Lathe duplicator

[Blake M Williams]

I've recently branched out and started to turn stuff. I'm still new at this and getting the same results each time is still hard for me.

In my searches I came across a lathe duplicator. This sounds like an awesome add-on.

I was thinking of making one. Can I use a router as the cutter? Slide it back and forth, push in and out along a premade profile? Does lathe speed matter if using a router?

[Brice Rogers]

I have seen some videos of a person using a router as a cutter. Finish is rough, but great for rough turning or initial turning.

I also visited a large shop that specialized in larger architectural turnings. One of their many machines used a higher powered circular saw with a lathe follower setup. The saw was decent sized to it worked quickly. IIRC, they were removing at least 1/4" per pass initially and then did a much lower depth-of-cut for the final pass. Plus 80 grit.

[Blake M Williams]

I searched some more. Found a couple examples. Looks like I could use some linear rails or even drawer slides for the moving parts. What bits are best for use with a moving lathe?

[Richard Coers]

Drawer slides would be a bad choice. Little dust and chip tolerance, and grease on full extension slide ball bearings. As mentioned, most DIY duplicators leave a horrible surface finish with a simple scraper tool and have trouble with chipout on details like small beads. Cheap purchased duplicators have the same issue. Even a Vega duplicator had trouble until they introduced a carbide insert with a high shear angle accessory. But it still had trouble and required extremely high lathe speed to get any kind of a reasonable finish. Commercial duplicating lathes like HAPFO have high shear angle cutters. Really like v-shaped skews, held nearly vertical over the spindle.

[Blake M Williams]

Can a router and lathe combination have both parts running at high speeds or should this combination be slowed down and hand cranked?

[Brice Rogers]

hmm...

A typical router cuts in a clockwise direction. So, I suppose that it makes the most sense to cut from right to left so that the typical lathe direction isn't working against the router. But if a person wanted to cut in both directions (left to right and right to left) then it would make more sense to slow the lathe down. I think that a typical router speed is 10,000 rpms and up, so you could probably cut in both directions (at lower lathe speeds) and using a hand crank probably isn't needed as long as you keep the lathe speed reasonably low.

The router bit selection depends on the fineness of the details. The finer the desired details, the smaller the bit should be. But if a person uses a rounding bit, it should give an acceptable finish with perhaps some tear out on the cross grain. But you'll still need to plan on using courser sandpaper.

Lathe speed that works well, is also dependent on the depth of cut and rate of feed and the diameter of your turning. For instance, if you were trying to remove 1/2" or 1" of material all in one "gulp", you better slow down the lathe speed or slow down your rate of feed. In fact, for removing 1/2" of material, you WOULD want to either hand crank the lathe or drastically slow down the rate of feed. So, you've got to use some common sense.

If I were you, I would watch some Youtube videos, take a bunch of notes, then make your duplicator and tune/experiment with your set up with the lathe speeds, depth-of-cut, rate of feed and other variables that works for you.

[Ed Aumiller]

A few years ago made a plywood platform to set on lathe ways. Mounted a router horizontally with the shaft/chuck at the same height as the center of the lathe. Used a template pattern to guide the router. Turned lathe speed down to very minimum, about 5rpm, left router run at normal speed, about 12,000rpm... took very light cuts..when almost to final pass took extremely light cuts and it worked very well... needed very little sanding...

HOWEVER, it was VERY slow method... by practicing using normal tools quickly became able to get close enough on duplicate pieces that have not used it in years..

The nice thing I found out about turnings is that the human eye tries to make things look the same... made a cradle for grandson with about 40 spindles was reason for duplicator...after making about 10 with duplicator, just made the rest by hand... and it was much more enjoyable.

Unless you want to make duplicate parts for a commercial (business) reason, recommend you just practice doing it by hand... you get a lot of satisfaction knowing it was hand made....

[Blake M Williams]

Ed I can see your point of view. But something I'm worried about since I'm still so new is getting a consistent pattern on a long piece.

Would you guys recommend that I use a longer tool rest?

[Perry Hilbert Jr]

My main work horse lathe is an old Delta high school shop lathe. Since I got that, I have located and acquired the outboard tool rest and a Delta duplicator with factory bits . The fellow I got the duplicator from showed some table leg pieces he turned , both rough, sanded and finished. The rough was certainly "rough" but the pieces are within a 64th of an inch of identical by width and length. I suppose it also depends a great deal on the wood turned. However, sometimes it is also the operator. I built a few long rifles over the years. CNC precarved stocks are available from many suppliers. Some have 75% of the work done and some have 95% done and look almost finished. I haven't set up the duplicator yet. The project I wanted it for is still months away.

[Mick Fagan]

Ed I can see your point of view. But something I'm worried about since I'm still so new is getting a consistent pattern on a long piece.

Would you guys recommend that I use a longer tool rest?



Depends on what you call long pieces, within reason that is.

This is an interesting method of doing very long pieces, from what I can see from various posted videos, his work always seems to be pretty good. I have met him in a social gathering, his advice to me from a direct question was sparse, but super practical. If you look carefully you will see the chalk marks where different cuts are required. Doing something like this certainly helps and makes what may seem to be something daunting, into individual jobs on the one piece.

When he takes the finished piece off of the lathe, then places it in the stack of other work, you get to see the precision cutting he has done. Yet he didn't seem to be too precise when he was cutting the material, getting to that standard of spindle work can be achieved quite quickly if you adhere to a plan.

If you watch it through, there are some techniques which seem worlds away from a small lathe, but technique is technique and can usually be adapted to ones own situation.

https://www.youtube.com/watch?v=uah0y4WnmH0

(https://www.youtube.com/watch?v=uah0y4WnmH0)As for a longer rest, it certainly can help. Even one you make yourself from wood, should be advantageous. I myself have had a 400mm (15¾") long single post tool rest custom made by Vicmarc, it complements the standard 305mm (12") rest that came with my lathe. That longer tool rest is now my standard go to rest for most of my spindle work and anything else it is sized for. I have been doing some long spindle work up to 1300mm (51") and I am now considering getting a 600mm (24") double post rest.

In the interim I have jury rigged a 600mm tool rest made entirely from wood to test my need for a steel tool rest. Unfortunately I don't have pictures of it, but I can say it is better than continually moving the tool rest.

Attached are the 400mm rest on the lathe, the second picture is the OEM (black) rest and my Vicmarc tool rests, 100mm, 200mm and 400mm.

422030422032422034

Mick.

[Blake M Williams]

Thanks for the input guys. I've learned where cheap tools get ya, so ifvyou were to pick the two three or four most used spindle turning tools, which would you get? So far, I have a roughing gouge, 1 inch flute from Hurricane. Good brand?

[Brice Rogers]

For the single most spindle turning tool, I'd suggest a skew, followed by a spindle or bowl gouge, followed by a roughing gouge. The skew can do roughing but is not the best tool for small coves.

[Blake M Williams]

Ok, I ordered a skew. Says it's a 1 inch standard flat skew.

[Brice Rogers]

Blake, that is a perfect sized skew. I'd recommend taking your new tool to the grinder when you get it and slightly round the square sides. That'll minimize the dings to your tool rest and help it glide a bit better. Otherwise, when you're rubbing the bevel and cutting, the tool will be in contact with the tool rest at a fairly sharp intersection of two sides. I think that most people who use a skew to make slicing/shearing cuts do this.