I am looking at buying a Kuroda UPB-3S boring and facing head for use on my Bridgeport. As far as I can see the head is an improved copy of the Wohlhaupter UPA-3, but specifically intended for the Bridgeport; to the extent that "Bridgeport" is engraved on the body.

I have a Wohlhaupter UPA-4 head that I use on the horizontal mill and love it. But does anyone have practical experience of the UPB-3S head and how it performs in the real world? Or even better access to a manual! Unlike the UPA-3 the UPB-3S has two feeds for facing, 4 thou and 8 thou per rev. Does anyone know if these are independent or, like the UPA-4, can be used in conjunction to give 12 thou per rev feed?

The internals look pretty complex, basically epicyclic gearboxes for the feeds, so I am being slightly wary as the seller claims the head and accessories are in excellent condition. But after asking for extra pictures he "discovered" that one of the boring bar holders was broken. That should have been pretty obvious. Again, after asking, he also confirmed that one of the reducing sleeves is missing; no big deal but should have been mentioned. I am wonder what else is hidden?

Andrew

That is very perceptive, and correct. The little voice is no longer little, but is now hammering on the door and shouting don't buy it!

Following on from the comment by Baz and John a close look at the pictures shows some slight scarring that indicates a possible crash, despite the overall head looking to be in very good condition with nice clean edges and none of the little dings and dents one normally sees. I am assuming spares are not available at any price.

On the plus side it looks to be a lovely head and I am fed up to the back teeth with my R8 import boring head. On the minus side the seller has responded quickly, but has avoided my direct "does it all work correctly" questions with woffle about the slides moving freely. The head has been on the same site, at a higher price, before but was withdrawn by the seller, which is a red flag. Asking price is £600 which I would pay for a fully working head. But not this one; listing ends on Wednesday so I am going to walk away and see what happens. If it dropped below £100 I might take a punt, but not otherwise.

The seller is in Rugby, so not out of the question to visit, but an hour and a half or so each way. Slightly strange selling history too, lots of bench vices, but then the odd large Harrison or Colchester lathe.

Andrew

Quandary solved; the seller accepted an offer from someone else. For their sake I hope it works.

Andrew

Addendum

Over the past few months I have continued to look for a boring and facing head for my Bridgeport mill, without much success.

Recently I looked at a Wohlhaupter UPA2 head, but it didn't have any accessories and had an integral Morse taper shank. The seller also used the "I don't know anything about this" routine when asked if it was in full working order. I then looked at a Wohlhauper UPA3 head in excellent condition with a full set of accessories and a helpful seller. But sadly it had an integral MT3 shank and I couldn't think of a satisfactory way to replace the shank without a lot of work, and devaluing an expensive item.

Then I lucked upon a Kuroda UFB-3-F head with an R8 shank and a full range of accessories. A big plus was that the seller was 15 miles away. After an exchange of messages I went to look at it yesterday. The head is in good condition, plus the seller was a professional machinist and clearly knew his way round the unit. He had bought it from his workplace so also knew it's history. The upshot was that I agreed to buy it and he let me take it away on a promise of paying today. Here is the box of goodies:

The only downside is that one of the sleeves has been split, although it is still usable. The extension arms look to be unused and it even comes with the tapered lever for pulling and pushing the various pins in and out. Everything seems to work as it should and there is no evidence of any crashes. Of course the acid test is to run it on the Bridgeport, which I will do later this week.

I'm not going to say how much I paid as it will probably upset some people. Let's just say I fall into SoD's category of those who like to own, and use, nice tooling and am fortunate enough to be able to afford it. No significant other to stop me for a start!

Andrew

I never really got on with my budget Soba boring head for the Bridgeport, hence the Kuroda purchase. The socket head grub screws (Whitworth thread) were poor quality and have been replaced where possible. I found it difficult hold a tolerance as the adjustment screw was quite sloppy.

I have used insert boring bars with my Wohlhaupter boring bar in the horizontal mill. But I had a lot of trouble with chatter and a poor finish. To be fair I was pushing my luck on the length versus diameter of the boring bar. But I don't think boring heads really run fast enough to gain benefits from insert tooling. In the end I reverted to boring bars with HSS tool bits with the Wohlhauper:

With a HSS toolbit it is easy to control the shape of the cutting edge and the reliefs.

With the Soba head I found it to be a crap shoot as to whether one could hold a diameter to a few thou. Whereas with the Wohlhauper, and I hope the Kuroda, holding to less than a thou is straightforward.

Andrew