Did I ruin this? (Towbar revery point) - Page 2
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  1. #26
    Join Date
    Jun 2012
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    Bemidji MN
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    Re: Did I ruin this? (Towbar revery point)

    Quote Originally Posted by farmersammm View Post
    If the situation presents the possibility of tear out on the thinner material.

    Attachment 1699301 This area is relatively thin. The underlayment is 3/16 material. Not strong enough for mounting a D ring. So the area is padded with thicker material (with higher yield), and the force is spread out over the thin material with long welds around the perimeter of the pad. Always think about what you're building for, in terms of stress. This ring is designed, and has been used, to drag the truck and fully loaded gooseneck out of the mud. Sometimes, due to the angle required, only one ring is hooked to the chain instead of a bridle arrangement connecting both rings. You have to forsee these things.

    Anyways...…..it's just some thoughts that might be helpful
    A very good pic of what to do when adding a D-ring.

    I disagree with "spreading the force with built up weld" though.
    Strength is still limited to the thickness at the toe of the final weld no matter how many welds are made - in my opinion.

    I do not believe you will be able to source material that allows for "over-welding" in lieu of a flat plate for the pad.
    But I've been wrong before

    AWS Table for fillet welds:

    Name:  Table 5.8 AWS D1.1 page 209.png
Views: 137
Size:  66.4 KB
    Last edited by MinnesotaDave; 03-18-2019 at 11:07 AM.
    Dave J.

    Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

    Airco 300 - Syncro 350
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    Tried being normal once, didn't take....I think it was a Tuesday.

  2. #27
    Join Date
    Dec 2018
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    1,066

    Re: Did I ruin this? (Towbar revery point)

    Now, here's a guy who I admire for his ability. Works at K'kins shop.

    Name:  wire2.jpg
Views: 149
Size:  145.4 KB You can see that the weld was built up because the underlayment was in question. This is a tie down ring for an oilfield float trailer. They haul insanely heavy stuff. Again...……..you can see how the force is spread.

  3. #28
    Join Date
    Dec 2018
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    1,066

    Re: Did I ruin this? (Towbar revery point)

    Quote Originally Posted by MinnesotaDave View Post
    A very good pic of what to do when adding a D-ring.

    I disagree with "spreading the force with built up weld" though.
    Strength is still limited to the thickness at the toe of the final weld no matter how many welds are made - in my opinion.

    I do not believe you will be able to source material that allows for "over-welding" in lieu of a flat plate for the pad.
    But I've been wrong before

    AWS Table for fillet welds:

    Name:  Table 5.8 AWS D1.1 page 209.png
Views: 137
Size:  66.4 KB
    One would then have to abandon the lowly fender washer. https://www.bokers.com/fender_washers.asp

    I believe what we're trying to prevent is tearout, and yield. Moving the moment further from the concentrated point of stress is generally a good thing...….consider a gusset.

    The builtup weld is not ideal, but it's a microcosm of the pad situation. Spreading a concentrated load.....either in shear, or tension.

    If we accept the pad as an ideal solution (or at least as ideal as we're gonna get) to a problem, then we have to really look at why we consider it a good solution. There's additional weld length over a larger surface area. If we were to limit the strength to the base metal, we'd have to find some way to say that the thinner base metal will tear/bend at the toes of the additional weld length...……….but it exhibits a tendency to resist more than simply welding a concentrated load point connection.

    Sorta like the lever.

    Some ill fed slaves, building the pyramids, started using a lever to move those bigazz stones.

    The guy in the clean clothes, sitting under an umbrella, sipping whatever they sipped in those days, looked at what was goin' on, and had to admit it worked. Didn't know why it worked, but it sure was movin' some stone. MSPD...……….More stones per slave death…...your mileage might vary

    So...…...this guy taps his mathematician/physics guy on the shoulder...……"Hey doooood,, go figure out why that works, or at least put some numbers to it, so's we can impress the Pharaoh. Observation, and rote practice, precedes "knowledge"

  4. #29
    Join Date
    Dec 2014
    Location
    Australia
    Posts
    20

    Re: Did I ruin this? (Towbar revery point)

    Thanks for all the feedback. It is late here so I will have to read all the references tomorrow. Just to clarify:
    - There is a clearance issue with the plastic bumper obscuring the tow bar hence the length of the arms;
    - I have to locate the attachment point off centre because of clearance issues when a bike rack or similar item is attached to the hitch receiver. I would have liked any attached accessory to have included an inline hitch extension but the Yakima Backswing, for instance, is not designed that way, and I did not want to modify it;
    - The arms of the attachment were firstly welded to a 75x75x10mm plate to provide a larger attachment surface for welding to the 6mm thick tow bar. This plate was actually “L” shaped with the 20mm lip at the rear for added weld area but that now sits at the front (all a bit hard to photo with the bar installed).
    - It might be possible to support the raked pin holders with a vertical support welded onto the vertical face of the tow bar. - the addition of lateral supports to counter sideways bending might be difficult because if its close location to the anderson plugs that can’t easily be moved but a small gusset might be possible. I could also add an internal breace between the legs to stiffen it up.

    Sorry for showing my ignorance regarding what “hot” means, I guess I was trying to imply that the welds seemed to go down nice and smoothly (I was having a lot of fun burning the 7018s and in the interest of full disclosure they were not dried in an oven before use but had just been stored in a sealed rod holder since the packet was opened some time back.).

    So given the situation, what is the consensus thought of fixing this? i am happy to redesign it if necessary.
    Last edited by Dunk_c; 03-18-2019 at 12:32 PM.

  5. #30
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    Dec 2018
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    Re: Did I ruin this? (Towbar revery point)

    Not to hurt your feelings, but you really have to practice your welding. Learn to drag that rod, not whip it, and do dollops.

    Turn the machine up to at LEAST 125amps, and just drag the rod along while watching how the puddle flows, and builds. It shouldn't take very long before you get it.

  6. #31
    Join Date
    Dec 2018
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    1,066

    Re: Did I ruin this? (Towbar revery point)

    On thin material, use 3/32 rod, and run at about 85amps. You'll get it

  7. #32
    Join Date
    Dec 2014
    Location
    Australia
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    20

    Re: Did I ruin this? (Towbar revery point)

    No hurt feelings. Very happy you guys are taking the time out of your day to provide some advice

    Just want this thing to be safe to use. Should have asked advice before starting - lesson to be learnt there!

    Quote Originally Posted by farmersammm View Post
    Not to hurt your feelings, but you really have to practice your welding. Learn to drag that rod, not whip it, and do dollops.

    Turn the machine up to at LEAST 125amps, and just drag the rod along while watching how the puddle flows, and builds. It shouldn't take very long before you get it.
    Last edited by Dunk_c; 03-18-2019 at 12:11 PM.

  8. #33
    Join Date
    Dec 2014
    Location
    Australia
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    20

    Re: Did I ruin this? (Towbar revery point)

    Sorry that should be 75x100x10mm base plate

  9. #34
    Join Date
    Oct 2006
    Location
    Illinois
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    8,727

    Re: Did I ruin this? (Towbar revery point)

    Quote Originally Posted by farmersammm View Post
    On thin material, use 3/32 rod, and run at about 85amps. You'll get it
    We do pipe welding using 3/32'' Lo Hi 7018 even on 6'' schedule 40. First pass is 1/8'' 6010 5P and then the 3/32'' 7018 Lo Hi. Generally the heat setting for 1/8'' 6010 is good for 3/32'' Lo Hi. Some prefer to set for 3/32'' Lo Hi. Most times the machines are hundreds of feet away. The reason one setting for both rods.

  10. #35
    Join Date
    Dec 2018
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    1,066

    Re: Did I ruin this? (Towbar revery point)

    Quote Originally Posted by Dunk_c View Post
    No hurt feelings. Very happy you guys are taking the time out of your day to provide some advice

    Just want this thing to be safe to use. Should have asked advice before starting - lesson to be learnt there!
    Most of these discussions can get interesting...……….have a life of their own.

    I was looking at a discussion concerning padding. This thread got me interested in looking into it further.

    https://www.eng-tips.com/viewthread.cfm?qid=189663

    I've always stuck my tongue out the side of my mouth, and guestimated the thickness of the pads I use. Idea being to use something thick enough where it won't bend under load. I'd never heard of the method discussed in the thread I've linked to. Interesting stuff.

  11. #36
    Join Date
    Dec 2014
    Location
    Australia
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    20

    Re: Did I ruin this? (Towbar revery point)

    Poison pad. What is that?

  12. #37
    Join Date
    Dec 2014
    Location
    Australia
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    20

    Re: Did I ruin this? (Towbar revery point)

    OK. This weekend it is coming out. I will cut off the arms with a portable bandsaw and reattach in correct orientation. I will also tie the arms together or add gussets to stabilize aganst lateral bending if the tow rope is angled to the vehicle. I will use all the welding advice provided and will upload some weldment pictures before painting as I would like some feedback.

  13. #38
    Join Date
    Dec 2018
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    Re: Did I ruin this? (Towbar revery point)

    Quote Originally Posted by Dunk_c View Post
    Poison pad. What is that?
    Has to do with dissimilar metals touching each other.

    https://www.materials.sandvik/en/mat...nic-corrosion/

    http://www.designbyinitiative.com/fi...anic_Table.pdf

    You'll hear guys talk about isolating aluminum, and steel, to prevent corrosion. This is what they're talkin' about.

    Let's say...……….you got an aluminum frame trailer, with a steel suspension...…….you have to provide a physical barrier to keep the two metals from coming into direct contact...……. https://www.trailer-bodybuilders.com...similar-metals

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