On 24/07/17 12:30, jkn wrote:
On Monday, July 24, 2017 at 8:01:37 AM UTC+1, jkn wrote:
Hi John

On Monday, July 24, 2017 at 2:08:02 AM UTC+1, John Rumm wrote:
On 23/07/2017 23:27, michael adams wrote:
"jkn" wrote in message
...
Hello all
This is an enquiry about how to use a router to cut a slot in the end of a sheet of
wood.

Below is an ASCII-art side view of the sheet. The wood is around 18mm thick.

The slot needs to be say 3mm across, and perhaps 15mm deep.


| | slot approx 3mm from edge

| | 3mm slot, 15mm or so deep

/ / / /
/ / / /
/ / / /
/ / / /
|-| |------|
| | | |
| | | |
| |_| |
| |
| |
|SIDE VIEW |

| ~18mm | thickness of wood

I have a Router (1/2" chuck) available to me. I originally presumed that the
approach would be to get a suitable 'deep pocket' router bit and cut the
slot in several passes. However I cannot find such a router bit and am
wondering if there are any other options.


You need to fit an arbor and a slotting cutter which is like a miniature saw blade.

You'll need to check sizes although you can alter the diameter of the bearings
on the arbore to determine the depth of the slot.

You lay the work flat , run the router along the top and the bearings in the arbor
either side of the blade run against the side of the wood.

And be very careful planning your movements - its wickedly easy to
forget you can't lift or plunge, and end up taking a lump out of the
face of your wood. DAMHIK!

Yes, I get that, thanks!


Use an extra bit of wood on the other side of the router base to add
stability when doing this type of cut - otherwise its difficult to
balance it on edge and then slide it into the cut.


I worked that out for myself last night after visualising things in a bit more detail - thanks! ;-)

As it happens there will be a 'scrap' area (to be cut away subsequently) of a few cm at the start end end of the slot, so the cleanness of the entry and exit points are not over-critical.

This has all been very helpful, thanks a lot.

Jon N

oh, a supplementary...

After the earlier discussions I was thinking of using the router 'bit down',
with a side piece of the same thickness to ensure the router is stable. However
I do have a router table and so could use the router 'upside down' in that.

This would give the benefit of being able to use the fence; however the slots
need to be quite long (the wood is ~600mm wide) and I guess I would need to
extend the table so that the wood is stable at the extremities.

(I s'pose I could do half the slot in each direction and turn the wood over -
but since the slot is not symmetrical in the wood I would have to do some
height adjusting which I am reluctanct to do.)

Does the team think that this would still be preferable to clamping two bits of wood down and going in from the top? I guess with the table and fence I would
not need to fit a 'depth bearing' on the arbour?
use the table and dont worry too much about extending it. Get a mate to
support it and feed it in whilst you control the wood near the router bit.




--
Theres a mighty big difference between good, sound reasons and reasons
that sound good.

Burton Hillis (William Vaughn, American columnist)