries again, so will go for a new chapter later on as I think is better to make full chapter each time rather than leave it half way..

    Cheers
    Aimar Fraga Angoitia
    www.amarobikes.com

  8. #28
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    Default Re: Tig Steel from zero

    Hi all, sorry for taking so long on the chapters updating but 2013 is being quite hard on health :(

    Anyway, here we go with next steps, this time we'll take care of the rest of miterings, beginning with chainstays.

    First of all we check both chainstays do have same bend/curve, as sometimes there're slight differences and it's better to find the closest pair to each other. Once we got the pared chainstays, we take one of them and measure an approximate first cut depending on our wheel choice, tyre width, chainstay length, chainline, etc. Once this first cut is done, we begin filing at the BB shell end. As we're going to do it entirely by file and hand without jigs or hole saws, it's important to triple check always all our squareness and perpendicularity on the shell. I try to use half round files with an external diameter (on the round area) similar to the "back-tube" (in this case the bb shell), this makes easier to make a nice miter. Following picture shows how to attack the chainstay with the file to ensure a good phase on it:
    cs1.jpg

    Once we have done some file work, we check it's all tight with our dummy shell:
    cs2.jpg

    Then we check if the angle is good or if we need to file more one of the sides so to have the chainstay properly aligned with our dropouts:
    cs3.jpg

    Once we've end the miter of the bb-shell end part, and it's properly "aligned" with dropouts, we use a marker so to know an approximate cut area on the dropout side. And then proceed with cutting, being always cautious and leaving enough play (I prefer playing chicken rather than loosing a chainstay for being too short):
    cs4.jpg

    Then we go with the file, again trying to attack it as perpendicular as possible so to make a right phase with the bb shell end. As this is pretty eyeballing, it's good to take the rear axle about 10mm backwards, so we have 10mm longer chainstay length, and we begin checking from there. Once we have the phase between both ends properly done (will take some essay-error), we can just keep filing the dropout end with this reference till we match the right chainstay length. If you locate the seatstay and file properly and make sure it's all good, the phase will happen pretty easily with just a couple of goes.
    cs5.jpg
    cs6.jpg

    Now that we have one chainstay mitered, we "copy" it to the other one, so we place both together and use the marker for the raw cuts:
    cs7.jpg

    And repeating same procedure as we have done with the previous chainstay, we should reach something like:
    cs8.jpg

    Will follow with seatsays in a new message
    Aimar Fraga Angoitia
    www.amarobikes.com

  9. #29
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    Default Re: Tig Steel from zero

    So, here we follow with seatstays.

    It's probably the most difficult one to do without help of hole saws and jigs, but with a bit of practice you'll end up doing it pretty naturally and with quite accurate result. Just remember to triple check always everything the first times, and then time and practice will make it much more easier.

    Procedure is almost the same as we've done with chainstays, just a bit more difficult to do it as seat tube miter end is a bit more complicated than the bb shell one, but the main idea is the same.

    First we take one seatstay and make some calculations for the raw cuts:
    ss1.jpg

    Then begin with the file the usual process (again, makes a big difference on easiness if you use a file with a round diamenter as similar as the back tube as possible, in this case the seat tube diameter)
    ss2.jpg

    We use our dummy seat tube section for checking, and would look something similar to this:
    ss3.jpg
    ss4.jpg

    Till we are happy with the angle and general seatstay position:
    ss5.jpg

    Then we mark the raw cut line according to the dropout intersection:
    ss6.jpg

    And proceed with the mitering keeping both eyes in the proper phase between both ends. This time we're not able to do the trick of having longer chainstay length, but we can begin having a first mitering with a bit higher seatstay-seattube intersection (5mm for example), and then check phasing, once it' good we keep filing so the intersection goes tot he right place. Till we got the seatstay proplery placed:
    ss7.jpg

    Once we have a seatstay done, we go for the "copy" procedure, beginning with the top end:
    ss8.jpg
    ss9.jpg
    ss10.jpg

    Checking that both of them are actually at the same place, plane, angle, etc:
    ss11.jpg

    Once we're happy with the seat tube area, we go for the dropout end, as we did before (raw cut ,etc):
    ss12.jpg

    And there you go:
    ss13.jpg

    No we have pretty much all miterings done:
    fr.jpg

    Next steps are all the braze ons, the seat tube cut, and begin with some welding.

    Cheers
    Aimar Fraga Angoitia
    www.amarobikes.com

  10. #30
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    Default Re: Tig Steel from zero

    Hi all

    Some more updating on the process. This time will go on braze ons.

    It's highly encouraged to do braze ons when tubes are still "independent" and not creating a close structure, mainly because:
    -Heat produced distortions will not affect to the triangle structure, as tubes will increase-decrease without restrictions at their ends. (same reason why jig should obly be used for tacking, not welding)
    -Cleaning the flux left inside of tubes is much more easy as you have fully access to the inside of the tube.

    So, once we have gone through the miters, it's the most recommended time to go for braze ons. You can actually do them by brazing or welding. If you're into titanium or even stainless steel you will do all of them by tig welding (for sure in titanium, most likely with stainless steel). But as in this case we're talking about carbon steel frames, you can choose either of them. In my opinion, brazing is probably a better option, specially when using the ultrathin tubes as Spirit, etc, where fusion welding can get too close to the material limits. Also, if you like to use "decorative" braze ons, tig welding makes much more difficult to left those parts untouched, as tig "melts" both rod and parent material.
    I've ended up doing all braze ons with low temperature brazing (40-50% silver rod 1mm), which it's "easy" to do and keeps such thin tubes as Spirit well below overheating.
    I would not go too much into brazing as there's already loads of info about it and I'm not either a great expert on the subject (I just do braze ons), here is pretty much how it all would look like:
    First of all, we mark the holes for bottle cage bosses, here is where the centerline we marked in the beginning comes quite handy:
    1brb.jpg
    1brb2.jpg

    Then we proceed with the standard brazing procedure (flux, etc)
    1brflux.jpg
    1bz1.jpg
    1bz2.jpg

    In those two pictures you can see already mentioned issue with "hidden" flux inside of tube, which should be removed or might create future rusting problems.
    1bzrflux2.jpg
    1bzrflux3.jpg

    Rest of braze ons depends a bit on type of frame (mtb, road, etc), but not too much to think about, just place them in place and braze. Of course, you might have chose to go for the fusion welding procedure, in which case you can sometimes even do it without rod, pure fusion wellding, just take care of using the braze-on as "bed" where to take material from and then move the melting puddle into the thin tube, always with very low amperage and cautious so to avoid making holes, etc. It might look something like
    1bzrfusion.jpg

    So, now we have all tubes mitered and with their respective braze ons. Time to begin welding the front triangle.
    Aimar Fraga Angoitia
    www.amarobikes.com

  11. #31
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    Default Re: Tig Steel from zero

    Before going into actual front triangle, let's have a fast talk about general tig welding questions. As this is not intended as a TIG welding course, just will cover some of the main things to keep in mind, then it's all about practicing and learning from both your own experiences and outer references as instructors/classes/videos/pictures/books, etc, it's a never ending process where everyday you learn something. Even in this wonderful forum are some incredibly clarifying posts about tig welds which can help you out learning the whys and hows things happen. That's pretty much the key question, understanding the puddle and welding so to decide on what's going on (too much heat, slow speed, rods, etc).

    We can use either carbon steel rod or stainless steel rods, each one has different feeling (stainless seems to flow better but tends to be stickier into the puddle) and it will just depend on your own likes. I do prefer stainless steel rod, in 1mm diameter, as feels really smooth and 1mm size is good balance for average needs (speed/heat, penetration, size, etc). I've used 309L and 316L but I've been advised by velocipede wisdom to change into 312L as has much better properties on the austenitic puddle % and hot cracking, so definitely recommendation should be 312L (or also 880T weldmod in the us). In the picture you can see a 312L (clear) and a OKTIGROD 13.12 ("brown")
    2rods.jpg

    Stainless steel rod will create a weld with more blue colors, so if you're welding with ER70/ER80 steel rods do not worry if your welds are not having same blue range as many of the talented ones (carl, brent, tyler, etc). As visual samples, here is first a inbox rod weld and second an ER70 rod weld
    2tig312.jpg
    2tig70.jpg

    In either case, one of the main indicators on the welds "health" is both the shiny color all around the bead and surounds. Any dead-matt or grey colors and most likely you're overcooking the weld (either slow travel speed or too high amp). Here is a couple samples appeared on the salon some time agot with bit overcooked welds (in different grades) as indicated on the matt grey colors:
    http://3.bp.blogspot.com/_IJzNAF8Pxf...0/bike4-09.jpg
    http://1.bp.blogspot.com/_IJzNAF8Pxf...0/Headtube.jpg

    Another one of the main things to keep in mind are material cleaningness and gas coverage. You can never clean enough, so it's always good to be pretty sick on that and clean both the tubes and the tig rod. Also, use a clean detachable cotton glove on your rod feeding hand (I do use thin ones over the leather one, so kept safe from heat with always clean contact area).

    Finally, the weld geometry is extremely important for fatigue, as stress will hugely depend on the beads. Instead of trying to go for the stack dim beads (which is not good or bad by itself), main target should be to make smooth concave shape where the bead is some kind of "fillet brazed structure", trying always to make the bead as constant and equal as possible, avoiding peaks, unparalell bead sizes, craters, etc.

    About tungsten, I find best results using a gas lens with 8-10 cup, butalso important to do a proper tungsten sharpening, grinding it in the same direction as the tungsten (longitudinally) and end up with a small flat nozzle, not like a sharp cone but flatten like a truncated cone.
    2tungsten.jpg

    About machine settings, that's really impossible to specify as anyone has different preferences, each machine is different, etc, etc, it also depends a lot if you're using pulsed arc, remote pedal, tube thickness, travel speed… For example, I do have weld with two different settings (Do not take this as a reference to keep fixed, but just as a reference of a couple of settings that work fine with me):
    1,6 tungsten with 8mm cup and gas lens
    Peak Amp 70
    Bed 16
    % Pulse 48%
    Hz 50
    Gas pre 1 sec
    Gas post 2.5 sec

    Another one (same torch)
    Peak Amp 75
    Bed 22% Pulse 48%
    Hz 0,9
    Gas pre 1sec
    Gas post 2.5sec

    In both cases max amp is continuously regulated by the foot pedal depending on how the puddle goes, so the max 70amp does not necessarily reached (although will happen with BB shell, dropouts and thick ht)

    As a final consideration, it's the use of heatsinks, which is a bit up to anyone, I've seen very respected and experienced builders both using them and others not using them at all, so… I find them specially useful on the seat tube and bb shell, as they help maintaining the original shape of the tube, avoiding heat distortion, which comes quite handy when reaming as will allow not "eating" too much material from the tube. They do also make a "cheap" backpurging function as do place out the oxygen from inside. Their backside is they'll "eat" a lot of heat which might need more heat input from the torch and this has to be kept in mind so to avoid overheating the weaker side on the join (thinner tube). You can "protect" the thin tube by locating the rod over it, or simply pointing the tungsten in a closer angle to the thick er part (bb or ht), it's just a question of not forgetting heatsink will affect to the "usual" heat flow, just that. Here is a couple fo pictures of the ones I'm using, nothing too fancy, a couple of bronze halts which get bolted facing the tube.
    2wheatsink.jpg
    2wheatsinkht.jpg

    Boy, I didn't realize how many things could be explained for the whole process :o Feel free to ask any specific question and I'll try to do it better and deeper.
    Aimar Fraga Angoitia
    www.amarobikes.com

  12. #32
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    Default Re: Tig Steel from zero

    So, let's go for the front triangle welding.
    First of all we do the seat tube with bottom bracket. Place both on the jig for assuring good alignment and then tack them. I do like to make a small tack in the back side and a short root pass on the front side. The use of short root pass helps a bit on making sure the tubes will go out of the jig with true alignment. Here is both tacks out of the jig
    3bbtack.jpg
    3bbtackroot.jpg

    Then we proceed with welding them (all welds OUT OF THE JIG!!), and we should follow a sequence so to assure less distortion and maintaining alignment best. In this case it's easy as we divide the welding "ring" in 4 parts, as a clock, and then we weld in 4 sequences, for example 12-3/6-9/3-6/9-12.
    3bbweld1.jpg

    Once it's welded, we check alignment, but before doing so we do need to use the facer in case bb shell faces had distorted (which will "contaminate" the alignment read on the table)
    3bbweldreamer.jpg
    3weldstalign.jpg

    Once seat tube is welded to bb shell, I do make the seatclamp slot hole (again, previously marked centerline comes handy) as later on, with top tube welded, drill access will not be as "clean"
    4slot.jpg

    Now we have the frame main "column" done. So it's time to complete front triangle. For doing so, putting back the seat tube on the jig and I do like to tack the downtime first, alone (so not having the top tube will help on accessibility). As I did with the seat tube, I do like to make a short root pass on the bottom part of the downtube-bb shell area. For the downtube-headtube part, I do mark three small points, one on the top side, and two "lateral" ones on the bottom side, somehow as a three point star:
    5dthttack1.jpg
    5dthttack3.jpg

    Once downtube tacked, I go for the top tube, here I do not make any root passes, just a couple of small points at each end, on the same direction as the seat-tube and head-tube:
    5ttstack1.jpg
    5ttstack2.jpg
    5ttstack3.jpg

    Once all front triangle is tacked, take it out of the jig and check alignment before welding, so to double check if it's all ok (sometimes miters has not been perfect and frame will have slight disalignment once out of the jig). Depending on the alignment table read, we'll have to decide the welding sequence, so to correct (or not) any deviations:
    5wtackalignm.jpg

    So we place the triangle on the welding bench and I do like to write with a big pint marker on the tubes the sequence order (as it's a bit more complicated and longer than the seat tube one)
    6potro.jpg
    6sequence.jpg

    We weld the front triangle and then it's time to final alignment check, so again we need to be sure the bb shell has perfectly paralell faces
    7thread.jpg
    7wefacer.jpg

    And there we go for alignment check:
    7weldalign.jpg

    Once front triangle welded and aligned, time for the ss/cs (will begin a new post)
    Aimar Fraga Angoitia
    www.amarobikes.com

  13. #33
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    Default Re: Tig Steel from zero

    Ok, let's go with rear triangle

    We place our already welded/aligned front triangle on the jig
    8jig.jpg

    And proceed with the tacking. First we go with the chainstays. Procedure is pretty much the same as happened with front triangle tubes, so just tacking in the jig
    9csfustack.jpg

    Then we check alignment on the table
    9cstackdropoutalign.jpg

    And also make sure we'll be all good with tyre clearance, alignment, etc, we use onw of our dummy wheels (Good to have one rear wheel of each size)
    9cstackwheelcheck.jpg

    Once we're 100% sure it's all good, time for welding the chainstays. Once welded time to go back to the alignment table and check we have the three main points aligned (ht-st-dropouts)
    9csweldropoutalignm.jpg

    If all is good, we go back to the jig and get ready for the seatstays. As Murphy's law is universal, this being the last part of the process, it's the most difficult one (difficult angles and position). Well, no worries… ;) We make small vent hole on the dropout for gases (I did not mention it in previous "chapters" but improtant to always leave at least one hole so welding gases can scape from tube inside).
    10ssholevent.jpg

    Then, I do like to make left stay tack first, with small tacks on the dropout side, but small root pass on the inside part of the ss-st area, as this are will be less accessible once both ss are tacked.
    10sstack.jpg

    Once this elf stay is tacked, we just tack the other stay, take frame out of jig, and weld as previous steps, so here we have both triangles together
    11frame.jpg

    And time for another alignment check (this time no need to bb shell facer as bb has not received any heat)
    11framealign.jpg

    And that's all for the moment. Next chapters will go on some final touches that are not too complicated and also depends on frame type (disc brakes, bridges, seatclamp slot, facer/reamer, etc

    Regards
    Aimar Fraga Angoitia
    www.amarobikes.com

  14. #34
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    Default Re: Tig Steel from zero

    Very good reading, and educational. Thank you very much.
     

  15. #35
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    Default Re: Tig Steel from zero

    Quote Originally Posted by RCP FAB View Post
    Just my 2 cents, I'm not trying to be rude, or start any internet battles.....

    312L is the common replacement for 880T on your side of the globe. I would not use 316L, but thats just me. I would also not recommend using 316L.

    880T
    Tensile Strength - 120ksi
    Elongation - 35%

    ER312L
    Tensile Strength - 103ksi
    Yield Strength - 85ksi
    Elongation - 40%

    ER70 S2/S6
    Tensile Strength - 80ksi
    Yield Strength - 65-70ksi
    Elongation - 30%

    ER316L (when welding 316 to 316)
    Tensile Strength - 80ksi
    Yield Strength - 55ksi
    Elongation - 36%
    I hate to bump an old thread, but what type of 312 rod do you use that has 40% elongation? Most 312 rod has 20-25%.

    I've always been told by rod manufacturers that 312 has better tensile strength, whereas 309L has better elongation (in the 40% range). But if you have a source of 312 with that elongation and tensile strength, I definitely need to find some of that!

    Edit/note: I'm not recommending 309 over 312 or vice versa. I don't use either on non-stainless steels. Just wanted to be clear.
    Jared Jerome
    website.

  16. #36
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    Default Re: Tig Steel from zero

    Same method here,fast and simple.
    -Eric
    Quote Originally Posted by steve garro View Post
    Take a set of 1/2 blocks on the table & rest the tube on them - draw a line on either side using the blocks as guides.
    Hold the tube down, rotate one block 90*, mark, repeat with the other one.
    - Garro.
    Eric S. Zimmerman
    Zimmerman Bicycle works
    and Cinematography
    zimmermancamera@gmail
    check out the work here
    www.ericzimmerman.me

  17. #37
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    Jun 2013
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    Default Re: Tig Steel from zero

    hi everyone,

    I am currently building my first bike frame, and I am seeking a little incite. Up until now ive been able to find everything i needed through forums and i thank everyone for their awesome posts (this is actually my first forum post ever). Anyway here are the few questions that i have.

    1. I built a jig out of 80/20. I am wondering how most of you set up your jig. Do you usually set the jig up based on the drawings, then use the jig to check tub miters and lengths as you add the tubes into the jig. Or do you make all your miters and cuts then set the jig up as you add place each tube into it.

    2. Currently im just using a metal stainley tape measure to measure my tube lengths for my miters. This is kinda a pain and i feel like its not very accurate. Maybe a more accurate tape measure would work or some other method in general, any suggestions?

    3. Right now i have my seat tube welding to my bottom bracket. I am hoping this weekend to finish my dt and tt miters and weld those in. I have found some good info on checking for alignment of the overrall frame, sheldon brown string method. Is there a good way to check to alignment of the front triangle, without special tools, even if i can check its alignment is there anything i can really do once its fully welded.

    4. I am planning on welding all my cable routing fixtures and small parts (the brazeons), i dont have an oxy acetylene torch and no means to get one right now. does anyone foresee any big problems with this. I am guessing i want to shy away from the things middle section of the tube..

    Thanks for any input to this questions. And i apologize in advance if something was already answered and i missed it.

    Scott
     

  18. #38
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    Default Re: Tig Steel from zero

    Hi Scott

    For the jig, I guess it will depend a bit on the kind of jig you have, as there're quite a lot of sofisticated ones with all measures available and others with just the contact points ot keep your tubes in place (wich you'll have set up). In my case I do proceed as:
    1-Make the frame dawing and mark all important measures (miter to miter distance, tube angles, references from c-c, etc).
    2-Locate the bb, head tube bottom and dropout axle in their relative place according to this frame drawing.
    3-Tack bb to bb, weld, align.
    4-With dropouts, seat tube and head tube, all in place, I miter the rest of tubes with both the frame drawing and actual jig position as references. So first make the general cut/file with a couple of mm of margin (usually longer) to avoid no return points, and from there keep filing till all fits nicely and matching both frame drawing and jig position (no forced tubes, you know, famous "tube riots" band!)
    5-Tack, weld, align, etc.

    BUT, this is hwo I've got used to work, so just one way to do it, but you'll find your own way to do it depending on your own jig and how you feel comfortable and confident doing your frames, so frame by frame you'll get into your own routine.

    For measures, I do not have any high-tech stuff, just a measuring tape, a vernier gauge and an angle finder.

    About align checks, many different ways, from the usual alignment table, to some cheap and easy tools as the cyclus alignment check bars, etc. Depends on how accurate you would like to be on alignment. Muy opinion is that probably you can just go fine int he beginning with the cyclus check bar or even using your 8020 jig to see how it all fits once you've finished the frint triangle, etc. Place the bb and see how far from their place the st and ht seems to be. Again, for alignment table, as it would happen with the jig, those are useful tools, but you can also build a frame without them, just getting to know your own procedure and standards, etc.

    For the brazeons tig, it depends on the tubes you're using and the heat control you have with the torch. Obviously, if welding on 0,38mm spirit tubes you're more close to have problems with fusion weld on dt sti bosses, etc, same as would happen if you stay too long with too much amps on those thin tubes. Try to keep those braze ons within the thick butted section to void bigger problems, or even better, go for more beginning friendly tubes as zona/cromor.

    Cheers
    Aimar Fraga Angoitia
    www.amarobikes.com

  19. #39
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    Default Re: Tig Steel from zero

    Thanks for the detailed reply. Since my last message i have welded the st to the bb and mitered the ht and the dt which are now ready for tacking and welding. i noticed by just using my jig as a reference that the top of my st is about 2mm off center. is this something that i should try and fix now before i weld the rest of the front triangle. i talked to a welding expert at work and he suggested running a weld pass along one side of the bb/st weld to pull the st a little bit over. given that it is already welded i cant really foresee being able to simply bend the st over without causing damage, so the re-melt via welding seems like my best option. are there any other tricks to aligning tubes once they are already out of alignment.

    Scott
     

  20. #40
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    Default Re: Tig Steel from zero

    I start this by saying I've only ever tweaked a rear triangle a smidge (so no real frame alignment experience) but I would suggest putting a bar in the tube and as Ritchie says 'showing it who's boss' you'd be able to cold set the 2mm. Are you able to determine if the 2mm error starts at the BB or is the tube bowed slightly(!)?
    __________________________________________

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