Advice wanted on requiremnet for gussets or not on aluminum boat frames

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Hi Folks,I'll start by saying that this is my 1st boat build and my welds are getting better, but still a work in progress. Using an XMT304 and older XR15 push pull gun.  Cleaning well with wire wheel, then acetone, then a final handbrush, all used only for aluminum.Feel free to give advice on improving the welds as well, but the main question I have is whether or not I need a gusset, or overpalling section welded overtop of my butt wleds which join the each two half frames into a single frame.The frames were cut from 1/4" 5052 and I am using 5356 .047 wire and 24Volts in spray transfer. Don't know my feed rate, biut it feels good and just turned gas up to 40cfu as was running lower.  Some of these welds were at the lower gas setting.The plans (will post pic below) call for overlapping gussets, but as shown they would normally be made up of 4 pieces of flatbar (4" or 5") and therefore where each of the 4 pieces meet another, there is a gusset overlapping the butt weld.  However, I cut my half frames out of sheet material, (rather than flatbar) and left a large section where the two pieces meet, so my butt weld will be across a section about twice as wide as if it had been the 4" or 5" flatbar.  But, do I still require a overlapping section to give it more strength, or would the extra heat just take away strength or not be necessary.On 1 frame I did not have a real large cross section, so  I did weld an overlappin gusset, similar to the plans.Gusset or not, a 2" x 3/16" flatbar gets welded at 90 degees on top edge of frame s oit basically forms each frame into a pice of angle, to give its strength fore and aft. Attached Images
Reply:pic of plans howing gussets. Attached Images
Reply:I'm not a boat builder but I've done my share of designing and building, to me, plating this like they instruct would be best.  Lots of strength gained.  At bare minimum you need to weld both sides of the joint.  If it was mine, it would have the gusset to take some of the tearing force away from the end of your weld which would be the first place to crack.
Reply:If the plans call for them put them in I've built a lot of boats and we always put the gussets in those style of joints. You need to turn your wire speed up and pull back on your stops those craters will split your welds down the middle
Reply:Note- I did weld both sides of the 1/4" butt joint. Bevelled boths sides 1st with router table, tacked one side.  Flipped over, cleaned and welded other side. Flipped back over, used skill saw set to about 1/8" depth to backchip to good metal / weld and then fully welded that side (craters and all.....)  I will have to pull back and fill more, like you said Abec - funny I know to do that, just didn't seem to remember today... Can you tell me why you see that the wire speed needs t ogo up - not disagreeing, just would like to understand what to look for.  With mig on steel in short circuit, I am comfortable with knowing when the wire is too slow, burning back - or too fast, sputtering.  But in spray on aluminum, I don't know the signs - seemed to be spraying and hissing nice.   Is it more of a case that you see it needs more heat / amps and increasing wire speed will do this, with a given voltage?re: gussets, I guess my main point is that if I had used the much thinner flatbar, I would follow the plan to a tee.  But, as I have greatly increased the width at the weld section already, just wondered if it is required.  I can certainly just overlap a piece, the size of the original gusset called for in the plans, if you guys think it is necessary.Question, would you fully weld the overlapping piece(in short increments) or would you skip or stagger welds to reduce heat and HAZ zone?Last edited by Northeaster; 01-10-2014 at 08:25 PM.Reason: sp
Reply:The color of the weld and spatter at your stop show signs of to slow of travel speed and low wire speed what wire and setting are you using?   The gussets will help stiffen the weld joints Alu when welded loses about half it's strength.  With the gussets on the boats I have a tendency to fully weld them  but it really depends on the size of gusset  generally I'd say if it's under 12inchs on the longest side by the time you do start stops and stagger welds you can weld the whole thing . Hope this helpsLast edited by abec; 01-10-2014 at 08:50 PM.Reason: More info
Reply:yes, that does help - thanks for the advice!  Voltage was 24V, 1.2mm / .047 wire, but  I don't know the wire speed.  I have seen the way to measure it by pulling the trigger, counting for 6 seconds say, then measuring length that came out and multiplying by 10 for inches / minute....But, I have the run in speed set low (one of the few settings on my old feeder) so unless I make an arc, I can't use the method above as I don't get the true speed without an arc, just the slow run in speed.  I don't have it in front of me, but I don't believe that setting the run-in-speed in a certain position will set it the same as the gun wire speed control, so I could measure it.If there is an easy way to measure this, someone let me know!
Reply:The cwb guy had a wheel that will measure the wire speed. I run a xmt with a 30a  trying turning your wire up gradually and See what happins your looking for the oxide to burn off in the weld area kinda like this just keep turning your wire up and moving faster and see what happins Attached Images
Reply:I assume that welds like this one shown did have some layer of black soot that has been brushed off, correct?  I will try turning wire speed up and see what happens.Thanks!
Reply:I know that some guys are pausing to get the stack of dimes effect, while others don't try for this, but are you guys moving the tip in a straight line, or making any kind of pattern from side to side?In the top pics I was trying to follow a technique detailed by a very experienced and helpful boatbuilder, where he talks about whipping around the backside of the puddle, making backwards Cs, pausing at each front leg, then whipping around back, pausing at the other leading edge of the backward C, and then advancing one step.He describes moving somewhat from spary to short circuit and back as the arc length changes with the movemnets of this technique.I obviously don't have it right yet.  I found that when I made the Cs, I was really drawing the puddle from one side to the other, wetting out both edges, then adavcing one step - but there was not a well formed puddle in the middle, that I was supposed to circle behind, if that makes sense.Please let me know what you guys do.
Reply:[QUOTE=Northeaster;3552601]I assume that welds like this one shown did have some layer of black soot that has been brushed off, correct?  Nope that's a uncleaned weld. I do fig e when welding or a slit weave side to side but I never pause always keep moving. What is your gas flow set at I run 40cfh of argon at the reg that gives me 30at the nozzle. A lot of people and books say that to much but it works and I pass cwb with it.
Reply:I am using 40 cfh as well.  I was down around 25 or 30 in a coupel of the welds, but then bumped it up to 40.  I noticed this eliminated some holes / pockets that formed with less gas, and looked better.  But, I still get quite a bit of soot.
Reply:Stick to the plans. Place gussets wherever called for."Steel Boatbuilding" by Thomas Colvin is recommended reading.
Reply:Question - I refer to them as gussets, if they bridge across an open corner.  As in the plans, if i would have used only 4" flatbar, then the plans show a gusset which cuts across the open corner and overlaps each piece to also give strength to the butt weld.  But if the added piece does not go accross an open conere - ie only overlaps existing material, to give strength to a butt weld, is that still called a gusset, or is there a more correct term.I have not read Thomas Colvin's book but have read Stephen Pollards Aluminum Boatbulding book.  Left it at the cottage though, so can't refer to it right now.
Reply:I increased the wire speed today, and got some practice welding on the 2"x3/16" flatbar on to of a couple of the frames at a 90 degree angle.  Noticed better cleaning action - nice white line visible in a couple of pics.  Also much less black soot - only some outsde of welds - the welds in these pics have not been cleaned or brushed afterwards.  Did not try increasing wire speed further, until I noticed negative effects - may do that next time.Was getting a bit to much undercut in some welds, but I think that was when I was really changing / increasing the contact tip to work piece distance, and I think drove my amps up higher than I should have.The welds do not look similare or consistent, as I was playing around quite a bit with weave / patterns, travel speed, contact tip distance and gun angle, while pushing gun of course.Still appreciate any additional feedback or advice. Attached Images
Reply:more pics Attached Images
Reply:North, there a more than a few items of note in this topic.First, lots of designers are over cautious when they design for private builds, compared to how they provide details for professional yards. By this I mean the unknown for the designer versus the known. A pro welder and fitter, working in a yard can produce a more reliable weld joint than the one off builder as far as the designer is concerned.Gussets/fish plates/lap panels over Butt Joint(ed)  plate that is then lined with a flat bar at 90deg to the frame is mainly overkill by several times. Butt... (pun intended) the designer working with the public has no way to know if you're a high hour TIG welder so the joint is as good as the pro yard workers or, if the weld is cold lapped and not up to par?So, the answer to a question about the plans providing double framing element is: can your welds pass industry standard (Coast Guard, ASME, AWS) tests for the type of joint, alloy, and scantlings called out?  If you were to answer "What are those standards?" that would be a negative answer.  Sort of a "if you have to ask then......"I have seen plans sets from designers who knew what they were doing, but had features I thought were crazy until one of them stated "I have to design defensively because I can't know who buys my plans or what skills they do or don't have...."  Next is remarks about the welds shown. First the wire to weld power settings are not well proportioned because of several visual factors.One item is the sugaring or tiny spatter all over the place shows the arc (spray mode) is too long, the spray is too exaggerated. The weld surface when done should show tiny smooth but not 'melted' ripples. I hate to use the terms spray mode or short arc with aluminum because of some many confusing videos that are just wrong in terms about aluminum welding.   Let me say- the other welds shown recently here will not come from that wire speed to amperage to travel relationship you've shown on the first few overly hot and too long arc welds that have inadequate gas and cleaning.You could reduce the voltage/trim/heat/power so the arc was shorter OR turn up the wire speed but you are definitely showing some inconsistency in travel and puddle, and that usually means slowing down to increase the consistency of movement within the weld puddle.  In other words if you're not putting down a uniform step/puddle pattern at one speed, the increasing the speed probably wont' help.  Some may call it 'row of dimes' look but I more often associate that term with TIG.Even drag beads or 'machine beads' that have no pattern need to have a different surface from what your first welds show.So I'd turn down the amperage shown in those first few welds. Next, the lack of well defined puddle ripples indicates the spray mode is again too long and arc therefore the gas cup/contact tip is too far above the metal. If you're holding up so you can see then get used to holding the welding hand at arms' length off the body and crooking the head to that side and looking under the lead edge of the cup.  This cause neck problems later in life but is the main solution to the seeing the puddle= no see - no weld.The first few welds of the butt joint are too hot for the rate of wire and rate of travel and the lack of ripples is one key, the next is the sugary spatter and the last is the tie in of the two edges is not defined.The gas being too low is obvious because all MIG welds (even if you trail/drag/pull you can see the initial clean tracks) should show the two 'clean tracks'. One weld shown had them wider than normal because the inside uphill fillet formed what is called a huddling chamber of the gas. (not my term) This feature allowed the gas to be heater hotter, and to remain in the area longer and therefore the increased cleaning was from that joint's shape regarding gas flow, and weld direction.The last few welds (you) show that it would be better for you to take some time to work on your starts and stops and for you to work on the consistency before moving ahead with the boat.  First on starts, it looks like you have a 'run in' or slow wire speed start feature because the beginning of most welds I see are cold lapped shown the toe and top curling under and not fusing with the parent metal. Also these areas show excessive micro spray indicating the amperage maybe too high for a few parts of or full seconds while the bead gets 'lit'?Next, the starts are not overlapped or back tracked -some call it doubling back. It is not unusual to begin one or even two puddles into the weld area. Then to weld back away from the (real) direction of travel and after two puddles to reverse OVER the first two cold, overly small puddles and because the welder is running at full amperage, fuse them into the weld by welding over them.If this is done the travel speed is usually much higher in those first two 'wrong direction' puddles so there is little deposition mass to reheat, and the weld travel is established at the end of the first two puddles where the direction is reversed.It is also not unusual to reverse this at the end if you're not going to eventually make a continuous seam.  These two end methods mean the beginning of the weld is not cold lapped (lack of root face fusion) and the end is not cratered (potential for cracking)  and you shown both element to  your welds.What does consistency show? Consistency shows that the root fusion, total source of weld strength, is more likely to be even, not 'notched' and that is one reason I mention it would be a good idea for your boat if you were to take a few days and spend your time working on the weld consistency so the work you're doing is not a future structural problem?I hope you're not going to get upset about my recommendation that you spend some time practicing, as I have not reason to wish you ill. The welds seem to 'get going' in may places after half dozen puddles and that indicates your torch control is coming but not 'there' yet. I'm remarking that the 'middle' of may of the later welds show what you want to see, so the beginning and ends need a little more work- you're coming along fast.The bar on the edge of the frames would be better to be edge to edge than to lap. The reason is the welds will be much stronger if they are an inside fillet combined with an outside fillet compared to the inside fillet and the flat faced butt joint without grooving the weld area with a set of matching/mirrored bevels allowing the root face to provide balancing area compared to the inside fillet.The welds (shown) are too long and too heavy for the scantlings shown and therefore if you do not begin to place more careful and proportional weld you will distort your frame. Also if you become in the habit of putting out of proportion welds on the boat; the hull panels will be even more distorted.  The most common method used is to use set of black marker dots 1" or so offset the weld area to show the beginning and end of the stitches to hold the frames together. These are measured using a tape and followed in tack up, then very lightly gouged with a carbide tool to leave the fusion face but remove the bulbous top, so the eventual over/final/top weld full fuses the tack material into all final welds.You already see that MIG begins cold and ends hot so traveling over a weld tack can 'chill' the root face both sides of the tack if the mass is too large.Weld patterns are very very small movements inside the puddle and your top and toe areas illustrate you're getting the hang of that method but still need a little more practice before you weld on your boat.  You've described my attempts in one places to use words to describe the 'e' or 'c' or stepped patterns used and showing good progress in learning to do those welds.  I hope you'll find time to pause your project and spend a good 40 hours of practice and self-coaching so your 'learning & practice' welds don't become a weak link in our new boat? The solution isn't to over-weld the entire frame to compensate for weld irregularity.I'd help in any possible, I'm glad to see another builder learning, and I hope you'll take the advice as encouragement and not dwell on the fact that you've a some learning ahead before you're 'up to par'.  It's your boat, and all the preparation effort will only make it better.cheers, Kevin MorinKenai, AK
Reply:What he said lol your welds look better night and day better takes a lot of practice but your definitely on the right track
Reply:Kevin - Don't worry about me taking offence.  I have read countless posts and replies on several forums, where you have taken alot of time and detail to explain things to myself and others, and I would say that we all appreciate it!I am glad you provided many details and did not just advise me to work on the welds, so to speak.   You are correct hat I had quite a long arc length and spray going for most of those welds and I will definitly practice with a shorter arc length next time.I did not try to overweld those frames because I thought it required it, but (right or wrong) just decided to put down lots of welds for practice.  I am aware of the dangers of too much heat and distorting the material, so I took care to clamp them well, and take breaks when welding so I think it caused no harm.  But, I will practice on scrap next time, until i am more readly to weld on the boat.Not saying that I can do alot better than this yet but I was purposely playing around with different patterns, techniques, (long) arc lengths / and travel speed so it is no doubt that there is no consistentency in those welds.  If I did try to lay down a few welds, I could make them look reasonably consistent, but it still would not fix the other issues that I need to work on, as you have outlined.  I woudl like to try to reduce the arc length and increase the wire speed and travel rate if necessary to see how that changes things.  If I still don't improve, I will turn down the voltage some and see how that works.  You are right about having my run-in speed set really low, and I do know better- in that I know  I should double back and re-wet the start and then step back just before finishing - but as I was trying all of the other variables, I lost sight of some of the thinsg i should try to do properly anyway. Will make sure i do this in the future. So, I will work on the things you have pointed out.  I really appreciate the explanations about the cause of sugaring / splatter , lack of cleaning and the reason that the one weld did have better cleaning, etc.  This really gives me some concrete things to practice next time and after that.I have been holding off doing more frames anyway, at least beyond tacking them together as I may have a possibility of getting a very experienced aluminum welder to come over to the shop for a few hours to help me with my settings, techniques, etc as he lives in the area.  In the meantime I will practice, but not for about 10 days as I can't work on it until then - other family obligations.I get what you are saying about some of the choices that the designers have to make in providing plans for the rest of us...  And, I have no illusions to where my skill level stands at this hour.  But, I am confident that I will improve alot with some focused practice based on solid advice, from you and hopefully the local welder as well.Cheers Kevin! and never hesitate in giving me advice of constructive criticism.Abec - thanks for your advice and encouragement as well!Last edited by Northeaster; 01-14-2014 at 08:00 PM.
Reply:Just a little correction of a statement made some letters back. If the flow meter says 40 Cubic foot an hour ,  It will be 40 cubic foot an hour at the torch.   A flow meter tells how much gas is flowing an hour and is not concerned with pressure.  If you are using a pressure gauge for a flow meter you may have different readings, between the meter and the torch, because of resistance in the hose or the torch head. You can put your thumb over the cup and stop the flow altogether and it will drop down to zero on the flow meter.  but if you have a pressure gauge, it will still say 40 lbs. on the gauge.  MacLast edited by Tool Maker; 01-14-2014 at 09:16 PM.Reason: Left a 40 out
Reply:A few pics from today, in case anyone has a chance to look and offer advice.  Been practing most weekends.   Still need to wrk on crater fill.Just finished my 1st large roll of 5356.these are on 5052 alloy.23V  wire speed 6.5 on xr push pull gun - don't know ipm.40 cfH argon5356 wire. Attached Images
Reply:North, now you're on the right path, the images are somewhat dark to make out all the details but the welds are fused toe and top, much more uniform, much more flat on the face, and appear 1000% more useful to your project than the previous images.Cheers,Kevin MorinKenai, AK
Reply:Thanks Kevin - really appreciate you taking the time to look and comment on these, and other posts.  I am sure you have written about it before, but if you have a couple of minutes to write a few lines, I would love to hear your method of preventing craters.   I know that you have said to reverse direction, after reaching the end of the weld, so you don't finish at the "end".  But, do you also move the contact tip away or closer as you let off the trigger, or give a quick shot on the trigger after stopping....?Also, when you have reversed or stepped back and then let off the trigger, is the gun stationary at the new spot, or do you kind of fade away  i.e. towards the start, as you let off the trigger?Thanks again!
Reply:North, [we need to agree at each "?" following]to discuss cratering at the end of the MIG weld, we need to agree there is an 'arc core' that does have some depth into the parent metal, if the MIG weld wattage is correct?  This core or middle column of the arc, reaches down into the puddle (regardless of depth) to the bottom or the extent of molten metal?  The crater at the end of a MIG bead comes from the arc core stopping too soon so the cooling in the arc core column happens  at the same time INSTEAD of, like TIG, from the bottom to the top?When the highly expanded core area (small cylinder in middle of puddle) cools instantly the surrounding contracting aluminum pulls the sides of the core column uniformly outward?   Therefore the core, still molten, expands outward leaving a vertical column of cracked cooling aluminum because the cooling contraction has pulled it (the only remaining molten metal) apart from outward contraction of the surround metal?In aluminum AC TIG, the power is gradually reduced so the arc core are cools/chills/freezes from the bottom to the top?  In MIG welding with DC the arc core will not cool bottom up, solidifying the weld and parent metal if the arc is stopped all at once?So to avoid crater cracking at the end of the MIG bead there are three main ways to go.First we need to consider a long continuous weld seam. Keels, chines, shear weld are all continuous but not welded in one long seam-so we call these stitched welds, or chained welds but the primary idea is they are added together into the continuous weld not put down in one long weld?These welds could have a #1 type of anti-crater cracking method- not to be confused with the other two methods below?When you come to the end of bead that is going to be part of the next bead at some point in a long continuous weld; you can 'wipe out' the crater by using a rapid wrist twist of the torch while letting off the trigger.The last puddle is allowed to form about half way and instantly a very rapid (non-welding fast) turn or flip of the torch hand allows the wire arc to move more than a 1/2-3/4" in the direction of travel as the trigger is let off to stop the arc.  This method means the gun roll/wrist twist MUST be combined/timed with the release of the contactor/trigger/ON trigger so the arc stops and the wire does not continue to feed and scar the metal as it comes out from the gas envelope.This method leaves "1/2 of a puddle". That is, when the 'wipe out' move begins the arc does not have time to deposit enough metal to make a full puddle and chill. The time to end combined with the non-welding speed of the wipe- leaves just a partial puddle and the arc core has been "lost" to the rapid movement in the direction of travel.There is 'no' crater of any significance in this end, but the end is not correct for a stand alone intermittent weld either. This last point is very important and this is why a wipe-out end method is not used for stand alone stitching stringers or longitudinals.This (wipe out type) end, which is a hollow cup with very little or no arc core/crater crack, is to prepare for a tie-in weld in continuous seams ONLY?Next #2 is the stand alone stitch weld end anti crater crack method.Above I've asked you to agree the arc core reaches to the bottom of the puddle's molten metal so in the double back of this technique you're depositing a shallow puddle on top of the just welded bead's last puddle.We've discussed the idea of the race track weld pattern where the beginning and end of the stand alone bead are under then over the weld?  One other aspect of the arc core and the puddle is that at higher rates of travel, the puddle depth is reduced due to the rate of chill of the parent metal compared to the wattage of welding needed to attain the heat of fusion?  So let's combine some of the points of agreement.If you start at speed Weld X 3 (movement opposite the actual weld bead direction of travel) and then immediately slow to Weld speed, (when you've reversed to 'real' direction) then.....  continue the length of the bead ? You'd have low depth of fusion at initial speed, then deeper fusion as you continued as Weld speed? Similarly, the same is true at the other end, if you were to increase to Weld X 3 speed to double back onto the last chilled puddle in your weld (?) then; you'd have a 'one count' to leave that reversed puddle on top of the last puddle.This reverse at the end, done at higher speed and left for a 'one count' on the last puddle will be in A) Thicker metal so less penetration B) weld alloy metal so not melting parent metal C) hotter metal so less added heat of fusion D) shorter time of arc means less arc core depth.Then let off the trigger.The 2nd method will leave the shallow crater on solid weld beneath and will not create a weld damaging full-depth flaw in the underlying weld and the crater itself is very shallow, not very large in size due to the smaller volume of surrounding cooling metal.Method #3 is for those who have programmable power supplies with weld end sequences.In this method the weld is not stopped when the trigger is released but an end weld sequence is initiated that is designed to stop a weld and to cool the puddle exactly as though the MIG welder had TIG-like pedal controls.The welding amperage/voltage/wattage is sloped down to one or two preset levels, the wire speed is reduced to continue to fill as the arc core in the molten metal is allowed to cool bottom up and avoid the 'pulled apart' column of still molten aluminum.I use the Lincoln 350MP and it has this feature and with some tuning and adjustment for the weld types and conditions works flawlessly.  But since I have done the first two methods for thousands of hours and decades of welding aluminum it did take a few minutes to get used to releasing the trigger and holding still!Hope this set of three methods -in words not pictures- will help you in your practice getting your hand in with aluminum MIG?  If you don't agree or understand what I'm saying at any red question mark, I don't think I'm helping.  But as we all know trying to use words to show you something is not always the easiest way to explain.Cheers,Kevin Morin
Reply:Kevin - thanks one again for the detailed response!  Yes, this all makes sense.    I was not aware of the reason for the craters, so I appreciate  the explanation of underlying reasons.I do not have any crater fill / programmable options on my miller xmt304, so # 3 is out.  I will certainly practice #1 and 2 though, as both methods will be needed.Still lots of practice needed, but it's nice to improve in some areas and be able to work on others.Also still hoping to have an experienced local aluminum welder come by for a few hours of hands-on help, to speed up the learning curve.  He is out of town for 3 weeks, so on my own till then.