2 pc knee/elbow cops

[ArtemisGreen]

I was working on developing a pattern for 2 piece knee cops before I lost every bit of free time I had. Now I have some free time, but not much. Making these easy, weldable knees would save me an assload of time. Would anyone please help me out here on my pattern? I seem to keep sucking at it.





and the patterns that I tried...

Part 1
Part 2

The problems I'm having are self-evident. The "v" at the joint of the 2 is the biggest part. My second issue is the gaps I keep getting between them. That can be eliminated with some grinding, but the v still has yet to be figured out...

Any help (like always) is appreciated.

~Arty

[Wulfgar]

The gaps in the knee looks to me like you are dishing too much, what i was told was to dish the cop lightly so it was narrow and then get the edges as close as possible, weld and then pull fron the sides opposite the weld point and stretch the cop out, this will also dish it more, that may actually reduce the V shape somewhat.

i also think that the curve of the area you are trying to weld is too extreme, might need to be made shallower.

thats about all the help i can give.

Wulfgar

[Hew]

<warning>I've never fabricated anything by welding,</warning> but I think I understand what you mean by the "V" at the joint.

The corners of the two pieces would have to be 90 degrees for the joined corners to appear smooth, even if they curve along the seam. Think of the corners on either side of the round edge of a piece of pie.

After any dishing or bending, the edges to be welded (of both pieces) should be able to touch a plane surface all along the edge. I suppose one way would be to tape a piece of sandpaper to a flat surface, and then rub the edge of the piece to see where the high and low spots are.
Or, stand them up on edge and slide a marker around on the flat surface, marking the steel as you go. That line should define a plane.

Of course I'm just winging it here.

[Halberds]

Hi Arty,

I have been trying that too. I think your pattern is too rounded on the weld curve.

What I have found is to leave metal then dish each side then cut and match.

The single piece works better for me. The flared edge is no good with the welding. For your application the welded should be ok.

Dish the sides a little more to keep it from getting too sharp. If you can re-dish after welding you may be able to shape it better.

For such simple looking parts they can be quite tricky.... as I am finding out.

I hot worked my latest piece to some pretty good results:
http://home.armourarchive.org/members/h ... ttempt.jpg

What makes it fun, is a client is standing by asking about his custom knees and elbows.

It really sucks when you have to tell him that you are still learning how.


Best of luck on your quest Grasshopper.

Hal

[Halberds]

BTY your welding gap is excessive....

You can hammer it closer than that....

[sebastian]

As to your welding, Tack weld the center before doing the ends. This should keep it from gapping.

As to why you have that Huge V shape ...
I think you maybe dishing them to small. You have a lot of flat metal in that V. Switch to a bigger dishing form, and start about 1/4 of an inch from the edge and work in.
Remember you can always dish it more, but you can't effectively "un-dish" it.

[Halberds]

Ahhhh...... Un-dishing that is doable. I have found a way, quite by accident.

On my spangen panels sometimes the edges are dished too much. Oops...
now what? I have a 8" steel welding pipe cap, nice radius to the dome.
I lay my part on it and hit it with the weighted rawhide mallet.

For an elbow or knee the 4" would be quite nice. Come to think about it the 4" mushroom on the pedestal would be perfect. Wow... one could raise the reminder of the cop over it too.

If the metal was red hot it should mold like butter over the form..... Now we get into the raising hammer debate.

Damn... I like this construction board.

Hal

[Rhoetus]

Guys, please, don't waste your time, welding these.
ESPECIALLY if, as it looks, you are heating the metal...
You can bang out a knee cop in an hour, cold forge, and the time saved in grinding and cleaning will make up for that,.

[white mountain armoury]

Making a welded cop should be fast and painless, as Rhoetus said it does not take long to make one from a single piece, so if its welded it should be fast.
I just made the cop in the pic, from beginning to end, with all needed tools laid out, welder ready etc it took 17 min.
You simply need to dish your piece, its not nearly ready to be welded as its not close to being shaped enough.
This is a very basic cop, nothing special or fancy, 14 ga mild steel.
The pics should be pretty much cover the bases.
Trace pattern and cut, shape the halves, crease and curve the fan, tack weld, then a small weld for the front side, the piece will be to "closed" so stretch it open, i use a form made from a pipe,
Once its where you want it put a sound weld in the back, grind the weld on hte front and dress the fan crease. Polish.
Welding it from 2 pieces is nice because it can be very fast and therefor can be very cost effective, it should not replace traditional forming skills though.
<img src="http://www.whitemountainarmoury.com/weldedcop.jpg">

[sarnac]

thats a nice looking cop Adam.

you would never knew it was welded from the outside

[Greylond]

Yeah.. and he does it in 17 minutes.

I am positively green with envy.

[Halberds]

Holey cow 17 minutes......
I have been fussing with knees for over 10 hours. and only have this sloppy prototype to show.


17 minutes indeed.....where is my towel?

Thanks for the progress pics very nice Adam.

[belmtho]

adam, very very impressive

it takes me 17 minutes to cut and file my blanks(sigh)

what did you use to shape the halves are they just bent round something round?
or dished with a rawhide/rubber mallet?
cheers
tom

[white mountain armoury]

A rubber mallet into a dish, then i used a masonry chisel to start the fan crease, then a brass hammer to define the crease on a stake.
The fan is curled over a 4 in pipe.
Cleaned up with an expanding wheel.
I made the cop pretty much to help with Artemis question, but one cop wont do much good so i will make it a mate, if there is a part of the process you want to see let me know and i will take more pics.
Hal, i spent a bit of time fussing with my first, once the pattern was refined and the process it becomes very fast.

[belmtho]

so it is only dished a bit to start with then match them up then dish then match THen weld on just the frount then expand the inside then weld the back?
cheers
tom

[ArtemisGreen]

Thanks everyone! That helped me out a helluva lot

Hal- I knew that the gap was excessive. I only had a series of tack welds at the ends there just to hold it temporarily. That was what I was trying to improve. Thanks to Adam's pics, I see that the problem was in my forming, and not the pattern.

Now all I need is a good dishing form. All I have left is a sandbag, which I have trouble using. I need to find myself a stump again. Pity mine had to be left behind (still rooted to the ground) when I moved.

Oh, and btw Rhoetus, I'm not heating these. It's scrap I found at the dodge dealership I work at. Not intended for combat use by any means. Just something to try my pattern out on. That's just layers and layers of ugly/crappy paint. It's probaby 22ga, that comes out to @ 18ga with all the paint

[ArtemisGreen]

btw Adam, did you print, cut, trace, and cut the pattern that I came up with, and then form it into that!?

[white mountain armoury]

No, its my pattern ive been using for several years now, although its similar to yours.

[AB Hammer]

LOL welded patterns have been around almost as long as the SCA for our purpose. When I was getting started back in the 1980s I had the best of the hammer books which helped me and the only cops I saw other wise were very flat or they where welded.

You want some welded designs I have all kinds of them.

AB Hammer