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 Post subject: I hate wax
PostPosted: Tue Dec 01, 2015 3:25 pm 
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Well, dopping wax has just failed me for the last time, I won't be using it again. Not this batch anyhow. I now have to try any reposition as best I can and recut, a Scrub Lead blue sapphire (rough stone was $300) belonging to someone else.

The wax melted and the stone shifted across, turned on its axis and tilted over at the top. This was not on ceramic, this was on a copper lap, well llubricated with an oil based extender and no great pressure was being used.

Every significant mishap I have had since I started faceting has been with the same piece of wax. Most commonly, the stone has stayed adhered to the wax but the wax has released its hold on the dop while still staying on the brass rod, the wax and the stone turning loosely on the dop. Even after warming the stick and being sure there was no oily residue on anything. And of course, it's brittle as well, even if not burned. I lost a piece of topaz a while back when leaned over to plug something in and bumped the machine, it was only a pretty light bump but the stone went flying. I searched the room top to bottom but never found it. It's probably lying with its dagger-like culet facing upward so I'm sure my bare feet will find it sooner or later :)

I'm wondering if it's a dodgy bit of wax? It's the on,y stick of faceting wax I have ever had. It was supposed to be high-temperature black faceting wax but it seems to melt at a much lower temperature than the ordinary old reddish brown cabbing wax, you only have to wave the stick in front of a flame and you have an instant puddle.

Anyway, I won't be using it again. Epoxy only from now on. I have never yet had a stone move or come off with epoxy.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 4:02 pm 
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Lefty, you should not be having these problems with standard black faceting wax. If the wax is not adhering to your dop stick, but does adhere to you stone, then obviously it can't be that your stones is becoming heated enough to cause the wax to soften while on the lap. Therefore it must be that there is a contaminant between your wax and the dop. What is you dop metal and do you clean with ascetone? An alternative might be that you are not getting you dop hot enough to for a good bond with the dop.
I do recall having this problem on occasion when using aluminum dop sticks.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 4:15 pm 
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Wax does go bad after long enough. I thoughtlessly tried to use some that I think may have come with my grampa's cabbing machine (not used since the 70s). It ended up being more like play-doh than dopping wax-weirdly soft and mealy without good adhesion. A fresh batch worked just fine.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 4:18 pm 
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Location: Philadelphia, PA
I too have had problems with brittle dop wax breaking, until I followed Tom Herbst epoxy wax technique. I load the wax onto a warm dop, and then use a bull’s eye dop to create a “target”. Next I use a transfer stand to position “target” above the stone and melt together using a blazer torch (I do not let the wax boil). After the wax is cooled, I mix up some 5 min epoxy by Devcon. I then coat the wax and dop with the epoxy. I also make sure to add a small of epoxy beyond edge of the wax into the stone itself. After complete let dry for 24 hours. I find that this adds strength to the wax. Note, I only use this technique to cut the pavilion; I used Lock Tight cyano-acrylic glue and 5 min epoxy when I transfer to cut the crown. I hope this helps. :)


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 5:20 pm 
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TOM KIDWELL wrote:
Lefty, you should not be having these problems with standard black faceting wax. If the wax is not adhering to your dop stick, but does adhere to you stone, then obviously it can't be that your stones is becoming heated enough to cause the wax to soften while on the lap. Therefore it must be that there is a contaminant between your wax and the dop. What is you dop metal and do you clean with ascetone? An alternative might be that you are not getting you dop hot enough to for a good bond with the dop.
I do recall having this problem on occasion when using aluminum dop sticks.


Hi Tom.

The dops are brass (pretty sure anyway).

On this occasion, the wax has definitely softened and the stone moved. The wax and stone are still firmly attached to the dop but I can see where the wax has bent and stretched. The stone is no longer in the centre of the dop, it has moved some way across, twisted on it's axis and also bent over at the top. It's clearly movement caused by softening and melting. I normally clean with acetone.

Cheers


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 5:29 pm 
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Quote:
Wax does go bad after long enough. I thoughtlessly tried to use some that I think may have come with my grampa's cabbing machine (not used since the 70s). It ended up being more like play-doh than dopping wax-weirdly soft and mealy without good adhesion. A fresh batch worked just fine.




I bought the wax new but I guess it could have been sitting in a warehouse for God knows how long?

While it was sold as high-temperature wax, it definitely appears to have a significantly lower melting point than the wax I have used for cabbing in the past, though when cold it does seem harder. I had to heat the cabbing wax for longer and it still had a thick consistency, this stuff melts to a much runnier consistency at the drop of a hat.

Quote:
I too have had problems with brittle dop wax breaking, until I followed Tom Herbst epoxy wax technique. I load the wax onto a warm dop, and then use a bull’s eye dop to create a “target”. Next I use a transfer stand to position “target” above the stone and melt together using a blazer torch (I do not let the wax boil). After the wax is cooled, I mix up some 5 min epoxy by Devcon. I then coat the wax and dop with the epoxy. I also make sure to add a small of epoxy beyond edge of the wax into the stone itself. After complete let dry for 24 hours. I find that this adds strength to the wax. Note, I only use this technique to cut the pavilion; I used Lock Tight cyano-acrylic glue and 5 min epoxy when I transfer to cut the crown. I hope this helps. :)


Thanks Harry, I might give that a go.

The advantages of wax are that it is ready quickly and if the piece of rough has moved from where you want while waiting for it to set, you can just warm it up and re-position. Can't do that with epoxy and I still let even the 5-minute epoxy cure for a couple of hours at least. If there's no time pressure, I might leave it cure overnight. Slower than wax but very strong.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 6:04 pm 
Its not the wax its the sapphire. Sapphires conduct and transfer heat very efficiently. Copper while the standard prepolish disc generated too much heat for sapphire ,so I use my special alloy and a very rapid prepolish compound I recently made to cut a small parcel of Turacan sapphires. The stone still warmed up but a lot less and care is needed to not polish too long on the lap allowing heat too build up. I recently made a fast cutting rim in 800 mesh bronze and it made sapphire cut as fast as garnet.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 6:17 pm 
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Location: Wylie Texas but in Alaska for a while
What wax are you using?

I had similar problems using waxes that came with my machine (probably at least 5 years old).

The standard green as well as a very hard brown caused shifting problems.

Someone sent me a sample of the black wax, and I have used it twice. No shifting problems at all.


I have cut a cz, and a synthetic corundum with no shifting problems, including hard polishing on a batt with 100. (I was tryingto get rid of a pit, and was trying more pressure for a while.

(I need mre 13k prepolish which I have on order.... )

I did have one let loose from the dop, it was a brass dop and when the wax came off, there was none on the dop at all. So either I did not clean it well, or I did not get it hot enough. I was able to superglue it back on with no problems.


I have been using a modified approach, were I cold mold the pav into wax and then superglue it. The super glue really likes a tight fit, and this works well. It also makes it easy to reset if it does pop out.


I have been cleaning with acetone, but just picked up some 91% alcohol to use as a second clean.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 7:26 pm 
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Location: Gold Coast Australia
Hi Lefty,
I feel your pain mate! Had similar issues a fair while ago and fixed it by buying some new brown shellac wax and making sure that I heated the dop up quite hot to make sure it adhered well. I then warm the stone up on a little candle oven and apply a shellac mixture (just shellac mixed with metho to dissolve it) to the surface of the stone where it will be dopped to. Wait for it to bubble a little and then dop it up to the orientation you want. Have not had a problem since! (Probably just jinxed myself on my next stone lol.)

I don't know if this is the 'right' way to dop but it was how I was taught by my teacher who is an AFG member.

I would be interested to hear from others about their wax dopping techniques as I am sure there are probably many out there.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 10:40 pm 
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Location: Central Queensland, Australia
ultraset wrote:
Its not the wax its the sapphire. Sapphires conduct and transfer heat very efficiently. Copper while the standard prepolish disc generated too much heat for sapphire ,so I use my special alloy and a very rapid prepolish compound I recently made to cut a small parcel of Turacan sapphires. The stone still warmed up but a lot less and care is needed to not polish too long on the lap allowing heat too build up. I recently made a fast cutting rim in 800 mesh bronze and it made sapphire cut as fast as garnet.


I think this is the first time I've had it happen on copper. It was happening on the composite ceramic Matrix with water-based diamond compound but seemed to stop happening when I started using oil-based extender.

I heard that you should only polish very hard stones - from topaz upward - on ceramic but my Matrix has done a very nice polishing job on things as soft as feldspar. Of course, it's a composite ceramic, not sure of the difference between it and a standard ceramic.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 10:49 pm 
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wilsonintexas wrote:
What wax are you using?

I had similar problems using waxes that came with my machine (probably at least 5 years old).

The standard green as well as a very hard brown caused shifting problems.

Someone sent me a sample of the black wax, and I have used it twice. No shifting problems at all.


I have cut a cz, and a synthetic corundum with no shifting problems, including hard polishing on a batt with 100. (I was tryingto get rid of a pit, and was trying more pressure for a while.

(I need mre 13k prepolish which I have on order.... )

I did have one let loose from the dop, it was a brass dop and when the wax came off, there was none on the dop at all. So either I did not clean it well, or I did not get it hot enough. I was able to superglue it back on with no problems.


I have been using a modified approach, were I cold mold the pav into wax and then superglue it. The super glue really likes a tight fit, and this works well. It also makes it easy to reset if it does pop out.


I have been cleaning with acetone, but just picked up some 91% alcohol to use as a second clean.


It's a standard black faceting wax Wilson.

The chemistry of it is obviously different to the old red-brown wax I used for cabbing. I soaked that stuff in alcohol (methylated spirits) for 24 hours once and found the stone still solidly attached and the wax only slightly softer and sticky at the surface (I then discovered how easy it was to remove cabs of non-sensitive material by putting them in the freezer or iced water :) ). But when I wiped the handpiece of the machine with paper tower dampened with alcohol, I noticed all this black gunk on the towel - I had just brushed the stone and black wax and that was enough to start it dissolving.


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 Post subject: Re: I hate wax
PostPosted: Tue Dec 01, 2015 10:54 pm 
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aussiejamie wrote:
Hi Lefty,
I feel your pain mate! Had similar issues a fair while ago and fixed it by buying some new brown shellac wax and making sure that I heated the dop up quite hot to make sure it adhered well. I then warm the stone up on a little candle oven and apply a shellac mixture (just shellac mixed with metho to dissolve it) to the surface of the stone where it will be dopped to. Wait for it to bubble a little and then dop it up to the orientation you want. Have not had a problem since! (Probably just jinxed myself on my next stone lol.)

I don't know if this is the 'right' way to dop but it was how I was taught by my teacher who is an AFG member.

I would be interested to hear from others about their wax dopping techniques as I am sure there are probably many out there.


Thanks Jamie, I had read about an approach like that but have never tried it.

I'm kicking myself that it happened, it's a nice stone - blue on green but the cross-table is only a very light green and allows plenty of light in - and now it's going to be smaller, dammit!

Oh well, things are sent to test you, so they say :)


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 Post subject: Re: I hate wax
PostPosted: Wed Dec 02, 2015 6:00 am 
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Ok, repositioning: the pavilion is finished so can I put it in a larger cone dop, put that and a flat dop in the transfer jig and re-attach it to the flat ended dop with the jig standing on its end? It is meant to perfectly align two dops after all.

The quill will only accept the dops in a precise position due to the machined end. Can I then put the dop in the quill at the 96 index position which is the setting for the long side of the rectangular stone, loosen the index gear and turn it until the stone sis dead flat on the lap, the same way as you would use the T-dop?

Would that work?


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 Post subject: Re: I hate wax
PostPosted: Thu Dec 03, 2015 1:15 am 
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Location: Wylie Texas but in Alaska for a while
Until recently I did not have a keyed dop system. Loosening the index gear and aligning the stone is how I always did it. But I am mostly self taught.... so there may be a better way.

When I bought my machine, it had a piece of alum ablut 1/4 thick, 2 inches wide. and 1.5 inches tall. It was in 2 pieces, with screws to hold it together, and a hole drilled and reamed right at 1/4 inch. I eventually figured out that it was a transfer tool. You could put the index at 96, and clamp this to the dop. Then when the 2 dops were attached for the transfer, put them back into the machine, hold the tool flat on the lap, and tighten up the dop.

This same tool (but a different shape) is in the book on faceting. It was nice to see that I had figured out how to use it correctly.

They are really nice to have when there is not a big girdle to use for alignment.

I ended up making myself a few more, and they are b


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 Post subject: Re: I hate wax
PostPosted: Thu Dec 03, 2015 2:21 am 
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Hi Lefty,

If you tabled your rough before you dopped it the table should be parallel with your currently girdle. Using a well machined (straight) dop you should have no problems allowing the gem to self aligned in the vee cone, using your 45 / 90 degree tabling adaptor. Using a dopping glue like Dextone, rather than wax will help with this process. When the dopped stone is back in the machine you should be able to find your index alignment by testing the grind of your girdle facets. Its the same method one would use to do a crown recut. If all aligns well, you wont loose any extra weight from your half cut stone and your stone is saved.

Cheers,
GR


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