Router bit sizing - help!

[Copes]

Hello,

So I'm totally baffled by what size router bit I need to get.

I have a set of dowels which are 38mm thick, I want to completely round over one end making it a half ball on a stick.

My router is a 1/2 inch collet.

So my thinking is half the 38, 19... and find a 19mm round over bit, or 3/4" as they all seem to come in imperial... is this right? They look quite small!

Thanks

 

[Trevanion]

That is quite a large radius, which commands a large bit.

https://www.wealdentool.com/acatalog/Online_Catalogue_Large_Ovolo_187.html

Part number T1342-1/2 is what you want, just buy a rounding over bearing for the bit. Just make sure that the 54mm diameter bit will be able to protrude out from the base of the router properly before you buy it.

Although I would be curious about how you plan on routing the end of a dowel safely without making a mess of it, some kind of jig in the router table?

 

[sunnybob]

I think the router is going to chew your end grain to pieces. From the router bit's point of view, that is ALL end grain :shock: :roll:

Much better to make a template of the end in a piece of scrap, and then use a bench disc sander while rolling the dowel around.

 

[Copes]

Thanks guys,

I was planning on just clamping a bit of wood so my dowel is sandwiched between the wood and my router tables fence, and feed the dowel into the bit, obviously being stopped eventually by the bearing. Slowly and carefully chomping away at it, pull it out, rotate it slightly and go again until there's little enough material left to be able to spin it on the bit (the leg is long enough to overhang off the router table.)

I don't have a disc sander, i did contemplate filing it etc but oaks pretty tough and it'll take me a lifetime to file and sand them by hand to get them matching.

I only need to do 3, i have enough length to actually mess up per leg 2 or 3 times, and i have a couple of spare dowels as well... but warning heeded, i'll give it ago with a scrap bit of dowel first to see if it does just explode.

Thanks Guys.

 

[sunnybob]

Make sure you are wearing eye protection, it will get messy :shock:

 

[Phil Pascoe]

And body armour.

 

[Rich C]

Hand plane would be quicker than a file for rough shaping. Interested to see how you get on though.

 

[nev]

ovolo to the radius of dowel

from here
https://www.woodworkersinstitute.com/wo ... ig/?p=977#

or this

https://www.routerforums.com/jigs-fixtu ... ure-2.html

or this

http://www.binkyswoodworking.com/PegTip.php

 

[Copes]

Quick update on this.

I've managed to do my legs, turned out nicely! However I did have a bit of a set back when my new router doesn't fit in my little router table. Ended up clamping the router in the vice with various bits clamped on but essentially a fence either side of the bit to guide the dowel, and slowly raising the bit each pass worked just fine.

Probably a good job I can't post pictures, I'm sure the safety police would be down on me

 

[Benchwayze]

No portable belt sander? If not, I'd use a rasp and successive grades of papers.

John