I was happily working on my report for NAMHO 2014 and started to say something about the traditional (greaves) slate saw when I suddenly realised that I wasn't sure about something obvious - the size of the traditional circular slate saw blade. I found one this weekend 13" in diameter, but it was pointed out that it had probably been re-sharpened many times so was originally much larger, maybe 18"? Many quarry inventories simply refer to numbers of spare saw blades without quoting different sizes -so it set me wondering if there were very few different ones -does anyone have any definite information ?

Cheers

Grahami

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It was my comment to Graham that a saw's diameter might be reduced by sharpening – which on reflection was not a very well thought out suggestion ...

I now doubt that saws would be sharpened so much as to significantly change the diameter because this would seriously affect the size of the teeth. I think it unlikely that saws would get to the state where all the teeth were ground off and recut to re-establish the original tooth size and form (or that it would be even worth doing) as the smaller blade with fewer teeth would cut more slowly and would have a reduced depth of cut.

It's possible that the saw suppliers knew their customers' requirements and once an initial order had been made for a particular saw blade size, repeat orders would be to the same size as the previously supplied without the size being explicitly specified

Dave

Can anything be scaled from the numerous images about, max diameter must pass under the slotted pusher?

http://www.theviewfromthenorth.org/dinorwic-20 

Can anything be scaled from the numerous images about, max diameter must pass under the slotted pusher?

http://www.theviewfromthenorth.org/dinorwic-20 

As a guess, the sliding table rollers wouldn't be more than around 6" diameter, possibly slightly under that, they look very similar to the rollers on a Stenner VB42 timber rack bench I used to own and run, I would say the saw blade is no more than 16" to 18" diameter, anything larger would require mucho torque from the drive engine.

Reducing the blade diameter due to many sharpenings gets to a point of diminishing returns.

Lozz.

Reducing the blade diameter due to many sharpenings gets to a point of diminishing returns.

Lozz.

Going the other way beginning with a very large blade would require greater torque and risk burning out or stalling motors. Either event would wipe out any savings made by recutting.
....or maybe I'm talking rubbish. :stupid:

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Reducing the blade diameter due to many sharpenings gets to a point of diminishing returns.

Lozz.

Going the other way beginning with a very large blade would require greater torque and risk burning out or stalling motors. Either event would wipe out any savings made by recutting.
....or maybe I'm talking rubbish. :stupid:

No, your not talking rubbish, I was implying the same in my original post (torque). The saw (timber) I had needed around 40 hp. anything less and it would grunt when deep cutting logs.

Lozz.

A larger diameter blade would require a reduction in RPM to keep the tip speed correct.

As a matter of interest, would the bank of saws in the image have power feed, if so, would it be variable?

I'm fairly sure that we have several blades at work and also the files used to sharpen them. I'll run a tape measure across them when I'm back on Friday.

Martin

I assume from the set-up, the saws (in image) produced fairly standard small slabs for splitting into roofing slates. What sort of slab thickness (maximum) did the men doing the splitting require?

I suppose much larger blades (or wire saws) were used for other products.

Other photo's in that collection show the table from a more end on view, the slot width in the table would probably be no more than an inch if that's any help, on the big logging saw I had it was about 1/2 to 3/4" maximum as I remember, the band/tip speed was around 60 mph whatever that is in new money.

Lozz.

Given the number of slate lintels and stones in old buildings around North Wales that show circular cutting marks, maybe it would be possible to measure a few?

Thanks everyone so far for your ideas. I've juts uploaded some photos I took way back in 1975 at the Llanberis Slate museum of the saws they had there then. My copy of the gudiebook from the time says "There are three sawing tables, the biggest of which is 18ft long and 3ft wide. This was brought to the museum from Pen-yr-Orsedd quarry, in Nantlle Vale, where it was assembled in 1876, the other two tables worked at Dinorwic Quarry."

I guess from this that the singleton is the DeWinton Hydraulic feed - which just might give me a scale for the patent drawing of it - but unfortunately, I suspect the tables came in different sizes. Otherwise I might make an estime from the end view of the cylinder, which also shows half the table and the upside down U hoop link. I notice it has a distinct burr mark on one side - I think the saw blade did not run true....

I look forward to any measurements anyone has.

I have been trying to do some measurements of Hunter saw diameters from their distictive marks at Hafod-las and in Bettws y Coed itself, but I suspect rubbings might work better than trying to scale from photographs and rulers!


Cheers

Grahami

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Also consider that any teeth cut below the original would have to be "hardened" - - Heated to "cherry red" then doused in oil, a lot of hassell !.

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Just measured the saws we have in our stores, 24" in diameter and appear to be unused although a bit rusty. I'll try and find out if they have a history
🔗Personal-Album-407-Image-96627[linkphoto]Personal-Album-407-Image-96627[/linkphoto][/link]
There is another picture of the makers stamp in my album.

Martin

Makers name is

THOs HANCOCK & SONS

(SAWS) Ltd

SHEFFIELD

Thanks very much for this - so we have one of 13" and one of 24" - I'm sure I've seen a reference somewhere to 18" - curiouser and curiouser.

Grahami

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Just in case anyone is interested we are having a major clear out at work and the slate saws that I posted a couple of pictures of earlier in this thread have been declared surplus so if anyone knows of a home for them they are available free to whoever can collect them.

Call me on 01654 710643 if you need any more info, the blades are located at the Talyllyn Railway.

Thanks,

Martin

The two small saws at Honister were 22 (or 24?) in dia. as I recall. The big one was 65 in dia. - all diamond tipped. We used to "sharpen" them occasionally by running them through a lump of sandstone (wears the phosphor bronze matrix off a bit to expose fresh diamond).