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Duplicating Cylinders on the Lathe

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peteryu65

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Feb 6, 2008
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Ok, Folks, I need some sort of way to batch produce cylinders of a certain diameter on the lathe. The wood will have a hollow center so vibration is a issue. I need it to be somehow a perfect cylinder with the same diameter all the way along the axis so turning it by hand isn't an option. I've seen duplicators out there but they don't seem to do a very good job and I would hate to buy a duplicator just to turn cylinders. Accuracy is extremely crucial as the wood will somehow have to friction fit into a copper pipe. Does anyone know how this can be done? I was thinking about some sort of router jig that lets me mount the router to the top of the workpiece and run it along while manually rotating the spindle. However, this seems a little... cumbersome. Thanks!!!
 
Ron Sardo said:
Have you considered warping the copper pipe with veneer?
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Hmm, I don't think you understand. I need to turn the wood to fit IN the copper tubing, not to go around!!!:cool2:
 
You might try sharpening one side of an open end wrench and use that as a caliper/cutting tool.
 
The degree of accuracy, I assume, has to run the full length of the piece. That's very difficult for most of us to do by hand because if you use your hand as a guide the tools rest has to be aligned precisely parallel to the work piece and the angle of the tool has to be held constant. As you describe it, this is a machining task rather than a simple wood turning task. I know there are some out there who could do it, but I'm not one of them.
I might try building up an attachment to which I could mount a machine cutting tool and turn the piece by hand until I reached a tolerance fairly close to what I needed, then use the attachment to run the machine cutter through fine repeated sequences to obtain the diameter I needed. Before I tried the fit I'd made sure to debur the openings of the tubing and check it for out of roundness.
 
Hand turn slightly over size then use a piece of pipe with saw teeth cut on end and run over turning to do final sizing is what I would try. Just file some teeth on the end of the pipe.

You did not say how long these pipes are, if to long this may not work.

John
 
Since I've been doing a lot or router work on the lathe I think that is the way to go. it's very easy to set up a table to hold the router. To route a straight cylinder I would make a jig to hold the router above the work piece. This would allow the weight of the router to do some of the work. I'd be glad to sketch out an idea of how to build it if you think that is the way to go.
To give you some idea of how well this works. many years ago I was at Berea college visiting. They were using a router and lathe to make bowling pins for a Skittles game. They turned the pins in about 30 seconds. Another 30 seconds for sanding and it was done. That got me started along that path.
 
john lucas said:
Since I've been doing a lot or router work on the lathe I think that is the way to go. it's very easy to set up a table to hold the router. To route a straight cylinder I would make a jig to hold the router above the work piece. This would allow the weight of the router to do some of the work. I'd be glad to sketch out an idea of how to build it if you think that is the way to go.
To give you some idea of how well this works. many years ago I was at Berea college visiting. They were using a router and lathe to make bowling pins for a Skittles game. They turned the pins in about 30 seconds. Another 30 seconds for sanding and it was done. That got me started along that path.
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Actually, that was the way I was thinking. I did see a jig similar to that in an issue of Fine Woodworking a while back that was designed to dupliacte patterns but that plan had the router mounted horizantally and looked pretty cubersome. I do think this is the way and would be glad if you drew out a set of plans as long as it wouldn't intefere with any of your regular activities 😱. Thanks!
 
Wood is hygroscopic, it shrinks and expands with changing humidity making it difficult to get precision fits. A perfect fit on a rainy day can result in a sloppy fit after a couple days of dry weather. Probably better the other way around, fit it dry then let it expand in the copper pipe. Hopefully, it won't expand the pipe itself and result in a loose fit after the next dry spell. Not out of the question with copper!

A router mounted on some type of platform that slides along the lathe bed sounds practical to me. It could be maneuvered freehand, cutting at the top, and as long as the head- and tailstock points are even with the bed, it will cut a straight cylinder. Otherwise you will get a taper.

Also along the lines of the sharpened wrench idea is a sizing tool made by Sorby, which is a guide that fits a flat or diamond profile standard parting tool.
 
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john lucas said:
... I would make a jig to hold the router above the work piece. ...
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Wish I had thought of that. That's the best idea I've seen so far.
 
I have to agree with Ken. Inserting wood into a pipe can be a problem due to wood movement. You would need to use a glue that can handle the movement. Ferrule's frquently come loose on wooden handles because the wood swells, the metal squashed it, then the wood shrinks and it's loose. I'm not sure how that will work with a piece of metal longer than 6". It would be interesting. Of course you could always use MDF.
Building the router rig is very easy. If you can look up my articles in Woodturing design I show a couple of horizontal rigs that just fit in the banjo. The rig to go over the piece is even easier to build. Just 2 boards with a rabbit cut in the top. Then put spacers on the ends to set these apart just far enough that the router base sits in the rabbit. Cut slots to fit around the spindle and tailstock quill and then some sort of riser blocks to get it to the proper height. If I have time I'll build one this week. Shouldn't take more than an hour to do. I already have one that I use for fluting that doesn't use the lathe at all. I just sits on the workbench and has screws for the centers.
 
What are you trying to do with the finished pieces Pete?

You can buy thin copper and wrap that around wood
 
Here is my fluting jig that I use off the lathe when I do fluting demo's. I propped it up on the lathe with 2x4's to give you idea of what I'm talking about. The risers that support the box need to be adjustable so you can adjust it to be parallel with the bed and for height if you don't have a plunge router.
 

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precise cylinders

What you need is a machinist who will turn the wood with the inherent precision that comes with metal working. I have had my bro-in-law turn metal for me and he always gets it too precise!!!!! Phil
 
The problem with a thickness gauge like you show is that you MUST keep the bottom piece of metal firmly pushed against the work. If you don't you can still cut too deep with the scraper. I've played with homemade versions and they just don't seem to work 100 percent of the time.
 
You can buy cross feed style tables from Enco for less than $100. Then just mount your cutter on this. You would have to build a block to hold the cutter or you can buy one of the commercially made metal lathe tool holderss.
It's a scraper so you could do the same thing by making a platform that fits on the lathe bed and a guide board that will give you the finished dimension and then just build a block that holds the cutter and use it just like a copy lathe attachment.
Of course if you do that you can also build the router stand that will cut the wood faster and cleaner. Same concept.
 
John, if you draw up some plans for the above project, I would be interested in seeing them.
 
john lucas said:
You can buy cross feed style tables from Enco for less than $100. Then just mount your cutter on this. You would have to build a block to hold the cutter or you can buy one of the commercially made metal lathe tool holderss.
It's a scraper so you could do the same thing by making a platform that fits on the lathe bed and a guide board that will give you the finished dimension and then just build a block that holds the cutter and use it just like a copy lathe attachment.
Of course if you do that you can also build the router stand that will cut the wood faster and cleaner. Same concept.
Click to expand...

As of right now, I still think that the router method is better because any form of scraper-mounted-on-sliding-table configuration is basically still the same thing as a copy attachment or duplicator. And we all know how well that works.

BTW, since you used a router jig before, I have a quick question: How clean is the surface after you routed? I would hate to spend so much time building a jig, routing out a cylinder, just to find that after sanding the cylinder is too loose.
 
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Give me a few days and I'll show a photo of a router platform and will have a routed piece to show the finish quality. I have a meeting tonight and have to repair a dryer for a friend on Thursday so it might be Friday before I have time to do this. I may be able to set up the compound sliding table and try that as well. You've got my curiosity up. It just dawned on me the compound sliding table won't work for you because they don't have enough travel. I have a large one and it's travel is about 8 to 10" I think.
Actually on a flat turning a duplicator doesn't do that bad of a job. You might actually want a slightly unclean surface for the glue to bite onto because you won't be able to use wood glue for this application. Where a duplicator fails is turning fine details which it tends to tear badly.
 
I'm surprised that no one in this discussion has suggested a Legacy mill yet. I don't say go out and buy one, but it should not be all that hard to find someone who could make these things for you. But as has already been mentioned, it is going to depend on what day of the week you do this as to whether or not it is a friction fit, and that will change from day to day.
 
peteryu65 said:
Hmm, I don't think you understand. I need to turn the wood to fit IN the copper tubing, not to go around!!!:cool2:
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Shaper and the proper bead/bullnose bit. Same basic technique as is used for making big dowels. Leave a reference squared portion on each end and bullnose the center.

Bore after shaping.
 
If the wooden cylinder is to fit inside copper tubing, why do you need to have such accuracy for the entire length of the cylinder? Seems to me that an inch or so at each end would be all you should be concerned about. If the measurement is exact for the entire length, I think you will have a problem inserting it into the tubing. BYW, a little liquid dishwashing soap will make things slide very easily.
 
I'm curious too, but why should that limit the challenge?😀

For best assembly, the copper pipe could be heated, and then allowed to shrink onto the wood (turned and sanded to slightly oversize) while cooling to ambient temperature. This is very common in machine assemblies - called "interference fit."

Joe
 
Ken Grunke said:
This question hasn't been addressed yet, I'm curious!
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Yeah? Tell you what. The wood that has to go into the copper tubing is designed to strenghen a DIY Photo Project. Also, if it turns out well, it may find it's way into my Prototype Turning Tool Handle (See the other thread called "R&D of New...".) After all, it's a prototype and I'm still not sure if copper will work very well in terms of weight and strength but still, even if it fails, I could still use it in brass or aluminum tubing.

Also, the exterior of the handle is probably going to have some sort of wood to it so dupliucating cylinders is also going to be applied to the exterior of the handle.
 
I spent a few minutes in the shop this morning playing with the router on the lathe. This is my first box designed to let me use the router as a sort of carving tool on the lathe. The bottom is adjustable in and out. The box then is pinned in the center and has a circle routed in so I can adjust the box by swinging it in an arc. The top platform also has slots cut in the top of the box so the top can also be adjusted in and out. I think I will put a micro adjustment and alignment pins on the top so that I can fine tune the adjustment.
As you can tell in the second photo the finish isn't very good. It could be cleaned up quickly with 80 grit. I put a block plane on it while it was spinning on the lathe and cleaned up the tearout pretty quick. I suppose you could fine tune the size this way. Cutting with the router wasn't all that fast on a spindle this size and the spindle wanted to flex so the middle was slightly bumpy.
The first photo is a Sears Router Crafter. They are no longer made. It was designed to turn spirals on turnings but will work to turn cylinders using the router. They can be found on EBAY but be prepared to pay. The sold originally for $139. I saw about 8 sell for well over $200 before I managed to buy one for $89. It had 2 brocken Idler wheels but those were easy to turn out of aluminum.
 

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I have good experience by making a stable toolrest. The toolrest is as long as the cylinder has to be. The fact that you can put the long horizontal toolrest very close to the piece makes it very easy to scrape or turn a perfect cylinder.
Squirrel
 
But you still have to align the tool rest. Any misalignment and you get a tapered cylinder. If you have hard and soft areas you can also get a slight raised portion here and there that's barely noticeable until you measure it or try to push it into a metal cylindar. This method does work however because I've done it for years.
My normal method is to just make repetitive cuts with my parting tool and calipers the full length of the piece and then connect these cuts with my skew until all of the cuts are gone. This is pretty accurate.
He is wanting to put the wood inside a metal cylinder so it needs to be more accurate than these methods unless you want to use a gap filling glue which I think will be necessary anyway.
 
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