Nicely beveled slate coaster break ?

[threedee]

Been looking at options to cut slate coasters myself as i have abundance of material.
However, i couldn't find anything beyond traditional slaters knife, angle grinder and tile saw mehods that would produce presentable edge to coasters.
I've tried hand cutting with slaters knife - chips in way too deep into surface. Tried hacksaw/grinder and then hammering on the edge - nope again.
Went out and bought a pair of coasters from poundstretcher as an example of what i want to achieve. This is what i want:

Those are 100x100mm. +-1mm.

I'm pretty sure there's supposed to be a method to cut these in their potentially millions, to exact dimensions with nice steeply angled break line ?
Breaking with some sort of hinged implement ? Dont think its done by hand and i might be able to construct a gadget to cut/break roofing slate neatly like this ?

Anyone here with experience in working with slate for quickish method to manufacture these ?

 

[MikeG.]

Cut them as you have been doing, then use a belt sander/ linisher to clean up the edges and apply a bevel.

 

[morturn]

They are cut on a guillotine type machine that has a blade like a cylinder lawn mower, so it shears the slate. There’s a small gap between the blades of around 5mm.

You may manage with a slaters knife, but they do take practice and skill. You need to use with a heavy steel straight edge. Lay the slat on the straight edge face down and chop down along the straight edge with your slaters knife. You sort of need to be bold, confident and have a good aim.

 

[MikeG.]

Both of those produce a riven edge. I think our OP wants a smooth beveled edge.

Edit....re-reading the OP that's what he says he wants, and then goes on to show a riven edge. So yes, a slate guillotine is the answer. It's an easy thing to fabricate if you can't buy one ready-made.

 

[Nelsun]

There are assorted shrouds (Metabo and Festool for sure and likely others by now) for angle grinders which make them run on tracks like a track saw. Not sure if they bevel or not but they do make for a quick, clean and very precise cut.

It's "perhaps" overkill for a few coasters but, if you're looking at banging them out, it may be worth a look. I've made a few one-piece mirror frames by cutting out the centre section with one with no self generated mistakes [that's not the phrase I used] so far.

 

[Lons]

I bought a hand guillotine something like this years ago for a couple of renovation jobs and they work very well indeed for a nice riven edge. We cut several thousand mostly reclaimed slates as they were too big without issues, I still have it and use it on occasion.
https://www.aboutroofing.com/heavy-...MI6tvAq7HM6wIVKIBQBh2OUQztEAQYAiABEgI9ufD_BwEYou can hire them if you want to try out beforehand though possibly just as cheap to buy.

Edit. Have just seen Mortuns reply, before the guillotine we cut them as he described but using a brickies trowel rather than a knife, also works fine but not as easy for a beginner.

 

[Rorschach]

I would suspect when cut in a factory en masse they are using a guillotine that clamps the top and bottom which reduces the flex and shock that causes the chipping. You may find this difficult to achieve at home.

 

[threedee]

Both of those produce a riven edge. I think our OP wants a smooth beveled edge.

Edit....re-reading the OP that's what he says he wants, and then goes on to show a riven edge. So yes, a slate guillotine is the answer. It's an easy thing to fabricate if you can't buy one ready-made.

Ah, so thats the term - riven edge. What i want is a steep edge, not what i can produce by hand, which is usually very shallow, unappealing sort of affair. I've tried a good number of times and nothing good comes out of me hacking at the slate.
I could buy them coasters but its an unneccessary expense when i already have material to work with, all i need is to figure out process/tools.

I bought a hand guillotine something like this years ago for a couple of renovation jobs and they work very well indeed for a nice riven edge. We cut several thousand mostly reclaimed slates as they were too big without issues, I still have it and use it on occasion.

Edit. Have just seen Mortuns reply, before the guillotine we cut them as he described but using a brickies trowel rather than a knife, also works fine but not as easy for a beginner.

Actually, in my original post by "slaters knife" i meant trowel Same thing more or less. I used a big one for weight. It works, but leaves way more mess and waste than i want. (Also, yeah, practice...)
Guilliotine would produce quite a lot of waste to take away, dont care much for loss of material.

I would suspect when cut in a factory en masse they are using a guillotine that clamps the top and bottom which reduces the flex and shock that causes the chipping. You may find this difficult to achieve at home.

I suspected some sort of edge clamping action going on there.
I have a guy who helps me with metalwork, making all sorts of implements. I just need to figure out what to make. Ideally to see the process and way of clamping so i can replicate part of it for manual operation, or some variation of..

 

[MikeG.]

.......Guilliotine would produce quite a lot of waste to take away, dont care much for loss of material.
......

Why do you say that? It produces less waste than any other method.

 

[threedee]

My assumption (about slaters guilliotine) was wrong. It has support on both sides of the blade. I was thinking your usuall guilliotine with one edge unsupported.

Upon closer inspection of slaters guilliotine, i see blade moving in between two supporting/shearing edges. Which makes sense.

 

[MikeG.]

Exactly. Even hand-held slate shears (AKA slate scissors or slate pliers or slate cutters) use the same principle. If you are making repetitive cuts, you just need to make a jig/ table with a stop, and crack on.

 

[Lons]

Exactly, there is no unsupported edge, clamps are not necessary and the guillotine blade slices through the slate with ease as the slot is only wide enough to allow waste to drop through, the only waste is the thickness of the blade similar to using a circular saw and the blade from memory is just a few mm thick and produces a clean riven edge. You have to cut from the back as the riven edge is formed under the cutter.
As I said while a fair number of the slates we cut were new, the vast majority were reclaimed from old colliery houses and covered in soot so had to be cleaned as we cut but the cuts were no problem.

I can lay hands on mine if you want actual pics of a working cutter.

 

[threedee]

No need, i'm good. Found some examples online, will make my own with couple of iron angles and a flat bar. I'll share pics when done.