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After getting a few responses in this thread about rosette cutters for the Dewalt 611 trimmer: viewtopic.php?f=10101&t=48642

I took some time to look at those but the least expensive was $125 (the wells Karol design) and some were close to $200... I thought that in principle the function was simple but i didn't have the tooling know-how to build anything like the ones pictured, nor did I particularly like all the set screws and hardware associated with the jigs.

The Charles Fox design was simple, but not adjustable enough.
The wells/Karol design was nice but still had all those setscrews and adjustment knobs, so I couldn't make that and i wasn't happy with the cost.
Trevor's design was nice, but i don't have anything (or i don't know how to use what i have) to make all that hardware.

So i set out to see what i could make.

I came up with a prototype that seems to fit all my needs.
- fairly simple to build. took me about 8 hours to build and most of that was sanding to make things fit cause i suck at accuracy yet.
- Cheap!.. I figure i spent less than 2 bucks to make this. certainly under $10 if i bought everything new.
- Accurate!! Has the adjustability of Trevor's but almost none of the hardware.

so... without further ado... here she is:


Best view of construction.




You can see how adjustable it is by the test cut. I tried to leave a small thread between a couple of channels. If the wood could have sustained it and the cutter been better i could have easily reduced it by half.

The range of cut is from about 1 3/8" to 7 1/4". infinitely adjustable in-between.

The handle is an old nut driver. The first design had a knob but i had two issues. I used two lock nuts to eliminate any play and i didn't have enough torque to be able to adjust it. I probably should have used one, but it works fine now. Also i used a knob that was too big and it lifted the jig off the wood (DOH!)

Welded a socket onto the threaded rod to allow for use of the nut driver handle.

You can probably see everything you need to be able to tell how it's built, but here's the breakdown.

A u-shaped piece of plywood. Mine is 4" x 7". A slot is routed in the center of the inner surfaces of the U.
Another piece of plywood is cut the width of the center of the U plus enough to route two "wings" to slide into the slots of the U.
That section is cut into 3 pieces.
- piece #1 is used to close the end of the U later. and serves as the threaded section that adjusts the pin holes.
- piece #2 supports the threaded rod and becomes the adjuster.
- piece #3 has the pin holes for the center pin of the circles.

In my first test, piece #1 was just threaded but it was too loose and i worried that the threads wouldn't last, so i counter sunk two lock nuts (with the plastic centers) one on each side to firm up the adjustment. I probably could have used one. They were expoxied in.

Piece #2 has a non-threaded hole that allows the threaded rod to pass through and turn freely. I welded a washer on the end of the threaded rod to provide the pushing and pulling surface to move piece #3. Actuqlly #2 and #3 together as one.

Piece #3 has a small divot to accept the washer without allowing any play. i wanted no play when i changed direction.i put a small dab of wax on both sides of the washer and then glued pieces 2 and 3 together.

The thing seems to work well. An unexpected bonus is that the handle acts as a nice handle to spin the unit around the pin.

easy-peasy!

Things learned:
Do NOT use plywood for this. Too chippy.
One lock washer may be enough.
Accuracy is your friend.

Hopefully someone will find this useful and simple enough to build.

Enjoy!

Rob

Well done. That's pretty cool and you can't argue with the cost. Looks like it works just fine. I assume it doesn't have a plunge function so how are you starting a cut?

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

We've made up a batch of Wells-Karol jigs each year for students and other to take with them when leaving the shop - cost is about $25 in Delrin or Lexan (while Delrin is smoother running, a transparent jig is handy!) and hardware, and they work well, but your design is a nice alternative that appears to be free of precision milling and the challenge seen with the Wells-Karol jig of making two exactly parallel, relatively deep holes for the dual rods.

A few questions:

- Is there some functional reason to have the router base plate installed? It seems as though you could pick up some additional vertical adjustment with the plate removed, and better visibility on the bit.

- If I understand the design, the friction from the nylon insert stop nuts takes the place of the locking function of winged set screws used on other bases, but inserts wear out over time (hence the admonition to never reuse an insert stop nut for critical locking tasks), so are there provisions to replace the stop nuts with new ones as the jig sees service and the insert wears? Could the rod end be captured with stop nuts and a delrin washer against the two sides of the #2 piece to better allow renewal?

I had some trepidation re: starting/stopping the cut prior to milling my first rosettes, but like other Wells-Karol users, have not found the lack of a plunge function to be an issue in starting a shallow cut like a rosette with bits that are under 3/16" diameter. It does not look as though Mr. Lak's design would need any special technique for starting the cut beyond the usual start router/index pin to base/drop approach. The rule of thumb in this shop is to always start and stop a rosette channel cut with the bit entering and exiting the wood in the area where the purfling ends are hidden under the fretboard extension area - seems to work well enough to allow us to forego the need for a dedicated plunge function on the base.

_________________
A constellation only takes shape when one maps the whole.
- Beth Brower

Thanks!

Just used the adjustment ring to drop the bit into the wood. Do you think there will be a problem with that? I did buy the plunge base as well but thought it might be too bulky to use and the others (i think with the exception of the unit that was near $200) did not have a plunge unit attached.

Just looked back at the original thread and i see that Treavor's saddle mill has a plunge unit on that. My base is bulky and enclosed and i was also worried the visibility would be limited. Maybe it comes apart? (Haven't used it yet.)

No, except that for the first time mounting to the router, i couldn't get the screws aligned, so leaving it on helped. I don't need to put the plate on anymore.



There would have to be a couple of changes to allow for replacement. Mainly that the welded socket would have to be replaced by a removable knob to allow for the outer locknut replacement. Also, in this design the nut on the inside is not removable, but i suspect that it isn't needed anyway so on the next iteration i will eliminate that one. I am not sure, due to the bi-directional nature of the threaded rod, would just a lock nut and washer loosen if not glued?

When i replaced the first knob and welded on the socket, the expoxy on the nut decayed and broke apart so i had to reapply the epoxy... that would imply i could use expoxy and remove a worn nut. I have no idea what the life will be of the lock nut. I guess they are not intended to be used in this way...

I also thought of using a threaded sleeve in place of the nuts, thinking that the stress is not rotational and there really isn't much of a concern that a lock nut is needed at all. I could also use teflon tape on the threads to help make it tighter and that might be enough.

But this is all by-the-seat-of-my-pants stuff, so i am guessing at it all..



Makes sense to me! Thanks for that!

Well, for what it's worth (maybe not too much?) here's my version. It's made of UHMW plastic. The lead screw is an ordinary 10-32 screw. I drilled 1/16" holes through the nuts and the shaft of the screw and put cotter pins through them to trap the moving section of the jig base between two washers. The lead screw runs through a nut embedded and glued into a Corian crosspiece on the stationary section of the base. There are a few pivot points, spaced at the limit of the screw's adjustment. I use it with the plunge base on the Dewalt router.





Having used it a few times (for instance, for this rosette) I'd say I'm satisfied with adjustability and repeatability except that I wish the base was transparent. It's hard to see the bit and that bugs me.





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I am going to have to look at the use of the plunge base. That looks like it works well. What's at the adjustment end?

The adjustment end is just the phillips-head screw. Not the greatest. But it's easy enough to adjust with a screwdriver.


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hi woodie do you know where I can get a set of plans for the wells/Karol jig ?? thanks