slug, completely agree to nibblers being good tools, very helpful and being high quality they hold value so reselling after well cared use makes them a low cost 'rental' while the boat was in build.
I was sort of focusing on elect/Doug's remarks about saw chatter and grinders used to cut accurate lines. I'm in the saw camp on that comparison and I use a plaz the rest of the time.
By setting up a lower cost, smaller free air compressor with a hugely over sized reservoir capacity for storage a small size plasma torch can be the most versatile cutting machine on a steel boat. By adding several 100 gallon pressure tanks, and letting a smaller capacity compressor run for an hour or so, the capacity to cut with plasma can be changed to manageable from -too expensive.
A Victor/Thermodyanamics 42 series will handle 1/2 at a slow even pace and is only 800 new. So a used plasma and a large air storage could be a worthwhile investment in terms of versatility at affordable costs. Not saying this is needed but is about the most versatile of all modern cutting tools for steel.
electric tug wrote:The guy I called about buying a Mig said the mig would not work even with multiple passes on heavy 1/2inch plate such as in welding up the three sections of my half inch keel?
I'm not saying all small MIG systems will do the work you need, but small MIG can be used to multi-pass heavier plate- the 'guy' you talked too would have had to be discussing and exact power supply and torch and wire combination before I'd be willing to accept this as a Rule of Thumb. Not true, tiny small MIG beads can be used to build up weld a 1/2" plate section.
electric tug wrote: the inverter types have less heat, and less distortion.
I'm not wiling to buy this assertion, melting steel is done by the arc, no matter what type of arc controls, melting steel is done by the heat of the arc. No amperage/power/wattage = no arc melting. Adequate amperage of arc and the steel will melt; if you can melt the steel with the arc- you can weld. Welding is melting steel and adding some filler.
electric tug wrote:, could this 200 amp inverter stick work?
Yes, it could. Countless boats, ships and other marine craft have been built with coated electrode welding processes and are still built today. What I was pointing out was the skill level needed to plan and place welds in an overall weld-out with MIG vs stick. Stick requires more knowledge and skill to place well compared to MIG due to dwell time of weld time. Longer time = more heat. More heat has to equal more joint expansion. More expansion has to equal more contraction. MIG is fast- less time to do the same weld. Stick is slow= more time to do the same length of weld.
electric tug wrote: I also wasn't too clear perhaps on this. I am actually pretty confident with my welding skills, that wasn't the issue,
Welding is like learning to read. First are the ABC's then related sounds individually. This is like learning to turn the power supply on and make beads start and stop. Next, in reading we begin to group sounds into groups called words, and finally we can read a sentence.
The welding process is not limited to practice beads on plates on the bench- that is like ABC's or even sounding out words. Welding is being able to understand what is needed in power supply adjustment for what is to be welded. Then what techniques are needed for that joint>? Uphill, downhand, horizontal, or overhead are all part of welding. Don't have one or two? Not a welder yet, still in the sounding out words reading class.
Now, once the beads are all happening in all positions, then the welder begins to 'see' the effects of different types of welds on different types of fabrications and boats, unfortunately, are one fabrication with nearly the most different welding knowledge needed in order to put the correct size and sequence of welds together.
Bread is not a bunch of flower, water, yeast and salt in a bowl and heated. Bread is a sequence of all the needed steps, in ORder, and at the right time and with the correct technique - then and only then could bread's ingredients become what we know as "bread". Welding a boat of any metal requires the correct sequence to get the correct result, by your own description elect/Doug you need to work on understanding the various aspects of the keel that went amiss? Without pictures of the plans, or images of the keel as built, I'm not trying to say I know what the problem may be- or is? I'm just making sure you don't equate some bench weld practice padding exercises with welding as a whole trade applied to your boat?
electric tug wrote:.My welding i am happy with, although i still cannot figure out how my keel warped, as i am certain i did veverything properly in the execution of the weld sequences...(scratching head)
Sometimes the descriptions of the designer are references to experienced tradesmen and there are terms used that can be understood differently based on the experience in the work? So I'm not up to speed on the plans, just on your remark that your resultant work was not up to par? That may reflect on all sorts of communications issues?--- my point is that is sounds as though the welds were added in some manner that didn't result in a desirable finished product? OK, some work is needed- was the exact bead sequence and size given in the plans? Did you use a weld gauge to insure the cross section? Was every single bead planned and laid out and prepped in a weld chart before the first pass? If not then I can see lots of room to upgrade the welding knowledge applied.
So, read your quote above and see if you're really happy with the results of your welding
knowledge and skills combined? I don't get that impression? My take is you're not connecting the real world results- you may be happy with some types of welds but overall, as applied, you're saying there is room to improve some welding related part of your build!
Have you done break bends? Have you tested our own beads to see how small they could be and still 'beat the metal'? this is always informative for newer welders. Have you ground or etched you weld sections to see how your settings are penetrating? All these are needed before you can say you're happy with your welds- how could you know what's down below with the normal self tests? Trust- but Verify.
electric tug wrote:Thats why nest time, i will be having the steel fab company roll my round bars. this is the greatest source of problems in the build.
On this subject I'm going to make some assumptions- (my favorite form of goofing up an entire thread!! ) Does this design call for chines (hull seams between plates or hull panels) to have a round bar at the tip of the frames. The hull panels land on this round bar and there are four lengthwise welds on each chine bar?
IF this is the case, I have already had at least some discussion of this design element on another thread, and I've mentioned it sometimes on the Metal Work Methods thread as well. I suggest you consider skipping this part of your build. Here's why.
#1 The bar is hard to bend fair to the frames in most displacement hulls because of the increased curvature toward the bow stem of all chines in both plan and profile views. However if this bar is include in the build BUT is not fair, then where will the adjacent hull panel plates/sheets' edge get their fair chine layout curve to cut??? So if the bar is not fair when installed - it will almost deny any possibility of a fair hull.
#2 the bar may add strength but that is not needed due to the fact that the entire mass (displacement) of these small boats is less than the tensile failure of the hull material. So.. and entire steel boat dropped by a wave on an underwater steel 'spike' will just dent the boat since the entire boat will bounce off before the forces will actually puncture the boat. This includes rock impact at the chines.
Now the biggest items the strength issue of discussion- adding two extra full length welds does not leave the final joint that much stronger than it would if the joint were two hull plates fitted well and welded inside and outside. Finally strength issue IF there is a rock crusher future or ice breaker future to the hull ???? (!) move up to the next scantling size material ( a few thousandths inch increase in thickness) an call it a day.
#3 This design of using a bar to line out (define) the seams is mainly intended to give a first time builder a 'bigger target' and is not used by the full time, longer service time, more experienced builders- so ... ?? up your skills - skip the rods/round bars and save time without sacrificing anything in your final quality.
I have a thread close by that take you though the steps to layout and fit the hull panels (faired through a plate model or the frames' chine points) that will allow you to plate your hull to 1/4 of the sheet thickness accurate curved lines. Think I'm exaggerating?? great! take a little extra time and build your boat in small scale model and learn that you can 'take off' the sheet outlines to a fraction of their own thickness in error- don't take my word- do it "yo' own seff"
IF you do use chine bar (fine by me its your boat!!) then please don't make the mistake of holding them onto the chine tip of the frames with ANYTHING but wire!@!! do NOT, heat them up! no tacks-they will just bend as you've already found out. If you tack them to the frames its almost impossible to fair them back out again! don't allow any
hot spots along the bars or they will deform plasticly (not elastically!) at the heat- that could be translated into - kink or hogg.
Finally, if you build the boat and the seams cave in from your wild helmsman-ship??? then cover the seams with some 1/2 pipe or an angle or some other exterior shape! These could be stitched on and removed when crushed and replaced without rebuilding the boat.