Pansy firehole door runners - how?

The drawing specifies that they are 5/32 square (OK), 3" long (OK) with a 1/16 wide by 3/32 deep slot for the door to slide in. A 1/16 end mill will break if I look at it funny but I can't think of another solution. You chaps are clever, ideas appreciated

Phil

Slitting saw if you can hold the material to use one?

John

Some people make them of two strips with spacers between, so that the slot has an pen bottom and doesn't get blocked easily.

Neil

Saw the slot into the edge of some 4mm plate and then saw off a square so its easier to hold. As Neil says a few 1/16" drilled holes will let dust/ash drop out.

Or just get used to using a 1/16" slot drill NOT an endmill

Out of interest why a slot drill and not an end mill? Good ideas thanks. I have a small slitting saw but the arbor fouls the vice or the milling machine fouls the vice depending on how I organise it. I think I will get a couple of slot drills and go slowly, presumably the machine speed is pretty much as fast as it goes? 2500 rpm ish for me

2-flute slot drills are designed for cutting slots which is what this is, they do't get pulled to one side by the cutting action and in the smaller sizes will clear swarf better too.

Forget using the vice, clamp your bit of square or flat material to the top of some packing, that way you can get the saw to the side of it and the bit that holds the blade on won't foul on anything.

Similar sort of arrangement to this

But it's weeney, 5/32 square, hard enough to see never mind hold but I will have a go soon, have ordered slot drills from Tracy Tools. Where can I get smaller fingers and better eyes from?

Hand hacksaw with 4 blades with two outer ones upside down as spacers. Clamp plates each side of target as guides and off you go. If you are not very accurate you could then clean up with an end mill which will be less unhappy since the bulk is gone.

Slot drills are for ...............slots. End mills are only suitable for going down the end of a job, not the middle else they would be called 'middle mills'.

The 4 teeth/flutes on an endmill cannot advance straight into the face of a slab. Just try holding one up against a flat surface and you will see the difference compared to a 2 fluted item such as a drill. (for the feeble minded no I am not suggesting you can use a drill sideways on steel just because it has 2 flutes though people do do that in wood).

To let the dust out file a small gap in the outside ridge at the middle or make it in reverse with slot in door bottom.

Thats one of the reasons I first suggested doing the slot on the edge of a larger piece, than hacksaw off and holding in the vice mill it down to 5/32" square, the other advantage of working with a larger bit of metal is that it won't want to flex away from the saw. But its easy enough to hold 5/32" square material as per that photo.

ive made many GWR firehole door assemblies in 5"g and have had no difficulty milling the slots for same with a 1/16" slot drill.

how to get the doors to be central is another matter!

cheers,

julian

Done it ! Used a 1/16 slot drill to cut er, a slot. 3000rpm and 10 thou cuts got me there without breakage and I went right through on one runner for the central 1/2" so the dust can fall out. Thanks for ideas, I'm sure I will be back