Sanding turnings to "exact" size.

[Richard Coers]

Thanks to all the great responses and ideas from the turners. I took as much as I could from each post. I was in the middle of a run of Oboe pegs when I said screw this and stopped. The detail cutter on the duplicator is getting dull leaving flaky cutter marks. The coarse sandpaper I was using cut like butter on the walnut and left scratch marks to be sanded off with more sandpaper. Bad circular logic!

Based on what I learned here I set the template oversize and then moved around to the front of the lathe (my duplicator is on the back) and used a skew with a planer cut to bring down to .5 mm over and remove the cutter marks. I then started with 150G and up to 320 to bring the pegs down to size.

I am a little afraid of the skew so I ordered a carbide skew which is more like a scraper and has a 30 degree shaft. I am hoping to sand starting with higher grits. This is still a work in progress but no more melting down pegs in a cloud of dust!

My father-on-law always said: "Green you're growing, ripe you're rotten.

Thanks,

Gordon

If you have the diamond shaped carbide cutter on your duplicator, turn the rpm on the lathe way up. It works best at 2,500 rpm or more. Carbide skew? Sounds like snake oil tool to me. You can't sharpen carbide to shaving sharp unless it's a super nano carbide and even then I'd be very surprised that it meets the same quality shearing edge you get with a honed HSS skew.

[Gordon Stump]

If you have the diamond shaped carbide cutter on your duplicator, turn the rpm on the lathe way up. It works best at 2,500 rpm or more. Carbide skew? Sounds like snake oil tool to me. You can't sharpen carbide to shaving sharp unless it's a super nano carbide and even then I'd be very surprised that it meets the same quality shearing edge you get with a honed HSS skew.

Thanks Richard I do run the lathe fast. I ordered a new diamond cutter. I also prefer hss over carbide. And I have kept away from the carbide turning tools. I had moment of weakness!! I designed some measuring little sticks with the bottom and top measurement of the contoured pegs. A cnc router makes this easy. calipers.jpg

[Marvin Hasenak]

If you search Google "Eugen Schlaak miniature tart press video", you will find that he used a "semaphore jig", It is basically a set of arms that drop down as a certain size is reached. There is also a book that has a good description of semaphore jig for lathe, but the name escapes me. I have one that I used to make tenons on game calls, easy to adjust the size because the falling arm has to adjustments. To get to the size before sanding is strictly a guestimate, or a SWAG. It will take a while to get it set up the first few times, but after awhile you will find a method to make another jig so that it only takes a minute or 2.

[Gordon Stump]

If you search Google "Eugen Schlaak miniature tart press video", you will find that he used a "semaphore jig", It is basically a set of arms that drop down as a certain size is reached. There is also a book that has a good description of semaphore jig for lathe, but the name escapes me. I have one that I used to make tenons on game calls, easy to adjust the size because the falling arm has to adjustments. To get to the size before sanding is strictly a guestimate, or a SWAG. It will take a while to get it set up the first few times, but after awhile you will find a method to make another jig so that it only takes a minute or 2.

Thanks. There is so much to learn from those who came before.

[Brice Rogers]

I think that most lower cost duplicators use a scraping action to remove wood. It is accepted by most that scraping leaves a rougher finish (e.g. tear-out) than, say, using a skew. A sharp skew used in the slicing mode can leave a great finish - - say starting sanding at 220 grit or better. It takes a little practice but isn't all that hard if you practice.

There is a production turner in the UK that is a master on the skew. On Facebook his id is The Woodturners. On Youtube, either google Steve Jones or Woodturner21. There are also a lot of other good videos on using a skew. And some bad ones.