Boring Head?

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DaddyHeath

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Hey all!
To preface, I have a Micro Mark Sieg mini lathe and a 1HP Series 1 J Head Bridgeport.
Also have rotary table, dividing head, and enough end mills to choke a boar (plus the requisite 60 degree dovetail end mill)
Currently torn between dropping some coinage on a quality boring head or attempting to make one.

My questions then lean towards what alloy steel would be best for the body and slide, what screw size and thread should be used for the adjustment, and what would be the largest size I could use reliably on my milling machine?
 
I use a Criterion DBL-202. It does a great job and I don't think it's made with anything particularly special. A BP should be able to run some good size boring heads, but really how big do you want to make holes? Most of them have a horizontal hole to hold tools for big bores.

I recently finished a boring/facing head project. This one is made from cast iron body castings and is quite a bit larger and heavier than the Criterion. http://mlatoolbox.com/MLA-7.html

It's a fun project, has good instructions and drawings, and considering the cost of other facing heads, it's a deal. :)

As an interesting aside, you don't need a big boring head to do big work. Though I wouldn't really recommend it, this worked well for me.

www.hobby-machinist.com

Large work on a Bridgeport

I got a spacer for it. It fits great on the column, but the turret is a few thou too big. I was thinking of clamping it to the table and boring it out a little. I figured I should ask here in case I might have missed something and to get tips for the setup. I tried lining it up with the long...
www.hobby-machinist.com www.hobby-machinist.com
 
DaddyHeath said:
Currently torn between dropping some coinage on a quality boring head or attempting to make one.
Click to expand...

I've been plenty happy with the relatively inexpensive (<$100) kits for 2" or 3" bars. I have both, if I'd known better I think the 3" would have been enough by itself.
 
I bought a 2" with an R8 adapter from Shars a few years ago. Works just fine.
 
DaddyHeath said:
... and what would be the largest size I could use reliably on my milling machine?
Click to expand...
Practically speaking, the biggest I would go would be a 3" head. It's big, relatively speaking.

Rather than make one, I would buy this one. For a Criterion DBL-203 that has seen very little use, that guy is giving it away. Clean it up and it will work fine. All the important screws are there. It is missing two of the three screws that hold the boring bars in but they are simple to find and replace. Otherwise the head is in really nice condition.

Making a head is not a big deal for an experienced hobby guy but I would use at least medium carbon steel for the body and bar holder, maybe 1144, and you will need to be pretty good at screw cutting. My personal opinion is to buy this kind of tool if a high quality one is available at a fair price, like the one I linked to above. Build the tool when the one you need doesn't exist.
 
mikey said:
Practically speaking, the biggest I would go would be a 3" head. It's big, relatively speaking.

Rather than make one, I would buy this one. For a Criterion DBL-203 that has seen very little use, that guy is giving it away. Clean it up and it will work fine. All the important screws are there. It is missing two of the three screws that hold the boring bars in but they are simple to find and replace. Otherwise the head is in really nice condition.

Making a head is not a big deal for an experienced hobby guy but I would use at least medium carbon steel for the body and bar holder, maybe 1144, and you will need to be pretty good at screw cutting. My personal opinion is to buy this kind of tool if a high quality one is available at a fair price, like the one I linked to above. Build the tool when the one you need doesn't exist.
Click to expand...
Well that's a winning deal right there! I'll have to turn the shaft down just a tad, but that's no big issue. Wonder if it's integral or removable.
Guess I'll find out when it arrives!
 
All DBL heads have a 7/8-20 mount so you can buy or make an adapter to suit your needs. Yes, an R8 adapter is readily available.
 
I have a Wohlhaupter UPA2 that I absolutely adore, although I paid dearly for it. I really prefer boring heads that use a large ring rather than a screw which requires an Allen key, and being able to do facing ops in the mill is just awesome.

The Criterion boring head recommended above will absolutely serve you well, however.
 
DaddyHeath, I forgot to mention that the best bars to use with these heads are cobalt HSS. They will cut really well at much lower speeds than carbide, either brazed or inserted. The DBL-303 uses 3/4" shank bars that are unfortunately more expensive.

High quality cobalt bars are hard to find nowadays. Sit down when you look but this is the set I would suggest. Used properly, they are the last set of bars you will need to buy. They are M42, so 8% cobalt, and they have a 5 degree lead angle at the tip so they will cut really well with lower cutting forces, which means less potential for chatter in the bore. At the right speed and feed, the finish a cobalt bar leaves in the bore looks like a mirror.
 
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