[How do I?] Chamfering large hole on manual machine

[projectnut]

There's the head-slap I needed. I didn't even think to look for XL sized countersinks. I just assumed they stopped at around an inch or so. I will look at these more. Thanks!

I currently have several sizes over 1". I believe the largest one is 2" in diameter. The truth be known, I don't even remember what job they were originally purchased for. It really doesn't matter, I've used them on many jobs since then.

If you're considering countersinks I would stick with brands like Keo and MA Ford. All my stand alone countersinks, 45* 82*, 90* and 100* are all these brands. Personally I prefer the "uniflute" design to the others available. They don't chatter, even when used in a hand drill or drill press. They can also be sharpened to any profile you choose using a surface grinder and an MA Ford sharpening jig. The jig is somewhat expensive if purchased new, but far less expensive when available on eBay.

Here's are some pictures of my older jig. The new ones come in a plastic box rather than the wooden one.




I do have some smaller size Magnavon's that were originally made for aircraft work. I do like them because of the "microstop" feature on the cage. Here's an example of some Magnavon cages with the microstop

Lot of 4 used Magnavon ATI Microstop Countersink Cages aircraft aerospace tool | eBay


These were heavily used in the aircraft industry, and readily available on eBay for quite some time. They're fewer available these days, and the actual countersinks are getting somewhat harder to find

 

[schmidty13]

It might be hard to find the 3/16" mark on the Z dial, but you can always raise the table .187" which should be close enough

Thanks for the pro-tip!

 

[MrWhoopee]

Is this aluminum? How thick? If its aluminum and thick enough, just use a 45degree chamfer bit with a flush bearing in a hand held woodworking router. I have even done this, even with a piece of steel with a variable speed mechanism to get the routers speed down so you don't burn out the cutter.
Just a thought anyways
Cheers
Martin

I have used 1/2" shank router bits on steel, they work just fine.

 

[schmidty13]

I have used 1/2" shank router bits on steel, they work just fine.

In a mill, sure. I guess I dismissed it because he was suggesting to use it in a wood router. But now I see I didn't read his entire comment; slowing it down wth a varible speed mechanism of some kind for use in steel would work. It's an interesting idea that I will look into more.

 

[schmidty13]

This is what you would be looking for . I have 50 or so if you need one .

I tried to private message you about purchasing a couple of them, but I must have done something wrong...

 

[mmcmdl]

Hey schmidty , never got a pm .

 

[NortonDommi]

https://www.mesatool.com/boring-head-accessories Plenty of rigidity. Should be easy to fabricate something similar to cut any angle chamfer you want.

 

[schmidty13]

https://www.mesatool.com/boring-head-accessories Plenty of rigidity. Should be easy to fabricate something similar to cut any angle chamfer you want.

I looked at those and was frustrated they didn't make any for chamfering. And you're right about fabricating one...I just thought that sort of thing was beyond my skill set. But I guess I'll never expand my skill set if I don't move out of my comfort zone.

 

[NortonDommi]

The least I think you would need is a pedestal drill. a vice and some files. If you have a mill, well luxury. The increase in rigidity over a standard boring bar is phenomenal. You can buy import Criterion style boring heads cheap and they work well.
Most tools made for a 'one-off' continue to justify the effort for years to come.