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Post by victor1941 on Jul 17, 2020 18:21:44 GMT -5
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pizzano
Cave Dweller 
Member since February 2018
Posts: 1,390
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Post by pizzano on Jul 17, 2020 19:48:13 GMT -5
The first 3 trial run videos, with moist corncob, regular media (whatever that is), and small rocks (whatever that is), look like the "slurry" base texture has blended. But, without knowing how long that run has been going, I wonder if any actual stone grinding is taking place.......?
The whole purpose of developing a "good" slurry (as you know) is to get media and grinding compounds to interact with the subject stones. Once that interaction takes place, the residual stone material coming off the subjects, increases the the slurry texture to better allow the grinding compounds adhere and grind against the subjects..........increasing the slurry thickness. Adding moisture helps "thin out" the paste that starts to develop.......It appears, your blend has already started to get pasty without the benefit of any substantial grinding material benefiting from the "paste"........!
I'll be more impressed after witnessing the stone results once that blend stage has been completed.........and since, from the looks of the volume that bowl has, I'd be watching it closely for seepage, due to the corncob breaking down, adding more "paste" to the blend, which will require more moisture (water) to thin out in order to continue with a decent stone circulation through out the grinding/polishing aspect.........Just my experienced bowl vibe observation.
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Post by victor1941 on Jul 17, 2020 21:56:25 GMT -5
Pizzano, thanks for your observation. Let me try to answer correctly so maybe you can help with what I want to vibe polish. My goal is to polish pompom agate and a few soft stones in dry or semi-dry corn cob chips without undercutting. I have the materials to move through the different stages in a scientific method and will do this in about a month. I posted the video's really for new members to show the motion of a vibe. The corncob video's are a changing mix-add of corncob to ceramic media, petrified wood edge trimmings, and the leftover polish from a three day run with a few soft cabs to see how a one day run would affect the surface. Specifically, I wanted to see what, if any, surface imperfections would be removed or if any polishing might occur. My observations indicated that the polish should work but the little ridges will not be removed and a complete cycle is needed. The question then becomes what stage do I start with?
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pizzano
Cave Dweller
Member since February 2018
Posts: 1,390
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Post by pizzano on Jul 17, 2020 23:48:53 GMT -5
If I understand this correctly, the purpose and intent of the "blend" is for polishing not grinding stages......?
If that is the case, and the Agate has come through the normal grinding stages without glaring imperfections, the mix of corncob and ceramics (ones used previously for polishing purposes), may well provide for a decent polish......be it a bit slower than just polishing compounds and ceramics......and just maybe less likely to add additional imperfections........but I don't believe any pre-existing imperfections will be dramatically changed/removed with this process.
It has been my experience with bowl vibes, with almost all kinds of 7mohs type Agate, starting out with the least amount of visible imperfections as possible is the key. In most of my cases, the underlying imperfections, that were not visible initially, start showing up during the 500 and pre-polish stages, and I only use ceramics exclusively in the vibes. I've never considered the ceramics being the issue since I've tried several different sizes and shapes with the same or near same results.
I've even spent a good amount of time (in the beginning learning stages of my experience), using plastic beads, resin based media, aquarium gravel, glass marbles, residual small left over grindings, river pebbles.....all under wet conditions, I've also tried dry polishing methods of walnut shell, corncob, resin media mixed with various polishing compounds..........none of which polished the same stone types as well as any water based ceramic method......not even close.......and forget trying to remove any imperfections with those methods.
The best I've been able to do, is once I started noticing fractures, blemishes, undercutting that were not initially evident, I'll stop, remove those stones with problems in that batch and return them to a batch of the previous stage (cycle) like material. Then fill the void left by the removal with ceramics and keep going. Quite honestly, I use that method regardless of the cycle (stage) I'm currently in, unless it's just a bunch of mix match material I just want to get polished in a hurry......lol.......I'm always in a hurry.
To answer your question...."what stage do I start with..?........If you mean with your current experimental blend, stick with the pre-polish and polish stages. Once your at that point, no amount of mix and match media, compound, or time, are going to remedy any imperfections........that must be done during the grinding stages, and sometimes depending on the stone, even that is not enough.........time to get out the Dremel or take to the grinding wheel (I use diamond faceting discs)...........That's the best of my knowledge in a nut shell....!
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Post by HankRocks on Jul 18, 2020 3:57:10 GMT -5
I am following with interest as I use a UV-18(Polish only) and also interested in polishing softer material or hard material that has "soft" areas that undercut. The later being the classic problem especially with some of the West Texas material I have tumbled.
All soft seems straight-forward, just select a load of all soft and and alter the process, start the first stage with a 220 and less of it, maybe even a 300 or a 400 (SiC). Also reduce the run time. I am about to start a load of all soft in a couple days and still deciding on the first step.
For the under-cutting material, how far do you take the grinding/shaping step?, I assume you are using diamond wheels to do this. What grade wheel do you use before the going to the tumbler?
Apologies if I mis-understand your test.
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Post by victor1941 on Jul 18, 2020 10:33:23 GMT -5
Thanks for the responses. Yes, I am trying to polish and you both understand what I am trying to do with this experiment. The material from Needle Peak is pom pom agate in nodular form that has beautiful but soft inclusions intermixed with agate/chalcedony shells or intermixed areas and undercuts in a regular vibe sequence. I am working with flat pieces and also a few cabs and want to find a way to polish using the vibe if at all possible with little undercutting. I use the flat lap on almost all material for shaping and then finish in the vibe. I am flat lap grinding this material to 350 but have 3000 with the goal of removing small surface imperfections before polishing.
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