Boring heads..

Pcmaker

Pcmaker

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I have a few questions about boring heads for mills.

I have a Precision Matthews PM-25MV mill and I was wondering what type of boring head to get? Is there a specific one I should get for my mill or anything with an R8 shank will do?

I'm countersinking block of steel for an allen shoulder bolt. The diameter I need to drill is something like 13.13mm

I don't want to keep buying odd sized drill bits, so I'm thinking of getting a boring head so I can just adjust for the size hole I need by the thousandths.

I used a 1/2" drill bit to drill the hold and I need to make it slightly bigger. Will a boring head do the job?

Does the boring head also cut the bottom of the work piece all the way to the center or does it just cut the side of the hole?
 
Hi PcMaker,

Yes a boring head will do everything that you are wanting, and more. There are a couple of caveats though, the mill must be properly trammed, or you won't get a true hole with vertical sides, and the tool that you use needs to be properly ground. Often the tool bits that are supplied with boring heads are not shaped properly. Last don't buy a boring head that is too big for your machine. My mill is similar to yours and a 65 mm head is about as big as you need to go.
 
What diameter hole is the smallest a boring head can start working on?

I'm still working on better tramming the mill. I'm at about .003 thou off on the X axis and about .002 thou off the Y axis. Having a hard time getting better than these numbers.
 
Pcmaker said:
What diameter hole is the smallest a boring head can start working on?
Click to expand...
It depends on the size of the tool. My boring head is adjustable through center so the boring tool determines the minumum size. Aside from the cutting surface itself, the heel of the cutter needs clearance. but micro- boring is possible with the right tool.

A boring tool will face the bottom of the hole if properly ground. It ius not a good practice to cut through to center as you will have the tool rubbing on the back side. I will usually drill a pilot hole, even if the hole is blind. If I need a flat bottom with no pilot hole, I drill the pilot to just short of bottom and finish with a boring tool that can cut to the center.
 
Hi PcMaker,

You are going to have to do better than that ! I can tram within 1/2 thou along the table. The problem across the table, is down to how much the mill head nods. I've shimmed mine to just under a thou, but don't seem to be able to get any better than that.

As far as hole size is concerned you can drill holes if you really wanted to, but I think it is easier to drill and ream if you want precise hole sizes. Its only when you need larger holes that a boring head becomes really useful. I used to use mine for surfacing as well as counter boring and counter sinking.
 
I've been using a 1/8 endmill as a small boring bar in my PM25, I can bore any hole over 1/8 in (3mm) in diameter. Bottoms are kinda touchy, go a tiny bit too far and my may break your boring bar.
PS, I rigged a handle on my downfeed knob, so I can crank it down smoothly. It's 2mm per rev.
 
Pcmaker said:
I have a few questions about boring heads for mills.

I have a Precision Matthews PM-25MV mill and I was wondering what type of boring head to get? Is there a specific one I should get for my mill or anything with an R8 shank will do?

I'm countersinking block of steel for an allen shoulder bolt. The diameter I need to drill is something like 13.13mm

I don't want to keep buying odd sized drill bits, so I'm thinking of getting a boring head so I can just adjust for the size hole I need by the thousandths.

I used a 1/2" drill bit to drill the hold and I need to make it slightly bigger. Will a boring head do the job?

Does the boring head also cut the bottom of the work piece all the way to the center or does it just cut the side of the hole?
Click to expand...

I have the same mill, but heard (I don't remember where -- maybe a Stefan Gotteswinter video?) that boring heads required power feed in the z-axis, in order feed the boring head at a steady rate.

Otherwise, making holes with diam > 1" would come in very handy.
 
Just bought a metric counterbore set from Amazon. Still want to hear more about boring heads before I make my decision about buying one. Especially about the Z-axis power feed requirement.
 
Just trammed my X axis to a hair under .001

The problem is the Y axis. Just checked it and it's off by about .006

Gotta check the manual, but I think I'll have to do some shimming, which I ididn't wanna do.
 
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