Wohlhaupter Boring Head Shank

1968FJ40 · Oct 27, 2019

Recently I was given a job that required a 7" deep by 1.250" bore. Fearing that my little 1/2" Emco boring head wouldn't be up to the task I asked a friend if he had something bigger that he could lend. Happily he had a bigger boring head. Since the thing had been in his possession for many years, and he had never used it he just gave it to me! WOW! It is a Wohlhaupter UPA 5-s6 with (he said) an R-8 shank.....perfect for my Bridgeport. I thought it a little strange that the spindle was about 3/4" shorter than my R-8 collets and the draw bar threads were 5/8-11 whereas my collets are 7/16-20. Somebody had previously adapted the thread by threading in a piece of brass or bronze that had the 7/16 thread cut into it. I stuck it into the Bridgeport spindle, set up a bar, and started to cut. I COULD NOT GET A DECENT FINISH TO SAVE MY LIFE! Tried EVERYTHING. Finally, in disgust, pulled the boring head out, made an adapter with a back brace so I could stick a 5/8 bar into my old 1/2" Emco head and completed the job.
Now, I am back looking at the Wohlhaupter head trying to figure out what went wrong. It looks to me like the taper at the nose is slightly different than my R-8s. So I am figuring that this is definitely NOT an R-8. But what is it then? I am not familiar with any collets that are this deceptively close to an R-8? anybody got any answers????

Kirk

MattiJ · Oct 27, 2019

Not aware of any "almost R8" machine tapers.
R8 is also ridiculously small for that monster so I'm guessing someone before you did botched DIY conversion.

johnoder · Oct 27, 2019

UPA 5-s6

Now that you found out its incapable, I think you ought to send it right down here - to keep the other one company

Clive603 · Oct 27, 2019

Yup. Operated on by unqualified surgeon.

5/8 - 11 thread suggests it started out as an NT 40 series. Which is sensible for a head that size. Turned down depth at the end looks about right for that.

Allegedly the conversion can be done if you figure an effectively cunning way to make the longer parallel portion at the upper end and provide appropriate threads without either bottoming out the drawbar or having the end pull off under pressure. The latter being somewhat undesirable with a head that hefty spinning round.

Clive

1968FJ40 · Oct 27, 2019

Hmmmmm, No John, you can't have it. Mattij, given the quality of the workmanship on the shank I am having a hard time accepting the "botched" theory. But I'm with you in that I was not aware of anything "similar" to R-8 and agree that seems undersized for this head??? I think I'll try to see if another Shank can be fitted to it and set it up to run on my Gorton 2-30 TraceMaster instead of the Bridgeport. Would sure like to understand the history behind this piece!

Kirk

LexD · Oct 28, 2019

It looks like you might have the interchangeable shank model, remove the brass insert and have a look down inside the shank for a hex socket screw.

donie · Oct 28, 2019

The 5" Wohlhaupter head is way too big to run on a wimp machine like a Bridgeport! Also, the Bridgeport only has 5" of quill travel.
Just my opinion, and from experience, I have been much happier using regular boring heads for boring straight holes, using the Wohlhaupter for facing, grooving, and things standard heads don't do.
Adjusting the Wohlhaupter for precision boring is more difficult because the slides fine adjustment goes through the gear train that drives the slide for automatic facing. The coarse direct screw adjustment is only for positioning the slide for facing.
Nice head, on the wrong machine.

LexD · Oct 28, 2019

The Wohlhaupter fine adjustment is actually very precise and uses a worm screw not a gear train. There is a type of gear drive for facing only.

1968FJ40 · Oct 28, 2019

Donie
As I said before, I agree the head is too big for normal use on a Bridgeport. But when you ask a friend if he has something he can LOAN you.....and he GIVES you a Wohlhaupter head WITH an R-8 shank that seems to fit your machine are YOU really gonna say "oh gee, that's too big for my po lil machine"? As for the 5" travel and the 7" required bore depth......I just did that in two steps, it was no problem. There was NOTHING too big about the Wohlhaupter when used as a boring head for that diameter bore. I would have never tried to swing it to face or bore anything substantially larger. Of course the reason that Bridgeports are so popular is their versatility. My Gorton 2-30 is a MUCH heavier machine and could easily handle the Wohlhauper (if it had the correct shank) BUT That machine does NOT have the vertical capacity to even come close to completing this particular job. In order to do it on the Bridgeport I had to swing the head out away from the saddle and hang the part off the front of the table......something you cannot do on most larger, rigid machines.
And, Lex, yes, I do think the shank is replaceable. I tried to remove the bronze insert.....But it seems to be VERY stubborn. I hope to be able to set it up for the Gorton......

1968FJ40 · Oct 28, 2019

The set up

eKretz · Oct 29, 2019

Nice adaptation. Prop shaft outboard support, eh? What kind of boat?

donie · Oct 29, 2019

LexD said:
The Wohlhaupter fine adjustment is actually very precise and uses a worm screw not a gear train. There is a type of gear drive for facing only.

I don't know what is inside the head, but the adjustment being through other elements, I find not as positive as the Romicron, or other dedicated boring only heads.
The larger Wohlhaupter heads are different mechanically from the smaller heads that are used on regular vertical mills, the really long slides on the large heads pretty much limit the spindle speeds.
Anyway, I have been using the 5" head for close to 20yrs, tried using it for straight boring just a few times, and just didn't gain enough confidence, I may not have been patient enough to get familiar with it. I am using it in a jigborer, its easy to change out heads.
One of the better heads I used on a Bridgeport, was the old Square Criterion boring head with 1" hole, very ridged, I use them for roughing, then snap in a balanced precision head, speed the machine up for the finish on the jigborer.

1968FJ40 · Oct 29, 2019

1928 Hacker Dolphin, 29 feet long, 40mph with BIG flat head six.

eKretz · Oct 30, 2019

Nice. Those are beautiful old boats.

donie · Oct 30, 2019

I am still curious about using the large Wohlhaupter heads for straight boring.

I found a pretty neat job that the 5" Wohlhaupter head does very well.
The Harley Davidson big twin crank cases prior to 2000, mating surfaces can warp after weld repair, throwing the main bearing journals out of alignment.
Each case half can be set up and aligned, then faced with the Wohlhaupter head correcting warp, and restoring alignment. Saves considerable time doing it any other way.....rotary table or face plate on a lathe, being there is a lip and a groove to deal with.

Many already know this but some may not, the Wohlhauper number is the travel distance of the slide, so, a UPA 5 will face a circle from center to 10". If the center of the part is hollow like the Harley crank case half that when measured is over a 12" span to clean up, an extension tool holder attached to the slide will extend the diameter capacity.
Another benefit of using the head is, the faced surface will be slightly concave, extremely important for sealing on high pressure flanges, good lathes are purposely set up at the factory to face slightly concave. I found that to be aprox .0003" concave in 10" with the Wohlhaupter head.
The amount of concave can be controlled to some extent by how tight the slide gib is.

GregSY · Oct 30, 2019

I think the Germans were developing an R7.5 taper as part of their ongoing effort to avoid standardization and make things unnecessarily complex, intricate, and difficult to work on. That's probably what you have.

AlfaGTA · Oct 30, 2019

Yep those overly complex German machines, aren't they just a pain.....
Having an integral rotary/tilting table is such a problem when you need to tram an out sized non square part.....Oh and that sensitive quill on both spindles
why would anyone go to that trouble...Too complex!

Donnie:
Been running a UPA3 for years...great head, no issue with setting size here. setting ring on my head has vernier graduated to "Tenths"
In my case the head has a 1" straight shank, which allows use across several machines....On my FP4NC i hold the head in a short (one set screw) Welden style holder.
The short length saves head room. To run the head on my FP3 manual machine i simply remove the head form the holder and grip it directly in a 1" collet.

Oh and that allows suing the boring head for other applications...
Here the head is being run at the end of a "Capto C5" setup.

Head used here to face the mounting seats for the mains on a 183 Miller......

Now if we are talking plain boring...In my book the "Capto" fine boring heads are pretty nice,,,,handle long overhangs and are very repeatable....

Cheers Ross

eKretz · Oct 30, 2019

OK now I'm really drooling.

MetalCarnage · Oct 30, 2019

eKretz said:
OK now I'm really drooling.

Ditto!

-Ron

1968FJ40 · Oct 30, 2019

Wow, Ross, very nice.
As for my little project, I had no problem with repeatability (including all the chatter marks) I think if the head I "inherited" had a proper shank on it everything would have been fine. It seems very accurate and once I get it squared away I'm sure I'll enjoy it very much! I don't really understand the negative comments about doing straight bore's with it. The graduations are in tenths and like any tool that uses a screw device to set it you have to take out the lash and know your machine.
I have come around, thanks to all your posts, to believing that my R-8 shank really must have been a "home brew" job. Yes, the quality of the modification is superb......except that the guy that did it appears to have been incapable of measuring a taper. Kind of weird. But the thing I haven't shared is that this head is Boeing surplus. Certainly that is an outfit that has the equipment and people capable of doing this mod......and as current events bear out they are also capable of making mistakes. It was probably surplused cuz they knew that it was F*%$ed up!

Wohlhaupter Boring Head Shank

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