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Dave, slight off-topic, but how long does it take you to rough-out a set of plates(assuming spruce and maple) with that rig?

My inlay pantograph is similar to everyone's here, but much cruder and it leaves a visible line all around the inlay that I fill with slightly darker filler than the headplate. It's become part of my "look" that a good many of my clients have mentioned as something they like. I've been wanting to re-build a better version lately, if for no other reason than to make it take-up a smaller footprint(running out of room in my shop!), so this thread it timely..!

For those corners on the OP's hex inlays, if I really wanted them to be tighter(they look just fine to my eyes as they are in the photos, and remember that in ebony or most dark rosewoods, any gap(s) will be filled and invisible) I'd just finish them up with a sharp chisel instead of changing to a smaller bit.

I used this casting kit from Smooth-On. The silicon rubber comes off any kind of part real easy. Then you can use the hard resin to make a duplicate for your cutting template. The rubber and resin castings show no shrinkage.

http://www.smooth-on.com/index.php?cPath=4_1217

Well, with my little router, I'd take no more than .100" per pass, so it took a while..... maybe 1 1/2 hrs per outside. A lot easier on the shoulders though.

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Dave
Milton, ON

Barry,
Thanks for the info. Do you cast the resin directly on the inlay piece to get the inlay template?

You could do that. But I took a different course for my signature logo. I made an original out of brass that I intend to keep as the master. Then I made a rubber mold of the master. I made another rubber mold of that rubber mold. Then I made a hard casting of both rubber molds. One of the hard castings is used as a template for cutting the shell and the other is used to cut the recess in the headstock. The parts fit together very precisely.

Oh good! I wasn't sure if you could cast the rubber to the rubber.
Thanks a lot. I will give it a try.

They include mold release in the kit to allow any of the materials to be used together.

Just for interests sake I think one would call this a duplicator rather than a pantagraph. The pantagraphs that I'm use to can copy at a larger or smaller scale depending on set up. A bit more complicated than the one shown but should be able to be constructed in the home workshop. But than maybe the blow up or shrink feature would not be of interest.
Tom

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A person who has never made a mistake has never made anything!!!

I built one of the Sargent duplicarvers but I don't use it any more because I found out that I could rough a plate out a lot faster with a gouge. I really want to build an inlay duplicarver though.

Totally agree with you.

My last sentence. Plus symmetry/lines/consistency are assured. But lots of other ways you're welcome to try.

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Dave
Milton, ON

We do not have to agree or dissagree. I wondered about the double panel thing myself and I did not get a good answer (that made sense to me) from Keith. Yet, I decided to do the same thing. Where I discovered its value was in changing the depth of the cut. A few spacer cards between the cutting side and carrier, light cut. Remove a card, it goes deeper. And so on. Thus, I can set the clamp on the router for max depth and gradually cut down to that depth without risking breaking the bit. Or overexerting the rig which could lead to overshoot.

The corners on my last cut were pretty tight. A little chisel work and it was perfect. I have not noticed shrinkage issues... I will be looking. I am working on a more precise mold holder.

BTW, I need to correct an earlier statement, I am using a 1mm guide pin and a 1mm bit

I checked my mould for shrinkage. After a week, the piece I created the mold for still fit in the form.

You can always use a slightly smaller pin (than the bit) to add a little relief to the cut.

But I agree that a resin based mould would be better for some repeatable things that you will do time and again. My little hex pieces are not similar and I will have to make several moulds.

Mike

Chris, I make the initial mold with the soft rubber compound because it peels off the master easily. The rigid plastic would not release easily, or at all. But you are correct that the soft rubber would not work for the working template as it compresses when slight pressure is applied. So you make a rigid plastic casting off the rubber mold for the working template. That kit is probably large enough to make a half dozen or so castings, depending on the size. You are also correct that this would be for multiple inlays. Using it for a one-off would be excessive.


Now that I think of it, the template shrinkage I had was probably with my epoxy experiments. I believe the reason I abandoned the Friendly Plastic was that I had difficulty peeling it off the master and it ended up with some voids. Sorry for that mis-information.

Mike, the hex inlays would be really easy to cut by eye the old fashioned way. Seems like the duplicator approach would actually be more work for those. The application where the duplicator really comes in handy is doing a thin signature inlay, which is very challenging by traditional methods.

Perhaps, though I am not exactly set up for it, nor do I have the necessary skills (and I do not care to develop them). I've done it before and I don't care to anymore. I think this tool is for what ever I care to carve. Thats the neat part. I do have more complicated plans down the path, and this is a good place to start/practice.

BTW, I thought epoxy was zero shrink?

I used the epoxy putty from the local hardware store and it definitely shrank.

So what type of bit do you use for cutting the shell?

What kind of bit? Ok, I'm fitting for precut shell. Someone else did that. However, I am now formulating a method for cutting shell using the negative mold. I have to believe that a good spiral down bit would work... But I've not done that yet. Any others here know? This would be the same bit I'm using for the wood routing, just use a slightly smaller pin

I use carbide end mills like these; http://toolinghouse.com/endmills.aspx?g ... 7Qodo2ol8g

Chuck

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PreciseBits.com has end mills specially designed for cutting shell. They are pricey but work better than standard mills. The main thing though is to get a high speed grinder. Trying to cut shell with a standard dremel is asking a bit too much.

Well, with my little router, I'd take no more than .100" per pass, so it took a while..... maybe 1 1/2 hrs per outside. A lot easier on the shoulders though.

Forgot to reply....

Thanks for responding! The reason I asked is that I've built myself a really solid and precise duplicator for carving mandolin and archtop(guitar) plates(soon!), as my fingers and elbows are beginning to beg for a break, and wondered if it was normal to take as much time to carve a plate as I've found, and apparently it is. But as you stated, much easier on the 'ol body, and of course, more precise and repeatable!

Dave Stewart
A couple of years ago I made a duplicator similar to yours for carving banjo necks.

I abandoned the idea after one neck. It was loud, sprayed sawdust everywhere, left a rough surface that still needed a lot of hand work, and took longer to do than with rasps, files, and knives.

Yessir, definitely not the best tool for neck craving. Archtop plates, on the other hand....

I do my headstock inlay a little differently. Most of the time I make a jigsaw type puzzle with my reducing pantograph rather than actually cutting a channel to inlay into. The red king snake is inlayed however so I kept the out cut. I cut out my patterns with a scroll saw with jewelers blade My reduction is 2.7x, I use a dremel with 1/32" endmills. I have it down now so I get really nice fits and don't need to do any filing on the inlay materials. I like to get pearl @ 50 thousands. It is a lot nicer to cut recon stone, wood, or ivory, ablam than hard white MOP.

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Michael F Smith
Goat Rock Ukulele
http://goatrockukulele.com

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