Official Luthiers Forum!

Hello folks
I've been trawling the interweb in search of why there is such an array of sizes of router inserts,
or more so... trying to find an example of things going wrong regarding too large of a gap.
From what I can make out, there seems to be quite a bit of a margin "allowed"
and being a hand tooler for the most part, likely not finding the "go to" folks to further my knowledge,
(best I've found is Roy Sutton's old VHS videos on the subject on YT)

I'm just wishing to know if you had the choice of three inserts, for a decent 1/2" router, then what sizes you'd pick?
[edit: I've sized the bore to cater for a 3 1/2" panel cutter, if that's any help]

Getting started on making steel ones, so would be nice to know if some have only needed three?

Many thanks

Tom

It would depend on the size of the cutter head, not the shaft size…

Indeed Meddlingfool, I can re-phrase the question, as perhaps I've been asking it backwards.
I'll try again if I may.

Which three router bits do you find most useful, and what would be the max clearance of a gap will you allow for them?
If the answer is four or five I'd still be interested reading, as I could at least choose, should the tablesaw cover one of those jobs
perhaps.
(This work is actually part of a tablesaw soup up, in a roundabout way, and there's no want for urgency on the matter,
as I'm just ticking this job off the list)



Nice to see a fimiliar name after a decade, as I've been down some deep rabbit holes since.
Cheers
Tom

Cabinet makers use some big bits, but for guitars about the largest bit I have is a 1/2” radius round over bit that has an overall diameter of 1-1/2”. My preferred gap is small. I like to keep it around 1/8”, even though it would probably be fine at 1/4” to 3/8”.

My insert has snap in plastic collars to adjust the opening. I’ve had no problems with this router plate.

That's great Barry, and exactly the kinda answer I was hoping to get.

I see the diameter of a bit like that is likely about the same on most, @38.1mm diameter,
which would suit one of these inserts well, as there's a pair of existing holes in one of the blanks,
spaced at what I think might be about 40mm apart, so hopefully that's that one sorted.


Now I only have to ponder about the next ones down,
and since I've only got a new half inch straight cutter as of yet, just to test this old Elu router really
I'll be making one to suit that.... or possibly a size up? ....
should there be a bit for the router table, which I should be considering thereabouts around that size?
(It's not too much of a bother to be undersize, as I can open them out if need be)
so I guess that's that one sorted aswell.

Next being the smallest bit, which I've already drilled out to 8mm, to perhaps account for a 1/4" bit with some wiggle room.
In the same thinking as the above, better too small than the opposite, it seems I'm good to crack on with the job....
though with that said,
I would like, not to have to open these out at a later date if I can help it.

Many thanks for nipping any analysis paralysis I might have made for myself in the bud,
as I haven't delved that much into router techniques for the luthier/guitar builder,
well... specifically regarding jobs what can be done on the router table, that is.

Happy to read of some suggestions, should someone have a different take on my choices for the other two smaller bores.

Many Thanks
All the best

Tom

If you use a plastic material like Lexan or Corian You can sometimes use the router bit to cut the hole by raising it slowly up through the material. Some bits (like the round over with a bearing) might require a pilot hole first to allow the bearing to pass through. That should make a "zero clearance" insert for that particular bit.

Thanks Clay, but plonking ahead as I do, I kinda left myself short of material on this being a stingebag.
At the time, I was stuck into getting my tablesaw assembled again to get that stage finished with,
whilst wrangling everything into submission on this uneven floor, hence why the saw is oriented strangely.
(been working on various parts for this machine since last year)




Not much to play with in the end, as I lost the measurements and being perhaps too optimistic when cutting stock...



More plonking on my part thinking I had been generous with the bore size, eyeballed somewhat,
it wasn't until I decided to google "router bit won't fit in table insert" or some such,
that I found an answer to the maximum size cutter one is likely to find... a 3 1/2" panel cutter, that is,
(that's an assumption on my part, but I'm likely being reasonable here)

Sorry for rambling, but to mention that meant not having the luxury of a wider supporting shelf,
which would facilitate either rare earth magnets, or fixings, which in my mind might need to be required with plastic,
compared to steel which will hopefully be very resistant to being removed.

Likely the closest thing to a rosette I'll be making for some time

Should have clamped this down, as I've likely got to fettle things yet.


Cheers
Tom