Thank you for the care you took to give me this answer.
You are right, an upcut spiral cutter should do better.
Unfortunatly, i was not able to find one except asking for a special make.
Some manufacturers could make it from solid carbide but I did not even ask.
As I am very sure it would bee a bit too expensive for me.
For my specific problem of finding cutters, I started a new thread, as it is a specific
problem to me, having soon to make gig mortices: http://www.routerforums.com/router-b...p-mortice.html
You can see there I ordered a 1/2" diameter 3 "" cutter, hope it will be a good tool.
The plunge router for this job is a Metabo OFE1812 (discontinued type) and has a plunge
capacity of 82mm so a 3"" (75mm) cutter will fit.
Nowadays there is an other router that plunges 80mm: the trend T11.
I think your construction of pantorouter is a great tool and that I may be able to build
something similar, using my plunge router or an other motor to move the bit.
So, like for you, plunge distance wouldl not be a problem anymore.
Traditional Japanese house building uses dovetailing in large woods like 120mmx120mm,
the use of a router or milling machine would help a lot making those nice joinery.
I keep thinking of it and of milling machines for making a better job.
Just a last thing: the cutter I ordered is no spiral, then the same problem will affect
my work: the mortice will be full of dust. I will try my air compressor with a thin copper
pipe to blow air in the mortice. At 6 Bars pressure it blows quite a lot.
I hope things go well for you and that you find good solutions for your works.