This cutter....

[throbscottle]

What do you call this type of cutter? It's the largest one (3mm) out of a set I got off eBay some years ago. Really annoyed because I just broke my 0.8mm one. Then I broke the 1mm one. Apparently they jam quite easily!

Is there a more suitable micro cutter to cut a slot in a board, connecting two holes?

 

[Ollie78]

Looks like an endmill to me.
For that size of hole you could use a 30 degree engraving bit, they are quite robust and very cheap.

 

[Sachakins]

Looks like a Corn Cob/ Corn Teeth end mill.

https://huanatools.com/applications-of-corn-teeth-end-mill/

 

[worn thumbs]

You can still buy them easily on amazon or ebay. Amazon.co.uk
The obvious alternative is the type of diamond grit cutter that might normally be used for trimming GRP,which isn't dissimilar to circuit board material,they last longer but can't be fed too rapidly.They also tend to be scarce if you need to go below 3mm diameter https://www.startpage.com/av/proxy-...8cf8f65e5d274c2d0eb239312b728d3d5a3145aa426d7.

 

[Tony51]

Have a look at rotozip the machine and it's accessories.
Tony

 

[throbscottle]

Oh yes, found them on Aliexpress. Thank you.

I think the diamond grit abrasive ones might be mores suitable for me though - so thanks for that.

The 30 degree engraving bit - I actually have a couple of those, never used! But I need the slot to be parallel sided so that wouldn't really work.

Rotozip - interesting. Spiral saw would be what I need, but at a cursory look I'm not seeing anything really tiny.

Thanks for all the responses

 

[worn thumbs]

Rotozip cutters in the small size are 1/8" shank,but I believe they are "only" tungsten carbide,which really doesn't like composite materials.The problem with those small carbide burrs is the extreme length/diameter ratio and even with very cautious feed rates they are unlikely to last long.Being long and skinny they tend to flex a tiny amount and since they rotate at a fairly high rate it doesn't take long for fatigue to set in.When it does the shank and the teeth tend to part company at the point where the transition occurs.If you could locate something that is say 5mm long and 3mm diameter it might last a bit longer.

 

[throbscottle]

Yep, broke exactly as you predicted. But i found the diamond coated burrs go right down to 0.8 mm, and I think those will be much better for me (cutting very tiny slots in grp board - circuit board fabrication to be exact). Probably won't be as neat at the corn mill ones, but that won't matter.