[How-To] How to: reduce diameter

[DavidR8]

I have a need to make a 16” long rod with a diameter of .96” and I need to machine a reduced area on one end.
I have some suitable stock at .99”
Problem is I don’t have a steady or follow rest and the spindle bore on my lathe is only .867
So I’m stuck on how I’d center drill the end for tail stock support.
Any suggestions on how I can do this?

 

[682bear]

Do you have a 1" boring bor holder?

If so, you could clamp the stock in it, use an indicator in the chuck to center the stock, then put a center drill in the chuck...

It would take some 'fiddling' to get it indicated, but it's doable.

-Bear

 

[DavidR8]

Do you have a 1" boring bor holder?

If so, you could clamp the stock in it, use an indicator in the chuck to center the stock, then put a center drill in the chuck...

It would take some 'fiddling' to get it indicated, but it's doable.

-Bear

Brilliant idea. Unfortunately I only have a 5/8” boring bar holder…

 

[RJSakowski]

If you look in the South Bend "How to Run a Lathe", they show a method for center drilling the bar in chapter 4.

 

[jwmelvin]

If you look in the South Bend "How to Run a Lathe", they show a method for center drilling the bar in chapter 4.

I’m case you don’t have a copy:

Seems like you’re still going to need a follow rest though. Perhaps make something to that effect?

 

[Lo-Fi]

Got a Bridgeport or similar?

Swing the turret, hang the stock off the back of the table vertically with a section above, indicate it in and take down with a boring head. Joe Pie has a video, though I can't seem to find it. I think he made a little V block that saints on the rear of the table.
Great for getting an initial centre drill going too if you want to do the actual machining in the lathe.

 

[RJSakowski]

Here is an online copy: http://www.vintagemachinery.org/pubs/detail.aspx?id=17727

 

[Eddyde]

.99 to .96 so you have about .015 + - margin of error. In my experience, it would be fairly easy to do better than that using a divider or height gauge on a surface plate. Even a centering head on a good combination square would get you close enough.

 

[francist]

If you turned a small cup that fit the OD of your existing rod on the lathe you could centre drill it while it was still chucked. Then take it off the lathe, slip it over the end of your bar (should be a nice snug fit) and use the hole to guide a centre drill. Or for that matter, if the cup were durable enough you could just use it as your centre.

 

[homebrewed]

You might be able to make yourself a purpose-built follow rest out of wood. Plywood would do. Figure out how to attach it to your carriage, then install a 1" end mill in your lathe chuck. Advance the carriage to cut the hole & there you go. Lube the wood up good before using it.