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 Post subject: New to faceting, need help mounting mast!
PostPosted: Tue Jul 06, 2010 9:18 pm 
Hi all,
Most of you here know me as one who cabs opals, well, I now want to learn how to facet, and have a faceting machine, well, the mast, yoke and quill part anyhow, and I'm trying to mount it on my flat lap that I built, so that I can use it also as a faceting lap.

I'm confused about how high, and how close to the disk to mount it.

I'm mostly confused because I haven't actually "faceted" anything yet, and it's very difficult to know what I need, if I haven't done it yet to "know" what I need!

Everything makes sense to me "except" the part about cutting the girdle of the stone, I've seen some machines where the mast is pulled back away from the disk, so that the quill is parallel with the plane of the diamond faceting disk to cut the girdle facts, in other words set totally horizontal, so the edge of the girdle is contacting the cutting disk, at which angle, the mast has to be pulled back and mounted as far away from the cutting disk as possible, so that the quill (I think the long part that the dop stick plugs into is called the quill...duh) is laying flat, and then only the gemstone on the end of the dop just barely overlaps the edge of the cutting disk.

I've seen other step by step techniques that show the girdle getting cut at a 30 some odd degree angle, or whatever the design calls for, and when cut like this, the mast needs to be mounted close to the cutting disk. The girdle is not totally round in this kind of cut, it is faceted, it meets all the other facets to create the girdle. In the technique where the mast is pulled far back so that the quill lays flat, I've seen some machines even have a little motor drive that spins the dop and creates a totally round girdle, and all the facets barely mreet this round cut girdle.

So you see, my confusion in how to mount the mast on the flat lap machine comes from all the different ways I see the girdle being cut, some are cut round when laid flat on the lap, and others are cut as a result of the facets making contact with one another, it's really confusing me, especially since when I first thought this through, I thought up a sliding mount system where I could pull the mast back so that it could do that laying flat thing, and mount it up close to cut all the normal facets, the problem is the "height" of the bracket that hold the mast to the flat lap.

If I set it low, low enough so that I can slide the whole yolk quill assembly down as far as it goes, in order to lay it flat to polish the girdle that way, and move the mast as far back from the flat lap as possible, then, if I leave it at that height, when I move the mast forward towards the flat lap machine again, as if to cut all the normal factes in a gemstone, the yolk quill assembly needs to go up so high to the top of the mast, that if I needed to attach the table adapter to cut the table, I'd run out of mast! It can't go high enough!

I hope I'm explaining this correct without using the proper technical terms, sorry about that, it's pretty basic, if I mount the bracket at a height for cutting the girdle by pulling that it back as far as I need to, and lower it to where the quill is horizontal and on the same plane as the cutting disk, it won't be high enough for when I need to cut the rest of the gemstone.

I've been looking at pictures of some of these faceting machines, and some do indeed have a sliding mount feature where the mast gets further and closer to the disk, but I don't think the unit I have is designed to be used like that.

I actually bought it from ebay a while back, with the intention of mounting it on my flat lap some day soon, it's a cheap unit, only around $170.00, from China, and I was told by the seller that many commercial gem houses in China pump out alot of gems with this exact unit. I'll post pics below so you can see what I'm talking about.

Hopefully, someone can set me straight about how to mount this thing, and set it up in such a way that I can start faceting some stones with it soon, and learn how to do it!

Maybe if someone knows of a good start to finish tutorial on faceting that they could forward to me that would be great too, this is one of those cases where the more you read, the more you get confused!

Thanks!
Chris ;)

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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Tue Jul 06, 2010 9:57 pm 
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Forcing your flat lap to do something that it wasn't designed for, will make hard work of faceting. How will you ever get repeatable results?

Seeing that you are bent on doing things different than most, maybe a mixed marriage is in order.

Consider a deal like this on eBay-
http://cgi.ebay.com/FACETING-MACHINE-BASE-GRINDING-POLISHING-UNIT-W-MOTOR-/290450896581?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item43a038f6c5


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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Tue Jul 06, 2010 11:09 pm 
I must not have made myself clear, I HAVE a machine like that which I built myself, and i HAVE the faceting device that I posted pictured of, so all I need to do is MOUNT the faceting device on the flat lap, just as I would have to do with the one in the ebay link you posted, the only difference is, the mount is not built into the unit like the one on ebay, I have it separate, and need to "mount" it on the side of the unit.

The EXACT same issue would occur with that unit, it's the "height" that I need to figure out. That unit's mount is kinda lower than the face of the polishing wheel, if that long slot is the mount that is.

It's about the measurement of the height of where to mount the mount for the faceting unit.


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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 12:05 am 
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Oaky, I think that I get you now.

In order to cut the girdle, the angle is always 90'. Some people ease the edges of their girdle or leave it rounded. This is mostly a courtesy to setters. Meetpoint cutting pretty much requires faceted girdles in order to establish and maintain meetpoints. You will need to lower your quill horizontally almost to the bottom of your mast. You can calibrate the height for your bracket based on this measurement. A master lap under your cutting/polishing lap can give you a 3/8" boost if your mast won't travel low enough. Basically bring the lap up to your stone.

Cutting the table will most likely require you to use a table adaptor. This way you will not need to raise your quill to the tippy top of your mast.

The "bracket" that you are side mounting to your flat lap will need to be rigid and parallel to the lap or else you will get many compounded errors. That is why I recommended a Graves base. It's already sorted out. You seem determined to follow your path and I wish only success to you. Many people have homebuilt machines and they work great for them.

Lorne


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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 3:48 am 
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Nope. You're not doing this the easy way. :) I know, because my faceting quill and mast are exactly like the one in your picture. It can, however, be done.

First, to mount your mast, notice the slot in the base of your mast assembly. That will need to be bolted to your flat lap machine on a surface that is exactly parallel to your spinning lap. You need this surface to be as close to precisely parallel as possible. As you change faceting angles, you will want to rotate and lock the mast at different positions so you are different distances from the lap. For angles near 0 degrees, you want to be very close. For girdling at 90 degrees, you want to be far away.

My machine has a slot with a t-bolt coming up out of it. The mast is held down by a large gnurled nut that I can tighten or loosen by hand. When I change angles, I loosen the nut, rotate the mast assembly toward or away from the lap, and tighten it up again. I have the bolt positioned so that when the mast is closest to the lap, it is about 1/2 inch from the lap's rim. That gives me all the range I need for everything from cutting a table to cutting a girdle. The trick is that at every position, the mast MUST be as perfectly perpendicular to the lap as you can make it!

Once you get that done, you can try to use it. I have noticed two main problems with this setup. First, the quill tends to jump out of its bracket, altering the angle of the facet in unpredictable ways. You have to use firm pressure by hand to hold the quill in the bracket as you are cutting. As you get closer to the table angle, this effect is more pronounced. It is essential that you get, or make, a table tool to cut designs with tables. Mine is a rectangular piece of steel with a tube on one side that slides along the mast, and parallel tube and set screw on the other side that holds the dop.

Second, the collet does not hold the dop firmly enough, especially for harder stones. To counter this, I have adopted the practice of locking the stone in place, then putting two drops of Loctite on the collet where it meets the dop. You have to wait until the glue sets before you start cutting, and you have to dissolve all the glue out of the collet before transferring or starting a new stone, but it works.

You are going to be very frustrated at first, but if you are persistent, patient, and a pathological problem solver, you can eventually cut some beautiful stones. On the other hand, you could just shell out the cash for a Graves or Facetron or something, and save yourself a lot of time and frustration. As a reference, I have been using my machine for almost 2 years now, and I still take a day for a pavilion, and a day for a crown, and my meetpoints are still not exactly to USFG Master Faceter standards. (OK, so I'm only actually cutting for maybe half of that time. But still.)

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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 4:03 am 
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NovaScotiaCreations wrote:
It's about the measurement of the height of where to mount the mount for the faceting unit.


Make the mount high enough so that when the dop in the quill is aimed at 90 degrees, and the height adjustment collar is between 1/4 and 1/2 inch from the bottom of the mast, the dop can touch the lap. That's how mine is arranged, anyway.

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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 6:01 am 
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I will reread this later and see if I missed it (need to go 1 min ago)... This looks like it will mount on a Graves IV base. And with a master lap under a lap (or pull the adjusters off), it would cut 90.

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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 6:55 am 
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Gearloose has posted designs for a home mede faceting machine. This might help you figure out how to mount your faceting head. You can find the plans for this machine here.

http://www.gearloose.com/index.html

If you still need help with faceting girdles, there are several excellent book out there. you might try the local library or the library in a gem club. If you don't have access to any of these books send me a message and I will scan off the pages form one of the books I read when I first began faceting.

Hope the information helps

Stewart

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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 12:02 pm 
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Hi Steve,

If I comprehend that mast arrangement correctly, there is no bearing assembly that will allow the faceting head to swing on. It looks as though the 2 spacers are fastened one above and the other below the faceting head, with the faceting head pivoting on the shaft it self. This creates a bit of a dillema as you are stuck with at least the bottom spacer which is eating into your mast adjustment going down.

It seems the only solution is to space the lap up to a practical height, Ive done this before using plexiglass, not expensive and easy to work with as well as pretty flat.

I can't understand why you would be running out of height though, the mast looks tall enough.

If it's just the 45 degree adapter giving you grief it may be advisable to cut and polish the table by hand.

Good luck whichever way it turns out.

Sean.


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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 12:09 pm 
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Brass doesn't "eat" into steel much.
Wonderful stuff, brass. The closest thing I've ever seen to a self lubricating metal.
Old brass is better than new brass for some reason, pre and post WWII stuff is much better than what you can buy new today.
Must have been the copper source. Butte, America was good copper.


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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 1:25 pm 
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You don't run out of height, the mast is plenty tall enough. The height adjustment collar takes up some room, so you want the mast mounted an inch or two below the lap surface to ensure that you can cut girdles. The faceting head swings freely around the mast because the mast is a round rod. The arrangement works nicely, and is quite simple and easy to manufacture.

The problem with cutting at steep angles is due to drag on the stone overcoming the weight of the quill assembly. If you notice, the quill rests on two pins that are seated in two slots on the faceting arm, cut at about a 45 degree angle. If you apply side pressure to the end of the dop, one of the pins will tend to rise out of the bottom of its slot, so you have to hold it down. When you get near 0 degrees, the quill is vertical, and the drag forces are maximized. It also becomes more difficult to hold the quill in its proper place. Therefore, you need a table tool.

Even with a steel-on-steel faceting head, a bit of light oil on the mast makes the assembly swing easily, and you just don't spend enough time at any given height to grind away anything important.

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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 2:23 pm 
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Oscartg, steve,
Yes the simplicity of the device is an attraction, just the technique that needs a little adjustment.
I don't mean the brass is being eaten by the steel, the bottom stop is limiting the downward travel of the facet head.

Steve you've got a pretty good handle on this one, I'm really curios to hear how it turns out for Chris.

Good luck.

Sean.


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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 4:09 pm 
Thanks for all your replies,

I know this is hard to understand, because putting a "picture" into a thousand words is difficult for this 2 finger typer at best...lol.

Literally, I think I would need to take pictures to explain this, but I "think" I "might" understand what my issue is, I cannot get the base of the mast close enough to the edge of the polishing disk, I dunno. I'll "try" to explain it a bit better, now that I've actually had 8 hours sleep..lol.

First of all, I know it's hard to comprehend, but the mount isn't the issue. I made a right angle mount, and on top of that mount, there is a long rectangular plate of thick aluminum. On each corner of that aluminum plate, there is a 2" bolt sticking straight up, and that bolt has a nut on it, securing it in place, so on every corner of that plate, it a bolt sticking up, secured in place.

On each of those bolts is a nut, set at a certain height for each corner, on each nut lays a washer, and placed on top of that washer a 2nd rectangular plate of equal size as the bottom one.

The top rectangular plate has a long slot cut into it, for the purpose of mounting the base of the mast of the faceting unit, so that it can slide back and forth the length of the plate and be secured either far or close to the flat lap.

So, there now is the ability to fine adjust each corner's height for the purpose of fine tuning the leveling of the top plate, to ensure it is completely in the same horizontal plane as the top of the polishing disk.

Initially, to get a basic angle of the top of the cutting plane, I drilled a hole in a long aluminum bar, and mounted that where the cutting disk would mount on the lap, so that the bar was protruding horizontally from the unit, thus providing the exact same angle as the top of the cutting surface, which would be the bottom of that aluminum bar that was mounted to the place where the disk mounts. Make sense?

This procedure basically ensures that the top surface where the mount of the faceting device is mounted is roughly flush to the top of the cutting plane of the disk, but just in case it is off slightly, those 4 nuts on each corner can be adjusted to make it any angle, and thus ensuring that any tiny amount of anything out of angle can be fixed to ensure it is totally flush with the top of the cutting plane of the disk.

I had to explain this part first, so you can focus on the problem at hand, which is not the angle of the mount, but the height at which to mount the mount.

So, having said all that, it's a matter of the mount height that I am struggling with, if I could figure that out, I could mount this thing and Bob's your uncle!

Here's the "actual" problem.

When I put the quill totally flat, so as to polish the girdle, I MUST lower the mount to such a height that the mast base is lower than the cutting plane of the disk, obviously, because there is a minimum distance between the top of the mount, and the bottom of where the quill meets the yold device, so this makes it so that I need to have the mount a few inches BELOW the top cutting plane of the cutting disk, in order to lay the quill flat, and pull the mast as far back as I need to in order to accomplish this.

So, no problems there, all good....right?

Now, if I LEAVE the mount mounted at that height, a few inches below the cutting plane of the top of the polishing disk, I then slide the mast FORWARDS as far as it will go, so that with the table cutting device that mounts onto the end of the quill, the bottom of the table adapter is totally flat on the cutting plane, as if to properly cut the table of a gemstone.

Now herein lies the problem. When I leave the mount mounted at the proper height to be able to cut the girdle by laying the quill totally flat horizontal, the base of the mast is slid as far forwards as possible, (which is 1 and one quarter inches from the edge of the polishing disk) for the purpose of making all the usual cuts of a gemstone, every thing is fine, the mast is high enough for that, although the yolk is almost at the top of the mast, EXCEPT when I put on the table adapter for the purpose of cutting and polishing the table, because THEN, with the added height of the dop stick in the table adapter, as well as the table adapter itself, I would THEN need to raise the yolk higher than the mast actually IS, and it would slide off the collar.

I sat there measuring it at it's extremes, in order to figure out the height of the mount, and the same thing kept happening, if I mounted the mount LOW for the horizontal position of cutting a girdle, I could not have the height of the mast needed to polish a table.

If I mounted it at the height needed to properly polish the table, I could then not lay the quill flat, at a slightly lower distance from the top of the cutting plane of the polishing wheel.

If I were to remove the locking collar from the shaft, and set the yolk at the VERY bottom of the mast, then I "might" be able to get away with it, not sure, but it seems to me that I should be able to just mount this thing in the state that it is, and simply be able to slide it forwards or backwards, and lock it into position on the mount, to accommodate whatever step of the cutting procedure I am doing, without having to modify everything to accomplish that task, know what I mean?

So, I'm stumped, trying to figure out WHY I cannot mount this mount "permanently" at one height, in order to be able to have the full range of motion to properly cut the gem from girdle to table, without having to make any height adjustments.

Sure, I could spend a whole lot of time and effort trying to make a height adjustment device, but WHY, when I KNOW that there is something wrong with what I'm doing, but just cannot figure it out!

IF I needed to make the brass mount part with the slot cut in it of the mast of the faceting device closer to the edge of the cutting disk, I can do that, so instead of it being 1-1/4" away, it would be only 1/4" away from the edge of the cutting disk's edge, but would "that" remedy all this issue? Is the ONLY problem that the mast is not mounted close enough to the polishing disk?

Everything would be FINE if I didn't need to lay the quill horizontal to polish the girdle, i could have it mounted and running in 5 minutes, but just could not lay it flat to polish the girdle in this way.

Since I am at the disadvantage of trying to LEARN faceting, at the same time as trying to build a device FOR faceting, I would know how to fix this, as I would know exactly everything I NEED to do during the cutting process, but it's what you don't even know that you don't even know that gets ya every time, and I don't want to mount this thing wrong, and find out later on that I have to yank it off, and rethink the whole thing!

When I read several cutting techniques that did not lay the quill down flat to polish the girdle, and just cut the girdle at angles like all the facets, I wondered WHY the method was like that, while other methods seemed to spin the dop while at that flat angle, to create a totally round flat edged girdle, instead of a faceted one. Still other techniques called for doing that, creating a totally round girdle by spinning the dop while the quill was laying flat, and THEN after doing so, ALSO then faceted the girdle, which results in still a totally round shape while looking down at the table of the stone, but having facets in the girdle as well.

So there are all these different techniques for faceting, and all I want to do is ensure that the way I mount this thing can accommodate ALL of them, without being limited to what I can do.

I know that there are 2 ways to go, buy cheap, and have some work to do myself (which is what I normally do!), or spend more, and have it all done for you, and have no hassles, but some people like myself just cannot pull money out of the thin air and have the convenience of buying all the fancy stuff, I have to make due with what I can, and in this case, the $170 faceting device was ALL I could afford. In the future, I can always upgrade my flat lap to a proper professional device, that this faceting unit will quickly and easily mount onto right away, with no issues, but for now, I just want to get it working, as I KNOW it can be done, especially since Sierra Gems advised me that there would be NO problem mounting it on my existing flat lap (which actually isn't home made, it's a modified dual vertical flat lap made by crysalite, laying on it's back, I think it was originally called a demon or something like that, I had to reinforce it all over with wood, as it arrived totally smashed in shipping!)

So, hopefully this painfully LONG post will explain further and properly what my exact issue is, and someone out there can advise me on what I'm doing wrong, or how to remedy this issue, to mount it at the correct height to make it work!

Thanks!
Chris ;)

Here is a picture of my table adapter, note the added height required to raise on the mast to accommodate the table adapter.

If the table adapter were lower, it might not be such an issue, but still, doing all the normal facets of a gemstone while the yolk is raised to almost the top of the mast permanently just "feels" wrong, it is much more sturdy and stable if it were half way down the mast when in the regular position, don't you think?
WHY should I have to lower the whole thing SO low just to be able to lay the quill horizontally to polish the girdle?

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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 7:29 pm 
Here are a few pictures of my ugly lap with the hole cut into the side of it to accept the faceting device when mounted onto the bracket on the side of the machine.

I have another half built flat lap that I built myself and it has a totally flat steel top which the faceting device could be mounted directly to, such as on the ebay auction picture that was suggested here earlier, but I abandoned finishing building that lap when I acquired this crysalite "diamond demon" dual vertical flat lap machine which I "also" bought on ebay.

I would much rather mount the faceting device onto the side of this machine as intended, to save space, as then I would only have one machine to serve the purpose of both cabbing and faceting, and not have to have 2 separate machines.

It's ugly because when it arrived, it was TOTALLY smashed, and a refund was not an option, as it would have cost me a ton to ship it back, so it was pointless, I therefore made the best of what I had by reinforcing it with wood, and creating a moisture splash guard around the top of it, which significantly cuts down on over spray when cabbing. It's also quite dirty because of recent cabbing ;)

The reason it looks SO gross and ugly, is because the inside of the cutting area is sealed with a few layers of motomaster rokkor panel asphalt sealant which is usually used on the rokkor panels of a vehicle, to seal it from rusting, and provide insulation and protection from rocks, it works great to create a non-leaking spray on barrier for this kind of thing to seal against leaks, like I said, it was totally smashed, so it all had to be glued, screwed, and sealed up to make it usable again.

As you can see, it's nice and close to the edge.
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 Post subject: Re: New to faceting, need help mounting mast!
PostPosted: Wed Jul 07, 2010 9:16 pm 
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I could be wrong, but it appears that the distance from the pivot point of the quill (at the protractor) to the collet is too long, mandating a taller mast for the range of angles commonly used in cutting.

Also the 2 rings for locking the height adjustment are too thick, limiting your downward motion excessively.


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