Applying to join this forum, you HAVE to activate your membership in YOUR email in the notice you recieve after completing application process. No activation on your part, no membership.

Lapidaryforum.net

Please login or register.

Login with username, password and session length
Advanced search  

News:

Welcome new members & old from the Lapidary/Gemstone Community Forum. Please join up. You will be approved after spam check & you must manually activate your acct with the link in your email

Congratulations to Bobby1 and his Brazilian Agate Cab!

 www.lapidaryforum.net

Another cabochon contest coming soon!

Pages: 1 2 [All]   Go Down

Author Topic: Unusually hard jasper or chert?  (Read 2131 times)

0 Members and 1 Guest are viewing this topic.

Kaljaia

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 812
Unusually hard jasper or chert?
« on: March 03, 2017, 01:07:58 PM »

I don't know if this is a material question or a saw question.


(Apologies for the dirt, hadn't gotten to the wash stage yet)
Found this in stream bed float. I was curious to see if the staining went in at all and maybe indicated a scenic jasper, but my saw is utterly uninterested in cutting it. I've run the saw over a red brick as recommended and it's cut a lot of other material just fine, but this is the first time it's said 'Nope!' Maybe too much oil, maybe too hard a rock- does anyone have experience with absurdly hard scenic material, or should I just let it keep trying for a while longer next time? It's a drop-saw, so the only pressure on the blade is the weight of the arm. It can cut through agate without getting hot and the blade is only a few months old. The material is not nearly as glassy as jasper or agate, has a slightly gritty texture.
Logged
- Erika

I rock hunt in the Antelope/Ashwood area of the John Day river basin in Oregon.

Stonemon

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 591
Re: Unusually hard jasper or chert?
« Reply #1 on: March 03, 2017, 01:50:22 PM »

Some of the jasper's from the Blue Mountain deposit are so hard they will stall my 12" power feed Lortone. I have run across others that will do the same thing.
I also have a twin of your 14" drop saw and find it to be much less able to handle the "tough" stones. Different materials act differently to the grinding of a diamond blade and some require more pressure to yield. I do not recommend any addition of weight. When I tried that on my 14" I smeared the surface, reducing the blade life. There may be a way to make it work but I am not the one to say.
The good news is that when you do find a way through that rock, it will probably take a heck of a polish. Those tough jasper's grade on up into the "porcelains."
Good looking material you are bringing in!
Bill
Logged


Bill

Kaljaia

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 812
Re: Unusually hard jasper or chert?
« Reply #2 on: March 03, 2017, 02:44:23 PM »

Thank you very much for that feedback! I appreciate it. I will let the saw try again but won't use weight on it. Maybe patience will win.
This is from enclosed BLM land. BLM material is 'non-commercial' but does that refer to business use or to all transfer of material from the person who found it to another party? (Can I send some to someone more experienced in hard rock?)
Logged
- Erika

I rock hunt in the Antelope/Ashwood area of the John Day river basin in Oregon.

peruano

  • Retired Zoologist
  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 410
Re: Unusually hard jasper or chert?
« Reply #3 on: March 03, 2017, 04:33:04 PM »

Drop saws are funny.  Sometimes even with a reasonable blade, they take an inordinate amount of time on something that a normal slab saw would plow through in normal time.  A new blade would speed the process, but that's not the answer you want.  There's nothing wrong with letting something saw for 30 min or 45, but if you have an alternative saw where you can slab it, I'd try just to see if its just a blade/drop saw issue.  I've seen things take forever in our sr. center's drop saw, and taken them home to my humble 12" slab saw and cut them in 1/3 of the time.  Nice stuff. 
Logged
Combining a love of bikes (pedal and otherwise) with hiking, hounding, lapidary, and the great outdoors

Kaljaia

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 812
Re: Unusually hard jasper or chert?
« Reply #4 on: March 03, 2017, 04:54:02 PM »

Yeah the drop saw is my only option. I have a six inch trim saw with a tile blade... Don't think that'll do it! I will bring a book next time and wait it out. As long as the continuous contact isn't going to damage the blade.
Logged
- Erika

I rock hunt in the Antelope/Ashwood area of the John Day river basin in Oregon.

Stonemon

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 591
Re: Unusually hard jasper or chert?
« Reply #5 on: March 03, 2017, 05:11:56 PM »

As far as passing a piece of rock to someone to cut, I doubt anyone will try to cuff you for that.
Bill
Logged


Bill

fossilman

  • Full Member
  • ***
  • Offline Offline
  • Posts: 186
Re: Unusually hard jasper or chert?
« Reply #6 on: March 03, 2017, 07:11:13 PM »

I cut jasper a lot,no problems with it........I am running newer blades too... That really helps out a bunch..
Logged
God,family and life!!

lithicbeads

  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3214
Re: Unusually hard jasper or chert?
« Reply #7 on: March 03, 2017, 07:27:54 PM »

That is a chert , a sedimentary jasper as are many Oregon jaspers. Cherts are almost always at the top of our semi-precious rock hardness scale. The oceanic cherts we have out on the coast can be very hard also but in some cases they are remetamorphosed and take on characteristics of quartzites which tend to be more granular and act less hard when cutting.
Logged

Kaljaia

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 812
Re: Unusually hard jasper or chert?
« Reply #8 on: March 16, 2017, 06:18:39 PM »

Got a piece off. Took half past forever but it is kinda pretty!
Logged
- Erika

I rock hunt in the Antelope/Ashwood area of the John Day river basin in Oregon.

peruano

  • Retired Zoologist
  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 410
Re: Unusually hard jasper or chert?
« Reply #9 on: March 17, 2017, 05:19:31 AM »

It just doesn't look like it would be especially hard.  At least you are rewarded with a material that made the effort worthwhile, and that you want to charge a lot for it if someone asks for a slab.
Logged
Combining a love of bikes (pedal and otherwise) with hiking, hounding, lapidary, and the great outdoors

Kaljaia

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 812
Re: Unusually hard jasper or chert?
« Reply #10 on: March 17, 2017, 07:15:08 AM »

Yeah, but it's from BLM land so no monetary value if I understand their rules right XD
Maybe I should look more closely at claim laws...
Logged
- Erika

I rock hunt in the Antelope/Ashwood area of the John Day river basin in Oregon.

vitzitziltecpatl

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1176
Re: Unusually hard jasper or chert?
« Reply #11 on: March 17, 2017, 07:36:18 AM »

The Lortone manual for the LS14 says you can add up to 5 lbs. max extra weight without causing "unsafe conditions".

That would be with the original motor in the original location on the back of the arm. If a heavier - or lighter - motor was added at some time it would change the balance a bit. Wish I knew the exact weight of the original motors that were on these units, so I could calculate any changes with a replacement motor.

Nice slab.

rocks2dust

  • Guest
Re: Unusually hard jasper or chert?
« Reply #12 on: March 17, 2017, 10:24:05 AM »

Nice picture rock!
Logged

Jhon P

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1755
Re: Unusually hard jasper or chert?
« Reply #13 on: March 17, 2017, 12:23:12 PM »

How's the rock cutting going. Have you dressed the blade?
Logged

Kaljaia

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 812
Re: Unusually hard jasper or chert?
« Reply #14 on: March 17, 2017, 01:14:08 PM »

How's the rock cutting going. Have you dressed the blade?

I've done the "cut a red brick" thing but nothing beyond that. The blade is not yet a year old. definitely open to advice, as always!
Logged
- Erika

I rock hunt in the Antelope/Ashwood area of the John Day river basin in Oregon.

socalagatehound

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1418
Re: Unusually hard jasper or chert?
« Reply #15 on: March 17, 2017, 01:42:34 PM »

Hi Erika

Run your fingernail along the edge of the blade (NOT running) and see if you can feel the roughness from the diamonds. If so, the blade is fine. If not, dress it with a chunk of old silicon dioxide grinding wheel. You can clamp it in the vise and cut it or do it by hand. One pass all the way around should be enough.  If the blade still won't cut any faster, flip it around. Dense agates  (like Brazilian) and porcelain jaspers (Oregon especially) will cause the edge to glaze and hide the diamonds, especially if its a brand that does not have a super high diamond concentration. Also, thicker blades can require more time to cut through hard materials because their grinding away more rock. My only experience is with 18 and 20" slab saws, and a 10 inch slab saw set up as a trim saw. I run smaller rock thru it by hand and use the thinnest blades so I don't stand there all day on one rock.  :grin:

Hope this somehow helps.

Craig
Logged

Grayco

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 95
Re: Unusually hard jasper or chert?
« Reply #16 on: March 17, 2017, 02:28:43 PM »

You might try hammering the edge of the blade as shown on page 6 of this document.

http://www.beehiverockandgem.com/files/rocksaws.pdf
Logged
If women don't find you handsome, they should at least find you handy.

-Red Green-

vitzitziltecpatl

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1176
Re: Unusually hard jasper or chert?
« Reply #17 on: March 17, 2017, 06:06:08 PM »

One more thing others here might (or might not) confirm for us all. I was told to cut a plain ol' brick when I first got into lapidary, but was told later on to use fire brick instead of red brick. It has more abrasive materials in it than regular brick, but a chunk of old grinding wheel is best of all.

peruano

  • Retired Zoologist
  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 410
Re: Unusually hard jasper or chert?
« Reply #18 on: March 17, 2017, 06:47:47 PM »

I'm as law-abiding as the majority of the world, and a retired Department of Interior scientist,  . . . but no commercial collecting is more likely to refer to your hauling out dump truck loads and staging major store fronts, than your selling a slab or six of a rock removed from public land.  The day that rocks removed from public lands are not available for trade or sale in reasonable amounts is the day that we all fail to trade or buy material.  We all must make our own decisions on what this means, but I don't think the commercial issue is a big one unless its pushed beyond reasonable.  \
The point about porcelain jaspers and similar stuff glazing blades is probably right on.  The way to prove it is to swap out a different blade to see if difference appear to be blade related. 
Logged
Combining a love of bikes (pedal and otherwise) with hiking, hounding, lapidary, and the great outdoors

Kaljaia

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 812
Re: Unusually hard jasper or chert?
« Reply #19 on: March 18, 2017, 10:20:31 PM »

Thanks all for the advice! I don't have any old grinding wheels but will keep that in mind. I do have a fire brick laying around someplace.
Each cut took about fifteen or twenty minutes. I don't know how this compares...?

The blade is still 'rough' to the touch. I'll get a picture of it next time I have the saw out. It is a thick blade, but I have a loose bolt somewhere so it's got more play than I want. I think it's a loose carriage bolt on the drive shaft, tends to cut a wider slot than the blade itself and is also at a very slight angle. Blade makes contact with the stone on one side, has a gap on the other. I've remounted the blade a couple times so it doesn't seem to be a problem with the mounting. I'm going to chalk it up to a hard rock at this time, but I'll set a timer next time and compare it with cutting a t-egg and some other agate, see how it goes.
Logged
- Erika

I rock hunt in the Antelope/Ashwood area of the John Day river basin in Oregon.
Pages: 1 2 [All]   Go Up
 

Page created in 0.106 seconds with 62 queries.