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Need some roundover bit input

2294 Views 11 Replies 7 Participants Last post by  JOAT, 
JOAT
I've got a project I'm designing that will require a roundover bit. Have never used a roundover bit, so want some advice before I buy anything. I will be rounding 1/2" plywood, which I know may splinter; and no, I will not be using any wood but plywood. I will be gluing two pieces of 1/2" plywood together, with a flat edge, then rounding over what will be the top of the piece, with my in-table router - will flip it after routing. I want a fillet, as show in the picture. Not sure yet if I want the fillet 1/8" or close to 1/16" yet. I would like a 1/2" radius, and need a 1/4" shank - heck, if I could get away with it, I would actually prefer 3/4" or 1", but don't see that happening with a 1/4" shank. But, I have been researching on-line and read that 3/8" radius, and above, required a 1/2" shank. And, I read that 1/2" radius, with a 1/4" shank is perfectly fine. Typical on-line advice. I am not sure that the people writing this had actually done it or not.

I want just the one layer rounded, with fillet, and prefer the second layer not be rounded. However, I would prefer the 1/2" radius, so can accept a bit of rounding on the second layer, after all they will be solidly glued together, so no biggie. But I can live with the 3/8" radius if need be. My questions are:
Can I safely use the 1/2" radius bit, with 1/4" shaft, realizing that I may have to make very small cuts
Or, should I go with 3/8" radius instead?
Or, will I have to bite the bullet, and have to settle with 1/4" radius?

Forgot to say, I normally use just a 1/2" flush trim bit, 1/4" shank, in my table mounted router, and have no problems with that.

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DonkeyHody
A 1/2" radius roundover with 1/4" shank will work fine as long as you don't take too large cuts or feed it too fast. I'd take about 3 passes. Make sure the LAST pass is a very light cut to avoid any chattering.
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JOAT
DonkeyHody said:
A 1/2" radius roundover with 1/4" shank will work fine as long as you don't take too large cuts or feed it too fast. I'd take about 3 passes. Make sure the LAST pass is a very light cut to avoid any chattering.
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That's what I was hoping. No problem taking light cuts, learned that long ago with my 1/2" flush trim bit. Thanks.
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Semipro
you can buy a 3/4” round over bit with 1/4” shank,but like with the 1/2” you can not do it one pass.
till I start doing raised panels I did not even own a half inch shank of course now I don’t buy anything but half inch shanks. because i now own routers that accept them and do prefer them.
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Cherryville Chuck
Theo if you use a 1/2 for both sides with one side having a fillet and the other none then you'll necessarily have a flat in the center. If you use a 3/4 for both sides with one having a fillet then the curve will be off a bit, i.e. not a smooth radius. To have a smooth (but not uniform) radius you would need to leave a 1/4" fillet on one side with a 1/2r and the full curve on the other with a 3/4r. You can vary the radius or the fillet and get a number of different combinations but the only truly uniform cure would be 3/4 on both sides and no fillet. I don't know what you are aiming for so I don't know what's acceptable but just pointing out some of the issues.
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JOAT
Chuck. The two pieces of plywood will be glued together before the roundover bit is used, and only one piece will be rounded, with a fillet. I'll not say what I'm designing, because I'm not 100% sure it will look like I want it to. It'll go together like I want it to, no doubts about that, but just not quite 100% sure about the final look until I try it. And, if it turns out like I hope it will, I am certain someone is going to come along and call it art, and me an artist. Bah. Humbug. I ain't no steenkin' artist, and I don' make no steenkin' art. But if I can go with a 3/4" bit, that will make it more likely to come out like I want it to. Think I'll give that a shot first, and make the 1/2" my Plan B. There will be pictures if it turns out well. There may well not be pictures if it does not turn out well.
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R
Your honesty and enthusiasm is addictive. I'm guessing you're you are an artist that doesn't like being called one. I've been called one many times over the years by my customers. I'm appreciative, but the mention of the word feels kinda cheesy. Miracle worker, magician, genius, rocket scientist...... aaaah, so many more comfortable words out there.
There will be pictures if it turns out well. There may well not be pictures if it does not turn out well.
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If it doesn't turn out as well as hoped, blurry photos can compensate. :wink:
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JOAT
I will accept woodworker, craftsman, or even artisan, but calling me an artist usually just irks me, and you really don't want to irk the old man much, he does carry a cane that won't break easily.
:angry: I don't do magic, because I lost my magic stick.
An artist is someone that does paintings, that actually look like things, or does sculptures, or carvings, that actually look like things - which includes skilled chainsaw carving.
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JFPNCM
Aw come on Theo, we need pictures regardless of the outcome.
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JOAT
JFPNCM said:
Aw come on Theo, we need pictures regardless of the outcome.
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OK, OK, pictures it is. And I'll make special effort to make sure they are lousy. >:)
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T
Theo, I wouldn't be concerned if I was you, what they called me. Just be sure they don't call you late for lunch.
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JOAT
Is it lunchtime yet? Well, been doing a LOT of looking for carbide tip 1/2" and 3/4" radius roundover bits. That won't break the bank. Well, just ordered both off of eBay. Very low price, and free shipping. And, of course, made in China. Bah. I am not counting on them actually lasting very long, but that's fine, because the reason I'm going that cheap is because I want to prove that my theory on my project will work, and do not want to spend a lot on that, just in case. It will take close to a month to get here likely, but that's OK, got a lot of other things to do first. Once I get them, and if they actually work out as hoped, then I will upgrade to a decent, carbide tip, American made bit. I don't think the 1/2" radius bit is carbide tip, but ridiculously cheap. The 3/4" radius bit is supposedly carbide, but also ridiculously cheap. As long as they work once, that will be enough, then I'll upgrade.
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