An actual woodworking question - routing a deep slot

[Theo]

Suppose I have a roughly 100x100mm post of (green) oak, that I want to route
a 1m long slot out of the back for cables - let's say 20mm wide by 20mm
deep. I have a 1/4" trim router but nothing bigger. I also have a 65mm
cutting depth circular saw.

Is that something I can do with the trim router, in which case what kind of
router bit would I need? Or should I do depth cuts with the circular saw
and then try to chisel out the remains? Or some combination of the two
tools?

Once this is done, I'm thinking of drilling a hole at the end of the slot
and having the cables turn to go through to the other side of the post. To
do that they will have some kind of turn radius, so how could I make the end
of the slot gradually deeper to meet the hole? Drilling a series of
holes of increasing depth and chiselling them out is one option I suppose.
I don't really want to make a huge hole to accommodate the bend inside the
hole itself.

Any better ideas?

Thanks
Theo

[Bill]

Post by Theo
Suppose I have a roughly 100x100mm post of (green) oak, that I want to route
a 1m long slot out of the back for cables - let's say 20mm wide by 20mm
deep. I have a 1/4" trim router but nothing bigger. I also have a 65mm
cutting depth circular saw.
Is that something I can do with the trim router, in which case what kind of
router bit would I need? Or should I do depth cuts with the circular saw
and then try to chisel out the remains? Or some combination of the two
tools?

I don't think a trim router is designed for this sort of work. I would
make multiple passes with your circular saw and then it should be very
easy to chisel out what you want. I'm assuming your post is square,
otherwise I think you would require a fancier set up, or it could be
dangerous (IMO, but lots of folks here know more than I do).

Post by Theo
Once this is done, I'm thinking of drilling a hole at the end of the slot
and having the cables turn to go through to the other side of the post. To
do that they will have some kind of turn radius, so how could I make the end
of the slot gradually deeper to meet the hole? Drilling a series of
holes of increasing depth and chiselling them out is one option I suppose.
I don't really want to make a huge hole to accommodate the bend inside the
hole itself.
Any better ideas?
Thanks
Theo

[pyotr filipivich]

Post by Theo
Suppose I have a roughly 100x100mm post of (green) oak, that I want to route
a 1m long slot out of the back for cables - let's say 20mm wide by 20mm
deep. I have a 1/4" trim router but nothing bigger. I also have a 65mm
cutting depth circular saw.
Is that something I can do with the trim router, in which case what kind of
router bit would I need? Or should I do depth cuts with the circular saw
and then try to chisel out the remains? Or some combination of the two
tools?

Use the saw, chisel out the remains. One issue is that you will
not have a "square" end to the slot because of the saw blade curve.
But it is in back, so who will see it?

Post by Theo
Once this is done, I'm thinking of drilling a hole at the end of the slot
and having the cables turn to go through to the other side of the post. To
do that they will have some kind of turn radius, so how could I make the end
of the slot gradually deeper to meet the hole? Drilling a series of
holes of increasing depth and chiselling them out is one option I suppose.

Depends on how deep the slot is, and can you just let the cables
"rise up" to point out the hole.
Other wise, drilling a series of holes is pretty much the
"easiest" solution. Could drill that hole first, the cut to it with
the saw. "Like this {Insert sketch}!"

Alternately, you could work the sides down with a chisel and
chisel out the middle, much as you would for a mortise and tendon.

Post by Theo
I don't really want to make a huge hole to accommodate the bend inside the
hole itself.
Any better ideas?
Thanks
Theo

[Scott Lurndal]

Post by Theo
Suppose I have a roughly 100x100mm post of (green) oak, that I want to route
a 1m long slot out of the back for cables - let's say 20mm wide by 20mm
deep. I have a 1/4" trim router but nothing bigger. I also have a 65mm
cutting depth circular saw.
Is that something I can do with the trim router, in which case what kind of
router bit would I need? Or should I do depth cuts with the circular saw
and then try to chisel out the remains? Or some combination of the two
tools?

With your tools, I'd go for the latter. Note that it will be tough
going for a 8mm trim router (I saw that switch in units, above)
to route a 3/4" x 3/4" x 39" slot.

Set the saw for a 3/4" deep cut and build a jig to guide the saw,
don't try to freehand it.

If you have a drill press, you can hog out the waste with a 3/4"
forstner bit, then trim with a chisel.

Post by Theo
Once this is done, I'm thinking of drilling a hole at the end of the slot
and having the cables turn to go through to the other side of the post. To
do that they will have some kind of turn radius, so how could I make the end
of the slot gradually deeper to meet the hole? Drilling a series of
holes of increasing depth and chiselling them out is one option I suppose.

Again, that's probably your best option.

[Theo]

Post by Scott Lurndal
With your tools, I'd go for the latter. Note that it will be tough
going for a 8mm trim router (I saw that switch in units, above)
to route a 3/4" x 3/4" x 39" slot.
Set the saw for a 3/4" deep cut and build a jig to guide the saw,
don't try to freehand it.

Thanks, that makes sense. Alas it's not a track saw which would make it
easier, but can probably jig something up.

Post by Scott Lurndal
If you have a drill press, you can hog out the waste with a 3/4"
forstner bit, then trim with a chisel.

That's a good thought, rather than trying to chisel out big chunks of
material. I don't have a drill press but I suppose doing it by hand might
be safe enough (then tidy up the edges).

Post by Scott Lurndal

Post by Theo
Once this is done, I'm thinking of drilling a hole at the end of the slot
and having the cables turn to go through to the other side of the post.
To do that they will have some kind of turn radius, so how could I make
the end of the slot gradually deeper to meet the hole? Drilling a series
of holes of increasing depth and chiselling them out is one option I
suppose.

Again, that's probably your best option.

A forstner bit to make stepped depth holes might work too. I should have a
play...

Thanks all,
Theo

[Bill]

Post by Theo

Post by Scott Lurndal
With your tools, I'd go for the latter. Note that it will be tough
going for a 8mm trim router (I saw that switch in units, above)
to route a 3/4" x 3/4" x 39" slot.
Set the saw for a 3/4" deep cut and build a jig to guide the saw,
don't try to freehand it.

Thanks, that makes sense. Alas it's not a track saw which would make it
easier, but can probably jig something up.

Post by Scott Lurndal
If you have a drill press, you can hog out the waste with a 3/4"
forstner bit, then trim with a chisel.

That's a good thought, rather than trying to chisel out big chunks of
material.

Note: If you run the circular saw, having an 1/8" inch blade (!)--not a
thin one, multiple times up the post, there won't be any big chunks to
chisel out. If you can put the post on a sturdy table or bench, a
clamped 2-by-4 ought to give you an ample jig to support the circular
saw. Clearly the post should also be clamped/secured. I used this
technique (on an admittedly smaller scale) once, and was really
impressed with it! I do not take any credit for it.


I don't have a drill press but I suppose doing it by hand might

Post by Theo
be safe enough (then tidy up the edges).

Post by Scott Lurndal

Post by Theo
Once this is done, I'm thinking of drilling a hole at the end of the slot
and having the cables turn to go through to the other side of the post.
To do that they will have some kind of turn radius, so how could I make
the end of the slot gradually deeper to meet the hole? Drilling a series
of holes of increasing depth and chiselling them out is one option I
suppose.

Again, that's probably your best option.

A forstner bit to make stepped depth holes might work too. I should have a
play...
Thanks all,
Theo