I have a 20 inch spindle in the lathe and want to run flutes along its length by way of a trim router held on its side in a jig. The width of the spindle is 2 inches. My lathe will handle any number of flutes (up to 48) though I think this width will call for 10 or fewer flutes.
Would anyone know of how to calculate the number of evenly spaced flutes?
(The project is for a tea table with three splayed legs.)
Many thanks, Tom.
Need Help With Formula
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Re: Need Help With Formula
#2
tmc007 wrote:I have a 20 inch spindle in the lathe and want to run flutes along its length by way of a trim router held on its side in a jig. The width of the spindle is 2 inches. My lathe will handle any number of flutes (up to 48) though I think this width will call for 10 or fewer flutes.
Would anyone know of how to calculate the number of evenly spaced flutes?
(The project is for a tea table with three splayed legs.)
Many thanks, Tom.
Just divide the number of flutes you want into 360 (degrees). That'll give you the degree spacing you'll need. Example: ten flutes would be 360° ÷ 10 = 36° spacing.
Re: Need Help With Formula
#310 flutes on a 2 inch diameter would require rather shallow flutes?
What is the actual number of holes in the indexing ring on your lathe?
If it is 48....then it would seem that 10 will not work?
The closest would be 8?
Am I misunderstanding?
Re: Need Help With Formula
#4Brian, I think you are right. With 48 steps he is restricted to moving 7.5 degrees at a time so the number of steps has to divide evenly into 360 degrees and the number of degrees per step/7.5 has to divide evenly to get even spacing.
So for 8 we get 360/8=45.0 and 45/7.5=6 which divides evenly. For 10 we get 360/10=36 (OK) and 36/7.5=4.8 degrees (not OK).
For 9 we get 360/9=40.0 and 40/7.5=5.33 not OK.
If you want to cheat a bit, you could hide the mismatched last flute under the table where it wouldn't be obvious.
If the workable number of flutes isn't a desired number, then you could get a strip of paper the circumference of the leg and mark it evenly into the desired number of flutes. Tape it to the workpiece and somehow keep the spindle from turning while you are fluting. The inaccuracies in setting this up are not likely to be noticed.
You can buy indexing wheels to give more settings but IIRC they aren't cheap. Depending on your lathe, you could make one for this specific job, perhaps out of some aluminum or hardboard, but it does require you can locate and lock the spindle.