[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.

 

[JOAT]

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.

That's what I was hoping. No problem taking light cuts, learned that long ago with my 1/2" flush trim bit. Thanks.

 

[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.

 

[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.

 

[JOAT]

Aw come on Theo, we need pictures regardless of the outcome.

OK, OK, pictures it is. And I'll make special effort to make sure they are lousy. >

 

[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.