Author Topic: "Proper" lapidary solutions for slabs  (Read 1231 times)

0 Members and 1 Guest are viewing this topic.

Rei

  • Newbie
  • *
  • Posts: 6
    • View Profile
"Proper" lapidary solutions for slabs
« on: January 07, 2016, 11:40:22 AM »
A little backstory, if you don't mind, for context  :)  Or you can just skip to past to the  "---- Question Stars Here ---- " line  ;)

----

So, a couple days ago, I was getting bored of the slow pace and getting sore and tired of all the dust while make slabs of hard minerals (jasper, for example) from my rock collection with my angle grinder and diamond pads.  That is, my normal process is that I cut my pieces first with a tile saw, but there's usually some unevenness in the sawing, and there are plenty of pieces that have to be sawn from multiple angles due to their size or shape or can't be properly sawn at all, means having to grind down through several millimeters (maybe to upwards of a centimeter) of unevenness before I can give them a proper polish.  And sawing is a messy process on its own  ;)

So, I build myself a homebuilt automated slab grinder - rigged and tension-loaded the grinder, built a safety cage out of a bird cage, with plastic to control the dust, bolts to help hold slabs in place, a tray of water to catch the dust, etc. It worked... "okay", about as well as you'd expect for a first-generation prototype at least  ;)  I had been coming up with all sorts of ideas for an improved version - three times more powerful grinder, 15cm/6" discs instead of 10cm/4", a cooling system for both the grinder and specimens, soundproofing, a ratcheting net to hold the samples better against the disc, etc. So when on the third night of testing two of the support wires on my grinder broke, I figured that now was the time to make "version 2.0"  But when I took my grinder out I noticed it was leaking oil.  I'd only been running it through maybe a 25% duty cycle to give it time to cool, yet it still looked unhappy.  Even though the new version would have a cooling system and stronger motor, it sort of shook my confidence in its potential longevity, whether one really can use angle grinders like this.

Sooo.... instead of just rushing off to try the new approach...

---- Question Starts Here ----

.... I'm wanting to learn more about what "proper" lapidary solutions are out there  :)  I mean, I know there's flat laps; although the pictures I've seen show people holding their pieces against it, which is not something I want to have to do (although I could rig up a system to hold them), and a lot seem to have a "spike" in the center which would limit the size of pieces I could polish (again, I'm making slabs and some of my specimens are kind of large, I don't want to be constrained to a tiny work area). 

My needs are:

1) Price - unfortunately - is an issue.  Anything I buy will have its price nearly doubled by shipping and customs by the time it reaches me (I live in Iceland).

2) Size is important - but of course, anything helps.  Space to smooth off, say, a circle 30cm (12") in diameter would probably be big enough for 97% of my specimens, including my largest (and neatest) specimens.  15cm (6") would be enough for 90% of them, 10cm (4") for 75% of them, 7,5cm (3") for 55% of my needs, 5cm (2") for about 30% of them, and so on down.

3) I don't want to have to stand over the thing for hours, so a provided solution for holding specimens in place would be ideal - but I can jury-rig something if need be.

4) It doesn't need to be fast - it can take a couple days to smooth the side of a specimen for all I care.  So long as I don't have to stand there the whole time.

5) Noise and dust do matter - but I can also rig up solutions to deal with them as needed.

6) 220-250V.  I can use devices through power converters, but I really prefer not to - they're unreliable, they tend to cause ground faults, they're heavy (and thus expensive to ship), etc.

So... what should I know?  :)

bilquest

  • Full Member
  • ***
  • Posts: 203
  • Gender: Male
    • View Profile
Re: "Proper" lapidary solutions for slabs
« Reply #1 on: January 07, 2016, 12:57:29 PM »
Holy smoke... step aside Rube Goldberg!

That's some serious re-purposing of tools, but I admire your resourcefulness. If I understand correctly, you want to polish slabs? You probably want one of these:

http://covington-engineering.com/glass-equipment/horizontal-laps/automatic-vibrating-laps/16-automatic-vibrating-lap/

However, with your creativity, you could probably build something similar out of an old washing machine and metal scrap. Let us know what you come up with.

Back

  • Full Member
  • ***
  • Posts: 162
    • View Profile
Re: "Proper" lapidary solutions for slabs
« Reply #2 on: January 07, 2016, 01:01:20 PM »
Hi Rei

Welcome and WOW. There are a lot of really smart people here and I am sure you will find some answers.

My first question is what size is your saw? Can you get a bigger one there? Many tile saws have been converted for lapidary work. Braces can be added to help the rock keep centered. There are also ideas here that can help to build a real lapidary saw.

Polishing slabs the way you want will be way expensive unless you can study the design and make something that works on the cheep.
Some links.

http://www.gemworld.com/viblaps.asp

http://www.cyberrockhound.com/Vibrating_Lap.htm

Bless
Shawn

Rei

  • Newbie
  • *
  • Posts: 6
    • View Profile
Re: "Proper" lapidary solutions for slabs
« Reply #3 on: January 07, 2016, 02:08:55 PM »
The vibrating lap sounds like it may be a good fit, if I can get one for a reasonable price.  I just put a bid on a used one on ebay, hopefully I'll get it  :)  Only 110V, but if I can get it for a good price, it'll be worth buying a power converter. And if it's too noisy I'll build it a housing.

The size of my tile saw's blade is a tricky question - it's only about 3 cm / 1,3" over its board, but it's about 3-4 times that size as a whole (only a bit of the blade sticks out over the cutting board - since it's designed for tile, and tiles aren't that thick).  I could cut the saw off of its framework and the rebuild a new framework for it, but there's a lot I'd have to reengineer, and I have a lot of stuff I've already cut that I want to polish, so that project is more on the backburner.  :)

Thanks for your help everyone!  (if you're ever in Iceland and want to hunt chalcedony, iceland spar, zeolites and the occasional bit of opal or pyrite, I can point you in the right direction  ;)  )

Allen

  • Hero Member
  • *****
  • Posts: 749
  • Gender: Male
    • View Profile
    • Savannah Agates
Re: "Proper" lapidary solutions for slabs
« Reply #4 on: January 07, 2016, 02:41:33 PM »
Rei it might be time to look outside the normal square.

They say there is more than one way to skin a cat. I use a product known as liquid glass, a 2 pack epoxy.

It is used on bench tops and has a durable high gloss, glass like finish.

Only draw back so far is if left in the sun over time it may yellow a little.

Check out the local hardware store.

Polishing slabs can be boring work.

Rei

  • Newbie
  • *
  • Posts: 6
    • View Profile
Re: "Proper" lapidary solutions for slabs
« Reply #5 on: January 07, 2016, 03:25:51 PM »
Oh hey, I've been looking for something like that - not for slabs, but for minerals that I want to keep the natural surface of but bring out a better shine.   Does it bring out the same look that the rock has when it's wet?  Because I have a number of specimens that look dull when dry but gorgeous when wet.  I've tried wax sprays and clearcoat sprays - they seem to do okay when the stone has no porosity but when they do they don't really work at all.

(One of my ultimate goals is if I can get lots of slabs I'd love to make a countertop out of them  :)  I collect the minerals on my land, as I have natural veins of various minerals (mostly chalcedony of various types, plus massive calcite, the occasional bit of potch, etc).  I can get as much as I need just by going out with a pick (and every spring some new stuff comes loose on its own)).

Ranger_Dave

  • Sr. Member
  • ****
  • Posts: 346
  • Gender: Male
    • View Profile
Re: "Proper" lapidary solutions for slabs
« Reply #6 on: January 07, 2016, 03:49:13 PM »
Rei it might be time to look outside the normal square.

They say there is more than one way to skin a cat. I use a product known as liquid glass, a 2 pack epoxy.....

I wonder if that would keep hanksite from oxidizing? I have a huge hanksite that I can't display because it gets a white, powdery, coating when exposed to humidity. Or I could just trade it for something else......

Allen

  • Hero Member
  • *****
  • Posts: 749
  • Gender: Male
    • View Profile
    • Savannah Agates
Re: "Proper" lapidary solutions for slabs
« Reply #7 on: January 07, 2016, 08:33:53 PM »
I have only used the glass on flat services. It goes on liquid and if not level tends to run off the other side.

Part of the process is giving the surface a lick with a flame like a small gas torch. That breaks and gas bubbles.

Took this pic in the back yard this morning. Three slices of thunder egg from Agate Creek, have got felt on the back so they can be used as coasters.

55fossil

  • Sr. Member
  • ****
  • Posts: 269
    • View Profile
Re: "Proper" lapidary solutions for slabs
« Reply #8 on: January 08, 2016, 04:51:01 AM »
    Time to start saving some money. I have made numerous machines myself. But when you get right down to it, you save money if you can buy the right machine "used" for a good price. Of course there is also the problem of having enough space. That said, I did make a flat lap that was cheap and has worked for ten years. I purchased a 1/3 HP motor, a shaft adapter, the heavy flat base and built it into a wooden case. Added a water drip system and it works great. A 60 grit diamond flat lap will tear down the worst cut marks in no time. I will try and pop some photos tonight.

Rei

  • Newbie
  • *
  • Posts: 6
    • View Profile
Re: "Proper" lapidary solutions for slabs
« Reply #9 on: January 08, 2016, 12:06:11 PM »
Oh hey... I do happen to have an old industrial circular saw motor that I stripped last year lying around here....  ;)  I had been thinking about using it for a different project but it was too high RPM / too little torque - but that's what you want for a lap.    I think if I don't win the ebay auction and don't see any odds of another one coming up at an affordable price, I may give that a go.

Allen: wow, that's some serious shine you got there!  Okay, I'm pretty sold on giving it a try on my non-slab specimens that I want to give a wet look to  :)  Is this the stuff?

http://www.amazon.com/EPOXY-CRYSTAL-Gallon-COATING-TABLETOPS/dp/B00UW74EK8/ref=sr_1_2?ie=UTF8&qid=1452285361&sr=8-2&keywords=clear+epoxy+gallon

Any clue what the mohs hardness of the coat is (very approximately)?   And also, any clue as to how fast they'd yellow in interior, not-by-a-window conditions?  Aka are we talking more like 10 years or 100?

Allen

  • Hero Member
  • *****
  • Posts: 749
  • Gender: Male
    • View Profile
    • Savannah Agates
Re: "Proper" lapidary solutions for slabs
« Reply #10 on: January 08, 2016, 02:31:36 PM »
Rei, different brand and bottles, but it looks to be the same epoxy.

1 Gallon will do heaps. My kit is a quart and lasts some time.

Yellowing is not a problem indoors, I have a big specimen on a verandah in full sun that yellowed a little.

Hardness, No figure, but it is used for tables and bench tops.

Best of luck.