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I Forge Iron

dovetail taper

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Sorry, brevity is usually a virtue, but I guess not in this case.
The taper I refer to is usually on one side of the dovetail on a die. The male dovetail. I believe one would normally use a straight key (for the straight side of the dovetail) and a tapered key for the tapered side.
The reason I ask is that I want to have some dies made up, or at least have the dovetail component (for bolt on dies) machined up. No taper means simpler and cheaper. If it also means ineffective then simpler and cheaper have to take a back seat.
For clarity, dies are not available for my hammer. For all I know it is the only one of its type still in existence, and the existing dies are knackered.

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So far as I can determine either way is is OK. I have two machines with dovetailed ways. On my power hammer the machine ways are straight/ parallel with the dovetailed surfaces on the dies tapered from one end to the other . On my screw press the machines ways are tapered while the die tapers are parallel.

In the case of my power hammer I have ignored the taper by using doubled wedges on both sides of the dies so that I can have exact alinement of the base dies for my quick change die system. I just use paired wedges on one or both sides so that the dies and wedges are fitted accurately to provide complete contact with with the machine ways. The power hammed dies have been wedged on the machine for years without loosening. From that I conclude that if the wedges are a good fit and make good contact between the dies and machine ways equally, either way is effective.

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The hammers I've either owned or worked on usually have parallel dovetail ways in the sow or ram and the keys are tapered around 1/8" over 12". Dies sometimes have additional taper and other times not.

I normally blue the parts and make sure there is a good level of contact on all surfaces; high spots are scraped down to improve the fit.

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Having a taper on at least 2 components in the die wedging arrangement is very important. It stops the dies falling out ;)

The standard im used to on a hammer is parrallel dovetail in the ram / sow block, taper in the die and key.

For small hammers, with multiple sets of dies it really makes more sense to have the taper in the ram and sow block. This means ease of manufacturing for all the die sets (parrallel dovetails)

Standard tapers im used to working with 1/8:12" taper (1:96) on most older hammers, 8 degrees angle. New chinese hammers are 1:100 , 7 degrees.

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