1030420W Welding the "monocoque" Y-Car

[Gerald_D]

"Monocoque (http://en.wikipedia.org/wiki/Monocoque)" <---click for Wikipedia definition
http://www.mechmate.com/Forum/messages/10/614.jpg
http://www.mechmate.com/Forum/messages/10/615.jpg

[Gerald_D]

These are terrible photos because the sun was still too bright when I got home from work http://www.mechmate.com/Forum/clipart/happy.gif


http://www.mechmate.com/Forum/messages/10/2567.jpg

http://www.mechmate.com/Forum/messages/10/2568.jpg

For the next step a good flat surface and a reference square is needed. I happen to have a granite slab and a right-angle plate at home, but you can use simpler tools.
http://www.mechmate.com/Forum/messages/10/2569.jpg

Place the car upside-down on the flat surface and make sure it touches at all four corners. Then get the vertical plates to be truly vertical before making welds O on each side side
http://www.mechmate.com/Forum/messages/10/2570.jpg

http://www.mechmate.com/Forum/messages/10/2571.jpg

[Gerald_D]

1. Weld A from the top, completely fill the square hole and then grind smooth afterwards to make weld invisible. There is NO welding underneath of point A.

2. Find the point on the other side of the car that is similar to point A and do the same weld & grind as in para 1. above. (Upper right of photos) Effectively, you weld one point and then go to a mirror on the other side.

3. Do the same for points B C D E F G H I & J, in that sequence.

4. Then welds at K & L

5. Weld N over the top only, find its diagonal partner and do the same. Same with M

FROM HERE EVERYTHING MUST BE SQUARE AND LEVEL........

6. Weld O & its partner, and so you carry on alphabetically

[Greg J]

I must be getting old (and in the way);).

I've finished my Y car weld up tonight and have all the welds gound down.

Still waiting on all my kitchen project parts to arrive. Hopefully everything will get here this week.

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[gmessler]

I took these photos (combined into one) of the same end plate to show the gap between the end plate and the main frame of the y-car. The left side has about 3/16" gap and the right side has about 1/8" gap. This is the same on both end plates. The main frame was bent waaay off.
Is there going to be an issue with trying to weld these ends?

[Gerald D]

Greg, that is not pretty. You will have to fillet weld those places from the inside of the car if you can't pull the gaps closed. The weld needs to be no longer than the tab. Weld in the tab area only - don't try to weld all the way to the edge of the thin plate. It shouldn't be a strength problem.

[gmessler]

I can cut a piece of scrap the size of the tab, place it behind the tab and weld from the inside. Frame to scrap, scrap to end plate. Problem with that is that the finished product looks like it was poorly built. T
he other option would be to check with Donald to see if he can bend me a new one.

[Greg J]

Greg,

Sorry I didn't mention in my earlier post and pictures. My weld up had the same gaps. I used long clamps and closed the gaps.

On another thread, remarks were made about the distance between the Y-car and spider plate being a tight dimension. My final Y-car and spider plate has about 0.25 inch (for the Imperially Inhibited ((Alan)) that's 6.350 mm :)) clearance. Not a problem, I can fill the void with spacers.

[gmessler]

Thanks Greg,

I'll try the clamps. My concern is that when I tighten the sides the top will bow up. Did you clamp after welding points c,d,e,and f?

How is your skate going?

[Gerald D]

Even if you use clamps, stay with the suggested sequence.

[Greg J]

Greg,

I welded strictly per the sequence. I can't remember at what point I used the clamps. It may have been at the very beginning before welding started. I made sure everything was square, level and perpendicular per the instructions.

I don't think the gaps are anything to worry about. Now, I haven't attached the V-rollers and seated the Y-car to the rails ..... but I think it's fine.

Greg

[Gerald D]

Only use the clamps when you get to the problem welds.

When you seat the car, remember there are some slightly slotted holes for 2 of the 4 rollers. The pic above seems to have caught one of the slotted holes.

[SteveE]

Just getting ready to weld up the Y car. I'm just making sure I get this right, In post #2, with the car upside down and squared, it implies that Weld O should be made. Then in post #3, it specifies the order of welds with one of the last welds to be made being O. Is O just tacked in #2 and fully welded in #3. Or is #2 just telling me to make sure all is square before I weld O in the sequence specified in #3? Last thing I want to do is get this thing distorted and out of square, so I figure a newbie question that seems dumb is better than not asking and paying for it later.....

Steve E.

[Gerald D]

I don't get your problem?

O is welded after M
O is welded before P
The sequence is: A B C D E F G H I J K L M turn over O P Q turn over R S <------alphabetical

Is it clearer now?

[Sherman McCoy]

Thanks Gerald for clearing that up, it was confusing to me as well based on the picture order and the text placement. I'm welding my Y-car tonight, and wondering if bolting the spider to the tower carrier plate before welding would ensure a better parallel fit for the assembly?

[Gerald D]

Your spider should be a loose fit inside the carrier plates, needing washers or shims to "fill the gaps" when you assemble. This leaves a little room to correct distortions during welding. In other words, don't be concerned with the spider while welding the y-car.

[jammer3808]

Thank you for your help ... I'm really enjoying this build

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[domino11]

Jammer,
Great looking pics, maybe start a thread for your build in the Construction started, but not cutting yet (http://www.mechmate.com/forums/forumdisplay.php?f=77) section. :)
Good Luck on the build. Gerald can copy the above posts over once you have started your thread there. :)

[Zouave]

My Y-car is sitting ever so slightly out of level and square. Will that be a significant problem in the long run? As near as I can tell, it might affect the wheels bearing on the gantry, correct? In which case I am going to want to pull this bad boy into square before I weld the next areas (at O right now). Should I worry about this? The perfectionist in me says yes, but the perfectionist in me wasted 6 hours of work today, so I figured I would ask...

[Gerald D]

The first post says: "Place the car upside-down on the flat surface and make sure it touches at all four corners. Then get the vertical plates to be truly vertical before making welds O on each side side"

[Gerald D]

The next post says:

"5. Weld N over the top only, find its diagonal partner and do the same. Same with M

FROM HERE EVERYTHING MUST BE SQUARE AND LEVEL........

6. Weld O & its partner, and so you carry on alphabetically"

[KenC]

Eric,
Follow those instructions religiously... Even if you must do it blindly... ;)

[Zouave]

Fair enough. :-) time to break out the clamps. Slightly off-topic, but lacking a good area to ask... in welding the nuts to the spider, I keep burning through the nuts, even adjusting my amperage down, and even doing relatively small tack welds. Will higher quality nuts make a difference in this? Ie, I am using cheap, low grade nuts that I had in the shop, should I go to an class 8 or equivalent? Will this make a difference in burn through?

[Gerald D]

Practice welding nuts onto some some scrap first. Strike the arc away from the nut and then bring the hot arc to the nut very briefly.

Or, weld some flat bar behind there and tap through (instead of the nuts)

(Different nuts won't really affect the welds)

[Zouave]

Alright, I'll give that a try. Worst case, I'll fill the holes, then tap them out and be done with the whole thing. Thanks again for the suggestions and help.

[bradm]

"Cheap, low grade nuts" - are they by chance zinc-plated?

If so, you should search on "welding zinc plated steel" (http://www.google.com/search?q=welding+zinc+plated+steel) - it will be more difficult. And don't breathe that white smoke!

[Zouave]

Once when I was younger and dumber, I welded zinc plated steel sans respirator. Never again...