Vert mill boring heads

[MarkLong]

I went to Cabin Fever hoping to get a look at some boring heads. Saw a few but nothing that I was really dying to purchase. Saw some Bridgeport #1 & #2 heads, Criterion heads, and a few others whose names escape me. Most have R8 shanks that were pretty well knackered up. I couldn't determine if the R8 shanks were replaceable or not, and the sellers weren't sure. Figure something about the size of the BP #2 would work best for me. Seems like most were priced in the range of $100-$135 or so. Couple of questions about boring heads:

* Are the R8 shanks replaceable?

* What features should I consider to determine what boring head will be suitable for my use?

* Seems like the BP & Criterion heads are the ones I'll find the most and appeared similar. Would there be any reason to favor one over the other?

I have a millrite mill, 7x27 table, manual quill. I'd like to use it for general use in making holes in the mill. Work mostly with alum and various grades of steels. Other metals on occaision. Any advice appreciatted.

[Hanz]

Yes, the shank is replacable, and unscrews. 2nd, I just bought a 3" from Enco, head, R8, and 12 pc 3/4" carbide boring bar set for $99! Seems to be accurate for what I need to do.

[Harold]

I have the same set that you have. For the money, ya can't beat it. As stated, the R8 shank is a separate piece and screws onto the head. I'm not sure what thread it is. The major diameter is 1.5", seems like national fine. I used mine to bore 3" hole in 1/4" aluminum, worked great, had to go slow ith my litle ENCO mill, but I was in no hurry.

[Roy]

Ditto on the Enco brand, and what the others have posted. About the only thing wrong with the enco head as is with most import tooling is the setscrews seem to wallow out pretty easy. First thing I do any more is chage them all out to a good quality setscrew and chuck the import ones in the trash. That said I have used mine quite a bit, from boring large holes in a 1 1/2 steel plate and a multitude of other things. It works quite well, and is as accurate as the person using it makes it. Price is right. Other than the setscrews (IMHO) they are of well made.

[Davey]

Criterion brand boring heads seem pretty tight to me .I've had good luck with them.I like to make sure a boring head has the capacity to hold a square tool.There is nothing better when you need to bore a hole bigger than youre boring head and spindle than using a lathe turning tool horizontaly in the boring head . It's about as rigid as you can get !

[MarkLong]

Thanks for the info. I have looked at the Enco boring head (3", 3/4" B-Bar diam). It does look like a good value for the $$. What is the country of origin of the head?

Well anyway, I've been looking at some heads on ebay and have a few questions:

1. What is direct reading and 1:1 when found in a boring head description? My guess is that both of these phrases means turn the dial "1 increment" (say .001), and the diameter will increase by .001 in the following pass.

Do most boring head dials read on the radius or diameter?

2. I have seen a few used American heads that have a vernier to get .0001 accuracy. Is it realistic to be able to expect to get that accuraccy? I ask this as I would like to be able to bore motorcycle cylinders at some point when I get competent. Here is one that reads in .0001:

criterion .0001 reading boring head

I'll buy a nicer, used (and probably higher priced than the Enco set) head if I feel I can justify the extra expense for future use. If not I'll look into purchasing the Enco head, or other used .001 reading American made head such as a used Criterion, APT, Flynn, etc. Bridgeport boring heads seem to be expensive, even when used. I suspect your paying for name recognition there.

3. The vernier feature on one of the heads I was looking at only has 7 lines versus the usual 11 found on a typical vernier. And from the pictures I couldn't make out what kind of increment each division was??



I'd appreciatte any advice. Thanks.

[dkinzer]

I suspect that the vernier marks represent .0001 graduation. However, you first have to determine which half of the thousandth you're in (low half or high half) and then interpret the vernier marks as either .0000-.0005 or .0005-.0010.

[JeffinWI]

Enco boring head country of origin? Don't know for sure, but they're probably about 10% to 25% of the price of others, so I can probably guess.
You're correct about the "direct reading", and I believe that is the only way to go. Make sure to ask when buying though, because they are made both ways.
I like the FLYNN and CRITERION heads. If you're working on expensive "stuff", the confidence in good tooling can make a huge difference between good parts and scrap. One junked part can easily cost way more than good tooling!
The vernier isn't a "must have" feature. You can easily split the .001 graduations to get .0005, and not realy that hard to quarter the grads to get .00025. Measuring, finish, taper, etc, variances will pretty much neate anything even that close.

[JimGlass]

Hi Mark;

Boring heads with R-8 shank may or maynot be removeable and I prefere a fixed mount shank, a little more rigid. Bridgeport heads have fixed shanks and so do APT heads.
Criterion is also a good boring head. I bought an APT head a year ago for 3/8 shank bars. APT is American made and a nice head but had to do some tweeking on the gib adjustment.

I also have a 3" boring head purchased from ENCO with 3/4 shank bar set. It is a very nice boring head even though it is Chinese. All of the Asian boring heads appear to be okay.
Jim

[Jon_Spear]

The vernier is weird in that there are 6 segments between the first and last lines on the vernier scale, which is on the outside of the circle.

However, on the inner circle, between the outside vernier lines, there are 5 segments, from .022 to .027

Because there are five segments, I believe that each line represents .001"/5 = .0002"

In the picture, it looks like the vernier lines up at .022 and .027, so I think that the reading you would take is .0220"

If the next line on the internal scale were to line up, where the .023" reading is, then you would read that as .0222", etc.

This vernier looks weird to me, because the vernier lines usually have a scale labelled on them, and you read from the vernier lines, which in this case, would be the outside lines. On the boring head you have pictured, it seems that you read from the non-vernier lines, which are on the inside.

Maybe they made the lines this way just because they were crmped for space in the dial?

I think this is right, but maybe someone here knows better.

Regards,
Jon Spear
San Francisco, CA

[MarkLong]

I contacted the maker (Flynn) by email. They stated that each grad of the vernier is .0002 as you have stated. I have looked at a newer Flynn with vernier and it appears that on the newer models 1 of those vernier lines was removed. That would certainly make it easier to read.

Thanks.

[Pat_S]

Yes, 1:1 means .001" on dial makes bore .001" larger. Some tooling makes the bore .002" or .0007" larger.

Grizzly sells a 3" boring head, R-8 adapter and a 12 piece set of 3/4" boring bar set for $90. Their 2" boring head set sells for $80. Grizzly has had these set for a while so they are probably good quality. I have had good experience with Grizzly as have many others.

Little story. I was working at Criterion Machine Works in Costa Mesa in 1978 when the 50 year patent ran out. The very next day the Asian knock-offs were in the stores. So the company bought a few and inspected them. We were impressed by the quality. That was the only production job I ever had. Boring tools indeed.