# Spiral or Double Fluted straight bits for this cut?



## 6f6 (Jan 4, 2009)

I'm looking to build a display case. It will have a glass top. I have a 2x3 ft sheet of glass. I have several 1x2 (3/4 in by 1.5in) pieces of oak. On the top portion (where the glass will be) I plan to cut a 1/2 in deep groove along the 3/4 in edge of the wood in order to hold the glass. The edges will be mitered to 45 degrees, glued, and fortify on the rear side with brackets. My questions:
1. In the interest of getting a good, tight fit for the glass, should use a 1/4 bit to route the groove which will hold the glass, or should I use a 5/16 bit and let the silicone do the rest of the job of holding the glass in place? 
2. Will I get a cleaner cut using a spiral fluted bit, or am I better off sticking with the conventional double fluted straight bit?


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## jschaben (Jun 21, 2009)

6f6 said:


> I'm looking to build a display case. It will have a glass top. I have a 2x3 ft sheet of glass. I have several 1x2 (3/4 in by 1.5in) pieces of oak. On the top portion (where the glass will be) I plan to cut a 1/2 in deep groove along the 3/4 in edge of the wood in order to hold the glass. The edges will be mitered to 45 degrees, glued, and fortify on the rear side with brackets. My questions:
> 1. In the interest of getting a good, tight fit for the glass, should use a 1/4 bit to route the groove which will hold the glass, or should I use a 5/16 bit and let the silicone do the rest of the job of holding the glass in place?
> 2. Will I get a cleaner cut using a spiral fluted bit, or am I better off sticking with the conventional double fluted straight bit?


Hi Mark - that's a pretty good sized hunk of glass. I think I would be more comfortable with the larger groove and silicone. Just seems like it would be more forgiving of expansion/contraction issues.
Normally, I would jump toward the spiral bit but one thing I've noticed about spirals. When running with the grain, they like to "unwind" the wood fibers rather than cut them:blink:. This case I think I would go with the fluted straight bit.
Good Luck


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