Wohlhaupter UPA4 Boring and Facing Head Operation

Thought I'd finally bring this thread to a conclusion. I recently got around to making the small 'tophat' detent for the coarse feed. I made some careful measurements, with a depth micrometer, of the depth of the housing to the shaft and the depth of the housing to the ball fully home. That enabled me to design the 'tophat' and then make one in silver steel. I bought the compression spring rather than make one. Once the parts were fitted the coarse/fine feed works exactly as advertised above.

This weekend I've been boring the HP liners for my traction engine cylinders:

Now that the boring head works properly it's a joy to use. Easy to rough out using the coarse feed and then swap to the fine feed for finishing. The feeds are spot on; for one liner I put on 4½ thou (on diameter) according to the fine feed knob divisions, and as far as I can tell with an internal micrometer the diameter increased by 4½ thou.

The bores measure round and are parallel, measured at each end, to within 2-3 tenths, and the bores on the two liners are the same to within 2-3 tenths. The bores are 4-5 tenths undersize to allow for honing.

One happy bunny here! Now celebrating with a glass of wine. It's just so nice to be able to use quality kit that does what it says on the tin.

Andrew

NB: Thanks to SoD for the link to the program for generating fractions that he posted recently in another thread.

Must be 50 years since I operated a Genavoise jig boring machine with a Wohlhaupter boring head. A joy to use, thanks for posting.