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Discussion Starter · #1 ·
I got some pretty cheap 1/4 inch shank router bits on ebay. One of them is a 1/2 inch round. I think there are 3 issues that will prevent getting a proper 1/2 inch radius round edge with this but perhaps this is how some bits are?
1) The curve of the blade doesn’t go a full 90 degrees.
2) The pilot bearing it slightly larger than the end of the blade so part of the blade will never contact the work piece
3) If just seems a couple of mm smaller than 1/2 inch.
(Photo attached showing these 3 things)

I did a test with it and the round isn’t too bad but definitely seems like it will need some sanding to get it there and i’d say its a fair bit smaller than 1/2 inch.

So, are these bits rubbish or have I misunderstood round over bits?
Thanks.
 

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Two things come to mind.
Is it metric?
Does it have to be a full 1/4 round?
If you are trying to make a full 1/2 round edge take the bearing off and use a fence,if possible, or get a half round bit. It doesn't look like a 1/4 round,more of an elliptical round.
Herb
 

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I suspect the bit w/ all of the above...
 

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Discussion Starter · #5 ·
Thanks. Yeah the shape of the round over I got looks more elliptical, partly due to the bearing being oversize I think as well.
I need the full 90 degree round so will probably need to get a better bit.
I also need to put a round on a curved edge so will probably need it to be bearing guided or I’ll make a mess of it.

Thanks for the feedback.
 

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@Daniel Green,
Bear in mind that if you are using a quarter-round to make a bullnose (i.e. rounding from the top and bottom faces of the workpiece), you may run into trouble if the is not enough edge left for the bearing to ride against. The second cut will be further in from the edge than the first. I think Herb, Charles or Stick explained it with illustrations, better than I can do in words.

If that is your aim, you might be better off with a bullnose bit and an auxiliary fence designed to follow curves, or go for broke on an adjustable bullnose bit with a centre bearing. The latter will not be an El Cheapo.
 

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Theo
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Upon occasion I buy a bit off of ebay. Not with the intention of continually using it, but to see if that type of bit does what I want it to do. If it doesn't, I stick it away, never know if it might come in handy one day. But, if it does work like I want it to do, I stick it away, then go out and buy a decent (more $) version. Beats the heck out of buying a pricey bit, then finding out it doesn't do what you want.
 

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Having the bit not being a full 90 degress may be a good thing. By not going the full 90 degrees it eliminates the problem of leaving a edge at the end of the radius at both ends. The bearing not being larger then the end of the bit is a no-no. The bit not being a correct 1/2 inch round is probly the result of cheap bit.
 
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