Boring Head Sets

[RandyM]

Hey guys, I am currently looking at boring head sets. What is it that I must consider to get the right size head? I see they come in 2", 3", and 4" diameter heads, with 1/2", 3/4", & 1" bars respectively. I am unsure as to what to even consider to get the right size. I am just looking to add a set as a beginning set-up. I do not have a specific application at this time, just want to be ready when the need arises. Thanks.

 

[bjmh46]

Randy,

It all depends on the kind of work you do. I prefer a 2 inch Criterion dbl head for the smallish work I do. I had a 3 inch head that never got used on the Bridgeport because with any appreciable offset you were forced to run 80 rpm in back gear to avoid shaking the machine to death. Besides that, a 3 inch head boring a largish hole in steel is a lot of load on the R-8 taper, and the Bridgeport spindle. Bigger machine? 40 taper? Get the 3 inch! The 2 inch head is a better match for the lighter R-8 spindle.

Regards,
Bob

 

[Pacer]

I agree on the "depends on what you're gonna be doing". I just dont have a use for large bored holes - I did finally spring for 3" in a Chinese clone of a Criterion off ebay for cheap - and have used it once. Started out with a 2" Phase ll from Enco and a set of the cheap brazed carbide bars (which I still use pretty often) I later lucked on a beautifully made Swiss (I dont know the name..) 2" head off ebay for cheap and I now use it exclusively - and often.

Sounds like youre in a HS situation, like me, so I would suggest do the 2" Phase ll from Enco and a set of those 1/2" chinese boring bars, wont break the pocketbook, and should handle most of anything you'd wanna do - As you get familiar with using a boring head, you could branch out into something else.

 

[RandyM]

Randy,

It all depends on the kind of work you do. I prefer a 2 inch Criterion dbl head for the smallish work I do. I had a 3 inch head that never got used on the Bridgeport because with any appreciable offset you were forced to run 80 rpm in back gear to avoid shaking the machine to death. Besides that, a 3 inch head boring a largish hole in steel is a lot of load on the R-8 taper, and the Bridgeport spindle. Bigger machine? 40 taper? Get the 3 inch! The 2 inch head is a better match for the lighter R-8 spindle.

Regards,
Bob

Bob, You are correct, I am planning on using this on my Bridgeport. I realize it depends on the type of work. And right now I am just doing a "general" tooling as I complete the rebuild of the mill. Currently I do not have an exact application though I have visions of the smaller holes as well as something in the 6 inch range. I do mild steel and aluminum work. Right now I feel your suggestion is to start with the 2" for my mill. Though I have absolutely no problem running at very slow speeds and feeds to do a job. The Criterion is what I am currently looking at from Enco. I realize this is a tough one to answer as I do not have an exact application. Your input is greatly appreciated. Thank you for some good advice.

 

[RandyM]

I agree on the "depends on what you're gonna be doing". I just dont have a use for large bored holes - I did finally spring for 3" in a Chinese clone of a Criterion off ebay for cheap - and have used it once. Started out with a 2" Phase ll from Enco and a set of the cheap brazed carbide bars (which I still use pretty often) I later lucked on a beautifully made Swiss (I dont know the name..) 2" head off ebay for cheap and I now use it exclusively - and often.

Sounds like youre in a HS situation, like me, so I would suggest do the 2" Phase ll from Enco and a set of those 1/2" chinese boring bars, wont break the pocketbook, and should handle most of anything you'd wanna do - As you get familiar with using a boring head, you could branch out into something else.

Thanks Pacer, sounds like you and Bob are on the same page. Looks like a 2" head is where I should start. Thank you.

 

[RandyM]

I didn't even think to ask, what kind of machine are you tooling up, and what size bores do you anticipate doing most often? If it's a smaller machine doing mostly smaller bores, you probably would be better-off with a 2" boring head.

Paddy, the machine is a Bridgeport and at this time it is really hard to tell what my needs will be. I expect to have needs anywhere from .5" to 6" bores. How do you propose to do the larger bores and radii? I just bought a Phase II 8" indexer that I think I will have many uses for. For now I am just looking for beginning tool-up. Thanks for you input.

 

[RandyM]

I will just show this and explain why.
I prefer the square style Criterion heads for general boring, I found them just a little more rigid, they are shorter, no side holes.
To greatly reduce shake from out of balance, and a more rigid tool, I try to minimize the head offset.
To reduce head offset for large holes, I make hollow round boring bars at near the diameter of the bore, and braze carbide blanks into them.
They can be made with set screws to hold square or round HSS bits if you wish.
I bore a lot of holes, and have made dozens of bars like this.
The bit was rotated 180 from normal cutting position for the photo.

Mumbles, you offer an interesting solution to larger holes. You have my interest. Could you possibly offer more info on these "hollow round boring bars"? I am really inexperienced and would greatly appreciate any additional info. For example, so how does your tool offset present a better arrangement than the head offset? I am struggling with the geometry being the same (tool offset from the spindle). Can you walk me through this? And, would I be able to accomplish large holes with a rotary table? Thank you for chiming in on this thread.

 

[bjmh46]

Randy,

My second most used head is a 2 1/8 diameter Chandler-Duplex boring and facing head. Slightly longer than the 2 inch round Criterion, 3/4 max offset, facing and grooving capable, and able to dial in tenths! I scored an almost new one about 5 years ago on fleabay for 65 bucks. These are worth it if you can find one--they aren't made any longer. Bigger ones seem to come up a lot more often. The square Criterions offer the advantage of greatly increased bearing surface and are commonly found on fleabay. A square Criterion would be an excellent choice for larger holes. The downside is you give up some flexibility (no pun intended!) with only a single bar position. I love single point boring on the mill. There is nothing (including circular interpolation on a CNC) that produces a rounder, truer hole. When I was still working at a company full of CNC machines, the machine of choice for super critical bearing bores was a 70's vintage DeVlieg jigmill, with a D'Andrea boring/facing head--real close to perfection!

Bob

 

[RandyM]

Wow! Guys, this is all great info. and greatly appreciated. I think that the really best way for me is to now get some projects to really sink my teeth into.

Thanks Mumbles, I will definately keep your idea in mind as I proceed. I obviously have a lot of learning to do.

 

[randyjaco]

Randy,
I picked up a Criterion DBL-203 at a yard sale years ago. It is a 2" round head, but has the addition of a horizontal tool hole. Thus it will bore from .035" to a whopping 11". There has never been a situation where I needed another boring head. You may be able yo find one on EBay. The newer version is a CB-202

Randy