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#1

Prooz
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From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
14 April 2019 07:51 pm

With the used Hall faceting machine I have just bought, it came with all laps although a bit worn but ok.
With these there is a solid plastic looking lap, I take it is a polishing lap? if so what polishing mix should I be using?

If anyone has an answer and can help thank you.

Cheers
Pro oz


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#2

Pat Hogen
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Joined: 02 January 2018
Posts: 167
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14 April 2019 07:59 pm

That depends on the stone to be polished. The lap in question is called lucite, perspex, and any polishing compound can be used on it though the most common for that type of lap is aluminium oxide, tin oxide or chromium oxide. Good for final polishing of most stones.

Yep, always ask, never be too proud or put off.

Last edited by Pat Hogen (14 April 2019 08:02 pm)


Absinthe makes the heart grow fonder

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#3

Prooz
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From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
14 April 2019 10:23 pm

Thanks PH, I am only new to this hobby are they a good lap to use? would they generate a bit more heat?
At the moment working with Garnet and Topaz.

Cheers


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#4

Pat Hogen
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Joined: 02 January 2018
Posts: 167
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15 April 2019 09:48 am

Some people swear by them, especially for cabbing. Some users would not use any other type of lap. I am happy with copper and mixed-metal. So the answer from me is ... experiment, experiment until you find your groove. The heat generated by perspex has definite benefits. I recall that perspex and fine diamond with a little diamond spray is a winner.

It would be interesting to find out how many laps people have in their armoury and how many they actually use. Uncovering the secret to a lap is part of the joy of faceting.


Absinthe makes the heart grow fonder

#5

Prooz
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From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
15 April 2019 10:03 am

Thanks again PH, at the moment I am using a tin lap with fine diamond for my polishing, the tin/lead lap that came with the machine is damaged, and I think beyond
machining.
The tin lap was given to me by a friend. Yes experiment and plenty of reading.

Cheers


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#6

Dihusky
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From: Gold Coast, QLD
Joined: 16 June 2017
Posts: 648
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15 April 2019 05:37 pm

Hi Prooz, welcome to the gang.

One thing you'll find with Facetors is everyone has their own preferred methodology and this can be very confusing to a newcomer to the art.

Probably the most critical thing to look at is your solid laps and try and identify what they are, the grit, the type of alloy etc, then the second part is seeing how flat each one is. Best way to do this is on a thick piece of glass with wet&dry. If it a useful lap and way out, get it skimmed on a lathe first, then do the wet&dry starting with 180 then down to 400 or 600 before finishing with solvol soap.

If you're laps are cupped it will do your head in as when you change between laps everything is out of alignment and you'll be cheating the hell to try and get a facet finished. The only lap you should ever need to cheat on is the final polish except when aligning a stone after transfer. If you've cut a facet down to the 'stop' so it's accurate to the degree setting, you should be able to put the next lap on, adjust down until you can just wipe the facet across the lap and start polishing, that's what a flat lap is all about. I check mine regularly, probably every 3-4 stones as I cut big stones so they have to do some work.

The next important thing to do is to check your master lap for alignment. There are several ways of doing this, my method is to mark the water bowl in line with the three adjustment nuts. I put a 45 adapter in the quill with a flat dop and place it above one adjuster, winding the mast down until it just grabs a feeler gauge or a cigarette paper, ( I don't smoke but they are good for this). Now move to the second adjuster and see if it grabs or is either tight or loose. Work you way round the three points adjusting until they are exactly the same. If you have a dial indicator you can also use that as well.

With the Hall you are clamping on an O-ring under each nut. These get hard over time so need replacing, what I use is a 12mm bore heavy electrical grommet and slice the two sides off the center reduced section. Undo the 3 nuts, and make sure you have 3 new nylocks, lift the spindle assembly and fit the new grommet washers, nip the nuts and go through the adjustment process.

Now your mast is true to the master lap.

The Hall is a great machine, we have two of them so know their quirks.

Bang up a pic of your machine and give a list of your laps

#7

Prooz
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From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
15 April 2019 11:01 pm

Thank you, Pat Hogen and Dihusky for all the information and appreciate it very much and have taken it all in.
Just of the top of my head my laps are 1 x 960 diamond lap ( this is marked on the box) 1 x 1200 diamond lap ( marked on the box) these two laps are very worn.
1 x solid copper lap in good condition, 1 x Lucite lap in good condition, 1 x tin lap has been machined.

I have almost finished a garnet in The Standard Brilliant Cut, will post a pic when that is done. Even though the 960 and 1200 laps are worn I am not having any trouble. To me a beginner the machine seems pretty accurate haven't had to use the cheater my facets are lining up nicely, and polishing with the tin lap but taking a bit of time and not having to use the cheater. The only trouble I have had is my own silly fault and not the machine.

I have taken all the info on board and have a lot to learn. Love the hobby.


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#8

Dihusky
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From: Gold Coast, QLD
Joined: 16 June 2017
Posts: 648
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16 April 2019 05:02 pm

Good selection of laps, probably need to add one around the 260 grit for roughing, then go to either of the two sintered followed by the copper using 8k before 50k on the Tin. With that sequence you should find your polish comes in pretty fast. It's pretty much the combination I use and my polish is around 5-10sec per facet depending on the size.

If you haven't had to cheat, that's a really good start. Well done, looking forward to seeing the first gem.

#9

Prooz
Member
From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
16 April 2019 08:49 pm

Dihusky wrote:

Good selection of laps, probably need to add one around the 260 grit for roughing, then go to either of the two sintered followed by the copper using 8k before 50k on the Tin. With that sequence you should find your polish comes in pretty fast. It's pretty much the combination I use and my polish is around 5-10sec per facet depending on the size.

If you haven't had to cheat, that's a really good start. Well done, looking forward to seeing the first gem.

Should have it off the machine tomorrow hope!
Was having trouble polishing the pavilion facets today, and getting frustrated and just not happy with it but finally got it. Yeah my mistake, I have been skipping the copper for the pre polish for some reason and going from the 1200 to the tin. I am learning and enjoying every minuet off it, and getting to know my machine.

What is the best /proper lubricant to use on the tin and copper? my mate uses a baby/olive oil I have been using olive oil but can't say I was happy with it, today when having trouble I tried 100% pure synthetic ( expensive ) charged with a new lot of 50k and big difference that made.


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#10

Pat Hogen
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Joined: 02 January 2018
Posts: 167
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16 April 2019 10:44 pm

-What is the best /proper lubricant to use on the tin and copper?-

Di-propylene-glycol, sparingly, as in 3-4 small drops around the lap.

Never omit 3k or 8k prepolish; can omit 1200 after using 600 and can go 600 to 50k if you know what you are doing but, for starters, never omit 3k or 8k prepol after the 600.


Absinthe makes the heart grow fonder

#11

Prooz
Member
From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
16 April 2019 11:27 pm

Thanks PH, big learning curve.

Cheers


Minelab Explorer SE. Minelab GPZ 7000 Equinox 800

#12

Prooz
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From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
17 April 2019 06:09 pm

Hi Dihusky, some time ago you asked what model my Hall machine was, I still don't know. It must be old this model came out without a dial gauge, I put the dial gauge on, had one in my tool box when I was working, it does the job.

Some one might know how old it is and what model by the photo.1555484793_sscn0300.jpg


Minelab Explorer SE. Minelab GPZ 7000 Equinox 800

#13

Dihusky
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From: Gold Coast, QLD
Joined: 16 June 2017
Posts: 648
Member
17 April 2019 06:42 pm

Looks like a Hall Mark 3 or 4, built in the 70's I think, the Mark 2 had a collet quill and was 2 speed via pulley change, yours looks to have a side clamp quill. Good solid work-horse and accurate. Does yours have variable speed? If so it may be the Mk 4 as I don't think variable speed was on the Mk 3.

For lubricants, we use Baby Oil, the Woolies stuff, only need a drop or two and then an occasional drop on tissue to clean swarf. Get some Eucalyptus Oil for cleaning laps, NOT the water soluble stuff, the good oil, cleans Laps beautifully, good prior to the Solvol treatment.

Some of my AFG colleagues use Inox as a lube, haven't tried it myself, another uses Vaseline Intensive Care cream and mixes with the Diamond to make a paste before sucking into a syringe, tried it, but find Baby oil easy and effective.

Remember.. when polishing less is more, don't load the lap as it will scratch, should be like there is almost nothing on the lap.

#14

Prooz
Member
From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
17 April 2019 07:59 pm

Dihusky wrote:

Looks like a Hall Mark 3 or 4, built in the 70's I think, the Mark 2 had a collet quill and was 2 speed via pulley change, yours looks to have a side clamp quill. Good solid work-horse and accurate. Does yours have variable speed? If so it may be the Mk 4 as I don't think variable speed was on the Mk 3.

For lubricants, we use Baby Oil, the Woolies stuff, only need a drop or two and then an occasional drop on tissue to clean swarf. Get some Eucalyptus Oil for cleaning laps, NOT the water soluble stuff, the good oil, cleans Laps beautifully, good prior to the Solvol treatment.

Some of my AFG colleagues use Inox as a lube, haven't tried it myself, another uses Vaseline Intensive Care cream and mixes with the Diamond to make a paste before sucking into a syringe, tried it, but find Baby oil easy and effective.

Remember.. when polishing less is more, don't load the lap as it will scratch, should be like there is almost nothing on the lap.

Three speed via belt change. the quill has three little grub screw evenly spaced


Minelab Explorer SE. Minelab GPZ 7000 Equinox 800

#15

Dihusky
Member
From: Gold Coast, QLD
Joined: 16 June 2017
Posts: 648
Member
17 April 2019 08:41 pm

Interesting, 3 grub screws... that's fairly unusual. Might be worth having a chat to Horst Ricker in Rubyvale, he knows the Hall machines well and might be able to make a collet quill upgrade. I have one of his on my 2000, it's awesome. What's the alignment system, an angle on the end of the dop?

Belt speeds, well at least you have 3 speeds. Probably good to start with as you will start to understand how different laps work on different stones at different speeds ops awful

#16

Prooz
Member
From: Cairns, QLD
Joined: 04 June 2014
Posts: 156
Member
17 April 2019 10:40 pm

The three grub screws are a bit of a pain, but that's ok I'm happy with what I have.
Yes the alignment system is an angle cut on the end of the dop.


Minelab Explorer SE. Minelab GPZ 7000 Equinox 800

#17

LoneWolf
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From: Gold Coast, QLD
Joined: 12 April 2016
Posts: 2,754
Member
07 May 2019 02:31 pm

Beware getting Inox on your skin.... It's a possible Carcinogenic...

LW....


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