Non-round roundover bits (aka squircle router bit!)

[danny777d]

Does every roundover bit have a circular arch?
Are there any roundover bits with non-uniform curve radii?

Apple famously uses the “squircle” shape to do the roundover on all of their products and icons. I’d love to do the same (please don’t shame me and say a standard roundover bit is close enough  :-X)

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[luvmytoolz]

There's plenty non-circular ones around but usually only along one side, like bits made for routing guitar necks.

I don't recall having ever seen one where both edges are not at right angles.

 

[Crazyraceguy]

I would think it could be done with multiple cuts, using part of a larger radius bit.
It might take a bit of hand sanding to blend the profiles though?

(More akin to a true "bullnose" than the perfectly matched 180 degree half-round edge)

 

[luvmytoolz]

Out of curiosity, what are you actually wanting to produce with this shaped cutter?

 

[Packard]

I typed out my initial thoughts before considering a different approach.  I think the second approach is better, but I am not deleting the first for your consideration.

Also note there are some asymmetrical radius round over bits, mainly for table edges and are likely too large.  The table I am sitting at in Starbucks features that type of edge.

Here are my initial thoughts:

Try experimenting with shimming the baseplate of your router asymmetrically.

I am not entirely convinced that this will work though. And I cannot work out in my head the sequence of cuts.  It might be easier to control in router table.

Filament packing tape stands up to abrasion well and had a low coefficient of friction and will slide across the stock easily.  Just make sure that the ends of the tape extend past the edges of the router. 

One or two thicknesses of tape may be all that is required.

Here is my likely approach to this issue.

I have made draw scraper blades from sections of old hacksaw blades. I ground the profile in the smooth edge of the blade and mounted it between two pieces of wood. I was able to get a reasonable beaded edge to a profile using just that tool.  The blade stayed sharp for the entire cabinet door. 

There are dozens of videos on YouTube showing how to make the custom card scraper and how to use it.  Cutting a profile with a card scraper was surprisingly easy to do (but I did later get a bead edge router bit).

NOTE:  I failed to mention that the radius would first be cut with a conventional round over router bit.  It would be modified slightly with the card scraper.  I would not try to cut the entire radius with a card scraper.
http://www.youtube.com/results?search_query=making+a+wood+%C2%A0card+scraper+blade+from+an+old+handsaw

 

[danny777d]

Thank you [member=74278]Packard[/member]! Great ideas.

I would want to use a squircle roundover in almost every situation where we usually use basic roundovers. Anyone who does enough CAD work becomes bored with a constant radius fillet — unfortunately not as easy in woodworking though.

 

[Packard]

Thank you [member=74278]Packard[/member]! Great ideas.

I would want to use a squircle roundover in almost every situation where we usually use basic roundovers. Anyone who does enough CAD work becomes bored with a constant radius fillet — unfortunately not as easy in woodworking though.

There are several companies that will make carbide router bits to your exact specifications.  I have no idea on cost, but they will quote based on your CAD drawings.

You can find several here:
https://www.google.com/search?q=custom+router+bits&client=firefox-b-1-m&sca_esv=5400d3f8397f2512&ei=9FxDZ6WOA9O05NoP6t7k6As&oq=custom+%C2%A0router+bit&gs_lp=Egxnd3Mtd2l6LXNlcnAiE2N1c3RvbSDCoHJvdXRlciBiaXQqAggAMgsQABiABBiRAhiKBTIGEAAYBxgeMgUQABiABDIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgAQyBRAAGIAEMgQQABgeMgYQABgFGB5I-D9QyBpY-CNwAngBkAEAmAGaAaABmASqAQM0LjK4AQHIAQD4AQGYAgegApcEwgIKEAAYsAMY1gQYR8ICCBAAGIAEGKIEwgIIEAAYogQYiQXCAgcQABiABBgNwgIGEAAYDRgewgIIEAAYBRgNGB6YAwCIBgGQBgiSBwM2LjGgB_sX&sclient=gws-wiz-serp

If this is going to your trademark “signature”, then the only sensible solution is getting bits made.  The cost per bit will go down quickly if you order several. I would get quotes on 3,5,7 and 10 bits, and find out if they will submit a first article sample for approval.

Good luck.

 

[flair woodworks]

Couldn’t this be achieved with a standard roundover bit set for a shallower cut? For example, with a larger bearing and depth at 90% of the full radius profile?

 

[luvmytoolz]

Couldn’t this be achieved with a standard roundover bit set for a shallower cut? For example, with a larger bearing and depth at 90% of the full radius profile?

The problem is the sides are greater than 90 degrees, so a bigger bearing won't help, that will just give a partially cut radius. The cutter itself needs to be like those made for doing guitar neck profiles, they're the only cutters I've ever seen in that profile.