# Radius size of roundover bit?

I am making drawer fronts and want the edges to be completely rounded over. The wood is 3/4". Now, I have a 3/8" radius bit that I found this morning but haven't had a chance to try as I had to get to work (damn job always gets in the way). Will that do it or do I need to stop on the way home and pick up something else?
I mean, 3/8 is the radius, so 3/4 would be the diameter... does that make sense?
-Jim
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On 7/13/2011 2:25 PM, jtpr wrote:

The wood is 3/4". Now, I have a 3/8" radius bit that I found this morning but haven't had a chance to try as I had to get to work (damn job always gets in the way). Will that do it or do I need to stop on the way home and pick up something else?

It all depends on the look you are after. That bit will begin the curve 3/8" from the edge of the front and end up down half the thickness of the board. IMHO that is about as strong of a round over that you would ever want to use on a drawer edge. Keep in mind that the larger the radius the wider the gab between the drawer and fac4e frame will appear if you are going for flush mount drawers.
See a.b.p.w. for a drawing of 4, 3/4" thick x 6" x 14" drawer fronts. Each group of 4 has a 1/8" gap between drawer front sides.
The top left uses a 1/8" round over, the top right has a 1/4" round over, and the bottom left has your 3/8" round over.
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The 3/8" bit run down the board on one side will leave a 3/8" flat on the edge of a 3/4" board. The 3/8" bit run down the board on both sides will leave a fully rounded bullnose edge on a 3/4" board.
It's all a matter of taste, and the look you're going for. A 3/4" radius bit run in one pass would make the drawer fronts look kind of 'puffy', and calls a lot more attention to the drawer fronts. There's also a fair bit more end grain visible, so finishing may be more tricky depending on the wood and how you plan to finish the piece. I'm not trying to talk you out of anything, just bringing up some talking points.
As an alternative you could use the 3/8" roundover on one edge, and then rabbet the back of the drawer front 3/8" so the drawer front is a partial overlay and the rest is recessed into the drawer opening. That's a totally different look, but I'm not clear what your intention is.
R
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RicodJour wrote:

Yep ______________
Oh, were that it were so :(
IME, pass #2 will cut a bit too deep because the bearing is riding on part of pass #1 that removed a bit of wood.
The fix is to use a fence, not the bearing. Or, as you said, a bullnose bit. I'm not overly fond of bullnose bits - on any that captures the entire profile - because a little vertical jiggle or a less than perfectly flat board will mess up the profile.
--

____________________________
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On 7/14/11 12:54 PM, dadiOH wrote:

Good advice. I'll add... Depending on the size of the shelves, it's often easier to clamp a straight edge to the shelf and run the router by hand. The straight edge can be the factory edge of another shelf. Although, as is being discussed in another thread, we can no longer take for granted that the factory edge of modern plywood will be perfectly straight or flat.
--

-MIKE-

"Playing is not something I do at night, it's my function in life"
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On 7/14/2011 12:54 PM, dadiOH wrote:

I have to do this quite often to make floating tenons (3/16" radius round over bit for a 3/8" thick tenon), and you're correct about the fence being essential.
Even then, the only way I've been consistently successful the past couple of years is after getting a router lift for precision bit height adjustment ... the combination of the fence and the router lift have finally made repeatable and desirable results possible.
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Last update: 4/15/2010
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On Wednesday, July 13, 2011 12:25:48 PM UTC-7, jtpr wrote:

If you set the bit depth less than 3/8", you can put a curve where there was originally a (roughly) square edge. That means your inevitable dents on the drawer edge don't draw attention. If you set the bit depth exactly 3/8", it'll not look good, because any small bending of the board will make the edge of the cut waver noticeably (you can sand away this 'feature', of course). If you set the bit depth more than 3/8", it makes a shadow line at 3/8" where the bit cut stops. Sometimes that's attractive. With an undersize pilot, you get two shadow lines (good for outside corners of upright members, but maybe not a drawer face).
I'd discount the 'completely rounded over' look, myself: it looks ugly to me. Are there any particular drawers you DO like, and can copy?
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On Wed, 13 Jul 2011 12:25:48 -0700, jtpr wrote:

One of the problems with a 3/8" bit on 3/4" material is that after the 1st pass there's almost no material left for the bearing to rest on during the second pass. Not a problem if you use a fence, but can be if you're depending on the bearing.
--
Intelligence is an experiment that failed - G. B. Shaw

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In article

Other posters have pointed out several drawbacks with this approach; I agree with them, and won't repeat their arguments here. Instead, I'll suggest that you condider this as an alternative:
http://www.grizzly . com/products/Door-Lip-Bit-1-2-Shank-1-5-16-Cutter-Dia-/C1333
Or, if you have a shaper available, http://www.grizzly.com/products/Shaper-Cutter-1-Door-Edge-3-4-Bore/C2103
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On 7/13/2011 2:25 PM, jtpr wrote:

The wood is 3/4". Now, I have a 3/8" radius bit that I found this morning but haven't had a chance to try as I had to get to work (damn job always gets in the way). Will that do it or do I need to stop on the way home and pick up something else?

I ask because "inset" doors, with a round over edge profile, can be very attractive. AAMOF, Sam Maloof, IIRC, was responsible for a "Hollywood" style cabinet where the doors were inset with rounded over edges which became very popular.
When I built my office "Texas Tansu" a few years ago, I used a 3/8" round over bit on 3/4" doors to get that Maloof, rounded edge look:
http://www.e-woodshop.net/images/StackedTansu16.JPG
Although a 3/8" round over bit was used, if you look at the profile on the desk trim, it appears to be a full round over:
http://www.e-woodshop.net/images/StackedTansu12.JPG
Just saying that using a radius bit can, along with some judicious sanding, appear to be a full round over.
--
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On 7/13/2011 6:17 PM, Swingman wrote:

That was meant to be "drawer fronts" ... another type of door, if you think about it. :)
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Thank you all for the replies. Swingman, while those are doors (nice work, by the way), the edge is what I want. I took a scrap last night and used the 3/8 bit on it and held it up. This looks fine.
I should mention that these are drawer fronts on drawers in a mission style kitchen island with a concrete top. The will overlay the face frame by 1/4" all around. So I think I will do one pass with the 3/8 bit on 3 sides, leaving the bottom of each one square. I am even considering putting a slight groove in the bottom in lieu of handles. But I must run that by SWMBO.
I will try and post pics soon.
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A picture is worth a million words:
http://www.freudtools.com/p-143-rounding-over-bits.aspx
On 7/13/2011 3:25 PM, jtpr wrote:

The wood is 3/4". Now, I have a 3/8" radius bit that I found this morning but haven't had a chance to try as I had to get to work (damn job always gets in the way). Will that do it or do I need to stop on the way home and pick up something else?

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