treadle hammer safety catch?

[shipto]

I am in the process of making myself a treadle hammer and have most of it built however I cant help feeling a little worried about the safety.
I have a single spring to hold the hammer up and if that spring should break obviously the hammer would just drop.
Now taking Murphy's law into account there is a chance that there could be a finger under it when this happens.
I was thinking of some kind of catch which if the spring breaks then this catch would block the movement in some way.
If anyone has a treadle hammer could you post pics of the safety devices on them to give me ideas please.
Thanks in advance

just a quick edit: I do work safe and will of course refrain from sticking fingers under the hammer I just want to make sure that if I forget myself I have a good chance of my fingers staying round rather than flat.

Edited November 1, 2009 by shipto

[Nakedanvil - Grant Sarver]

I think that would be hard to, but not impossible. Given that the hammer is made to come down, you're trying to keep it from coming down under certain conditions, tough thing to do. It would have to be connected to the treadle so the hammer is free to come down when you want. I would never bother with such a thing given that the spring will probably fail only when you stretch it out.

[shipto]

Thats a good point actually but just posting this and posing the question has given me an idea I could have a catch that is part of the foot rest that when I place my foot on the rest it will move the catch away and allow the hammer to operate normally but if there is no foot on the rest and it tries to come down it will not allow it.

[RainsFire]

could also just kick a brick under the pedal quick fix

[JNewman]

I used to just put a block of wood under the treadle. At Quadstate I noticed Mindy Gardner's treadle hammer had a heavy arm over the head with a chain to the head so that the head could only go so far down. She was using a lot of hand held punches under the head and that way if a tool broke or skated out from under the head her hand would not be crushed. The arm was quite heavy as that is a lot of force to stop suddenly.

[781]

I have seen several hammers with a chain from the top
At Saltfork conference Robb Gunter used an adjustable round pipe clamp.
This was mounted behind the anvil.
The pipe had a rubber bumper on the end and was adjusted up and down so the bumper stopped the lower arm from coming down further. He used the hammer to chase designs cold in 3/16th plate.
I would have footage of this clamp some where but not easily accesed.

[Iron Falcon 72]

Here's what it looks like. It workss on a swingarm. You'd have to have some kind of arm sticking out to catch it on a vertical drop.

[pkrankow]

That's part of a woodworking clamp that goes onto black pipe! You can get real good ones for about $50 a set, but Harbor Freight sells a decent unit for less than $10 (strange but true)

Phil

[SGropp]

I have a double ended hook that I use to lock the treadle in the up position when the hammer is not in use.
I built one of the ''modified'' treadle hammers from the ABANA plans years go. This design has two coil springs to lift the treadle,linkage and head back up. The head weight on mine is 85#, a solid 4 inch square block of steel about 16 inches long.
A couple of years one of the springs broke and the head came down like a ton of bricks.
No harm done, but it was an eye opener.
I'm not sure how you could make an effective safety for the hammer in use. The tool is just too darn useful to not utilize because of the danger, just be careful to keep your hands out of the danger zone.

I use my treadle hammer all the time for punching, cutting ,splitting and most any operation that you would use tools and a striker. Just like a power hammer the blow is limited to straight up and down. Someday maybe someone will come up with a design that can strike an angled blow.

[Jacob]

I just got my inline hammer built and have been doing some chasing in sheet metal. I've been using a block of wood under the treadle, but that would still be as bad for the linkage as stomping it to the ground. The best stop would catch the hammer head before the hammer and anvil meet. This would work well for chisels and tooling, but would have to be removed for mounted tooling including flat dies. I have seen another inline hammer design with a heavy pin that could be inserted into one of a series of through holes. I considered drilling holes through the top section of my 3" diameter hammer, but did not. A clamped on stop could be made for inline hammers, but it would not be as secure and it would tend to vibrate loose. It would also screw up my pretty new paint. I've been holding chisels by hand under the hammer, so this is a topic I've been thinking on. The heavy overhead arm with a chain is an interesting idea.

[shipto]

Thanks for all the replies I have started on the treadle catch and will add a piece of chain so i can lock the hammer in place when not in use.
I have included a pic of what I plan to do.

[pkrankow]

Looks like a trigger safety on a gun. You might be served better by having the spring elsewhere instead of between the safety and treadle. You could then use a piece of round or flat bent into a rim instead of a cover plate. Maybe looking up firearm safeties would provide additional insight.

Phil

[crij]

How about welding plates on the main support near the pivot, so the plates extends above the arm behind the pivot. Then all you need to do is add a pull pin that goes through the plates and prevents the arm from falling.

On the other hand with the over arm idea, how about just running the chain up to a ceiling joist?

Just some ideas,

Rich C.

[Iron Falcon 72]

I have a double ended hook that I use to lock the treadle in the up position when the hammer is not in use.
I built one of the ''modified'' treadle hammers from the ABANA plans years go. This design has two coil springs to lift the treadle,linkage and head back up. The head weight on mine is 85#, a solid 4 inch square block of steel about 16 inches long.

Is the "modified" a swingarm type rather than a straight up and down? If so the safety shown in my previous post is designed for it. One simply adjusts the pipe up or down to provide hand/finger clearance but still hit the tool.

[SGropp]

Ironfalcon,

Yes, my hammer is a swing arm type where the two arms swing in parallel. This makes for a dead flat blow, which is excellent for closing the hem on heavy sheet metal, among other things.

The safety stop with the pipe clamp looks like it would work for some applications. A lot of times ,I'll say, chisel a line or slit with a top tool and then flatten the piece which has curled up from the chiseling with a solid flat blow of hammer head. A fixed stop wouldn't allow that unless I used a flatter that was the same height as the chisel.

There is a a certain amount of jarring vibration to the hammer in use which might cause the clamp to slowly creep out of adjustment.

If you put a hardy hole in the anvil of the hammer , make it the same size as the one in your anvil to avoid needless duplication of tooling.

[Iron Falcon 72]

A fixed stop wouldn't allow that unless I used a flatter that was the same height as the chisel.

There is a a certain amount of jarring vibration to the hammer in use which might cause the clamp to slowly creep out of adjustment.

If you put a hardy hole in the anvil of the hammer , make it the same size as the one in your anvil to avoid needless duplication of tooling.

Just to clarify, only the clamp is fixed. The pipe w/the bumper on the end slides up and down and is held in position with the clamp. It didn't seem to move when Robb Gunter was using it. But, it's certainly good to keep an eye on it. Edited November 4, 2009 by Iron Falcon 72

[shipto]

just thought I would post a pic of my progress with the hammer, still a bit to go but hopefully should have the rest of it in place to complete it next weekend. Sorry the pic was taken in the dark but I had to wait to borrow the camera, will take better soon.