fixing warped lock plate help

[brokenflint]

I need some ideas on how to fix a rough casting that is warped.  It has a slight s-shape running its length, the casting is really not thick enough to just grid away both faces.  At this point I don't know the material it was cast from.   This is the first lock I've ever attempted to build, so this is a figure it out as you go deal 

I was thinking of applying heat and hammering it flatten, what kind of temperature should I use so as not to overheat the steel but then again not underheat to create cracks.   What do you guys do in this case?

[keweenaw]

The first thing I would do is to see if the person who sold it to you would replace it with a unwarped plate.  On a steel plate you don't need to worry about developing cracks if you hammer on it but you'll have to get it pretty uniformly hot to get it flat by hammering and taking out a twist will be hard to do that way.  If I had a plate with a twist in it, I would simply put one end in the vise, put a crescent wrench on the other end and twist it back.  No need to heat if you have a big enough wrench.  You should be able to get it close enough to straight to flatten the surfaces by filing or the disc sander.

Tom

[Acer Saccharum]

In clamping/twisting, bending, try not to put marks from the vise nor wrench into the pate...it can be $#*! to get those marks out.

Most plates are cast from malleable material. They should bend without heat.

[Stophel]

You can whack them without heat generally.  Put it in the vise and give it a thump with a rubber mallet.  It's not hard to bend.

[Roy S.]

You can whack them without heat generally.  Put it in the vise and give it a thump with a rubber mallet.  It's not hard to bend.

Thats what I do

[omark]

i would lay the plate on a flat hard surface (anvil), and beat the high spots with a hard plastic mallet. just another thought.    mark   

[Stophel]

Let me relay a tale of crooked lockplates...

One time a guy sent me a lock to work on.  I won't mention the lock maker, but will say that the lock did not come directly from the manufacturer, but went through a second party before getting to the customer.  Anyway, the tumbler was never hardened, and it was quite wore out.  As I was working with it, I noticed that the lockplate was VERY bent.  Whoever the numnutz was that assembled the lock saw this lockplate, and instead of simply bending the lockplate straight, he actually bent the mainspring to curve around and fit the plate!!!!

[omark]

stophel, even im not that dumb!!!!!!!!!!   mark     

[Tim Crosby]

Whoever the numnutz was that assembled the lock saw this lockplate, and instead of simply bending the lockplate straight, he actually bent the mainspring to curve around and fit the plate!!!!

 Noooooooo! I got a good laugh ot of that. 

Thanks, Tim C

[Tim Crosby]

 Question: If you file/mill the inside of the plate flat,  wouldn't you have  to make adjustments to the bridle (If there) were it touches the plate and sear? I would think you could end up with problems not only with the tumbler and sear but with all internals.
 Am I thinking right?

Tim C.

[keweenaw]

If you're building a lock the inside should be flat, period.  Anything other than flat will cause problems.  Any holes you drill should be perpendicular to the flat inside of the plate.

[Stophel]

Question: If you file/mill the inside of the plate flat,  wouldn't you have  to make adjustments to the bridle (If there) were it touches the plate and sear? I would think you could end up with problems not only with the tumbler and sear but with all internals.
 Am I thinking right?

Tim C.

Needs to be flat in that area (the rest of the plate is actually not that critical, but it really should be straight!).  The bridle needs to draw down tight on the plate at the top, and it needs to be square enough so that the tumbler doesn't bind in it.  The bridle should NOT draw down on the sear.  The screw should bottom out just before the head starts pinching on the bridle.

Modern made bridles ain't that great.  They really only anchor with one screw.  Old bridles will have a pin behind the screw to stabilize the bridle.  I suppose ideally, the bridle would be anchored at the top front, and there would be a solid stanchion at the rear where the sear could ride on and the bridle could tighten down on it.  That would defintiely make it more solid.  I think some of the later English locks had setups like that.

[Longknife]

Most plates are cast from malleable material. They should bend without heat.

I'm glad you said most, I tried to bend an L&R percussion lock plate once. I laid it on a soft pine block and struck it squarely in the center with a hammer-it did not bend-struck it again-harder-no bend-again-harder-it bent and cracked very nicely-they weld up good too!!!!!!...Ed

[Jim Chambers]

As long as the plate is made of mild steel you can bend it cold.  Very few of our lock plates come from the foundry straight.  I open the jaws of my vice about three or four inches apart, lay the plates on top and tap it with a raw hide mallet.  I hold the lock plate up to a light source with a straight edge held on the inside of the plate to check for straightness.  After doing a few thousand plates you get experienced enough to know just how hard and where to hit it to get it straight with one whack.  Yes, I do this with every lock plate we make.

[Steve Bookout]

Jim, you just may be the first recorded lock plate whacker in all history!  I can see it all now..."The Honorable Company of Lock Plate Whackers"!  Cheers, Bookie

[Jim Chambers]

Have mallet.......will whack!......I just might be the all time best whacker that ever was.  Ha!

[brokenflint]

Thanks all for the replies, I'm going to take a hard plastic mallet to it tomorrow, I that doesn't work I'll just sign up for Jim's  "Whacker class 101  "