Keeping the turned piece a certain size all the length.

[Vernon Jenewein]

I am making Duduks, a type of Armenian wind instrument/flute. It is important to hold the turned lenght of the Duduk to a certain size for the body of the Duduk. I am using a carbid square insert from Harrsion Specialties http://www.harrisonspecialties.com/mm5/merchant.mvc?Screen=PROD&Store_Code=HS&Product_Code=14mmSquareScraper&Category_Code=LatheAccessories I made a sort of U channel holder with a 90 deg flare on one end to rest against the tool rest as I turn down to size. This helps to keep the size even across the lenght of 12 inches of Duduk.

So I was wondering if anyone here has any suggestions on how to keep a steady cylindrical shape, same size, all the lenght of 12 inches or more? I have seen them work this wood in Armenia on a video and it appears they are using a metal lathe. This makes sense since the lathe can be set for depth and amount of feed and will run a constant distance across the wood. When you free hand it, this is more difficult. Any ideas?

[Roger Chandler]

Sounds like you need a steady rest.........you can make them in your shop or purchase.......the shop method can be done easily, using two or three wheels from an inline skate.

Here is mine with 4 wheels.....a shop made one and a one made for me by a machinist .........

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Some of the woodturning suppliers also have smaller versions with bearings for small spindle items like the flutes you make...........get the correct size for the swing of your lathe.

[Vernon Jenewein]

Hi Roger! Thanks for the reply, but I have a steady rest http://www.pennstateind.com/store/LSR3.html I got from Penn State Ind. Works great! I could not drill those 13" long holes 29/64" without it!! However, this only holds the spindel steady. What I need is something to keep the distance from cutter to wood constant so the size of the spindle is constant. I will attach a picture of my last, 3rd Duduk I made so you can see this. I need to keep the final diameter at a certain spec. for 95% of the distance of the Duduk. What method would I use to assure the evenness of diameter of the spindle?


http://www.duduk.us/files/pictures/3rd-duduk/3rd_duduk_oil_finished.jpg

[Tim Rinehart]

Vern, if the question is how to keep it "steady" as in not wobble while putting the tool to it...Roger's feedback is a good one that many of us use.

If it's a matter of keeping a 'true' cylinder of consistent diameter, that's a different issue. A metal lathe with the traveler piece advanced by a lead screw will do this...but adapting one may not be cost effective unless you're making alot of them.

For a relatively short blank (12" or so) and if I'm just doing a couple, I'd be inclined to try taking a caliper set to the diameter you need, and place carefully cut parting cuts every couple inches to provide a good gage as you turn down to it. The skew for me is the final couple passes, but I'm comfortable with it, though many folks aren't. You can do a fair job with a spindle roughing gouge, but takes some practice too. Your carbide tool will do the trick as well, but it's a scraper the way most folks use them, and will not leave a finish as nice as the skew or the SRG.
If you still have some tear out or unevenness, you may want to leave enough material to have the final step include wrapping a piece of 80 or 120 grit around a flat/true board to even things out.

[Vernon Jenewein]

Yes, Tim, it is the second paragraph, keeping a 'true' cylinder of consistent diameter. The Karek Mukayelyan Duduk I have is nearly perfect for dimension in OD thoughtout the body. It's within a few thousands of difference. Smooth to the touch and looks precision made. Definitely not the crudely crafted Duduks of 50 years+ back using 2 concrete bocks and a guy spinning the wood back and forth with a piece of cord. I have seen videos of them and the use of a metal lathe seems to be what they are using. I have digital calipers, which I use to measure the "original" Karen M. Duduk and then I open them up slightly to allow for just a little extra size in O.D. Then if I happen to go a little bit too much I am almost where I should be. I use 120 and 180 grit for truing up and smooth and finish on 400 and 600 grit rolls of emory cloth, folowed by a little steel wool. I have cut the piece down very slowly, and measured (after stopping) using the calipers and keep going until I manage to get it where I need for O.D. Then it is a lot easier to just move up the Duduk 2/3 of the distance of that carbide scraper and bring to that "step". I don't have problems with finish since I use a very soft touch when getting to the evening process with that carbide scraper. It actually finishes up pretty nice all by itself. I'll post some pictures I have saved in what they are using in Armenia.

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You can see, Karen Hakobyan in his basement working on a regular wood lathe. Others look like precision metal lathes.

[Eric DeSilva]

I saw a furniture maker at a DC/NoVA AAW demo take a open end crescent wrench, file a divot into the top part of the open end, thus creating a cutting edge, and run the tool along a spindle to achieve a constant diameter. You have to pick the right size wrench, but you can, in fact, still use it as a wrench at the end of the day. Seemed to work reasonably well, although I've never actually tried it.

I've tried to show in a pic below--the red area is the area filed down. The head on view shows how filing it away creates a cutting edge.
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[Steve Vaughan]

I like Eric's idea just cause that sounds like something cool to do! But I'm also interested in hearing the other comments cause now and again, it can be an issue keeping that diameter exactly the same all the way from one end to the other.

[James Roberts]

Just throwing this out there but could you put a stop collar on the shaft of your carbide tipped scraper then just have the collar run along the edge of your tool rest to keep the cutter a constant distance from the work? Don't know if it will work for you but you may be able to at least rough down the cylinder that way. Hope this helps.

[Sean Hughto]

It's a common lathe task to make cylinders and dowels of various sizes that have to be a uniform diameter from end to end. How perfect does the cylinder have to be for your purposes? You can get really close with a skew simply by running it the length of the tool rest at the same angle and projection. If you need super precision, make a test template by using a forstner bit on your drill press make a hole in a piece of board or sheet stock. After getting the piece close - you can work backward from the tail stock toward the headstock, repeatedly stopping the lather to test your progress by sticking the cylinder into the template hole. This takes a bit of practice and patience, but wiled a very precise cylinder.

[Brian Kent]

Another non lathe option is to work your stock on a router table with a round-over bit. Keep the ends intact for attaching to the lathe and for that flared end. Then on the lathe you can work the ends and sand the whole thing.

[David DeCristoforo]

It would be very easy to make up a simple jig for this. A platform with a guide block that fits between the lathe bed ways. A riser block with a cutout for a gouge and a cap on top with wingnuts to allow the gouge to move in and out. Set the cutting edge to take a light cut and slide the thing from one end to the other. You could probably cobble it up in an hour.

[John Beaver]

Vernon,

I take my parting tool and calipers and make a bunch of slots an inch or two apart. I then turn between the slots with a roughing gouge until it's even. A little sanding and I'm pretty darn close usually.
If you square the tool rest you can use your fingers as a guide along the rest.

[Vernon Jenewein]

Perhaps something on this lines, like what James Roberts suggested...

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[Rick Markham]

I'm with David on this. I think building your own jig is the best answer. I'd probably choose a way to bolt it to the ways, to make sure it is completely parallel to the spindle. If I was going for accuracy, I would trap the tool in a captive type system, then use your handy little depth gauge thing you got going there Vernon, and you could literally just turn a bunch at once, and finish them up one at a time later.