drilling 1" holes

Re: drilling 1" holes

Paul Grenier

How are you drilling the hole? What type of drill bit are you using? I always use a Forstner type bit.

Are you drilling the hole while the blank is mounted on the lathe in a 4 jaw chuck? i would think that it would be very difficult to drill an off center hole this way.

Re: drilling 1" holes

Mark Paulley

Paul,

2" Sq blank secured in 4 jaw chuck and using a 1" fostner bit with a short extension in tail stock to drill through the 3-3/16" long blank. I move the bit through a short way and then reverse so not build up chips and then move forward, back and forth. I use the 2" sq to give plenty of room in case there is some wandering of the bit

Re: drilling 1" holes

Dwight Rutherford

After drilling, do you mount the blank between centers and true up the ends and then shape the outside of your mill? Everything should line up.

holding pieces with holes in the center

John K Jordan

If you are drilling first then turning to size later I suspect the drilling is not the problem but the holding. You said you make cone-shaped jam chucks. How are they held on the lathe?

I use jam chucks too but instead of cones the pieces I jam on are cylindrical, more like short mandrels. (I generally don't like cone-shaped supports.) For the headstock end you can wood in a chuck and turn a short cylinder that fits snugly in the hole to hold the head end. (The mandrel will need a slightly larger shoulder at the end to keep if from being pushed too far into the hole in the work.)

For the tailstock end drill a hole in a short block and use a 3/4"x10tpi bottom tap to cut threads to fit the live center. Thread the block onto the center then put the live center and block in the headstock spindle (locking it from turning with a piece of wire) and use it as a drive center to turn a second short, snug cylinder to hold the tail end.

Before I had a tap the right size, I would simply drill a hole in a block sized to twist/jam onto the live center threads then turn a cylinder on it as before.

The way just described is actually the way I USED to make short concentric wooden mandrels, works well but what I do now is quicker: turn a short morse taper on the end of a block, reverse and jam it into the headstock, then turn a cylinder (holding it with the tailstock while turning). I use this method to hold everything from thin spindles to various other jam pieces. The morse taper doesn't need to be very long. Here are some on the ends of thin spindles.

I make a little gauge to aid in sizing the taper but a couple of calipers work as well. Cut a shallow relief in the center of the taper to it contacts the inside of the headstock taper in just two places.

Unlike holding the support piece in a chuck, these can be remounted in the headstock in perfect registration every time.

I don't have a picture, but I often do the same thing for the tailstock end - quicker than drilling and tapping. A short #2 morse taper fits perfectly in the #2 taper built into a Nova live center. I have a bunch of these in the drawer, different sizes, ready to turn to the exact diameter needed every time I need to hold the tail end of something that has a hole.

The Nova is the most versatile live center I've ever had; it is so useful I bought two.

It's cheap now too - I paid $90 for the last one. (Maybe I'll get another...)

https://www.amazon.com/gp/product/B0064JIZGC

BTW, when drilling a deep hole with a Forstner bit I started doing something a decade ago that helps a lot: direct a continuous stream of compressed air into the hole behind the bit while drilling. It not only clears the chips but keeps the bit a lot cooler. No extra charge.

JKJ

Re: drilling 1" holes

Don Stephan

I'm not sure of the entire process from the brief description, and I've never made a pepper grinder. The square stock is grabbed in a four jaw chuck and drilled from the tailstock end. Then?

I wouldn't expect the registration of a square blank in a 4 jaw chuck to be perfectly centered every time. And a cone can be angled into a round hole.

Re: drilling 1" holes

jake niedling

I'm thinking that the ends are not 90 degrees to the 1" hole. I took a look at the item you are making from PSI. If the ends are not cut perpendicular to the hole, then when you assemble the parts, it will push the opposite end of the shaft off center in the hole. Just my 2 cents.

Thanks to all for the help

Mark Paulley

Thanks to everyone on trying to solve my problem!

Re: holding pieces with holes in the center

Mark Paulley

John,

I made the head stock cone to be held in my 4 jaw chuck and the tail stock I dilled a smaller hole in a 2x2 pine with a cone shape and twisted/jammed it on the one way live center.

I will make the next set not with cones but with the cylindrical method you described.

Thanks!

Re: drilling 1" holes

John K Jordan

>>>I'm thinking that the ends are not 90 degrees to the 1" hole...

I agree completely, without square ends you are doomed! Well, have a problem. Yikes, that seemed so obvious I forgot to even consider it. It should be easy for Mark to check one of his existing blanks that didn't work (and probably easy to fix them).

How do you prefer to hold and square up something with a large central hole?

For pepper mills (and anything else with the block initially held in a chuck) I think it's best, of course, to face off the far end of the block before drilling.

Then for a pepper mill I part off (or remove from chuck and bandsaw as square as possible), reverse and hold with the wooden "jam mandrel" in he headstock and support the other end with another wooden mandrel and face off the far end. Wood is perfect for support since I can cut into it a bit when cleaning up the far end, even if I cut a little into the shoulder.

Maybe there is a better way but that's the way I like to do it. I suppose the wooden cone would work on the tailstock end but I haven't tried that. Or use the aluminum cone that comes with many live centers, face off most of the way to the center, then remove the cone and clean up the tiny bit in the center another way.

After the piece is turned round (and assured to be concentric), I wonder if the end could be made square on disk sander?

I'm scheduled to demo work-holding methods in July this year. Maybe holding something like this would be interesting.

JKJ