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Your Old Dog
10-24-2007, 08:08 PM
I'm looking for a cheap boring head for my mill. I don't know how they size these.

Will a 2" head with a 5/8 maximum offset bore a hole approaching 5 1/4" ?

Is there any advantage to buying a 3" head if I only plan on buying one, will it do the job of a 2" head as well?

thanks,

Here's the one I'm looking at.
http://cgi.ebay.com/ebaymotors/2-BORING-HEAD-W-R8-SHANK-1-2-BORING-BARS_W0QQcmdZViewItemQQcategoryZ43991QQihZ001QQite mZ110159879774QQrdZ1QQsspagenameZWD1V

Spin Doctor
10-24-2007, 08:17 PM
One big advantage. The ability to use 3/4" boring tools versus 1/2". Always use the biggest diameter boring bar that fits in the hole if possible

wierdscience
10-24-2007, 08:23 PM
How much mill you have determines how much boring head you need.You can run small diameter bars in a large head,but not the otherway around.

FWIW Used to a Bridgeport #2 boring head(3-1/4"x11/16"offset) with case could be had on Ebay used for less than $125 and those are good heads compared to a new Chinese model.

oldtiffie
10-24-2007, 08:24 PM
I'm looking for a cheap boring head for my mill. I don't know how they size these.

Will a 2" head with a 5/8 maximum offset bore a hole approaching 5 1/4" ?

Is there any advantage to buying a 3" head if I only plan on buying one, will it do the job of a 2" head as well?

thanks,

Here's the one I'm looking at.
http://cgi.ebay.com/ebaymotors/2-BORING-HEAD-W-R8-SHANK-1-2-BORING-BARS_W0QQcmdZViewItemQQcategoryZ43991QQihZ001QQite mZ110159879774QQrdZ1QQsspagenameZWD1V

Thanks YOD.

Yep - to both.

Have a look at the pic again and you will see a longitudinal/diametrical hole right through the "slider". It fits/suits a boring bar just as the holes in the bottom of the slider do. So your boring bar sticks out "side-ways" as an option to "sticking down".

So with care and the boring bar "sticking out side-ways" either head will do the job.

FWIW I have the larger of those and it works very well. Fit of the quill in the head is quite important - as you'd expect. But I don't anticipate you having any problems at all - least of all any that you can't sort out.

The only thing that a 3" can't do that a 2" one will is fit the body of the boring head into a 2" hole.

My choice would be the 3"

And do make sure that the adaptor for it is with it and suits your mill. If the R8 doesn't fit, it usually just screws in to the back of the head and a wide range of adaptors are readily available.

But having said that, I'd advise waiting for other posts to confirm or refute my comments and give further advice.

I hope this helps.

SGW
10-24-2007, 08:27 PM
A boring head typically has a side hole so you can get a pretty big diameter with even a small boring head. The only thing is, to use the side hole you need a left-hand boring tool; this will become apparent the first time you try to use it. I made one by silver soldering a chip of carbide to a piece of drill rod, so it's not a huge problem, just be aware of it.

I have a 2" dia. head and for the size work I typically do it's been fine. It's a "quality import" from Travers Tool, and I can see nothing wrong with it. I've had to use the side hole only once. I guess you need to decide if it would be big enough for you.

oldtiffie
10-24-2007, 09:02 PM
A boring head typically has a side hole so you can get a pretty big diameter with even a small boring head. The only thing is, to use the side hole you need a left-hand boring tool; this will become apparent the first time you try to use it. I made one by silver soldering a chip of carbide to a piece of drill rod, so it's not a huge problem, just be aware of it.

I have a 2" dia. head and for the size work I typically do it's been fine. It's a "quality import" from Travers Tool, and I can see nothing wrong with it. I've had to use the side hole only once. I guess you need to decide if it would be big enough for you.

Agree with you SGW.

But the link did say (I think - without checking) that a boring bar set was either included or "available".

jimmstruk
10-24-2007, 09:18 PM
YOD, Here is an E-BAY # 280166328401 for a 3 inch boring head, new, $39.95 with r8 shank. I prefer the larger head because of the heavier the more rigid, (less chatter). The same seller of the boring head also have boring bars at a very good price. JIM

Your Old Dog
10-24-2007, 09:21 PM
Thanks gentlemen,
The 2" set includes a set of boring bars but 1/2"

I happen to have 5 very nice 3/4" boring bars of variouos sizes and HS inserts. I could sacrifice one of those to size it for the 3" boring head.

I'll sleep on it and order something in the morning!

tattoomike68
10-24-2007, 09:32 PM
A boring head typically has a side hole so you can get a pretty big diameter with even a small boring head. The only thing is, to use the side hole you need a left-hand boring tool; this will become apparent the first time you try to use it. I made one by silver soldering a chip of carbide to a piece of drill rod, so it's not a huge problem, just be aware of it.

I have a 2" dia. head and for the size work I typically do it's been fine. It's a "quality import" from Travers Tool, and I can see nothing wrong with it. I've had to use the side hole only once. I guess you need to decide if it would be big enough for you.

Thats why you just weld the shank onto the boring head. Then you can run it on a mill in backgear and dont need a wierd tool.

A few little skip welds is all you need, it wont hurt a thing.

7018
10-24-2007, 09:47 PM
I have gotten stuff from jtsmach8xzw there good to deal with. I also got both the 2 inch and the 3 inch for both mills as one has R8 and the other has nmtb40.

Now I'm not made of money its just that I want to keep the different tapers at each mill...Althrough I haven't used the 2 inch yet, I'll have it if its needed...

jkilroy
10-24-2007, 09:48 PM
Like others have said, go big. As in always use the biggest boring bar you can for a given hole size. I have the opposite problem right now, I need to bore a .712 hole and the smallest boring head I have takes 3/4 bars. For a 5.25 hole I would use a 4" head. Try to keep the bars as thick and short as possible. If the head can go down with a short bar out sideways then you have it about a solid as you can get it.

LastOldDog
10-24-2007, 10:07 PM
A boring head typically has a side hole so you can get a pretty big diameter with even a small boring head. The only thing is, to use the side hole you need a left-hand boring tool; this will become apparent the first time you try to use it. I made one by silver soldering a chip of carbide to a piece of drill rod, so it's not a huge problem, just be aware of it.

I have a 2" dia. head and for the size work I typically do it's been fine. It's a "quality import" from Travers Tool, and I can see nothing wrong with it. I've had to use the side hole only once. I guess you need to decide if it would be big enough for you.

YOD, I'm with the 3" crowd. I have a 3" Criterion 203DBL, the other, a 3" 'cheapy' with the R8 shank TIG welded with three short beads around the circumference. This is used primarily for running in reverse with a ball mill to clean up around raised bosses for bolt holes etc, and, boring large dia holes from the radial mounting hole. Again, this enables use of convential boring bars turning the spindle in reverse. Additionally the 3" employing 3/4" tooling is better suited (stiffer) for large dia trapanning on plate.

Lloyd

BadDog
10-24-2007, 10:30 PM
On that small hole, you can always make a necked down bar, as long as the hole is not too deep.

I've got a 3" Armstrong. Never seen another like it, but I like it better than the typical Criterion that I've seen. It seems better made and is much beefier than Criterion, though it looks very similar in general design.

oldtiffie
10-24-2007, 10:34 PM
Here are some pics (posted recently) of my 3" boring head.

"Imported"? Sure but one damn fine bit of ewquipment.

Just remember to "lock" the slide for cutting - "stiffness"

I hope it helps.

http://i200.photobucket.com/albums/aa294/oldtiffie/HF45-1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/HF45-2.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/HF45-3.jpg

Your Old Dog
10-25-2007, 07:58 AM
I went with the 3". If need be, I can turn a bushing to use with the few 1/2 boring bars I have. As I mentioned earlier, I have several 1" boring bars for the lathe. I can sacrifice one of my 1" boring bars and cut it down to a reasonable length for the boring head. Thanks for the advice/opinions.

oldtiffie
10-25-2007, 09:05 AM
I went with the 3". If need be, I can turn a bushing to use with the few 1/2 boring bars I have. As I mentioned earlier, I have several 1" boring bars for the lathe. I can sacrifice one of my 1" boring bars and cut it down to a reasonable length for the boring head. Thanks for the advice/opinions.

Hi YOD.

If you get the "full set" - as I did when I bought new - there was a "split sleeve" adaptor/reducer (similar to that on a Wood-working Router) for smaller diam boring bars. Easy job to make really.

But as you say its not difficult to make a smaller boring bar either. I often get some cold-rolled steel stock to suit the hole in the boring head and turn a "small boring bar" (extention) and either braze, silver-solder or "arc/MIG weld" a small HSS tool bit to the "business end" of it and just sharpen the cutter. Works well with boring slowly - as you do - costs pennies, and about 30 minutes from "go" to "whoa".

Might not suit the "purists" but it works for me.

Hope it helps.

Your Old Dog
10-26-2007, 06:14 PM
I have gotten stuff from jtsmach8xzw there good to deal with.

Well you got that right. I ordered the 3" as suggested by many here on this post. It came today and looks like damn nice tooling for $36.00. I'll cut down one of my 3/4 Inch long boring bars to fit in it. Thanks for the suggestion of jts machine. It came two days after I bought it off of ebay.