How Many Flutes for Wood?

[SteveHGraham]

I'm going to make some recesses in a pine vise jaw today. I could use a router, but they suck compared to milling machines.

Question: what's better for wood? Four flutes or two flutes?

[JackF]

My Grandfathers' hand crank boring bits have 2 flutes and my forstner bits have 2 flutes. All the better for chip evacuation.

Jack.

[SteveHGraham]

That's what I was thinking.

[woodguy]

I think as long as the cutter is large enough and spindle speeds appropriate, you can use 4 flute cutters successfully. With very small cutters, I use one or two flutes in wood and plastic.

[SteveHGraham]

Sometimes I wonder what the bearings in mills will put up with. It would be neat to get an old BP and put a faster motor on it for wood. Say 10,000 RPM.

[GlennW]

http://oxtool.blogspot.com/2012/10/brid ... ideos.html

[WJH]

Sometimes I wonder what the bearings in mills will put up with. It would be neat to get an old BP and put a faster motor on it for wood. Say 10,000 RPM.

Today I ran my Bridgeport at 120hz, double the rated RPM of the motor. It sounded like it was on steroids, and the little voice in my head said this wasn't a good idea. My motor is the vintage that uses grease and bushings for the motor shaft, so I reprogrammed it back to 60hz.
If one had the appropriately rated inverter duty motor on their milling machine, they very well may get away with 200+ hz.

I also programmed my VFD to display motor current, discovered I was exceeding 5 amps when the motor was speeding up, which is higher than what the VFD is rated for, so I set my ramp up time to 3 seconds, keeps the motor around 3 amps. Set the decelerate time to 0.1, increased the DC braking level, and duration higher so my spindle stops quickly, great for power tapping, which I did for the first time today. Gotta love VFD's.

Does your mill have a VFD? Something to consider if the motor can handle it.

[BadDog]

You can also get a planetary spindle speeder. I've got one for my Bridgeport that is 1:6 overdrive.

[SteveHGraham]

My mill has variable speed. I think something fell down in the drawbar hole, because the head of the mill goes "WOOOOT WOOOOT" when it's at top speed.

[PeteM]

You want adequate clearance for the chips -- which usually means two flutes.

Frankly, your best bet is to use an actual router bit in your mill and run it as close to router/shaper speeds as you can. It will have the high positive rake and chip clearance you want. Second choice might be a bit meant for aluminum.

[dly31]

I have never used it but I have an air driven high speed spindle that will fit into a collet or end mill holder. It seems like it would be fairly easy to make something similar.

[WJH]

My mill has variable speed. I think something fell down in the drawbar hole, because the head of the mill goes "WOOOOT WOOOOT" when it's at top speed.

When I went Bridgeport shopping, I purposely went with a belt driven head. No one else could understand why, but along the way I learned that simplicity is the highest level of reform, less moving parts, the better. Perhaps my experience in Aviation has taught me that simplicity is always best. Anyhow, the vector drive VFD solved the variable speed issue on a belt drive head.