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Author Topic: Resin-bonded scissor-grinding lap  (Read 5018 times)

RoughCreations

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Resin-bonded scissor-grinding lap
« on: May 24, 2021, 05:33:21 PM »
For those of you, like myself, where too many disks are never enough, I present the Chinese-made resin-bonded scissor-grinding lap.

I was first alerted to these laps by MakkyBrown, he had bought one on AliExpress from "Brushless Motor Store", however they appear to be available generally on the net, too, such as https://www.moresuperhard.com/2/grinding-laps-for-gemstone.html. Makky can provide his opinions on this disk, too I am sure. The manufacturer also states these are suitable for gem material (see below).

I ordered an 80 grit version aimed at initial shaping of my large quartz pieces, and got it landed in Australia for just over AUD $100. I normally wouldn't go anywhere near that coarse a grit in electroplated disks for shaping quartz, due to the microfractures that can be created, but these disks are more like sintered disks in nature, and cut much more gently for the given grit size. In fact, an 80 grit electroplated topper disk would probably grind your nice piece of quartz into a pile of paving sand quick smart.











This little beastie is built like a tank and weighs a tonne - mine came in at 834g for 150mm diameter. They seem well-made and have a nice finish. They are a very thick lap, my 80# is 16.5mm, including 3.5mm of diamond-bearing layer on the 13mm alloy base plate.

It fits my Facetron nicely, with the disk surface at exactly the same height as the top of my splash-pan (will have to run slower to avoid too much mess).

The manufacturers guff reads:
Quote
Resin bond diamond grinding wheel, high grinding efficiency, low resistance, good wear resistance, not easy to wear, high grinding accuracy, can process all kinds of high hardness materials and metal materials 2. Resin combined with advanced technology, high-quality diamond production, uniform sand particles, not easy to drop sand, has extremely high hardness and is not easy to burn the workpiece, good concentricity, the wheel will not swing. 3. Grinding wheel with high concentration of 150%, longer service life, hard and durable. 4. Can process high hardness materials, metal materials, especially materials that are difficult to process with ordinary abrasives. Can be used for rough grinding, fine grinding and polishing. This grinding wheel is specially used for grinding hairdressing scissors, hair clippers, clothing scissors, jade, agate, sapphire, quartz, ceramics, etc.

My first experience with my new 80 disk went very well. I started cutting a large smoky citrine in a square Fusion 5x5 design, 22mm wide. The progress was smooth and fast, with no chipping of note - nice.



The disk is pretty flat and runs true, with no obvious peaks or troughs. The feel while cutting is gentler than I was expecting for such a coarse quoted grit size. The rate of material removal is what I was hoping for with big quartz facets such as I have with this stone.
Some of you may remember that I purchased some of Bert's vulcanised rubber disks from the Netherlands a while back, I still use these rubber laps as my primary disks (200# and 800#), and they are both going strong (see link to old post below). This 80 grit, whilst certainly smooth to cut with, isn't the silky smooth experience of Bert's fine disks, even allowing for the coarser particles in the coarser disk. It would be interesting to compare this with Bert's 80 down the track.

https://aussielapidaryforum.com/forum/index.php?topic=6707.msg58851#msg58851

RC
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FlashGP

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Re: Resin-bonded scissor-grinding lap
« Reply #1 on: May 24, 2021, 05:57:57 PM »
Thanks RC,

They look interesting and easier than making our own.

I have had a go at making a 600 grit resin bonded silicon carbide lap. As an experiment.  It works, but I need to dress it flat.  My work bench has a small slope in the step treads I used for it.  As a result the lap has a slight lean.  But otherwise it seems successful.  20 gems sc to 50 gems liquid glass.  Takes about 12 hours to set about 5 mm thick on a worn out topper lap.

Regards
Flash

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Flash (Gordon)

RoughCreations

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Re: Resin-bonded scissor-grinding lap
« Reply #2 on: May 24, 2021, 08:08:41 PM »
I have had a go at making a 600 grit resin bonded silicon carbide lap. As an experiment. 

I need to have a go at a DIY lap myself. I have the gear, I bought some 320 grit diamond powder a while back, have epoxy and some copper powder -just need to stop analysing it so much and just do it.
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MakkyBrown

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Re: Resin-bonded scissor-grinding lap
« Reply #3 on: May 24, 2021, 08:29:27 PM »
I have the 80,320,and 800. Still figuring them out. 800 is a great prepolish on softer materials but will start to give hints of orange peel on sapphire. Cuts a lot finer than my 800 sintered. 320 is probably a pretty good cutting lap and could probably got too 3k off it on most materials. They are quiet well behaved and produce a lot less deeper scratches than metal laps.
My 320 did have a scratchy/high spot but i think that has now disappeared.Not bad for about $100 each delivered.
MB

FlashGP

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Re: Resin-bonded scissor-grinding lap
« Reply #4 on: May 25, 2021, 08:53:11 PM »
RC, the Lightning laps don’t seem to use copper as a carrying medium.

Given diamond is carbon based I expect it will be happy enough bonding (hanging out) with the carbon atoms in the epoxy.

I used liquid glass because Bunnings no longer sell Wattyl 7008 epoxy floor sealer, which I expected would work well.
Yours Sincerely
Flash (Gordon)

RoughCreations

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Re: Resin-bonded scissor-grinding lap
« Reply #5 on: May 26, 2021, 10:09:35 PM »
RC, the Lightning laps don’t seem to use copper as a carrying medium.

Given diamond is carbon based I expect it will be happy enough bonding (hanging out) with the carbon atoms in the epoxy.

I used liquid glass because Bunnings no longer sell Wattyl 7008 epoxy floor sealer, which I expected would work well.

Very true, I have a Lightning Lap and it definitely has nothing resembling copper or other metal powder in it, looks like a fairly simple construction. I do like the idea of using stuff from the hardware store where possible. You have the right idea - starting it simple.
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TheRockThief

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Re: Resin-bonded scissor-grinding lap
« Reply #6 on: April 19, 2024, 06:05:36 PM »
Are those different from lighting lap? lighting lap say to not cut with their resin lap (even the 325), but we can cut with those?

RoughCreations

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Re: Resin-bonded scissor-grinding lap
« Reply #7 on: April 20, 2024, 11:55:06 AM »
Are those different from lighting lap? lighting lap say to not cut with their resin lap (even the 325), but we can cut with those?
Welcome to the forum RockThief.
These resin-bonded Chinese laps cut very well, my 80 grit is still going strong 3 years since purchase (and the start of this thread!) I certainly use it to cut, and rough out some big chunks of quartz to basically a refined pre-form shape. I am eyeing-off a 30,000 grit resin bonded diamond lap on Ali Express, wondering whether it would do a final polish on some materials, or at least get a facet surface where a few static rubs of 100,000 grit diamond (lap stationary) would finish off the job. They seem to generally come in 10,000, 20,000 and 30,000 grit in the finer grades, and currently cost $AUD 130 including shipping to Aus.
Note that some cutters and also well-known lapidary influencers still refer to these as 'sintered' laps, which is misleading and simply not the case. I see them nicely occupying the ground between sintered and plated laps, with performance and longevity closer to sintered, whilst price is closer to plated.

RC
« Last Edit: April 20, 2024, 12:14:17 PM by RoughCreations »
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TheRockThief

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Re: Resin-bonded scissor-grinding lap
« Reply #8 on: April 20, 2024, 06:16:17 PM »
Are those different from lighting lap? lighting lap say to not cut with their resin lap (even the 325), but we can cut with those?
Welcome to the forum RockThief.
These resin-bonded Chinese laps cut very well, my 80 grit is still going strong 3 years since purchase (and the start of this thread!) I certainly use it to cut, and rough out some big chunks of quartz to basically a refined pre-form shape. I am eyeing-off a 30,000 grit resin bonded diamond lap on Ali Express, wondering whether it would do a final polish on some materials, or at least get a facet surface where a few static rubs of 100,000 grit diamond (lap stationary) would finish off the job. They seem to generally come in 10,000, 20,000 and 30,000 grit in the finer grades, and currently cost $AUD 130 including shipping to Aus.
Note that some cutters and also well-known lapidary influencers still refer to these as 'sintered' laps, which is misleading and simply not the case. I see them nicely occupying the ground between sintered and plated laps, with performance and longevity closer to sintered, whilst price is closer to plated.

RC

Thanks :)

3 years, that's amazing, my plated lap get worn after just 10 stones.

I see that this aliexpress shop (are we allowed to post the link or shop name?) also sells "Tungsten Steel Alloy lap", that look like those green laps but are brown with more cutting medium,. are "Tungsten Steel Alloy" sintered lap? (they are only 20$ more than the resin laps)

do you need to reflatten those resin laps sometimes? I've seen people use 320 carbide grit on a large piece of glass to reflatten sintered lap (don't know if that'll work on resin lap tho).


RoughCreations

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Re: Resin-bonded scissor-grinding lap
« Reply #9 on: April 20, 2024, 07:42:02 PM »
Yes, feel free to post links to products or mention the shop name, I'd be interested to see the tungsten steel alloy lap that you speak of.
I haven't needed to flatten my 80 grit resin lap yet, but it benefits from a rub with some 600 grade wet and dry sandpaper (with water) on a flat surface from time to time as the cutting speed slows. This exposes some new diamonds and increases cutting speed once again. 320 carbide grit that you mention might be a little coarse for a resin lap, if 600 carbide or even a little finer works, I would probably use that.

RC
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TheRockThief

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Re: Resin-bonded scissor-grinding lap
« Reply #10 on: April 20, 2024, 08:14:50 PM »
600 grit, allright, by the way, I read eveywhere that contamination was such a big issue, to clean everything, to be careful, then why isn't using 320/600 grit silicon carbide on a 3000 sintered lap an issue? I saw a youtube video where a pro gem cutter was flattening his 3000 sintered lap with 320 grit silicon carbide. why doesn't it embed itself into the lap and make big scratches?

So I found them in "JY HQ Tools Store" on aliexpress,

here is the link for the green resin lap showed previously: https://www.aliexpress.com/item/1005005551790123.html
here is the link for the brown and thicker Tungsten Steel Alloy : https://www.aliexpress.com/item/1005006300520227.html

I ordered both of them in 80 and 320 version, so 4 laps, to test them out. I've spent so much money on crystalite/high end laps that stop cutting in less than a month so if they last even just a month it's money well spend.

I'll report how they work when I receive them.

If they work well I might try the finer grit ones, with shipping costs and VAT they are 2 times less expensive than lighting lap, and I love to polish with lighting laps.

RoughCreations

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Re: Resin-bonded scissor-grinding lap
« Reply #11 on: April 21, 2024, 11:42:45 AM »
600 grit, allright, by the way, I read eveywhere that contamination was such a big issue, to clean everything, to be careful, then why isn't using 320/600 grit silicon carbide on a 3000 sintered lap an issue? I saw a youtube video where a pro gem cutter was flattening his 3000 sintered lap with 320 grit silicon carbide. why doesn't it embed itself into the lap and make big scratches?

Good question, I don't know. Maybe silicon carbide grains don't embed easily in the sintered bronze. My best/most prized laps are made by Bert Smit, they are made of vulcanised rubber with diamond. I expose new diamond on these laps (80, 200 and an 800 grit) from time to time with wet and dry silicon carbide sandpaper, usually use 800 or 1000 grade wet and dry paper. I also do a light sand if a small fragment of gemstone has embedded itself in the disk, this occasionally happens and it is really obvious as large scratches start appearing. After laying a sheet of 800 wet and dry on a piece of glass and rubbing the lap in a circular motion with water a couple of times, the embedded gem fragment goes away. I then wash the surface with lots of water with a green fibre pot scourer. When I start cutting again, I usually end up with a top-quality finish on my facets, my 800 rubber disk obviously has no silicon carbide grains from the wet and dry sandpaper embedded in it as it typically creates a finish more like a 1200 grit or finer, and I can go straight to cerium oxide polish with quartz.

Quote
So I found them in "JY HQ Tools Store" on aliexpress,

here is the link for the green resin lap showed previously: https://www.aliexpress.com/item/1005005551790123.html
here is the link for the brown and thicker Tungsten Steel Alloy : https://www.aliexpress.com/item/1005006300520227.html

I ordered both of them in 80 and 320 version, so 4 laps, to test them out. I've spent so much money on crystalite/high end laps that stop cutting in less than a month so if they last even just a month it's money well spend.

I'll report how they work when I receive them.

If they work well I might try the finer grit ones, with shipping costs and VAT they are 2 times less expensive than lighting lap, and I love to polish with lighting laps.

They should be good laps. I think the thicker brown lap is still a resin lap on an aluminium alloy base-plate, from the picture. It looks like a beast, and should last nearly a lifetime!
I reckon what the seller is trying to say is that you could even sharpen a tungsten steel cutting blade on the disk.
I would be keen to hear how they cut, and how they last over time, please write up a small review here when you receive them,

RC
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Bucket

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Re: Resin-bonded scissor-grinding lap
« Reply #12 on: April 21, 2024, 05:36:26 PM »
RC, with the vulcanised rubber laps by Bert, I assume you have no problem with rounded edges on your facets? I read rubber and thought it might round them a bit.
Common sense isn't exactly common

RoughCreations

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Re: Resin-bonded scissor-grinding lap
« Reply #13 on: April 21, 2024, 06:45:47 PM »
RC, with the vulcanised rubber laps by Bert, I assume you have no problem with rounded edges on your facets? I read rubber and thought it might round them a bit.
Rubber lap - It sounds wrong, I agree. I haven't noticed rounded edges on my facets when using these, however having said this, I'm not certain I would recognise a slight rounding if it was there. When the rubber is vulcanised, it goes real hard and it's called Ebonite. a.k.a bowling ball material!
See https://aussielapidaryforum.com/forum/index.php?topic=6707.0 for a recap.
Apparently German cutters in Idar Oberstein use Bert's laps, I reckon they would be pretty choosy.

RC
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TheRockThief

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Re: Resin-bonded scissor-grinding lap
« Reply #14 on: May 04, 2024, 11:29:23 PM »
I saw a video about someone that was making his own rubber lab with silicon carbide grit and flex seal liquid clear, seem very economical and could be used for the 80/180 grinding. cannot source flex seal liquid in my country tho : https://www.youtube.com/watch?v=NPOmJwgH6TQ

I got more info from the brown and green laps :

Quote
me : Hello, what is the difference between the green disc and the brown disc? is one of them better for some materials? (I'm going to use them for gem faceting, topaz, cubic zirconia, amethyst)

Quote
JY HQ tool store : The red disc sand thickness is 5mm, most of our customers used  the red disc grind metal material, but can also try to grind high hardness material, the specific use effect we are not sure, depends on the actual situation of customers.

Green disc sand grinding plate is suitable for grinding these material you mentioned.

I've received some of the green ones, not all of them yet, and still waiting for the red/brown ones.

I've prepared a piece to measure grinding speed and will take macro shot of the result of each steps to compare once I get all of them. but metal being softer maybe the red/brown ones are not suited for gemstones

 

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