High quality manual rosette/circle cutter?

Construction and repair of Classical Guitar and related instruments
wombosi
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High quality manual rosette/circle cutter?

Post by wombosi » Sat Dec 08, 2018 12:14 am

I'm on the lookout for a high quality brass manual circle cutter. They seem quite scarce. I tried the one on Etsy made by a nice guy in Turkey. Gorgeous to look at but way too high a center of gravity and unstable/wobbly in use.
There's some nice stuff overseas but can't get a response from the maker and it looks like it might have the same problem.

I'd consider something like the LMI circle cutter, but it's a deal breaker for me to not be able to see the blade and have to set the blade by trial and error.

I'm using a router jig a la Bogdanovich, with spiral downcut bits but am still getting tearout in my cedar top. I'd like to have a manual cutter at least to score the margins.

Does anything exist out there? I could make something out of wood if I wanted to spend a day or two fiddling about with it, which I don't.

Thanks.

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Michael.N.
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Re: High quality manual rosette/circle cutter?

Post by Michael.N. » Sat Dec 08, 2018 1:03 am

I'm not sure about the LMI but can't it be set using a digital caliper? With them having inside and outside calipers it's usually very easy to put the caliper between the pivot point and the blade. You might have to account for half the thickness of the pivot and the blade thickness but those measurements never change. With the caliper you can get a very precise setting, in which case you don't need to see the blade. You can even zero the caliper and then increase the setting by 0.1 mm or 1.86 cm's should you wish.
I have a few homemade circle cutters. The one I use the most is a tank cutter but I adapted the arm and cutting head. I'll try get a pic up tomorrow.
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wombosi
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Re: High quality manual rosette/circle cutter?

Post by wombosi » Sat Dec 08, 2018 1:07 am

Thanks. I'd love to see a pic of your shop made cutter!
I thought about that with the lmi jig. Just not so into it. I'd prefer to either make one myself, or find one where I can see the blade and not have to do math and calipers. I know that sounds pretty lazy...

bftobin
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Re: High quality manual rosette/circle cutter?

Post by bftobin » Sat Dec 08, 2018 3:04 am

Have you tried sealing the area with shellac first ? I'm using the same as you and the little fuzz left around the channel afterwards comes off clean with a small block and some fine sandpaper.

wombosi
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Re: High quality manual rosette/circle cutter?

Post by wombosi » Sat Dec 08, 2018 3:10 am

bftobin wrote:
Sat Dec 08, 2018 3:04 am
Have you tried sealing the area with shellac first ? I'm using the same as you and the little fuzz left around the channel afterwards comes off clean with a small block and some fine sandpaper.
I haven't tried that yet. Thanks for the tip!

vesa
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Re: High quality manual rosette/circle cutter?

Post by vesa » Sat Dec 08, 2018 8:16 am

Hi wombosi

I have LMI cutter.
Positive things:
It is very stable and makes very clean cut
- you really have to mess up the things to get a tear off.
Negative things:
It is very difficult to set.
Set up mechanism is clunky and inconvenient to use.
The worst thing is that the center pin imperial
which is very stupid design as normally all the plans are metric.
Of course you can convert it and divide with 2
if you need check out or remeasure some of the distances from the center
but I find that difficult and total waste of time.
And I will not begin to make rosettes imperial because of the tool.
But - still - I have not found better alternative but you need to be very careful with setting it.

Vesa
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Richard Newman
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Re: High quality manual rosette/circle cutter?

Post by Richard Newman » Sat Dec 08, 2018 8:38 am

You usually get fuzz and tear out if you plunge the router too deep. You should only be cutting in increments of around 0.5mm to start. This should give a clean cut even with a standard cutter. Egg white can help too.

gjo
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Re: High quality manual rosette/circle cutter?

Post by gjo » Sat Dec 08, 2018 9:34 am

The dutch luthier Hans van Velzen (#3 in this year´s Granada competition !!!) makes some lovely tools. Google his name and you will find him.

wombosi
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Re: High quality manual rosette/circle cutter?

Post by wombosi » Sat Dec 08, 2018 12:26 pm

gjo wrote:
Sat Dec 08, 2018 9:34 am
The dutch luthier Hans van Velzen (#3 in this year´s Granada competition !!!) makes some lovely tools. Google his name and you will find him.
I came across his site. Very nice stuff indeed! But he's not returning my emails. I would buy his circle cutter and veneer scraping jig. Thanks.

wombosi
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Re: High quality manual rosette/circle cutter?

Post by wombosi » Sat Dec 08, 2018 12:28 pm

vesa wrote:
Sat Dec 08, 2018 8:16 am
Hi wombosi

I have LMI cutter.
Positive things:
It is very stable and makes very clean cut
- you really have to mess up the things to get a tear off.
Negative things:
It is very difficult to set.
Set up mechanism is clunky and inconvenient to use.
The worst thing is that the center pin imperial
which is very stupid design as normally all the plans are metric.
Of course you can convert it and divide with 2
if you need check out or remeasure some of the distances from the center
but I find that difficult and total waste of time.
And I will not begin to make rosettes imperial because of the tool.
But - still - I have not found better alternative but you need to be very careful with setting it.

Vesa
Thanks Vesa. That's exactly why I'll never buy this tool.
I don't care about the imperial pin, that's what I need actually. But everything else sounds right based on what I saw in the O'brien videos.

gjo
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Re: High quality manual rosette/circle cutter?

Post by gjo » Sat Dec 08, 2018 6:27 pm

wombosi wrote:
Sat Dec 08, 2018 12:26 pm
gjo wrote:
Sat Dec 08, 2018 9:34 am
The dutch luthier Hans van Velzen (#3 in this year´s Granada competition !!!) makes some lovely tools. Google his name and you will find him.
I came across his site. Very nice stuff indeed! But he's not returning my emails. I would buy his circle cutter and veneer scraping jig. Thanks.
The veneer scraper is very good, I have one and use it quite often.

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Michael Lazar
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Re: High quality manual rosette/circle cutter?

Post by Michael Lazar » Sat Dec 08, 2018 11:06 pm

Here's a photo of my cutter made by Leonard Letourneau. It was built to specifications by Geza Burghardt, a Vancouver luthier whose craftsmanship is the best I've seen anywhere. Very accurate and a joy to use. You can google Leonard to find his website and contact info. These are not cheap of course.
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wombosi
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Re: High quality manual rosette/circle cutter?

Post by wombosi » Sat Dec 08, 2018 11:10 pm

Thanks Michael. I had come across Letourneau's site awhile back looking for a veneer scraper.
I hesitated when I saw his circle cutter design because it was very close to the one I purchased from a maker in Turkey that I didn't like using at all.

Hans van Velzen has gotten back to me and has cutters and scrapers in stock. I may go that route!
Not entirely sure on his cutter as it looks like a high center of gravity, no micro adjust, and no outboard bearing for stability. But
he claims it works well and you can't argue with the results he achieves with it on his own instruments! He's also willing to convert the 5mm pin to imperial 1/4" for me, which is very awesome.

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Michael Lazar
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Re: High quality manual rosette/circle cutter?

Post by Michael Lazar » Sun Dec 09, 2018 1:03 am

My circle cutter has a 1/4'" pin as well. Leonard can make them to order of course. His veneer scraper is beyond anything I've seen and I have one of those as well. I looked at the Van Velzen circle cutter it looks like it could work fairly well though far less sophisticated without the mechanisms for micro adjusting the diameter and depth of cut. I'd think it might be even more wobbly given the size of the base and the absence of a stabilizing wheel. Of course the tool is one thing and the skill of the user is another. It took me a little while to get the hang of using it but once I had it down it works great.

wombosi
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Re: High quality manual rosette/circle cutter?

Post by wombosi » Sun Dec 09, 2018 1:08 am

Michael Lazar wrote:
Sun Dec 09, 2018 1:03 am
My circle cutter has a 1/4'" pin as well. Leonard can make them to order of course. His veneer scraper is beyond anything I've seen and I have one of those as well. I looked at the Van Velzen circle cutter it looks like it could work fairly well though far less sophisticated without the mechanisms for micro adjusting the diameter and depth of cut. I'd think it might be even more wobbly given the size of the base and the absence of a stabilizing wheel. Of course the tool is one thing and the skill of the user is another. It took me a little while to get the hang of using it but once I had it down it works great.
I was totally ogling that veneer scraper. Absolutely by far and away the nicest and most robust one of it's kind that I've come across. But I think he wanted $600 for it.

Van Velzen's veneer scraper looks to be every bit as nice, in aluminum, for about $180. You are probably correct about the circle cutter. I may pass on it.

Thanks.

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