Re: accurate bore

Karl Townsend wrote:
"The Kid", my 22 year old, is taking on a job for our Mazak M4 lathe. The part is 24" long by 3" OD, 2"ID, with a ton of features. The job is for 60 units a week, six to eight months a year.

On each end is one tight tolerance bore, 2.375" -0.0000 +.0005. Looks like they will put a Timken bearing race in that spot. The rest of the job demands that this bore be made with two feet of part hanging out of the chuck. What's the best way to do this? I'm guessing we should look for an adjustable boring head with two opposing carbide inserts. Or maybe a reamer that can be chucked in the back turret.


You didn't say if there's a concentricity spec between the bored ends. If they're for bearings, I'm guessing there will be one, and it'll be fairly tight.

   I hate to show my age; but...

This sounds like something you'll want to run complete on the Mazak, except for the bores. Leave some finish stock in those, and then go find an old Heald double end boring machine, or an Excello Borematic. I did a quick Yahoo look for Excello's and found hundreds of them, with prices that start at under $50.

These machines, even old and tired, were the fastest, easiest, most accurate way imaginable, to put bores in the ends of almost any tube or shaft. Considering the production volume, the likely price of the equipment, and the fact that you'll get better cycle times and less trouble if you don't have to worry about the bores on the Mazak, it seems like an easy investment to me.

   Good luck!

KG


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