# Smallest radius roundover bit?



## LaserBwah (Dec 30, 2021)

I want to round edges of 3/16" thick baltic birch. This would mean finding a 3/32" radius roundover bit. This will also need a super small bearing OR a thicker pieces to guide it with cut to fit. A guide piece to use over and over is not a problem. But I still need the crazy-small radius.

This is for results that have far too many edges to do by hand (100s of inches per finished product).

Is there any way to devise a table router that could work here? Might require a jig, there might be such a product out there (though I've tried to search), or it might just be impossible.

Chamfering both sides and then milling off the sharp end could work but that's three operations instead of two and wouldn't feel right.


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## John Smith_ (Jan 10, 2020)

I have a couple of 1/8" round-overs - never had a use for anything smaller.
will this be free-hand with a bearing bit or on a router table with a fence ?
posting drawings, sketches or photos of your project would go a long way for the most accurate responses.

oh, and Welcome to the Forum !!


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## old55 (Aug 11, 2013)

Welcome to the forum.


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## Barry747 (Jun 16, 2011)

I have a Dremel with a pretty small round over bit. Not sure of it's size but it's tiny. It doesn't have a bearing but with a straight edge and a jig to maintain balance and depth it might work. 

Another alternative is a an edge plane with a custom blade. I think there have been posts on the Forum about that a while ago. You can search the archives.


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## TWheels (May 26, 2006)

Amanda sells a point cutting roundover (no bearing) Amana-56143. Amana 56143 SCPOINT/ROUNDOVER 3/32Rx1/4SHK is one source. ToolsToday also sells this router bit.
Amana also makes 1/32 inch and 1/16 inch radius point cutting roundover bits.
Amana also has a line of bits they call miniature such as the Amana Tool MR0110 Miniature 3/32 R Corner Rounding with 3/16 D Ball Bearing x 3/8 D x 3/8 CH x 1/4 Inch SHK Carbide Tipped Router Bit


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## DesertRatTom (Jul 3, 2012)

A bit without a bearing begs for a table and fence. It will make the project go much faster. That small roundover will go in one pass. I'd want the smallest possible insert opening to see if it will help you avoid tearout or splintering. Interesting question. I also like the multilayered edge of BB ply.


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## TenGees (Sep 12, 2012)

Pretty sure you won't have enough material left for the second side to guide a bearing. I think that you would have to guide the baseplate of the router for hand routing or use a table. Either way you wouldn't need a bearing bit although it could have one. I wonder if you have an ogee bit where part of its profile will have that radius. Me (being a cheap guy) would look through my bits first and test it on a scrap.


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## mgmine (Jan 16, 2012)

Unless you want a completely rounded edge (in which case you can't use a bearing) all you need to do is to raise any size rounding over bit to the height needed to round the edge. Use a table and a fence as Tom said.


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## Souza1969 (Jan 19, 2021)

I'm a mechanical engineer, turned woodworker, machine design and automation, specifically. If this is something you'd like to discuss for a production environment, I'd be happy give my opinion. And if you need something designed and built we can talk about that after we nail down your actual requirement. The router bit isn't a big deal, Kowood makes very small metric radius, really nice carbide bits. Check them out on Amazon, you won't be disappointed. The other thing is, it is not over the top expensive to have a custom radius bit made, or several (definitely cheaper by the dozen in the machine tool world). Bearings are available in any size you want, and custom grinding is available. A huge part of woodworking is figuring stuff out, most of the time fixing a 'F' up! But its much like when I was an engineer, you put the pieces together to create. Any thing you want to do, you can! You just need to learn how. I'll be happy to answer any questions.....


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## Souza1969 (Jan 19, 2021)

TenGees said:


> Pretty sure you won't have enough material left for the second side to guide a bearing. I think that you would have to guide the baseplate of the router for hand routing or use a table. Either way you wouldn't need a bearing bit although it could have one. I wonder if you have an ogee bit where part of its profile will have that radius. Me (being a cheap guy) would look through my bits first and test it on a scrap.
> View attachment 400499


Why do you need the bearing at all....zero clearance router fence, or as close as yoj can notch that major diameter, let the fence deal with it. You can keep the bearing on the bit, notch in the fence needs to be taller. But won't effect the results


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## PhilBa (Sep 25, 2014)

I dunno, the amount of material you would be removing is pretty small. I'd be tempted to devise a sanding jig that holds a piece of sandpaper in a 3/16" cove. Adhesive backed paper is available so the size of the cove might have to be a little larger. a couple of quick sanding passes will take down the edge. Might actually be faster than setting up and routing.


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## wb8nbs (Apr 14, 2011)

I'd try a 1/8" beading bit in a router table. Would do both sides at once.


https://www.lowes.com/pd/Bosch-1-8-in-Carbide-Tipped-Edge-Beading-Router-Bit/1000580757


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## vichay (Jan 6, 2022)

I used a couple of different tiny bits and found it was too much work fussing around to get a decent roundover. I have better luck with using a sander to round over a tiny edge. I like the 'triangle' sanding attachment for my Dremel oscillating tool for this.


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## Steve Pack (Jan 1, 2014)

you can but 1/16 inch round over bit. set table, fence and featherboard to hold stock flat on table

Amana Tool - 49493 
3/32
Whiteside Router Bits 2000B


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## timreardon273 (Dec 16, 2021)

I use 3/4" MDF (CNC cut) as the pattern for some of my work with 8mm Baltic Birch. I pin nail the Birch to the MDF, cut it to shape with a spiral carbide bit and bearing, and then use a 5/16" round over bit to finish the edge. So long as I don't try to make too many copies the MDF holds up well. I'm sure the same technique would work for 3/16" material. Use an 1/8" round over bit and it should work fine.


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## RiovistaAndy (Feb 20, 2019)

Barry747 said:


> I have a Dremel with a pretty small round over bit. Not sure of it's size but it's tiny. It doesn't have a bearing but with a straight edge and a jig to maintain balance and depth it might work.
> 
> Another alternative is a an edge plane with a custom blade. I think there have been posts on the Forum about that a while ago. You can search the archives.


You may want to check with a Luthier builders supply company for just such a plane. I vaguely remember a guitar maker using one on YouTube.


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## RiovistaAndy (Feb 20, 2019)

Souza1969 said:


> Why do you need the bearing at all....zero clearance router fence, or as close as yoj can notch that major diameter, let the fence deal with it. You can keep the bearing on the bit, notch in the fence needs to be taller. But won't effect the results


I built a router table for my large 3/16" arbor Dremel Trio router. And have used 1/8 RO bits. But the company no longer supports this tool. 
The new standard 1/8" arbor Dremel tool can be used on their own router table. I have seen 1/8" RO bits on the web.


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## johnjory (Sep 19, 2013)

LaserBwah said:


> I want to round edges of 3/16" thick baltic birch. This would mean finding a 3/32" radius roundover bit. This will also need a super small bearing OR a thicker pieces to guide it with cut to fit. A guide piece to use over and over is not a problem. But I still need the crazy-small radius.
> 
> This is for results that have far too many edges to do by hand (100s of inches per finished product).
> 
> ...


I've used 1/16" round over bits and had no trouble. You might try starting with this even though it would leave a 1/16" inch flat.


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## old55 (Aug 11, 2013)

Welcome to the forum @vichay


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## old55 (Aug 11, 2013)

Welcome to the forum @timreardon273


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## Straightlines (May 15, 2013)

Freud makes a 1/16” RO with bearing, I have one that I use often.

in your situation, I would skip the router and use either a block plane to chamfer the edge or run the stock between a fence and the spindle on a spindle sander. Both are fast, stone simple, safe, and easy.

in practical terms, the radius is so darn small that a chamfer is virtually the same.


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## OCristo (Jan 3, 2022)

LaserBwah said:


> I want to round edges of 3/16" thick baltic birch. This would mean finding a 3/32" radius roundover bit. This will also need a super small bearing OR a thicker pieces to guide it with cut to fit. A guide piece to use over and over is not a problem. But I still need the crazy-small radius.
> 
> This is for results that have far too many edges to do by hand (100s of inches per finished product).
> 
> ...


If you have to round straight pieces my suggestion is to mount a small round bit like 1/8 in radius and offset the router table fence for the difference you need. A slightly sanding afterwards and voilà, you have a near perfect smaller radius... I use that procedure to make 4 or 5 mm radius idling my 1/4 in radius bit.

The error will be imperceptible. 

Regards,


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## Chris Itin (Oct 15, 2019)

Another source for smaller bits.









Brass Pilot Router Bits


Go where no bit has gone before with these Brass Pilot Router Bits! These bits allow guided routing into spaces that would stop bits with standard bearings dead in their tracks.




www.infinitytools.com


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## Rebelwork Woodworking (Sep 11, 2004)

The OP hasn't responded back in 19 days?


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