New turn on rosettes

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Spanish Could cutting rosettes on a lathe reduce tearout problems? July 22, 2003

Question
Has anyone tried to make rosettes on a lathe? Our shop has been making a few on the drill press, but we keep getting a lot of chatter. I think it has to do with the runout on our spindle - we've been running the cutter slow (around 350 rpm) but still get some tearout. I've read you can make them on a lathe, which seems like it would be a smoother way of cutting them out. Do you mount the wood solid and spin the cutter or vice versa? Any suggestions on how to set up?

Forum Responses
(Architectural Woodworking Forum)
From contributor J:
We have made a lot of rosettes on the lathe, both by hand and with a cutter. We use a quick change, self centering face plate, designed for bowl turners. The cutter is held with a chuck on the tailstock. We have had better luck with the Amana rosette cutters than the cheaper ones. We still have a 5 to 10% reject rate with this system. Hand turning using a v-point scraping tool works well for just a few blocks, with less rejects. The key here is a heavy duty machine with tight spindles, be it a lathe, drill press or milling machine. We are using a 1948 cast iron Delta lathe. This system works okay for the limited amount of rosettes we produce. If you have a lot of production, the single purpose rosette makers are the answer.


From contributor B:
In my experience you're going the wrong way with regard to RPMs on the drill press. When I used to do these, I added a secondary pulley on my press to kick the spindle speed up to around 6000 RPM. This worked much better than at the factory max speed of 2300.

I also added 3 brass screws drilled and tapped around the quill to tighten against the spindle sleeve. This took a lot of play out of the spindle. I also ran braces from the press table to the floor and wall to try and stiffen it. All these were little bit items that added up to make for about 80 to 90 percent success rate. Took a lot of time to set up, though.


I have an Amana bit and could not make it work with my drill press. I bought a mill/drill from Jet, much heavier than my drill press. The bit fits into a R8 collet instead of a drill chuck. You just need more mass.

From contributor B:
Actually, I also experimented making them in a friend's Bridgeport. I experienced many of the same issues that I saw on my drill press. My tear out rate remained about the same.

I think the runout on a drill press is the big problem. I ran some on mine, had tearout at slow speeds and chatter at high speeds - enough that it bent the tapered shaft! I wondered about mounting it in my mortiser with a chuck, as it seems stiff enough. Anyone tried that?

I also felt that the wood (red oak) was too dry and caused some of the tearout - it was less than 6% by my meter. Maybe it would mill better closer to 9%?


I use a 3 1/2 horse electronic plunge router at 500 RPMs with about 20% tear out. I have been using a Carbon-Tech solid body cutter.

There is an R200 Rosette Maker, which turns at 7500 rpm with no vibrations for tearout. Air over hydraulics. All automatic. Stock it and come back when rosettes complete.

From contributor J:
One person mentioned trying a mortiser. We tried our Kolle slot mortiser today to turn 60 alder rosettes. They were flawless with only one reject. Way better than the lathe we had been using.

From contributor B:
Contributor J, be careful with the RPMs at which you're running your rosette cutter. If it is a removable knife type, it will have a maximum safe RPM speed (as will any large cutter).

I know of an accident that occurred 6 or 7 years ago where someone was running a rosette cutter in an overhead router at about 22,000 rpm. The cutter came loose and the guy's wife is a widow.


From contributor J:
Thanks for the caution. The Kolle runs at 1500 and 3000 RPM. 3000 seemed to work good. The highest speed allowed for the Amana cutter is 10000, with 6000 advised for wood. I think one of the biggest dangers with this is the cutter itself. I am going to build a guard around it next time.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor I:
What worked for me was mounting a block on the face plate and then finding absolute center. I then mounted the square on that plate and turned at about 20,000. Worked fine.


The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor K:
To obtain a profile of a 100 year old corner block with a rosette off center, I cut a sample to trace at the center line. Blocks were 6" X 12" X 1-1/2". It revealed the original screw hole in the back that obviously was the face plate screw on a lathe. None of the original rosettes were identical indicating all were hand cut on a lathe. I had a cutter made and installed a drill spindle on the tail stock. The blank turned off center and the cutter advanced slowly at low speed and then faster for final minor cut for perfect finish. I cut over 100 for a job without one problem, tear-out, or mistakes. I always ask myself how the original was made 100 years ago and find we sometimes believe everything has to be precisely machined when all it has to be is "hand made".


Comment from contributor O:
I had the same problem with tear-outs. I tried soaking the wooden blocks in water and then turning them. This worked well with no tear-out but the blocks warped. I then stacked them together and clamped them face to face, put them in a 150 deg. oven and let them dry for several hours. Problem solved. I also turned them at about 1800 rpm. If they started to dry I sprayed a little water on the cut.

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