milling a 4mm wide slot

[Sean Hellman]

I want to cut a 4mm slot up to 14mm wide and 40 to 50 mm deep into end grain ash and beech. I am doing it in an amateurish way by drilling holes and then burning out with a piece of metal of the correct size. Not great for production runs and can look a bit messy.
Its for the tangs of tools I make.
The only other way I can think of is to drill a 14mm diameter hole and fill this with a dowel with a 4 mm slot cut most of its length.
Are there tools or processes out there I do not know about?

 

[baldkev]

im no expert, but aren't the holes normally stepped / tapered?
ie. you chisel out a quarter of the depth at 14mm, a quarter at 11.., a quarter 8, quarter at 4mm and then fit the handle ( with ferrule )
i believe they drive the chisel blade into softwood a bit to hold it, then knock the handle on the tang?
ive never done it, thats just what i read somewhere. @D_W has done a lot of these, so he'd be better placed to answer

 

[Jameshow]

I did it for a frying pan handle I turned.

3x 4mm holes and then joined them up with the drill at 30° spot of JB weld and it's still go 3 years later.

 

[--Tom--]

Look up handle broaches e.g.

https://www.gfsknifesupplies.com/Products/handle-broachUsed after drilling to form the slot.

I make my own by re grinding jigsaw blades to suit (keeping the teeth but narrowing the blade)

I use a hidden dowel for multi piece handles as it simplifies the process.

 

[Phil Pascoe]

Pascoe's patent stove clearing tool. Make the handle in two parts - cut the groove then glue the two halves together.

 

[TomTheToolMan]

The slot sounds like the type of slot a domino type machine would make. Unfortunately i dont think the 4mm cutter can plunge to the depth you need. But this makes me think that the solution should be similar. This is hypothetical but if I was going to do it regularly I would make a jig like people do to make domino style holes. It could be as simple as a couple of bits of mdf set at 90 degrees, joined in a T shape. This would be mounted to bench. In the vertical face cut a slot that accepts a router template guide and size accordingly. Then all you would have to do is clamp handle to jig with top at slot and cut to depth with 4mm spiral router bit. Once you have jig I can't imagine this taking more than a few seconds. You can then square corners if necessary.

 

[Sean Hellman]

Thanks for your replies, I make and use brooches, just wanted something a bit faster as drilling 4 mm holes in a line is always slightly hit and miss and time consuming to use the brooch.
I have also used the cut in half, rebate and glue back together method on push knife handles, a possibility but I am not sure.
I think that 4mm router bits are going to break on a regular basis and the cost is going to be too much, however careful i am in doing it.

I think I will go for the 13 or 14 mm dowel and hole and make a jig to cut a slot in the dowel. Question is what is the best method of making this slot, 115mm diameter tungsten saw blade or router bit?

 

[Phil Pascoe]

Did you mean broaches?

 

[baldkev]

What about those side cutting drill bits? Or an end mill..... you could start by drilling the 2 sides at the correct angle and then use the bit to pivot inbetween the two holes if you get what i mean?

 

[--Tom--]

Easy to slot them with a handsaw/bandsaw.

Would need jigging to do on a table saw and be a bit sketchy.

I find sawing out with a broach pretty quick.

Another option would be to slot all the way through and then add an endcap. Easy enough to do by threading a jewellers saw blade through the first 4mm hole.

A 4mm chain morticer would be ideal, shame the don’t exist

 

[Sean Hellman]

Yes I meant broaches but incidentally I do make brooches as well. My broaches are really floats.
I've settled on the process, tried it today, really quick and simple and faster than other methods, I reckon. I decided to use my mitre saw rather than buy a smaller 4mm kerfed saw and then make a jig up for the pillar drill. I do not have a milling machine.

I will let the pictures describe, note this is a prototype so please allow for all the errors you see in the photos. I also need a loose fit as hydraulic pressure with the epoxy is often too much to overcome when gluing up.