Making gear shift knob for daughter's '48 Pontiac. Think cigar. End needs to be tapped 5/16 inch tbreads. Question: Try and drill after turning? Hard to hold contoured product. Only have spur center, no chuck. Drill first and place in lathe using a home-made 5/16 step arbor? All advice appreciated. Ivan Vegvary
Making gear shift knob for daughter's '48 Pontiac. Think cigar. End needs to be tapped 5/16 inch tbreads. Question: Try and drill after turning? Hard to hold contoured product. Only have spur center, no chuck. Drill first and place in lathe using a home-made 5/16 step arbor? All advice appreciated. Ivan Vegvary
That last sounds pretty good. Drill first and, for the tailstock end, turn a stepped piece that fits the hole fairly closely. You wouldn't want to put the drilled end directly on the tailstock center for fear of splitting it.
Tom
I did a large batch of ultra-high-power refrigerator magnets from exotic woods featuring a semi-precious stone disk set in the end. The magnets required the insertion of mild steel cups and these needed to be bolted/screwed into a recess in the wood. I finally figured out that I could drill and epoxy a threaded brass insert into the recess made for the cup. Then I could easily used a threaded steel rod screwed into the brass and clamped in a chuck for the drive end. Doing it this way it would be possible to bring up the tailstock to steady things during the roughing process although with my small pieces it wasn't necessary. As the last step I chucked a Forstner in the tailstock and used it to cut the recess for the stone disk.
You could drill a 1/4" hole first, partially glue in a 1/4" dowel ("partially" so you can more easily remove it later) then turn. If you make a somewhat sloppy 1/4" hole and glue a piece of paper around the dowel with water soluable glue you should be able to get it out easily enough and then tap the hole.
The tapping is what I really wanted to comment upon. You said "think cigar" so I'm assuming the tapped hole will be in end grain. Isn't going to work. Not well, at least. The tap is going to be cutting across the grain making many tiny, insecure little pieces, most of which will break off. I had the same problem when cutting 1/2" threads on my cane. I solved it but it was neither easy nor entirely satisfactory. You would do much better to epoxy in a metal insert that also has internal threads.
What do you have for the tail stock center? A Cone center maybe? If you have a cone center, drill and tap the blank, chuck it up with the drilled/tapped end on the tail stock - just don't over tighten or you will split it.
If you don't have a cone center for the tail stock, take a threaded rod or cut off bolt (5/16"), and drill/punch a dimple in one end (make sure it's about 1" longer than you need. Drill and tap the blank, screw in the threaded rod/bolt. Put the wood end on the drive center, and the theaded rod/bolt end on the tail stock.
You could also make a wooded MT#2 (or 1 depending on your lathe) with a threaded rod sticking out of it - use it instead of the drive center. Then screw the drilled/taped blank onto it.
Gimp
Is it three on the tree? I'd want a metal shaft all the way through. The wood would just be covering the metal shaft. What's the original look like? Maybe make a pin chuck for the lathe, they're handy.
I think someone else suggested turning a morse taper, mount in headstock and drill. Let us know what you come up with. I always like to hear about new and novel approaches. There are so many ways to do these things. I think that's half the fun.
I like to challenge myself to make do with what I've got instead of buying some new tool and often I learn something new as well.
s to be tapped 5/16 inch tbreads.
ly have spur center, no chuck.
What tdacon said, but with this difference, since you have a tap for the th reads, I would assume you also had a die of the same size and thread. Turn a blank, thread it and insert in your gear shift blank (after you have dri lled and tapped it, of course) then insert your threaded piece. place on th e tailstock end and turn.
The reason to drill first and turn later is twofold. 1)you have more mass to stand up to the stress of the drilling process and 2) you can center off the hole, rather than trying to center the hole, which almost never works.
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