[j89martin]

Hello all, I'm a nubie and have just started doing a little carving. I am building a sculpted rocker which requires a certain amount of carving - mainly fairing the joints between the various pieces, and I have a heavy flex shaft whose max rpm is 6000. My question is - is this an adequate speed for using the kutzall burrs or should I look at another tool.

thanks much
Martin

[Claude]

The simple answer is another question: "how fast do you want to remove wood?" If it's removing wood at a speed you find acceptable, and it's not bogging down in the process, then it's probably fast enough. This question really has lots of variables: speed of motor, horsepower of the motor, size (diameter) of burr, coarseness of the burr, type of burr (kutzall, Monster, etc.), type (hardness) of wood, and probably a couple of others I can't think of right now. My personal opinion on what you've said is that for furniture, I'd rather go with a slower-cutting burr/motor/speed combo so I'd have better control of the cutting. For example, carving a ball on the end of a table leg is not something I'd do with a chain saw, even though the chainsaw would remove wood quickly...

Wood is basically removed as a function of the speed of the burr surface against the wood and the coarseness of the burr. In other words, a 1 inch diameter coarse Kutzall will remove wood a lot quicker at 6000 rpm than a 1 inch diameter extra fine kutzall rotating at 30,000 rpm. So, while faster can be better, the coarseness of the burr, I think, really determines how quickly wood is removed, all else being equal. I would prefer more control over quick removal of waste, but I'm not doing it for a living, either.

Having said all that, and at the risk of confusing you even more, have you looked at the package the burr came in? They usually specify the maximum speed allowable...

Claude

[j89martin]

thanks Claude .. very helpful

Just to describe what I'm using - is a 1 hp motor at 3400 rpm which thru pulleys turns the flex shaft at 6000 rpm. I was thinking of using about a 3/4 inch coarse kutzall and then going to a medium - this is on walnut and is for fairing the joints on the rocker.

thanks
Martin

[mark yundt]

Try it,,,if it takes off the wood,,,keep going. If nothing happens,,then stop and try something else.Ultimately a few dozen sheets of sandpaper would work too,,but I'm sure the bit will be better than that.Have you actually tried it,,even on a bit of scrap wood,,,see what happens and then make the call,,what's it going to hurt?.

[j89martin]

Actually, I've tried it using a HSS burr at 2300 rpm using a drill to drive it. It didn't work too bad. I am planning on getting it setup for 6k rpm with a kutzall burr. I've used the carving disc 4 1/2 inch on seats and was impressed.