[TheForge] fly press

[George Dixon]

A while back there was discussion about fly presses.  One thing to 
consider is that there are various types of manual presses, they look 
similar (as in 'almost identical') but work very differently.  One is 
worth having the other is not.......
A fly press has a screw that is cut at a steeper angle than a proofing 
press.  The steeper screw makes for much faster ram travel.
A proofing press has the same shape as a fly press but the screw threads 
are not nearly so steep.  These units are (were) used to check dies for 
alignment and such.  Speed was not an issue for a proofing press, they 
are for cold operations.

The critical issue in a fly press is the speed of travel and the length 
of stroke per turn of the top wheel or arms.  A fly press with a steep, 
triple lead screw will move the tooling fast enough for hot work, a 
proofing press will not.  
A fly press can have have from 2 to 3 inches of  vertical travel for 
each rotation of the screw (wheel or arm driven), a proofing press can 
have 2 to 3 rotations of the screw for each inch of travel.....the 
latter is too slow for hot work.

"Brad Silberberg's fly press", referenced earlier, has 3" of travel per 
rotation of the screw. (I bought it a over a decade ago).  It is an 'H' 
frame, with the work piece being set between the legs of the 'H'.  A 
smaller 'C' frame, in the shop, has less travel.  "C" frame presses also 
flex under load.

The larger 'BS' fly press can easily slit 6" to 8" of 3/4" bar stock, on 
the diamond, in a single heat.  The smaller one rarely gets used. 
 Bigger is better but check the screw.

George Dixon