Advice on offset boring heads sought

The "generic" boring head, like this one:

or

will work just fine. I've used one for a number of years. Mine uses 1/2 tooling and been very reliable/accurate. It is very important to measure frequently and "sneak up" on final ID by taking very light passes, if you want tight fit. Remember, when boring on a mill, as opposed to lathe, the boring bar flex flex outward, due to centrifugal force, which in itself can result in extra metal being taken off just because you increased RPMs

Joseph Gw> I'm in the market for an offset boring head to fit a mill with an R8

I hate to admit it, but I don't have very good luck boring on the mill with those carbide tipped boring bars. So, my favorite 1/2" diameter boring bar holds a HSS bit. This I can keep very sharp and I can grind plenty of relief behind it so it doesn't rub it's heel.

Pete Stanaitis

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Joseph Gw> I'm in the market for an offset boring head to fit a mill with an R8

HSS sounds good to me too.

What kinds of boring heads have you used, and what is your experience with them?

Joe Gwinn

=================== While I have not used mine extensively, the Enco unit works well for me. I got both a R8 shank to fit the school's Bridgeport and a MT2 w/ drawbar shank to fit my Emco mill head.

see

has these on sale from time to time or see (heads) be reminded that you generally have to order the shank(s) you want as these don't usually come with the head. ?ProductID=1001-0003(bars) Pro sets Carbide bar set that came with 'kit' seems to be holding up well. and has been adequate for my needs. I did take some 600 and 1200 grit wet/dry SC paper and using a 1/2 inch HSS lathe tool for a block, polished the face of the tool to a mirror finish, and used a diamond lap [medium and fine] to polish the sides with a few thousandths "bevel" at the cutting corner. Vastly improved the surface finish for me.

Also available are made in USA with higher quality such as

?PMAKA=505-2226&PMPXNO=952781&PARTPG=INLMK32 There are also some boring heads that will let you cut a groove in a bore, but these are expensive unless you need the capability to make snap ring/o-ring grooves.

While the better quality boring heads may be different, I would not trust the indicated measurements on the adjusting screw over a few thousandths of movement. Get an inside mike or telescope gauges to measure and use the adj. screw graduations for that 1/2 thou final adjustment. Be sure to tighten all the screws. and feed out as well as in, as it will cut both directions. When you get "real close" a "dry" pass will "whisker" out about another 1 thousandths the first time and about a 1/2 thousandths the second time in aluminum. Steel has a greater range of hardness so you might want to try a few "dry" [no change in tool setting] passes just to see what you get before you try for the final bore.

Remember this is a "finger tip" finishing tool. If you want to hog metal, use a drill or hole saw.

Unka' George (George McDuffee) .............................. Only in Britain could it be thought a defect to be "too clever by half." The probability is that too many people are too stupid by three-quarters.

John Major (b. 1943), British Conservative politician, prime minister. Quoted in: Observer (London, 7 July 1991).

I'm with unkie George here..

Have the same setup R8 and MT2... I routinely do .001 with the head.. in the BP...

Before I had the BP or the Clausing I used the MT2 in my import lathe head stock, so I could rough out things by clamping the work on the crossslide and use the longitiudal feed as a power feed... (old live steam trick) ... and yes I know it cuts ovals, but it was only used for roughing.. I'd finish on the Mill Drill by hand... Now days I just use the BP :-)

--.- Dave

I can only double that. Much better experiences with HSS. One should think, that carbide works the same. But then, I didn't find the trick yet.

Boring head is a Wohlhaupter. :-P

Nick

I looked at their US website. Look *very* good. I'm afraid to ask the price.

Joe Gwinn

Hmm. Good point. While currently I need only R8, the ability to use MT should be ensured, as it's likely to be needed someday.

I'm assuming that it's better to use the larger thread (1.5"-18tpi) to attach boring head to shank, versus the smaller thread (7/8-20), for rigidity.

None of the Enco links worked, but I have the paper catalog.

These are attractive.

I assume that by "tool" you mean the boring bits. I don't visualize which surfaces are being polished or ground, and which surface is the "face". Could you expand a bit here?

I saw one of these in the MSC catalog, for ~$2,000 US. I'm sure it works very well. But I don't yet need to make grooves. If I need one groove, I'll stop the machine, advance the grooving tool a few thousandths (springing it a little), spin the tool a few revolutions, advance the tool, etc.

Yep. All good advice. Thanks,

Joe Gwinn

ENCO boring heads are not indexed , takes too much time to adjust it .

Its a design thats too old , we need better .

The flimsy bars come in 2 size shanks cause they know it

isnt rigid enuf ....

Why not a mo rigid , easier to adjust head ?

Why not design it yourself ?

I bought it used for about 200$.:-))) That qualifies for a **GLOAT**. It was so old, that they didn't have any information at Wohlhaupter. But it works perfect. All parts are hardened ground and lapped. I once took it apart because I thought it doesn't work right (it did, was my error). Perfect craftmanship! Damned clever construction! If you can get one, you will **love** it. It does 1/100 mm in diameter without pain. Also has an automatic inward / outward feed (adjustable rate). You can make nice things with that which you normally can only do on a lathe (facing off). Even cones and conical threads if you can sync the feed of your table and the rotation of the spindle.

Nick

What do you mean by "not indexed"? The pictures do show a calibrated dial, which ought to allow one to get into the neighborhood at least.

All the non-automatic offset boring heads I've seen in the catalogs seem to have the same basic design, differing mostly in quality of implementation and attention to details. It seem to be a traditional standard design.

Can you suggest other brands and designs that are different and better that I should look at?

Doesn't one try to use the largest bar that will fit into the hole being bored? Smaller holes will require smaller bars, and one must just live with the reduced rigidity.

Heh. First, a little more practical education is in order for me. Like learning how to use this mill I just got.

Joe Gwinn

============= This occurred to me when I looked at one of my made in USA "premium" carbide lathe tools that gives me a super nice finish in the lathe, and compared it to the boring bar. Grind on the lathe bit was like a mirror on the face, and when I used a magnifier on the edges I could see these were mirror finish behind the wear zone at the tip. May be all in my head, but it seemed to make a big difference in the finsh I could get with the boring bar.

I don't know if this is standard, but I refer to the biggest surface as the face. I wrapped 300/600 grit wet/dry silacon carbide paper over a 1/2 sq tool bit for support, put that on a bench top and lapped the face to almost a mirror finish. Then did the same thing for the edges. Took my diamond hone and just touched the cutting corner to remove the sharp tip/edge and put on a slight flat (or radius most likely). Be sure and get enough relief as you "go around the corner" so the heel won't drag. [And in fact as I type this, that may be where all the improvement came from. You might want to try this first before going to the time/trouble to lap the tool]

I used tap lube to keep the paper from loading as this was handy. Wipe off with a paper towel or rag when it gets loaded. Most likely any light oil would work fine.

Unka' George (George McDuffee) .............................. Only in Britain could it be thought a defect to be "too clever by half." The probability is that too many people are too stupid by three-quarters.

John Major (b. 1943), British Conservative politician, prime minister. Quoted in: Observer (London, 7 July 1991).

Metal Lathe Accessories makes a nice kit:

Their kits are very high quality (castings, detailed drawings, etc). My boring head has still not been finished...the list is long.

Steve

I see them on eBay for ~$500. Maybe someday.

I'll keep my eyes peeled, but I think I'll start on something less glorious.

Joe Gwinn

They do look interesting. But first I'll have to get a lathe. It's in my plan, but has not happened yet. Maybe next year.

Joe Gwinn

I see. Thanks.

Or kerosene. Or water, for that matter.

Joe Gwinn