Slab Thickness?

[Knocker]

Hey Guys,
Trying to cut some slabs for the first time - Glass Butte obsidian.   I'm afraid I might be making them too thick.  Is there a rule of thumb for thickness?  Does the length x width of the slab figure into it, or is it based on what you are trying to create?

Thanks,
Knocker

[jcinpc]

if your pressure flaking yes the width does matter. Your flake has to be able to run at least to the middle. As for percussion 5/8 is a common thickness, thats all I have ever cut my rock for is the percussion thickness

[rileyconcrete]

Keith,

Have you tried any of the slabs I gave you?  I usually cut my slabs at 1/4 inch to 3/8 inch.  The widest I make the blades are as far as I can run a flake to the middle.  If you need any help PM me and I will Tell you my phone # and we can talk.

Tell

[caveman2533]

I usually cut my slabs according to the width they are coming off the rock. If it is not more than 1.5 " w then 1/4 to 5/16 as a slab get wider it becomes more of a percussion slab and will get thicker.  2 -3 inches wide 7/16ths to 1/2 thick   and if they  are 4  or more wide,  5/8ths and even more if they are really large, up to an inch or more.
Steve

[Knocker]

Thanks Tell and Steve... Increasing the thickness with width makes sense to me.  I think for most of the slabs I am making now, that I just want to work on arrowheads and small knives or spearheads, so even if they could be larger slabs, I might make them 1/4 to 3/8 thick and resaw the slabs into smaller pieces for pressure flaking.  I've got some dacite I can always practice percussion on.

Keith

[brian melton]

Keith,

             What are you using for a saw?

[Knocker]

Brian - I am using a 16" diamond blade saw with a screw drive rock clamp.  I'll probably spend the day tomorrow cutting slabs.

Keith

[sailordad]

just throwing this out there

i like slabs of obsidion 

[caveman2533]

Keith,
If you want slabs that are all the same just block a piece out  and then slice it like a loaf of bread. then they will all be consistent size.   I don't always cut them random size like I posted earlier.  That depends on what rock I am cutting also. If it is more rare material I usually cut them random as they come off the rock, if it is more common material like obsidian I will block them sometimes and cut them consistently.  But I usually cut as large a block as I can and will snap individual slabs from  larger ones with a tile cutter.
steve

[brian melton]

Keith a lapidary saw, or something you made, got a pic?

[Knocker]

Brian - Here is the saw I am using...

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[Knocker]

It amazes me how different some of this Obsidian looks with backlighting.  Look at these pairs...

The last one has a beautiful gold sheen, but I have no idea how to photograph it.

Keith

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[rileyconcrete]

Dang Keith.  Looks like you have lots to knap now.  You really picked up some nice rock.

Tell

[Knocker]

Happy Easter Tell!  And all the rest on PA as well! Yeah, the plan is to get it all cut up while the wind is howling and the rain/sleet/snow is rattling the tarp.  Hopefully my knapping skill will take a jump when it warms up enough to set a stool out next to the saw...

Keith

[caveman2533]

Man that is some beautiful rock,
Steve