How deep can I cut RO on router?

[radhak]

I need to cut stub tenon/mortises for a table; material - Red Oak. The legs are 2"x2" and the aprons are 1" thick.

I want 1/2" thick and 1/2" deep mortises that will be 'open' at the top, like so :



I think the router-table is the best place for this.

I have read/heard everywhere - take light passes, don't try to take off too much wood.

So am planning to set a 1/2" straight bit to a 1/2" height on the router table, and using a couple of strips of 1/8" thick hardboard as spacers; shall remove one strip after each pass. But it looks like a lot of work - too many passes!

So, the question is : how much wood could I remove in a single pass? 1/8" is quite less, could I go 3/16? How about 1/4" in each pass? I don't want the bit breaking or something, but how'd I know it was not going right?

The RO is pretty hard, but I have a 3 1/2 HP router with 1/2" shank bits (Holbren).

I also have a spiral upcut (which I think has a 1/2" wide cut) - is that a better choice?

[JR]

I'd think you could go 1/4" deep with that setup without any problems whatsoever. If you were a real pig, you could go the whole 1/2".

Having said that, you need to learn a little patience, son!

[LCHIEN]

i would think between 1/8 and 1/4th would be comfortable.
The consequences of too big a bite:
can't feed fast enough, get burning.
or feed too fast, you get chattering and mabe break a bit with near catastrophic results (to the wood being cut or to the operator).

Try some test pieces and see how comfortable you are.

I would think the spacers would be a bad idea... they would tend to slip and slide unless clamped somehow so as not to have the clamps in the way. That's why plunge routers and even the adjustment dials on the fixed routers are there... you should be able to turn x-turns of the dial and get precise steps without resorting to spacers.

[Popeye]

1/4" should be good but how big of a hurry do you need to be in? It's four legs times two grooves times three passes to cut a third of the depth. Probably not talking half an hour. Try each on scrap and see how it goes. As I say that, patience isn't one of my better qualities either. Pat

[radhak]

Thanks guys. True - might as well take an extra pass; but I was more interested in the principle of the thing.
Now am thinking I might as well cut the stub tenons on the same setup instead of the TS.

[steve-norrell]

Not more than 1/4 inch per pass.

I know from experience . . . . . .

Regards, Steve

[JR]

Now am thinking I might as well cut the stub tenons on the same setup instead of the TS.

Yes, you can do that. I did it on my recent table project. Two suggestions:

1. You'll want to cut the mortises first, then sneak up on the correct depth of cut for the stub tenons.

2. Use some sort of sled with a sacrificial fence to guide the stretchers through. The sled will keep the material oriented properly and the sacrificial fence will keep you from having chipout.

JR

[pecker]

"I think the router-table is the best place for this.

I have read/heard everywhere - take light passes, don't try to take off too much wood.

So am planning to set a 1/2" straight bit to a 1/2" height on the router table, and using a couple of strips of 1/8" thick hardboard as spacers; shall remove one strip after each pass. But it looks like a lot of work - too many passes!"

Why bother with spacers. Adjust the bit height to 1/4" or 3/16" or whatever. Run all your pieces through. Readjust the bit height, and repeat. That's what the height/depth adjustment is for.

[LarryG]

Actually, spacers are usually the better solution, depending on the height-adjustment method. The motor cylinder of a fixed-base (i.e., non-plunging) router will often shift laterally in the base as the height is adjusted, which can move the bit off-center enough to mess up precision joinery. Plunge routers can exhibit this same problem, too, if there's more than the minimal amount of slop in the works. By using spacers, the height is set only once, so the bit position remains constant.

If one has a good-quality router lift, this is generally not anything that needs worrying about -- you can simply use the lift to adjust the bit height. But I've known of people who own lifts to use spacers, too.

[cabinetman]

I agree with Loring. I would not use spacers. They could slip and slide. I would use the 1/2" bit, and make two depth passes. That router is beefy enough for that. That procedure can also be done with a two flute carbide tipped straight mortising bit. If there is doubt that an alignment change occurred with a change to the height, that can be checked before the second pass.
.

[radhak]

I do own a lift : the Precision Router Lift from Woodpeck, with a PC 7518.

But still, the spacers make life much easier : I need to measure the height (precisely) just once, and not worry about other issues as Larry mentioned. And moving a couple of spacers around proves less effort than moving the lift up/down.

But I take care to clamp the spacers to the table - rather safe than sorry.

Of course - all borrowed ideas, from Pat Warner/Bill Hylton/et al.

[LarryG]

Of course - all borrowed ideas, from Pat Warner/Bill Hylton/et al.

Yes, guys these are the REAL masters, the guys who REALLY know what they're doing, and have the credentials to back it up. They're the people I listen to myself.

[cabinetman]

I do own a lift : the Precision Router Lift from Woodpeck, with a PC 7518.

But still, the spacers make life much easier : I need to measure the height (precisely) just once, and not worry about other issues as Larry mentioned. And moving a couple of spacers around proves less effort than moving the lift up/down.

But I take care to clamp the spacers to the table - rather safe than sorry.

Of course - all borrowed ideas, from Pat Warner/Bill Hylton/et al.

If you're bent on using a spacer, make one like a ZCI, by easing the bit through it, so there wont be any gaps. I might even temporarily glue it down, maybe with hot glue. Use something slippery for the sliding surface.
.