I have a collection of straight router bits and a few mortising router bits. Can any one tell me how to tell the difference other than the straight bits being typically longer? What makes the mortising bit unique?
Cutting edges on the base of the bit?
-Zz
I'm thinking that the bottom of a bit that has dual cutting edges with a split in its centre is designed more for mortising as it allows for some chip movement in a mostly enclosed mortise.
I see no significant difference between the two. Both bits have the split on the end.
Appear to be basically the same to me.
The mortising bit moves waste chips better than a straight router bit. The mortising bit is designed to run at a slower speed to reduce heat buildup in deep mortises. May not be true for your bits, but that's the take on mine.
I certainly agree that a mortising bit makes a cleaner cut. But how can you look at a mortising bit and know it is a mortising bit other than it being shorter than a straight bit?
My mortising cutters are soild carbide and are of the upward spiral type to clear the waste from the mortise.
Yeah, so are my straight cut bits.
Sorry, meant to say my straight cut bits have a carbide cutting edges with a slight spiral twist just like the mortise bits. I have a couple of solid carbide spiral bits that I use with my D4. These however IIRC are not technically called Mortising bits.
See bottom of page (& note special cutter noted is not available) :
Damn!!!
Now this is the type of answer I love.
Frick> See bottom of page (& note special cutter noted is not available) :http:/=/patwarner.com/router_morticing.html> *************************************************************************=
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mortising bits should have a blade running across at least the full radius of the bottom of the bit... better is across the whole diameter... The reason is that mortising bits need to plunge straight in. Carbon spirals (from what I've seen) have an edge on the bottom as well also, these folks have something else
Thanks Pat but,,, my mortising bits look different.
Here is what my mortising bits look like,
OK, I got the answer. Mortising bits produce a downward sheer and therefore produce very clean cuts and they are better suited for entering into the side of a piece of wood rather than plunging.
Straight cut bits are better suited for plunge routing.
Having said that I am working on a project where I have several rabbet joints on the back panels of some towers that I am building. I used the mortising bit in my router table to create stopped but short rabbets. After assembly I used a free hand router to finish the rabbets. I pulled out an old end mill bit that I used to plunge and cut slots in Ipe several years ago for Steve Knight. I literally made a few thousand of these slots and this bit ran circles around any of my quality carbide tipped straight bits. The end mill was still sharp enough to cut you if you were not careful. The
4 flute end mill bit cut like butter in the oak and there was no grabbing what so ever.Seems strange that end mill bits are not sold over spiral carbide straight bits as they hold up really really well and are relatively cheap!
"Leon" wrote
Not strange at all. There is a lot more money in selling something expensive that dulls easily.
Well there is that but I guess what I was going for was the guys that sell end mill bits could also go after the wood worker instead of limiting themselves to the steel business. If you can make an end mill to out perform a carbide bit surely you could also make other design bits also. My end mill bit is a work of art compared to any of my carbide bits, they have the know how and resources. IIRC my end mill had a value of around $20, 3 years ago.
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