Official Luthiers Forum!

I have a very limited amount of space and although I would love to move into a nice large shop with stationary machines, I am kinda partial to my little mean-lean space. For example this you can see that I hardly have a any bench space left.

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Ken

From the above post, in the lower left you can see a round thing. That is my sander that I copied from Mike Doolin. It spins slowly with a flat plate covered with 60 grit . I sometimes put a piece of veneer over it and use it as a benchtop for sanding. It is nice because it spins freely and I can spin and sand the work as the dust collector captures most of it.

Here is the drivetrain. It is a 1/2 HP motor mounted on a hinge, It sits perfectly so that I just lean on the backer board and it spins, back off and it stops.

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Ken

The Robland Combo machine does a bunch of big work but must be rolled out and set up. That is fine because I don't do much planing or jointing and I try to do it in batches.

Now for my question.
I want to build a duplicarver with the capability to duplicate even a double bass size arched plate. These are 28 wide by 44 inches long and 2 inched deep. Due to my lack of space and infrequent use of this tool I would like to incorporate my combo machine using the cross cut table which has 50+ inches of travel. It is rock solid and I can easily cross cut a full sheet of plywood single handed.

I have a plan worked out. I don't draw that well, it is mostly in my head. But I want to build a jig that will have a router and a bit follower clamped to the jointer surface that pivots down and does not move otherwise. The plate and dummy will move across, sitting on the cross cut sled and will ride under the router routing one pass at a time. I will then move the plate/dummy down and run another pass, repeating until the dummy is copied.

Question: I have never used a router like this? Will I be able to make passes without the router jumping about? It essentially floats, I could add some counter weights if necessary.

Thanks for your help.

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Ken

Here is a photo showing the crosscut sled mounted on a x31, not mine. http://www.ncwoodworker.net/forums/showthread.php?t=25114

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Ken

So this is really a question to all my friends here. I have never used a duplicarver and consequently don't have a feeling for how it would work. My question above was a bit hard to understand I think.

My X travel is by moving the cross-sled and it moves easily with one hand. The plate blank and dummy plate are screwed to a sheet of plywood sitting on the sled and clamped down so it won't rotate or slip. There is no free Y travel to my proposed jig. I am running one X travel at a time, front to back, one push. Then return in the same path and un-clamp, move in the Y direction one pass width then re-clamp and push another one from front to back with a return again on the same path.

For my Z axis (up down) the router sits on a pivoting arm linked to the follower. This section is clamped down the the cast iron and can not slide in the X or Y direction, it can only pivot up and down. The arm with be stiff enough as not to flex when the operator moves the sled under it.

Imagine an arch top dummy that will be duplicated. If I set the height of the follower at the highest part of the arch and the router to be equal there will be no routing at this point. With the sled to the the operator start position, the operator pushes it in its path. The router bit will encounter the ledge of the blank and have to rout through considerable amount of wood. This can be fixed by limiting the amount of downward travel by setting the follower lower so only a limited amount wood is routed away. I could set steps depending on the amount of wood to be removed.

Can anyone foresee any problems with my design? Maybe I will have to just build it and test. But I thought I would pick some brains first to avoid a big waste of time, which is precious to me.

Thanks!

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Ken

No reason your idea couldn't work - the basic idea is more or less the same as you get with a conventional duplicator... just a bit more simple. I think the best thing you could do is just try it out... Frequently, it turns out that the things that "Can't possibly work right" on the web turn out to do pretty well.....

One thing I have seen with the home made duplicators is some way to track around the same "Altitude" of the dummy in 1 pass.... It solves the problem of trying to cut through a 2" section with a 1" depth cutter.... Another thing is to use a "Probe" that has the same profile as your router bit.... this way - you end up with a finished item that pretty closely resembles the original.... Another thing is to have some way to allow yourself to change cutting directions and paths - as climb cuts can be helpful when trying to minimize splitting when transitioning from long grain to cross grain cuts....

I still say try it out and see what happens... It may turn out to be exactly what you need when roughing out stuff like that....

Thanks

Thanks John!

I think I will mostly be cross routing, 90 degrees to the grain so I might just get away with it. Good point about the climb cutting though, I didn't think of that.

I will try to get a video when done.

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Ken

The widow of a local arch top instrument (Mando's, Cello's, Dbl Bass) maker is looking for homes for his equipment. There is an Inca (genuine Swiss model) 10" jointer planer, shop built dupli-carver, a very clever router based thicknesser for arch tops. It's all in Portland OR, so it will mean shipping. There is also a significant stash of wood available.
PM me if you'd like to get in touch with her. I have a few photos of the gear I can send/post.
-C

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Freeborn Guitars
and home of BeauGuard©

Thanks Chas, PM sent.

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Ken