Can someone explain what the radius, large diameter, and cutting length are for profile router bits?

I've used router bits for quite a while and googled Profile Router Bits. I consider all router bits "profiling" for the most part.

radius, large diameter, and cutting length

Radius: shown as the 3/4" dimension in sketch below (you could also have a round bit making a radius trough also vs. a round over)
Large Diameter: my guess is the overall diameter of the cutter. However, shank size is something you need to know when buying bits. Both 1/2" and 1/4" are common. Most smaller home stuff is 1/4" (what I run).
Cutting length: The 1" dimension show in sketch below.

Attached File


Attached File

Yup, what he said

Thanks fellas.

I am digging through the whiteside machine catalog. I need a bit to create the profile on the bottom of the desktop in the follow picture.

I do not really mind that style it is. The desktop is 6/4 so a small bit would not show much.

Can someone tell me what bit would work for this?

Whiteside catalog
https://cdn.shopify.com/s/files/1/1698/7023/files/WM_Catalog_50_email.pdf?v=1603140047

This is what I am making.

Hard to really tell but it looks like a simple rollover, by simple I don't mean plain... looks good and wears well.
Went out to the shop and snapped this pic. At 1/4" shank, that's my biggest rollover. Probably 5/8" or 3/4" radius.
Easily had at local hardware and big box stores. I'll get you a PN from your link.

ETA: Page 15 in your catalog lists rollover/beading.Your cut looks like a beading in that it cuts on the radius and the upper and lower straight areas of the bit.
But, those 1/4" shanks on that page only go to 1/2" radius... your correct with the 6/4 needing a bigger rollover/bead.
1/2" shank... or get something like I have below in 1/4"

Let me do some CAD work real quick.

Attached File

I'm a little stumped. Zooming in on the pic I'm starting to think that is an "ogee" bit cut. But it has two lands. The round over I'm showing will only give you one undercut "land".

I'm going to let someone smarter than me chime in...


Attached File

On page 21 of the catalog it lists French Provincial Molding.

3298 lists a profile width of 1" Does that mean that it would dig into my tabletop 1"?

The profile does not need to be the same. It just needs to be big enough to look correct on the 6/4 desktop/


I printed out page page 23 since it said the profiles are actual size.

I mistakenly laid out the desk pieces with a 1" cut in from a router bit. No mistake now since "profile widths" is the distance from the bearing to the end of the cutter.

Profile width is the cutting area... basically Diameter/2 minus Bearing/2

Attached File

If you put a smaller bearing on the round over bit you can get the what's in the diagram with the 1.5 inches.

Caution - you do not want an ogee bit as mentioned above.  You want a quarter round beading bit (see page 13).  

It is referred to as "beading".  Notice, there is a flat spot on both sides of the quarter round.  

Note the three different bearing diameters shown. You get the two flat cuts by controlling the depth of cut of both the major diameter of the cutter and the minor diameter of the cutter.  Both need to cut into the workpiece.   How deeply they cut controls the width of the "bead" (the flat spot before the quarter round).  

The bearing you use determines the depth of the bead.  You need a bearing that is smaller than the minimum diameter of the cutter.  The bearing diameter controls the width of the bead (how deeply the smallest diameter cuts into the work piece).

Otherwise, you need a fence to control the depth of the bead but I suspect you do not have a fence (or router table).

Ding! Yes, should have known, I have a bin with a variety of sizes.

You should also get yourself one of those profile pin copying gauges.
They are not very expensive.  
You can get the exact profile and then you might have an easier time matching the router bit you need

https://www.woodcraft.com/products/woodriver-plastic-profile-copy-gauge-large-10-width

I would also chime in that 6/4 is going to take a heavy cut. If possible, aim for a 1/2" shank bit and an adjustable speed router. Match the speed to the rating of the bit.

Table tops are too big to take to a fixed router table. Large routers used hand-held are a pucker tool for me. They can do things on their own if you aren't in complete control. Too many also have a power switch instead of an auto off trigger. Said switch often being well away from hand holds.

Don't try to take too heavy a cut in each pass. A 3/4 beading round over, what I would suggest for 6/4 material, should take 4 to 6 passes before you go for your "finish" cut.

Depending on the style you are shooting for of the piece. Other options include the afor mentioned ogee, as well as a simple chamfer.

I have a small router table but the desktop is far to big to run through the table.

I will free hand the cut.

I already that profile gauge but I am working off a picture.

I will take multiple shallow passes to get my desired result.

I do not have extra bearings and I have no interest in buying additional bearings. I will go with whatever profile the bit produces. Not super critical, profile is going on the BOTTOM of the desktop.