IanJ's Marquart Charger build thread

Discussion in 'Marquart Charger' started by IanJ, May 4, 2017.

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  1. Jun 9, 2018 #581

    taff

    taff

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    Making my I struts.
    For this weld, I started by tacking the sides and then start at the front making my way back. And the deep crotch was the last area I welded.
    I had and kept a good clean point to the tungsten (so that the arc wouldn't wander away from the target).
    I had about 1 1/2" of tungsten sticking out of the gas lens, to be able to reach up close.

    DSC_8351 (800x536)[1].jpg
     
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  2. Jun 9, 2018 #582

    Larry Lyons

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    Nice looking bead Eric
     
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  3. Jun 9, 2018 #583

    IanJ

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    Well, that answers the question of how you jam a gas lens into a space that tight. :D

    I tried TIG in my welding class, and didn't enjoy it. The gas torch made way more sense to me, so I'm going to stick with it until I run across a job where TIG is clearly a better choice. Then I'll have some pondering to do, and will be back with questions about TIG.
     
  4. Jun 9, 2018 #584

    Randy

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    IanJ, I am with you on being comfortable with gas welding. A couple years after learning to gas weld I bought a Tig on sale at Oshkosh, used it for about two hours and sold it. I learned to gas weld in the welding workshop at Oshkosh in the 70's. I told the instructor I wanted to go home knowing how to gas weld. He asked what that was worth to me, I said I would buy his breakfast every morning, he said count his wife in and I had a deal. So for 5 days I bought breakfast for 3 at 7am. By 7:45 we were in the weld tent with the flaps down and I got over an hour of undivided, individual attention. When the workshop opened at 9am I would just practice for a couple hours and again an hour or so in the afternoon. At the end of 5 days my instructor handed me a folded piece of paper, "Thank you for breakfast. You get an A+ for the class, see you next year." Best 15 breakfasts I ever bought :)
    You have taken welding classes so you probably already know most of this but for any others who don't here are some of the basic things I learned -
    1) If the flame is oxy. rich it will burn the carbon out of the steel causing it to be brittle.
    2) If the flame is Acet. rich it will add carbon to the steel making it soft.
    The solution is to set the flame so you can just barely see the acet. burning at the tip of the flame, better the steel is very slightly softer than brittle. If you cannot see this "soft" tip you do not know where you are and could be way oxy. rich.
    3) The torch tip should just 'whisper' as you weld. If you are turning the gas up past the 'whisper' point to get more heat you need to go to a bigger tip.
    4) If your tip is "popping" during the weld it is because the tip is to hot and you are igniting the gas inside the tip. Need bigger tip so the tip can be moved further away from the weld. "Popping" does two bad things, it can splatter liquid metal, which hurts like H-LL and sets clothes on fire or it can blow a hole through the tube - both are bad.
    Looking at your photo in post #570 the way I would weld it is to tack the tubes together in 4-6 spots. For me this works better than trying to jig the parts together. Weld up each side of the joint, welding thru the tack's, as far as you can and keep a good looking weld. Then connect these two welds across the top. My Oshkosh instructor taught me to weld up the sides to the point of being able to lay a piece of welding rod from one side of the joint to the other while it just touches the two angled tubes. Tack the rod to one side of the bridge then bend the rod down until it touches the other side of the bridge and burn it off. This plugs that deep chasm that all your heat goes into when trying to weld across. At this point you will need to go to the next diameter rod to reach from one tube, across the small dia. weld rod and into the tube on the other side but it will weld much easier. It also helps to use a larger tip just to preheat the cluster then switch back to the tip needed for welding. My wife is very adept at holding a handheld propane torch on cluster welds to give me the extra heat I need.
    When welding shorter tubes, the final closure weld will usually result in blowing a hole in the tube from the heated, pressurized air inside the tube. The way to prevent this is to drill a very small hole in the tube before closure. Finish welding the tube closed. After it cools you can go back and weld the small hole closed quickly enough that the air pressure does not reach 'blow thru' stage.
    As far as selecting the correct tip, that will come with experience. You will see how long it is taking to preheat your weld area and just know you need to go larger or smaller.
    And last but not least, whenever you finish a weld pull the heat away slowly, maybe 5 seconds or so before you take the heat totally away. This lets the weld normalize.

    P.S. I have done a fair amount of aircraft welding and have yet to find a place where Tig is a better choice for me. I think the reasons are, A) I know how to gas weld and B) I don't have a Tig welder :))
     
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  5. Jun 9, 2018 #585

    cwilliamrose

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    Your gas welding experience will help you if you ever decide to go the TIG route. I was a decent gas welder when I learned TIG and before I was anywhere near good enough at TIG I had already sworn off gas welding. TIG solved all the things I didn't like about gas welding mainly having to do with a lack of direct heat control. Hang in there....
     
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  6. Jun 9, 2018 #586

    wfrandy

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    Actually, a neutral flame is what you should always shoot for. An oxidizing flame while burn the metal causing it to be porous and brittle. A carburizing flame will add carbon to the metal increasing its hardness, which also makes it brittle. In fact, a carburizing flames primary use was to apply hard facing back in the old days. So, for good quality welds you need to adjust the flame so it is neutral with just a barely perceptible lean toward carburizing at most. If their are a lot of sparks coming from the puddle it is probably oxidizing, if the puddle is bubbling without sparks, it is probably carburizing, neither is good. The advantages of Tig welding over Oxy-acetylene are, 1. more control 2. smaller heat effected zone 3. Inert gas shields the molten puddle from oxidation or absorption of impurities, such as carbon 4. and specifically for 4130 thin tubing, the ability to weld slower with less heat into the weld zone, while still achieving full penetration. One other tip, about filler rod, while you can gas weld 4130 tubing with 4130 filler rod, in fact, it is often specified for certification welds, do not use 4130 filler rod with Tig as the welds will be too brittle, use ER80S-D2 or ER70s-2 or equivalent instead. Personally, I would never use 4130 filler rod, unless it was for a part that was to be post weld heat treated, I personally use ER70s-6 rod when gas welding 4130.
     
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  7. Jun 10, 2018 #587

    IanJ

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    Thanks for all the tips! I knew some of them, am learning others, and didn't know a few. The bridging trick with welding rod is neat, I'll try that.

    I'm using R60 welding rod, which is what the welding shop said was the right thing for what I'm doing. Some destructive testing suggest that this is the case -- I generally rip the steel at the edge of the HAZ like you'd expect, and the welds have been solid.

    I finally had the correct brain spasm today: I can use 1018 steel for my compression tube bushings. This means I can machine them right now instead of waiting for the never-ending ACS order (my own fault, I keep adding to it). There's no need for a glorified nut-and-washer to be 4130. A fine use of my current downtime as I wait for more materials from afar.
     
  8. Jun 12, 2018 #588

    sdeldred

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    Hey IanJ


    Stumbled upon this thread, specifically about fuselage tubing and buying a kit.
    I'm just puting the finishing touches on my Charger, (covering wings, finishing up FWF).
    My brother has a Charger Project - Fuse, tail, landing gear even some wings, engine mount etc (no flying wires)
    Let me know if you want me to put you in contact with him - He lives in Springville Utah.
    Stevee
     
  9. Jun 12, 2018 #589

    IanJ

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    Thanks for the offer! I'm going to stick with my plan to build on my own for now. Give me a few more years to get really discouraged with my progress, then I'll probably start looking at projects. :D
     
  10. Jun 14, 2018 #590

    IanJ

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    Heh, I spent 2.4 hours working on the plane last night, and all but .5 was actually spent getting the lathe back into happy shape. The cross-slide was being finicky and sticking rather than sliding. All the bearing surfaces got a light polish, and once I had everything back together in the right orientation with the right oil (note to future self: Tri-Flow is not the right oil) it was... just about the same. Slightly better. Oh the joys of maintaining the toys. :D If I had more space, I'd consider upgrading to a bigger lathe just to have things like cross-slides be higher quality with human-sized handles.
     
  11. Jun 26, 2018 #591

    IanJ

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    In late April, I ran out of rib materials, and placed an order with ACS. On June 1st, with the announcement of the steel and aluminum tariffs, I decided it was time, and added $2k worth of steel tubing to my ACS order, hours before the initial order was set to ship, so I could share the $200 truck shipping fee. Yesterday I called to see what the holdup was -- 7/8 x 0.035" tubing was out of stock. And when was it due back in stock? Oh, just August 15th. Too long! So, drop that from the order and buy it locally, so I can actually get back to building an airplane again. Got a call later, the capstrip (to make the final four ribs, plus some for random other use throughout the wing) was not ready, and the one and only "wood guy" is on vacation until the second week of July. Perhaps the capstrip that was ready to ship on June 1 was sold to someone else (or the wood guy is the only person who knows how to find it, if it's still around). Another 3+ month wait for stuff that's all listed as "in stock" on the website.

    This mini-rant brought to you by, "I always figured it'd be a years-long project because I was unskilled, not because I couldn't convince businesses to sell me stuff."
     
  12. Jun 26, 2018 #592

    IanJ

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    I am making progress on the compression strut bushings, at least. IMG_20180615_184507.jpeg
     
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  13. Jun 27, 2018 #593

    pbrannan

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    There is a place here in St. Louis called Shapiro Supplies, https://www.shapirosupply.com. They used to be cheaper than ACS or Wicks. And they ship. Given that I'm 15 minutes away I have never used their shipping. Might be worth a shot. Given the neighborhood they're in I've been tempted to ship anyway.

    I also use Wicks for steel and they tend to tell you what they have and get it shipped fast, though again I pick up most of the time. The only big holdup at Wicks is for spruce. Don't ever bundle a Wicks order with spruce if you want anything fast. Make two separate orders. But if I tell Wicks I'll be there for steel in 45 minutes they always have it ready. And when I ask for shipping it's always shipped same day.

    And as we've noted, several of the Charger steel pieces are no longer produced. That's it's own bit of frustration.
     
  14. Jun 27, 2018 #594

    IanJ

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    Yeah, I'm skipping the crazy size needed for the compression tubes, and just ordered thick 3/4 that I'll turn down in the lathe. Way cheaper than ordering the non existent stuff from Wag or whoever it was that claims they have it. We'll see if I regret that - I've never tried turning 4130, and it may suck.
     
  15. Jun 27, 2018 #595

    TFF1

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    Instead of turning, find an sympathetic auto machine shop and grind it down in a crankshaft grinder. There would be no record groves then. Maybe to much huh.
     
  16. Jun 27, 2018 #596

    IanJ

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    That would be easier for me, for sure. I was planning on turning and polishing (the polishing step is specifically called out in the plans) to get a good fit into the 3/4 x 0.035" tube. Thanks for the idea.
     
  17. Jun 27, 2018 #597

    Dave Baxter

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    Ian My lathe is covered with stuff and a lot of chips from numerous past little jobs, I use the table for an extra storage shelf but it always seems to work with the bed pushing stuff out of the way when I need it. Do not want to post a picture as you would probably be AGHAST!

    I have some cap strip, probably enough for several ribs, there are abut a dozen and around 52" long I would give you, but their not fresh? Dave
     
    Last edited: Jun 27, 2018
  18. Jun 27, 2018 #598

    Kiwi

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    Not sure what the fuss is about turning 4130N. Here is a sleeve I turned to go inside a stock sized tube similar to what you're doing Ian. Sure I polished it with some emery tape so it looked good, but I'm like that. With the right amount of cut, it can look darn good straight off the tool. And I'm no machinist, I was talking lathes with the son of the guy who let me use his lathe and had to confess it was 30 years since I'd used one.


    IMG_3568.jpeg
     
  19. Jun 28, 2018 #599

    IanJ

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    Dave: thank you for the offer. If ACS keeps delaying me, I may take you up on it, but for the moment I'm using my time well enough making bushings on the lathe.

    Kiwi: I've never worked 4130 before, and I know it's much stronger than the 1018 I have worked. I don't figure it's going to be too hard to work with or I wouldn't have ordered a bunch of 4130 with the intention of turning it down. ;) I just have to remind myself from time to time that assumptions like that are occasionally unwarranted, and I may have to find alternatives to the initial plan.
     
  20. Jun 28, 2018 #600

    cwilliamrose

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    Your intuition says the softer, weaker material should be easier to machine. That is often not the case. 1018 is soft stuff and sometimes it would rather tear out than cut cleanly, especially if the tool is worn, speeds and feeds aren't in the ballpark, etc. As an example 6061-T6 machines OK, 2024-T3 machines beautifully.
     

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