Boring heads for the mill

[DanH]

Ok, please school me on what to look for when getting a boring head for my mill. I need to bore an accurate (light press fit) hole for a metric sized shaft in mild steel. All of my tooling is in english units so the dia is .591".

How do you choose between 2" and 3" boring heads?

I think I want to get boring bars with replaceable inserts.

I want to use it with both steel and aluminum.

Thanks for the help!
Dan

[doubleboost]

Hi
Dan
Boring heads are like most tooling
Simply you get what you pay for
I have a cheap 2 inch oriental one it uses 1/2 inch brazed tip tools
On the whole i am happy with it
The adjuster screw is metric ,once you get a feel for it accurate results can be obtained
John

[Hopefuldave]

Choosing between 2" and 3"... I guess it comes down to how big you think you'll want to go! The rigidity's likely to be limited by the size of the shank / spindle and overall construction quality more than the head size, although a longer dovetail will always be more rigid than a shorter? I'd advise going for a dovetail / leadscrew type rather than a pivoting-arm, purely because the leadscrew makes it a lot easier to adjust to dimension.

Re your press fit - if this is for a 15mm shaft, and it actually *is* 15.00 mm, you're a touch on the loose side - .590" would be a press fit (14.986mm, 0.55thou" undersize), .591 would be a "close sliding" fit, at 15.011mm (about 0.45 thou" clearance) - shoot for 0.590" and then lap the bore if you need to?

Just my ha'pennorth,
Dave H. (the other one)

[DanH]

(06-04-2012, 02:22 PM)Hopefuldave Wrote: Choosing between 2" and 3"... I guess it comes down to how big you think you'll want to go! The rigidity's likely to be limited by the size of the shank / spindle and overall construction quality more than the head size, although a longer dovetail will always be more rigid than a shorter? I'd advise going for a dovetail / leadscrew type rather than a pivoting-arm, purely because the leadscrew makes it a lot easier to adjust to dimension.

Re your press fit - if this is for a 15mm shaft, and it actually *is* 15.00 mm, you're a touch on the loose side - .590" would be a press fit (14.986mm, 0.55thou" undersize), .591 would be a "close sliding" fit, at 15.011mm (about 0.45 thou" clearance) - shoot for 0.590" and then lap the bore if you need to?

Just my ha'pennorth,
Dave H. (the other one)

You are right Dave, I just gave the nominal dimension. The pin is grooved and had a roll pin to anchor it. The hole in the pot metal was nominal but I want a tighter fit than the original design.

[EdK]

I have a 2" boring head and it's done almost everything I've needed. I'll eventually get a 3" because there have been a couple of times where I could have used one. My 2" is the typical import with the dovetail/leadscrew setup.

Ed

[f350ca]

Hi the other Dave. I think its a 3 inch I have, where do you measure them? It takes 3/4 boring bars. I use the brazed carbide boring bars, they have to be sharp or you'll get lots of chatter if your boring very deep, ie long bar protruding. I'd be interested if the indexable bars work out, I've thought of trying one but think you'd need inserts with a very small radius to reduce your cutting forces.

[DaveH]

I also have a 2" (50mm) boring head a CCC one (Cheap Cheerful & Chinese)

Works quite well, I cut down a boring bar (for the lathe) with indexable inserts, so that enabled me to use the same inserts (CCMT) as I use on the lathe.

DaveH

[EdK]

For those deep bores a solid carbide boring bar with index-able inserts would be ideal, but pricey.

Ed

[DanH]

All good info!

Would it be better to buy a set or just the head and the boring bar I need for this project? I tend to lean to the set for some reason but I bet I will only use 1 or 2 of the supplied bars (based on past history). The hard part is determining which ones to get.
This set seems like a good buy.
http://www.ebay.com/itm/3-BORING-HEAD-R8...6523685855

[ukazak]

Some pictures for us onion heads please...!!!!

unal