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 Post subject: Dual Band Laps (and another dumb question)
PostPosted: Thu Mar 28, 2019 2:15 pm 
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To all,

I'm going to be converting to using the dual band laps (e.g. Dia-Z+). So, what is the scoop on how much you have to clean between the pre-polish and polish bands? In my previous use of the pre-form, pre-polish and then polish laps I'd always clean and rinse down the stone to prevent contamination.

Now I know the inner band leaking polish grit on the pre-polish is not a major issue, but is it safe to just pre-polish, pick the stone up and wipe it with a micro-fiber towel and then move directly to the polish band so that you don't have to go through the whole re-indexing each facet? I'm assuming that any minor contaminants will be flushed off via the water drip as long as I don't embed something into the polish band.

So, in a long round-about way, what do you do?

PS: I'm talking about something like 13K PCD outer going to 100K inner

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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Fri Mar 29, 2019 5:30 am 
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Bob Hodges wrote:
is it safe to just pre-polish, pick the stone up and wipe it with a micro-fiber towel and then move directly to the polish band so that you don't have to go through the whole re-indexing each facet?
Yes, that's the whole point of a dual lap. I use 8000 mesh on the outer band, and wipe the stone with a water- or WD40-dampened paper towel (depending on the type of diamond) between prepolishing and polishing of each facet.


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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Fri Mar 29, 2019 5:46 am 
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Duncan,

Thank you for the reply. I have two Dia-Z+'s sitting here waiting for the new machine to arrive. Now I just need to find out how much diamond they're going to suck up to charge. I've heard it can be like feeding a hungry bear until they're happy :)

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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Fri Mar 29, 2019 10:33 am 
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I have been using banded laps since I started. I agree clean them with paper towel, microfiber, a tissue and you are good.

One advantage of the diamatrix material is that diamond does not embed into it. so if you do get anything on it from prepolish, you can clean it with 409 and you are good to go.


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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Fri Mar 29, 2019 11:28 am 
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I have been using a Diamond Z with 14K outer, 60K inner. It is a great system that really speeds up the polishing process. However, I use it a little differently than you describe.

In order to use both band while on the same index, you hav to have the mast close enough to the wheel that the stone can reach the whole width of the center band center. This means that you are approaching the outer band at a different direction that the center, and at a different direction from where you pre polished (using a different lap of course). This often results in a very slightly offset that requires some use of the cheater to correct.

The address this I go ahead and polish the entire tier on the 14K band. I then clean the entire stone, move the mast in, and final polish that tier on the 60K band. Now I am approaching the wheel from the same angle I cut the stone. Never have to touch the cheater doing this.

I have found that the 60K is really just a brightener. Most commercial lapidaries only polish stones to 14K, and the stones look pretty good. No doubt the 60K looks a little better though. The 60K will not move a facet with the short polish time it requires.
Since I have confidence in the wheel using this method I do the entire tier with inspecting the stone. The brightener usually takes seconds per facet, so it goes super fast. I the clean the stone with alcohol and inspect the tier. It is very very rare to have to go back and touch up a facet using this method.


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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Fri Mar 29, 2019 11:43 am 
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1bwana1, wilsontexas,

So, as a starting process;

- set mast for best use of outer band
- run through tier 'n' (x, x1, x2, x3...) on the pre-polish
- check during and after the whole tier for meets and a proper pre-polish
- wipe stone down with alcohol/rinse/clean room procedures (said with a smile)
- move mast inwards
- run through tier 'n' again to polish and be a happy camper
- if any contamination occurs, just clean the center with 409 (and make sure the suds are moving away from the center to ensure I'm not pulling more diamond in?

Sound like a plan?

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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Fri Mar 29, 2019 1:03 pm 
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That should work as a starting point. You will probably end up fine tuning as you use it.


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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Fri Mar 29, 2019 1:07 pm 
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1bwana1, wilsontexas,

Thanks for the guide. I'm jumping up and down with joy my new machine will be here soon, and just to add insult to injury, I'll be out of town on business for two weeks before I get to unpack it :)

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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Sat Mar 30, 2019 8:25 pm 
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1bwana1 wrote:
I have been using a Diamond Z with 14K outer, 60K inner. It is a great system that really speeds up the polishing process. However, I use it a little differently than you describe.

In order to use both band while on the same index, you hav to have the mast close enough to the wheel that the stone can reach the whole width of the center band center. This means that you are approaching the outer band at a different direction that the center, and at a different direction from where you pre polished (using a different lap of course). This often results in a very slightly offset that requires some use of the cheater to correct.

The address this I go ahead and polish the entire tier on the 14K band. I then clean the entire stone, move the mast in, and final polish that tier on the 60K band. Now I am approaching the wheel from the same angle I cut the stone. Never have to touch the cheater doing this.

I have found that the 60K is really just a brightener. Most commercial lapidaries only polish stones to 14K, and the stones look pretty good. No doubt the 60K looks a little better though. The 60K will not move a facet with the short polish time it requires.
Since I have confidence in the wheel using this method I do the entire tier with inspecting the stone. The brightener usually takes seconds per facet, so it goes super fast. I the clean the stone with alcohol and inspect the tier. It is very very rare to have to go back and touch up a facet using this method.



I suspect that your machine may need to be adjusted.

If you have a digital display, you should be able to sweep the lap from inner band to outer band and the reading should be the same (or within one)

If it does not, then there is one of two problems:

1) the lap is not level with the base
2) the head is out of adjustment.

Bothg of these can be corrected, and if you get it in alignment, then you should be able to sweep from prepolish to polish band and have the facet polish without the need for a cheater.

The US Facet Guild had a good write-up on how to adjust the machines.


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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Sat Mar 30, 2019 8:54 pm 
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No digital display but I believe the machine is straight. I agree, that the cutting lap, and the polishing lap are not perfect matches. One or the other is out. I suspect it is the Diamond Z because this doesn't happen with my Batt or other polishing laps.


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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Sat Mar 30, 2019 10:34 pm 
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I find a very slight difference in the height on two of my duel bands, but on the new creamway dual band I find the two hieghts unnoticeable difference. In any case it isn't enough to fret over.

Greg

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 Post subject: Re: Dual Band Laps (and another dumb question)
PostPosted: Tue Apr 02, 2019 6:39 am 
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With use, over time the two different materials can wear differently, resulting in small height and slope differences. This may require small cheater and/or height adjustments when going from the outer to inner band. I have noticed this particularly with Gearloose Greenway Waterwing laps (no longer in production). It doesn't significantly compromise the convenience of the dual band laps.


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