Putting a small slot in wood

[Robert Smith]

I think I have a good question for the group

I am making a bunch of 3/4 thick parts out of oak and pine. They are various shapes, anything from a 3" dia. circle to 16" circle, 3" sqaure, to a

12"x18" rectangle. All these parts when done need to have a .05 wide slot around the perimeter, centered in the width. The slot must be a minimum of 1/2" deep. I work in a machine shop, so I purchased a .05 wide metal cutting slitting saw that is 3" in dia. I also got a bearing that had a 2" o.d. I then made an arbor to fit into my PC router, that mounts the bearing right above the slitting saw. My problem is, when I use it I think the router is going way to fast for the slitting saw, because it turned blue from the heat. It cuts the slot, but I don't think it's going to last through a whole lot of them. My next try was to get the thinnest 10" saw blade that I could get for my table saw. I then made and extension for my fence and stood the part on edge and spun it through the saw blade. This worked also, but it seems a little dangerous, if the wood would ever decide to take off. I really wouldn't mind doing it this way, but when I checked the slot width it is about .015 to wide. I mic'd the blade and found it was .065 across the teeth. My question is, does anyone have any better ideas how to put this slot in the parts. Or do you know where I can buy a really thin 10" saw blade?

Thanks for any help Bob

[bs]

Robert,

Check the Dremel displays or their web site...

is a mini-sawblade #546 made for high speeds and should work fine on your router. It's .025 thick so put two together on a 1/4" mandrel, use a safety shield and have at it.

Bob S.

[Lawrence Wasserman]

I don't thingk you will find a 10" blade near that thin, but there are some 7 1/4" blades that have 1/16" kerf. You want .05"= 1/20th so that is getting pretty close. If you can find a 7 1/4" steel (not carbide) blade you may be able to carefully grind it down on the table saw. Or a good sharpening shop could do it for you.

[Mark Jerde]

Can you run it in a drill press?

-- Mark

[Pounds on Wood]

You have diagnosed the problem correctly, the router is too fast. You can get a speed control for your router and try another slot cutter. You probably had a hss slot cutter, and if the job will warrant the expense you might want a carbide slot cutter.

Also, luthiers use very thin saw blade for cutting frets and such. You could DAGS for luthier suppliers and see if they don't make a .050 saw. I'm sorta remembering that they do.

[Dave Mundt]

On Fri, 24 Oct 2003 18:23:57 GMT, "Robert Smith" wrote:

Man...Although I have done exciting things like that myself, it kind of makes me draw up a bit to think about it.

Well, it depends...there is more than one way to do this. For the "round" parts, I would suggest running over to WoodCraft and buying a nice lathe that will spin them, and, a chuck/faceplate to hold them. Then, use that machine shop to mill a "parting tool" to the appropriate width. Spin the disk, and carefully cut the groove. If made of HSS, it should last 'forever'. As for the square pieces...I think I would get a cheap carbide blade, and, using the tools at the machine shop, carefully grind the teeth down a bit in width until I had an appropriate kerf width. I would then set the blade to about 1/2" depth of cut and simply run the square/rectangular stock through on all four edges. One could also use this to cut the groove in the edge of the round pieces by making a tenoning jig sort of thing and screwing the disks to it. A bolt through the center would work and make it easy to loosen and tighten for a safe cut. A series of passes through the saw, loosening and turning the wheel slightly after each one, would do the job. Now...if you don't want HOLES in the disks...I would put a couple of shallow, triangular ramps onto the jig, just to the front and back of the contact point on the table of the saw (which would hold a variety of disk sizes and stabilize them, then, use a couple of De-Sta-Co toggle clamps to lock the disk in place. Back to several passes through the blade to get the groove done. Regards Dave Mundt

[JMartin957]

A metal slitting saw is a poor choice for wood. They are ground with only a minimum of clearance, which will make them rub and heat up in wood. Also, the tooth design doesn't leave much room for sawdust.

The thinnest wood blades I've seen are the steel plywood blades, with thin rims. I've got an 8" Simonds that I use in my tablesaw. You have to watch it, though - if it starts to bind and heats up, the rim expands and gets wavy. Wavy by 1/4" or more.

John Martin

[Andy Dingley]

I've been making these lately:

need a narrow _stopped_ slot to take 18 gauge copper (about .05 ) and I had a lot of trouble working out how to do this.

First few were hand-sawn, which took longer to do than the rest of the tray, metalwork included.

Now I use a metal slitting saw, held vertical axis in a milling machine. A dedicated wooden fence clamps to the table of the mill. This works well and is quick to use, but it does have some drawbacks.

Slitting saws aren't intended for wood, so they have negligible chip clearance. Find the biggest teeth you can. I'm even considering grinding alternate teeth out. Don't plunge them in full depth, because if they heat up and bind, they'll smash your stock clear through any jig. A milling machine has huge torque, compared to a woodworking machine.

Fortunately the mill allows me to move the cross-slide back and forth in a controlled manner, which controls cut depth. I did consider clamping the stock down and using the slide's traverse to feed the saw, but decided to hand-feed instead, as I can feel the blade heating up and starting to bind.

Because it's a stopped slot, I'm using a tiny diameter saw. If I could, I'd use a bigger one.

-- Die Gotterspammerung - Junkmail of the Gods

[Nova]

Couldn't you fabricate a .05 thick blade and make a router plane?

-- Jack Novak Buffalo, NY - USA (Remove "SPAM" from email address to reply)

[Lew Hodgett]

RE: Subject

What you are trying to do is very similar to what is done to make stamping dies for gaskets.

I'd probably approach this as a two (2) part product consisting of a piece of 1/4" plywood and the 3/4" finish material.

Recess the plywood into the bottom of the piece, then layout the lines and use a scroll saw.

Wedge some "bridges" into the saw cut at the appropriate locations to maintain registration while you do the glue up, then remove them afterwards.

A flying red horse at 1,000 ft will never see that it is a two (2) piece construction.

HTH

[Andy Dingley]

I'm going about 1/4" deep in hard oak, so I think that's a depth/width ratio that's a bit unworkable.

I think what I really need is a saw with deep tooth gullets ground into it, to improve chip clearance, and a jig with a better hand-held sliding carriage with built-in end stops. I'm tooling up to make these in volume, so it's worth thinking about. I can make the copperwork in an hour for each, plus another hour to patinate and finish them.

-- Die Gotterspammerung - Junkmail of the Gods

[Nova]

What about something like a back saw blade clamped between two rabbeted pieces of stock? The rebates would keep the blade centered and act as a fence/depth stop.

-- Jack Novak Buffalo, NY - USA (Remove "SPAM" from email address to reply)

[Andy Dingley]

How I normally saw this sort of groove is with my azebiki saw

problems in this case are that:

- It's damn slow. There's four foot of groove in one of those trays.

- It's a pain to do the stopped ends

- (the real killer) I just couldn't find any sawblade thick enough (16 gauge) to cut it in one pass.

I made three trays by hand-sawing the slots and I won't do any more that way. I couldn't afford to, for one thing.

-- Die Gotterspammerung - Junkmail of the Gods