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Stan,

I don't ever recall seeing top bearing spiral bits..... have you spotted some somewhere?

It seems that the normal top bearing bits have straight cutters..... if you could find some with a shear angle they would cut better. I have a bottom bearing bit with the shear and it works well. Sorry I have no spiral bits for pattern cutting so I can not compare but in general spiral bits do cut very clean.

Ed

 

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I'm using some templates to route various items using Cherry, Ash, Oak and Walnut. In the process I'm getting occasional bad tearouts.

Right now I am using a standard straight 1/4" pattern cutting bit with the bearing on top.

Would a spiral pattern bit reduce the amount of tearout?

Thanks.

I was just looking at the June flyer from Lee Valley and on page three they have a double-bearing flush trimming/template bit....

I guess I missed the point of these bits....... what I failed to see was if you are trimming to a pattern that is on top of the workpiece and then get in to a place where the are going against the grain you simply flip the part over and adjust the bit height to use the other bearing and you can cut with the grain again...... Now I have to put an order in for one of these....

part # 16j09.90 or 16j04.90 if you have to look online.

Ed