# Boring Head Size



## ih8beingold (Jul 21, 2015)

Silly question but I'm new to this. I would like to get a boring head one day so I have been looking around. I want the cheapest kind but am a little confused as to what size to get. I'm not sure what kind of hole size range I can expect from each. What I mean is how big can a 2" or 3" size boring head bore. Is it 4", 5", 6", 7", 8" ....????? I don't see specs that list maximum diameters. I can only buy one size. Thanks


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## Franko (Jul 21, 2015)

I don't think anyone can answer that until we know what kind and size of mill you have.


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## JimDawson (Jul 21, 2015)

A 2 inch boring head would do an 8 inch hole if you can turn it slow enough and have a pretty heavy spindle, a 3 inch would probably max out at about 12 inches.  Pretty sure I've never gone over 4 inches with my 3 inch head.  Minimum diameter is dependent on the size of the boring bar.

I would spend the money and get a Criterion boring head.


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## GarageGuy (Jul 22, 2015)

I have both a 2" and a 3" boring head.  I've never bored a hole larger than 4 1/2" with the 3" head.  That was in a steel forging though.  I'm sure its possible to go much larger depending on mill rigidity and the material being bored.  Mine are cheap import units, but they seem to work OK for my needs.  If you plan to use it a *lot*, you might want to go with a good domestic brand name model.

GG


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## GK1918 (Jul 22, 2015)

I don't think Criterions are that expensive commonly going around 75 bucks for a 2 inch.  We have 2,3, & 4 inch and the two inch
gets the most use (boring valve seat inserts). Keep in mind what kink of shank you need?  Should be direct reading to make
life easier..............................


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## ih8beingold (Jul 23, 2015)

Thanks everyone. My mill is a Busy Bee 1977 (Rong Fu 30) clone. Round column and R8. Not exactly rigid.


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