Conchfish AL 17.6T build

[m32825]

Based on my results above I'm going to practice outside corners and fillets with my off-hand and out of position welding with both.

One thing I've figured out is that I'm definitely right-footed for the pedal! I think it's pre-wired due to driving. Are you guys able to easily swap feet?

-- Carl

[gandrfab]

I have just about forgotten if I'm right or left handed when welding.
Most of the time I set the heat on the machine and use a momentary on button at the torch for on/off control.

But, have sat in hulls or boxes or work on the ground and used my knee, elbow, shoulder for "foot" pedal control when needed.

Given the opportunity I'm going to right foot the pedal every time it's in use.
 

[m32825]

One of my kids has a small engine repair shop. From time to time he gets a piece of equipment that needs a little welding (e.g. mower deck). Right now he has to farm that out, but I'm going to get him set up for solid core mig on steel. I participated in a Kickstarter campaign and got a new welder today:

YesWelder dp200

Looks very capable, especially for the $400 campaign price. I'm going to build my rotisserie with it to "test it".

On the boat front, my three panel test assemblies sent me back to the practice bench. I want better consistency before welding on the boat. It's coming along.

    -- Carl
 
 
 

[m32825]

Here we go, first TIG on the boat.

    -- Carl

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[m32825]

Here's the off-hand side. The order I used is to do the back of the vertical first with the spool gun, then switch to tig and do the open corner, then the front of the vertical.

-- Carl

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[m32825]

Tied in the front, where everything comes together. Trimmed the tab off, planer worked pretty good for that, I did discover a couple ways to screw up but luckily on my first few passes. Suggest working in 1/16" passes, dropping to 1/32" when you get in the ballpark. Once there was less than 1/8" left to remove I switched to vixen file.

Going to take a good look at my keel longitudinal to see how straight and level it is before tacking hull panels to it.

-- Carl

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[gandrfab]

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[kmorin]

Carl, G&R,
I don't use a hand torch and off hand dip wire to TIG weld & my TIG gun is right handed so.... I weld from left to right pretty much all the time. I have two controls on the handle near my right thumb, one is wire feed speed the other is amperage or % of range set. I only use a pedal on the rotary table when welding something round.  But I do recall welding two-handed and hugging the pedal in my armpit while laying in the bilge of a boat. Now, I just "keep both hands on the handle" to avoid hitting my thumb.

Carl, I think the welds look good and all your practice in the training course was time well spent- IMO. If anything could be improved it would be to reduce the face cross section of the inside fillets; but the vertical bar came out nice and clean with no distortion so you're on the way.

I agree that the power plane is a great tool and thin depth cut passes are the key to control. Also, lots of power planes have a groove in the table/base and you have to make sure you don't get the depth set for a flat base plane reference if you fall into the groove! For flat cuts, using a fence attachment can help avoiding the beveling groove guide.  For beveling, I make sure the chamfer/bevel depth of cut is set inside the table/base groove so I can take advantage of the table's groove to follow the sheet edge. I have definitely set the cut depth for the 'flat' only to slip into the groove in the table and have the entire sheet edge gone! Sailor-like language follows along with increased attention result from those kinds of mistakes.

Vixen filing edges is somewhat reminiscent of wood working and I agree 'creeping up' on the cut line with a file is safer than using a power plane.

Good luck with your next few steps lining up and tacking on the bottom panels.

Cheers,
Kevin Morin
Kenai, AK




 

[m32825]

Kevin,

The power plane is definitely a double-edged sword. While experimenting on scrap I fell into the center groove and wrecked a set of blades, I seriously considered filling it and grinding it flat. When trimming on the boat I avoided the center groove but fell off the side once, with that "taper to nothing" I couldn't figure out how to use a fence. I was relieved when I got close enough to file the rest.

Checked my center longitudinal and made some adjustments to get it more straight and level, picture below. There was a 3/32 inch "dip" over the cockpit area, much flatter now. I found that a oscillating multi tool works well to cut tacks out.

I'm going to mock up some test pieces to practice the center joint fit up, tacking, and fill. I know this is a long way out yet, but when a segment of that joint gets welded am I filling it in one pass, or is it one side then the other, some kind of root pass thing? Having trouble picturing it.

-- Carl

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[kmorin]

Carl,
glad you could move the VKB to a better line w/o much work. 

The keel seam could be welded in one pass and that would be the best in terms of HAZ and distortion.  More passes will only add to the width of the HAZ and likely increase the 'cup' or hogg in the keel line between frames.  The contraction would be to pull tighter on the bottom and that means the VKB would tend to 'bow up' inside the hull.

If your mock up weld test for the keel shows you the required bead is too wide to weld in one pass (?) Then I'd consider moving the two inner most bottom plates inward to 'just cover' the outer edges of the VKB at the keel seam.  I'd tack one side, then dress the tacks flat to the plane of the VKB and then add the second side.   Then I'd dress all the tacks from the second inner panel's addition and make sure the seam's edges (inner edge of each bottom panel) are NOT right angle cuts.  As mentioned earlier the 'shoulders' or edge of the bottom sheet/panels will tend to diver the arc to those top edges (upside down 'top') and that will make wetting the VKB very difficult.

I've mentioned, I think? beveling the inner edges back at the outside edge so the groove formed is more W than U shaped.  In your test set up confirm you're able to get a good fusion along the VKB and not cold lapped.  Ideally, there will be a little penetration bead along both sides of the keel seam INside the boat.  This indicates your bead is fusing the VKB and the edges of the two plates and a little root 'sag' or penetration confirms the settings and rate of travel are the best you'll get from MIG. 

Since the entire length of the keel seam will be continuous welded- eventually- I'd use the above described layout 4"-6"-8" tie-ins to plan the final welds.  Also, "whipping out" of the puddle (trailing the arc off and rapidly moving the wire from the puddle in the direction of travel to end a stitch) will work fine to end these 'chain-welds'. That technique will help reduce the amount of time and work to gouge out the starts and stops. 

This entire seam will be back welded on both sides of the VKB inside the bilge once you roll the skiff to work inside. That means that the keel will be fine if there are a few cold laps or poor fusion in spots; but still, care should be taken to make that weld as sound as possible.  It will be important to test your wire vs heat to see if you can fuse to the VKB and fill the weld in one pass -depends on the wire dia.

I've used a multi-tool for lots of repair work- where getting other blades into corners to clean up or remove parts just didn't work.  I haven't used one to work on tacks but I can see their geometry and cutting action being handy and easy to control. Which of the blade types did you use? Abrasive or saw tooth?

Looking forward to seeing your work as you progress.

Cheers,
Kevin Morin
Kenai, AK


 
 

[m32825]

Kevin,

Great description, everything I asked for and the other stuff I need to know, too! I'll get lined up to do some test pieces before the weekend. 
​​
I used a cutting attachment, see below. It says "carbide" but who really knows? I tried a few other approaches before hitting on that one.

​​​​​​I was trying to figure out what a good straight edge would be for adjusting the VKB. It took me way too long to realize that the panels I was going to attach to it were the perfect reference...

    -- Carl

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[m32825]

Some practice. It's tough getting heat into the VKB when tacking up, suggestions?

     -- Carl

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[kmorin]

Carl,
the only thing I can think of, and it won't hurt to do from a layout point of view, is to consider using a ball type carbide bit and touching the edge of the bottom sheet where you'll be tacking to remove a small cup of bottom sheet edge.  This would be a single dime (puddle) sized gouge of 1/2 to 3/4 the sheet thickness out of the edge of the sheet on a layout pattern that will represent your tacks. These cuts or cups, once removed, will allow; the arc to initiate, the wire to feed, and the gun to be angled more toward the edge of the VKB, and less to the sheet edge. In a very short time the arc, focused on the VKB will fill that part of the tack and you can finish at the top as you fill the gouged edge of the bottom sheet?

Unless you can go to bigger wire the most you can do is reduce the cross section of the weld zone/tack zone so the arc initiation has more arc energy on the VKB and less on the sheet edge and the sheet edge is thinner at the tack point so the wattage in any tack heats the VKB with less taken in by the sheet edge; until the VKB is heated (tacked/fused) and the remaining tack fill happens in the small recess cut in the bottom sheet edge.

Another consideration is to use your power plane and the groove in the base to chamfer the lower most (now upward) edge of the bottom sheet to create a reduced edge mass.  This will allow the tacks to hold on the sheet w/o as much cross section and when you final weld the chamfer will allow  the arc to reach down into the \_/ shaped groove better than it will in a |_|shaped groove. 

Cutting cupped tack allowances will help make the tacking layout exact, so each set of tacks can be planned.  Removing about 1/2 to 1/3 or the shoulder will give similar results but will result in better fusion when you do the final outside weld bead.  But the wire diameter and open circuit voltage of the power supply are the main limits to how 'hot' you can tack.

You could also warm the VKB with a propane torch. Using a temp crayon or digital hand held, non-contact thermometer you could heat the VKB from the (now bottom) edge opposite the tacks, and that preheat can reduce the level of amperage needed to get tack fusion at the edge you're tacking.  Usually 200 degF preheat will make tacking easier compared to room temp or even cooler temps of the VKB.

However, the resulting bend tests show you're 'beating the metal' with your final as-welded cross section so unless lots of dressed tacks came loose before you get them welded with final seams (?) sure looks good in the photos.

Hope this addresses your question?

Cheers,
Kevin Morin
Kenai, AK
 
 

[m32825]

Kevin,

I'm chamfering the edges with the router to about two-thirds of the thickness but your reply makes me realize I've been focusing evenly on both sides of the joint when tacking. I'll try focusing more on the VKB and letting the puddle wash up on the hull plate.

I ordered some .045 wire to try. My new welder has a tack function which lets you dial in how long you want to tack to last, in tenths of a second. That might help me get better consistency with tacking, or at least experimenting in a more quantitative fashion?

My VKB pieces have curvature to them from when I was learning kink-bending. I figured this was good because I'm going to have that near the bow anyway. When I started filling the joint I had one of my tacks pop, and realized there wasn't much penetration into the VKB. There will probably be less joint movement on a full-up panel with the other edge tacked, but the curvature is going to be much more pronounced near the bow.

-- Carl
 
 
 

[m32825]

Experimenting with tacks, time in seconds above each one.

-- Carl

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[m32825]

Used .6s duration tacks and tried different voltages. I angled the gun into the VKB more and started off 1/16" away from the beveled edge of the 1/8" plate, letting the puddle wash up on it. I thought higher voltage would be better, but doesn't look like it dug into the VKB as well. 

Did a little black Friday shopping. Ordered a tig button so I can control amperage from the torch. A Spool gun is on the way for the new welder. The welder supports "double pulse MIG", which sounds really cool, but will have to see what it is useful for.

-- Carl

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[m32825]

Here we go, this combination seems to bite well. Able to aim in the corner and still dig into the VKB. About 50% more wire delivered in half the time as before.

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[m32825]

I've think I've got a decent strategy for trimming hull panel edges with the router. Here I'm making templates of the edge profile to use as a guide. I wire brushed the mill scale off the edges of one of the center panels, then beveled off about two-thirds of the center edge. Should I bevel all the way the bow? The hull shape there will open a 90 degree joint to 135 or so, seems like the arc will still be attracted to the corner if not beveled?

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[m32825]

Tacked first center panel to VKB. Leaving the front untacked for a bit longer. Working up the courage to trim the outside edge...

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[kmorin]

Carl, the open circuit voltage of a power supply has more to do with spot tack 'heat' than most other factors. Duration and wire speed contribute so does the set voltage but....Sometimes when you set the power supply to larger wire that OC voltage is bumped. The power of the tack is mainly set by the wattage of the open circuit voltage if we totaled the various contributions to the net energy that the power supply delivers when you pull the trigger. 

I think, but don't know your power supply, most are about 70V open circuit? How long this lasts before reverting to the 'welding' voltage in the panel settings I don't know. Wire speed can work to shorten the arc, or by slowing that value, lengthen the arc but even that setting may not be as much determinant of the tack's wattage.

I think it looks like your heavier wire tacked better but why isn't all that clear? Could also try fitting the power supply w/ 0.035 wire but turn the wire size selector to 0.045 to see if you can heat up the smaller tacks? 

Note about tacking the curved forefoot of the keel and the other panels. Just aft the curvature (which being very slight might have less impact) of the forefoot I'd do two or three short stitches of 1" solid welds as that is the area most prone to pull tacks loose when pulling the bottom panels into the VKB. The first weld would be 1-2" on the VKB exactly where the VKB curve begins. The other two aft a few inches each. Don't want dressed tacks to get an added outward pull as the VKB can 'unzip' from the bottom in this area if those short stitches aren't added.

As slow and easy as the curves of the inter-panel seam are; I'd not be concerned by using the offside sheet -even trimmed as the router guide. I doubt there's enough concentricity between the original and cut edges to be a problem but... going to the work to make templates surely is the best practice to make these cuts clean.

Beveling sheet edges can be gauged by holding pc.s of mtl. to the plane of the panel's final position on the frame. I'd say the keel's curve upward at the forefoot will be enough that the edges of the inner bottom panel may form enough W to allow the weld to fuse the VKB & the edge of both sheets. However, due to the flatter angle between the bottom panel's "inner-panel seam"; I'm pretty sure you'll need to continue the bevel all the way to the Bow Stem/VKB intersection.

Also, reviewing a few of the previous photos I'd say that the forward outer chine seam will need extensive beveling for the forward 8' or so? The bottom's shape comes to the chine at an angle that will work to close up that seam.  So back beveling both the existing sheet (topsides?) and the outer bottom sheet's outer edge looks like it will help weld penetration.

Re: weld mode names. Each power supply company produces the 'same' thing in essence. SO to help separate their products they hire 'sales people' who invent terms for the features and try to incorporate that sales language when talking to welders who might want their product. Lincoln's Power MIG 350MP came out with Pulse-with-Pulse MIG mode as an example. However, like your power supply's 'double pulse mode' - unless you're a pretty experienced welder or a welding engineer; could be challenging to exactly explain how all these features will be of much benefit?

Experimentation is about all you can do. Set up a series of tests and document both photographically and set of notes what the weld's conditions are- and what settings and parameters are and test till you're tired. I did, with my Lincoln 350 and spend a couple hundred hours over several months. I use about half dozen sets of settings after all that. The main reason is that I have about half dozen typical joints in my typical work. So I don't have much to recommend in that regard.   

Looks like you're on the right track, my primary advice at this time is a reminder that any weld bigger, thicker, wider, or heavier than 1.1 times the cross section of the parent metal you're welding won't improve joint strength but will degrade your skiff's hull by contraction distortion and a widened HAZ from which you cannot recover.

Cheers,
Kevin Morin
Kenai, AK 
 

[m32825]

Got a spool gun for the new welder. Really makes it apparent how much "slop" there is with the wire using a whip.

Trimmed a few feet of the outside edge. Came out fine but I want to try a template guide on top instead of a bearing on the bottom. That way I can keep my templates on top for trimming/chamfering, simplifying things and providing better visibility.

-- Carl
 

[kmorin]

Carl,
its kind of amazing to me to recall you'd been using a steel MIG whip lead as torch/gun/wire feed!  The results you show, using that system, are better than I've seen before from anyone using that wire feeder.  I've only tried it once or twice and then as a joke to compare with the several push-pull systems I was using. (MK Systems' Cobramatic wire feeders).

Needless to say, I think you'll find the pistol type, 1lb.gun a step up in hardware consistency. Glad you got the new torch ahead of your weld out.  I think you'll end up with much higher quality welds on your skiff using that tool over the push-only, steel wire MIG whip.

Would make one comment about trimming the bottom panels while one edge is already tacked at the VKB.  Lifting and lower the outer edge(s) to access the template, router and tool clearances will work to flex crack the tacks, especially if they're already back gouged for weld prep.  I know you've thought of this but I'm reminding you so you can avoid having the VKB/keel seam unzip while handling the inner-panel seam of the bottom panel.  The result is not catastrophic as you can remove and re-do tacks but its a loss of time that can be avoided.

Will be interesting to see how your 1lb gun runs 0.045" wire.  If practiced enough and traveling at fairly high speeds even form aluminum MIG you can create very hot 'drag type' beads that will make very tight and proportional welds in 1/8" material using that combination.  The key problem for most welders is they don't practice the needed speed of movement to allow them to run 0.045" wire in narrow beads.  To 'burn' that wire you need more voltage/wattage than for 0.035", obviously, but not many welders take time to get their bead up to the needed travel speed to keep the bead small when running the heavier wire.

The main benefit is that the heavier wire allows a much higher power setting (w/o burning back) and therefore; much more fusion energy in any given second of arc.  Those combinations provide a much higher 'wetting' factor (fusion at the surface) than the next size smaller wire. One down side of this circumstance is the "need for speed." You have to move much faster than using smaller dia wire. However, the gain is the higher energy brought to the weld zone in a shorter time, allowing for deeper penetration in that shorter time.  Another downside is that if you don't move the larger stream of molten wire along quite rapidly, and evenly, you'd end up with a gorilla weld. BIG, strong, & ugly, but that will distort, contract, and bend your hull. 

old guy's tale of skiff building.
I used to build commercial set net skiffs for the local salmon fishery.  My design included a full set of transverse ribs which were formed from sheets of 1/8" 5086.  I built a sheet brake to bend these, actually a large scale sheet metal leaf folding-brake, and bent each rib into an open U where the sides were \_/shaped and the outer ends would touch the topsides of the skiff- inside.  These edges were fit clean from gunwale pipe liner to the top of the transverse ribs (a larger scale version of the side ribs) and all of these seams were continuous welded and air tested.

The original version of this method (one skiff) had a cross section from chine to sheer that was almost flat. When welded the sides wrinkled.  From then on I put a 2x6 or 2x8 inside the hull and bulged the sides outward to stretch the topside into a convex shape from about 1/4 aft the bow to the transom vertical seam.  After fitting the ribs to this concave inner surface of the topsides, I welded them continuously top to bottom- fore & aft leaving an inch or so of the top and bottom for TIG.

To do this weld reasonably, I hung the skiff from an overhead so the chines were vertical to one another and the welds were almost downhill. Then using 0.045" at pretty high voltage and with wire speed cranked up, I did all the seams down hand using the Cobramatic.  It took some time to get used to moving that fast- even downhand.  I also could not stop the weld if I left a pin hole at a gouged tack- had to come back with TIG.  The welds resulting were about 1/8" to 3/16" wide and filled the gap formed between the inner topsides surface and the Vixen filed edge of the outer legs of the ribs that were about 110-115 deg to the topsides surface. This small gap, with its inner edge as guide, created a space for a narrow hot weld that held the skiffs' ribs in pretty well.

I sold one of my early skiffs, built as described & about 18' LOA, to a local cannery (freezer plant) who used it to ferry fishermen and crew from the shore to their boats anchored in the river in front of the plant.  One night in the summer of a huge salmon run, the average per boat catch was so high; the tenders sitting in the river were overwhelmed by the number of fish each was receiving and long lines of boats waited to unload.

It was decided to use the little ferry skiff to haul fish to the docks from the tenders or to unload directly into the skiff and use it to approach the dock where there was a crane but not enough brailers to unload fish.  The cannery yard workers motored the skiff out to the anchored fleet and filled the skiff with 4-5K lb of salmon.  It putted- in displacement mode- to the dock, and they lifted the skiff by the handrails up to the dock. They removed the gas can, and then used the full skiff as a brailer and upended it with the crane into the fish conveyor hopper like it was an oversized fish tote.

There were so many fish that opening that this operation kept on 'til the next day (not much darkness here during the summer months) and they kept using the skiff as an 18' self-propelled fish tub until early afternoon the next day.

I think that convinced the local fishing community of my claims that downhill, single pass, MIG on 1/8" aluminum was strong enough to hold up to most demands of landing salmon in a following sea on a beach in my skiffs. Up til that time I'd taken no small amount of criticism about my 'tiny welds' and their lack of strength.

Carl, long winded remarks about MIG drag welds in aluminum, but I think you'll find that hot narrow beads with 0.045" wire will provide very adequate, low distortion welds for you skiff.

Cheers,
Kevin Morin
Kenai, AK
 

[m32825]

Kevin,

We must've been typing at the same time last night! Still digesting your post, but discovered one interesting fact from looking at my welder manuals. Open circuit voltage for the old welder is 56V the new one is 81V.

-- Carl

[m32825]

Clarification on the spool gun vs whip... The old welder was only spool gun. When I got the new welder I didn't have a spool gun for it yet, but it came with a graphene liner, so I started experimenting with it to try out the tack function. Once I got the spool gun it was really apparent how comparatively "loosely connected" things were with the whip. Sorry for the confusion.

[m32825]

My mental model of how MIG welding works is slowly developing. I'm thinking the reason I got better tacks with the larger wire is because a larger volume of filler metal (i.e. heat)  is being delivered in the same unit time as the smaller wire. I kept the wire feed speed the same for both, maxed out.

I'm trying to sort out where to introduce the second center panel. For the one inch stitch welds near the forefoot, am I doing one side, then the other one later? Or am I waiting until both are in place then filling the W for an inch? Seems like bending and tacking the outer edge of the panels to their longitudinals needs to happen at the same time to keep the bending forces on the hull/frame symmetric?

I think I'm tracking on the beveling battle plan. Your description was very helpful. Also, good reminder about the cross section of the welds.

Did some trimming this morning, my edge ended up where I wanted it. I wanted to switch to a template guide so I could put the template on top, limiting the amount I have to lift the panel to trim it. That worked well, just needed an eighth of an inch underneath to provide clearance over the longitudinal. 

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