January 24 Through February 4—TUCSON, ARIZONA: Annual show
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Thu Mar 28, 2024 3:08 pm

All times are UTC - 4 hours




Post new topic Reply to topic  [ 12 posts ] 
Author Message
 Post subject: Faceting machine question
PostPosted: Sun Dec 23, 2018 7:45 am 
Offline
Established Member
User avatar

Joined: Mon Jan 30, 2017 4:06 am
Posts: 40
Location: South Hadley, Massachusetts, USA
I'm currently on a Graves Mark 5xl. It's serving me pretty well, but the main reason I got it was the price. I'd never tried faceting before and didn't want to drop over $4000 on a hobby that I wasn't sure I'd enjoy.

Well, I do enjoy it. Very much. Go figure. Now I'm contemplating getting a new faceting machine in light of the shortcomings of my current one. I'll lay out what my problems are and then ask for recommendations for a replacement machine.

-The fact that the entire machine is cast iron makes cleaning a chore. I've seen some machines with a removable swarf tray. That seems far easier to clean than using half a roll of paper towels to scrape the swarf out of my current one.

-The dops aren't keyed. I don't know if this is a beginner problem, but when I cut the crown, there's always that one damn facet that just doesn't meet up properly that I need to go back and re-cut. Without keyed dops, getting the stone back on with proper indexing is a royal pain. On square stones or really any cut with large girdle facets, it's not that hard to index. A small, 6mm round cut with 32+ girdle facets, on the other hand, is never indexed properly after putting it back in the spindle.

-No reverse setting. This isn't that big a deal, but I think it would be a nice feature to have.

-No dial gauge/digital angle display. The digital angle display works fine when setting the angle, but that's it. As soon as the stone touches the lap, that number bounces around by as much as .5 degrees. That means I need to cut everything by eye only, which takes a long time.

-Unable to unlock the gear index. It looks like the lever is meant to be able to be unlocked, but the little holes in the lever and the casing don't line up, so I can't put the provided metal pin in. This makes preforming a bit of a pain, as I have to either manually hold the lever up or remove the gear index so it can't be locked in.

Overall, I'd say the keyed dops and a better angle display are the most important things I want to address, but any suggestions on a good machine that will cover more than just that would be appreciated. Anyone who wants could also take this as a review of the Graves Mark 5xl, since aside from those issues, the machine is great. Thanks in advance for your help.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 11:36 am 
Offline
Gold Member
User avatar

Joined: Thu Jan 24, 2008 4:01 pm
Posts: 1902
Location: Pine City, NY and Dothan, AL
A couple of comments. First, all Graves dops are keyed. There's a 1/16" hole which matches a notch on the quill, and the brass rod supplied is used to align the dop. Insert the rod in the hole, then insert into the quill so that the rod fits into the notch. Tighten the quill setscrew and remove the rod. On the same subject, you're probably better off without using the keying. It may be useful if you need to remove and replace a stone midway through cutting, but for alignment after transfer it's a liability. Learn to align to a girdle facet.

I agree on cleaning, though I've never used a machine with a removable pan. I don't find it that bad - I spray with Formula 409 or Windex, then wipe with a paper towel.

It's easy to add a reverse switch, but I've actually used it only a couple times in the last 10 years.

I don't understand your problem with the angle display. The display is stable and accurate, but the spinning lap certainly isn't. You can watch the display until you get close to final angle, then watch the facet. It will help to always end the sweep at the same point on the lap. If you want to cut two facets precisely the same, stop the lap and measure both at the same spot. I do this to cut precise initial center points, for example. This is an issue of mechanics, not the display. It will be the same no matter how much you spend on a machine.

Old saying: "Cut a little, look a lot." Precision faceting does take a long time. If you go professional, you'll get faster, but never fast.

On my machine, I have no problem locking the index pawl, though I never do it. I never saw the point of the "spin" preforming - you eventually have to cut the facets anyway.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 12:22 pm 
Offline
Established Member
User avatar

Joined: Mon Jan 30, 2017 4:06 am
Posts: 40
Location: South Hadley, Massachusetts, USA
AlBalmer wrote:
A couple of comments. First, all Graves dops are keyed. There's a 1/16" hole which matches a notch on the quill, and the brass rod supplied is used to align the dop. Insert the rod in the hole, then insert into the quill so that the rod fits into the notch. Tighten the quill setscrew and remove the rod.


I honestly thought that brass rod was meant to lock the lever for the index plate. I didn't get an instruction manual with my machine, and I never used one before. I thought you just aligned the hole in the dop with the notch in the quill as a vague reference.

AlBalmer wrote:
I don't understand your problem with the angle display. The display is stable and accurate, but the spinning lap certainly isn't.


I guess I'm the unlucky schmuck with a defective one then, because my display is as "stable and accurate" as a blind drunk with a shotgun. The absolute best thing I can say about it as that it's usable. The numbers change based on just about everything, from whether the quill is over the lap or out in front of the machine, regardless of whether it touched anything, if I lift the quill to check the stone, the number is anywhere from 0.08° to 0.15° different when I put it back down than it was before I lifted it, it bounces all over the place when I'm actually faceting, then stops somewhere kind of random when I stop. It's a mess. From the sound of things, I just got a bad one. Unfortunately, customer service at Graves is non-existent, so I know trying to get it fixed or replaced would take forever if I'm lucky, and simply not get done if the owner's true to form.

AlBalmer wrote:
On my machine, I have no problem locking the index pawl, though I never do it. I never saw the point of the "spin" preforming - you eventually have to cut the facets anyway.


As I said, mine doesn't line up, so I can't lock it even if I wanted to.

I'm not saying the Graves 5xl is a terrible machine. It works, and I'll probably have it for a while yet, since I don't make enough money to just pick up a better machine like someone would order a DVD on Amazon. It does, however, seem marginal compared to other machines, especially since most reviews of it are mediocre. As for the company itself, reviews are terrible, and for very good reason. I'd like to get a machine that I could actually get support for when necessary, if nothing else. I'm just trying to set an eventual goal so I know what to save for.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 12:50 pm 
Online
Gold Member

Joined: Thu May 12, 2016 2:18 am
Posts: 1542
As Al has said, the dop is keyed and works the way he described. However, I found with some of my students who buy inexpensive used Graves machines, that using a Facetron dop can work better. The Facetron dops have a flat section machined on to them. They fit just fine in a Graves quill. Just insert it then use the set screw to tighten the dop. It aligns well, as it comes, but works better if you have a flat bottom on the set screw rather the the slightly rounded one it comes with. The Facetron dops used with the Facetron transfer jig will also likely solve your after transfer alignment issues.

As far as the digital angle meter bouncing around when cutting this is almost always a symptom of "runout" in the lap being used. If the gauge is stable just resting on a lap that is not spinning, then this is surely the case. Giving different numbers on different parts of the wheel is also usually the lap, and confirms runout. I find these issues much worse when using toppers.

You may have a misconception on the use of the gauge. No machine will let you just cut to a number and have perfect meets. I view the gauges (and dials) as a measuring device, not an angle setting device. You will still have to work the meets. A .1 degree variance is within a usable range. I find that as you get close to a facet meet in works better to cut in a postage size area of the the lap than sweeping across the lap, much more accurate and repeatable.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 1:06 pm 
Offline
Established Member
User avatar

Joined: Mon Jan 30, 2017 4:06 am
Posts: 40
Location: South Hadley, Massachusetts, USA
I have no idea what "runout" is. All I know is that it happens on all of my laps, from my solid cutting laps, to the Batt lap I use to prepolish, to the DarkSide lap I just got for polishing. Also, I could set the angle to 41.00° cut or polish one facet, check the stone, not rotate or change anything, then have the readout say 41.14° when I put it back down, then quickly drop down to 40.89° in 2 seconds, causing me to panic and check the stone again, starting the whole cycle over. That's a variance of 0.25°, which is well outside the 0.1° safe zone.

Also, I'm well aware that cutting to the numbers yields sloppy results. I'd just like a more accurate idea of when I should start checking the stone more. It would save me a bit of time, that's all. I'm more concerned with my angle display being schizophrenic than I am with the dial gauge.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 1:53 pm 
Offline
New to the Forum or The Quiet Type

Joined: Sat Oct 27, 2018 7:01 pm
Posts: 5
Location: Россия, Урал
CoreyB wrote:
........ Also, I could set the angle to 41.00° cut or polish one facet, check the stone, not rotate or change anything, then have the readout say 41.14° when I put it back down, then quickly drop down to 40.89° in 2 seconds, causing me to panic and check the stone again, starting the whole cycle over. That's a variance of 0.25°, which is well outside the 0.1° safe zone.
......


The problem is the angle sensor. The movable sensor disk has an axial backlash. It is necessary to check the quality of the Assembly of mobile connections.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 2:03 pm 
Offline
New to the Forum or The Quiet Type

Joined: Sat Oct 27, 2018 7:01 pm
Posts: 5
Location: Россия, Урал
CoreyB wrote:
..... Also, I could set the angle to 41.00° cut or polish one facet, check the stone, not rotate or change anything, then have the readout say 41.14° when I put it back down, then quickly drop down to 40.89° in 2 seconds, causing me to panic and check the stone again, starting the whole cycle over. That's a variance of 0.25°, which is well outside the 0.1° safe zone.
.

You must check the build quality of the mobile connections in the angle sensor. The movable sensor disk has an axial backlash. This is the main reason for display deviations.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 3:22 pm 
Offline
Gold Member
User avatar

Joined: Thu Jan 24, 2008 4:01 pm
Posts: 1902
Location: Pine City, NY and Dothan, AL
Have you tried a fresh battery?


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 4:02 pm 
Offline
Established Member
User avatar

Joined: Mon Jan 30, 2017 4:06 am
Posts: 40
Location: South Hadley, Massachusetts, USA
AlBalmer wrote:
Have you tried a fresh battery?


Yes, that was one of the first things I tried. I heard these things get a little confused when the battery gets low.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Sun Dec 23, 2018 4:37 pm 
Online
Gold Member

Joined: Thu May 12, 2016 2:18 am
Posts: 1542
CoreyB wrote:

I have no idea what "runout" is.

That's a variance of 0.25°, which is well outside the 0.1° safe zone.



Runout is how much out of perfectly flat the lap is when turning. This can be the result of the lap or the platen on the machine. Even a little dirt buildup on the bottom of the lap or on the platten can cause this. The Gearloose products are usually very well machined so runout is not much of an issue with them.

I still don't think that much variance is much of a hindrance to cutting. The 0.10 degrees I was referring to is the tolerance for setting the gauge. Of course you can buy a better machine, but I am guessing you will still have about the same issues.

Has anyone out there had a machine where the digital gauge isn't bouncing around by 0.25 or more? I use facetron which has a dial indicator, but all of the Ultra-techs with the digital head that I have seen bounce a little as well.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Mon Dec 24, 2018 1:57 am 
Offline
Gemology Online Veteran
User avatar

Joined: Sat May 22, 2010 2:51 am
Posts: 755
Location: South Africa
If the display doesn't return to the same angle when you raise and lower the quill, there definitely is something wrong with it. Perhaps the gearing is worn. My Ultra Tec DAD returns to the same angle setting each time I raise and lower the quill. The displayed numbers do change with lap runout. I finish cutting each facet of a tier at the same place on the lap and cut until the second decimal place number just stops flickering. You still have to check the meets visually, especially when prepolishing, which moves them a variable amount because of differential hardness.


Top
 Profile  
Reply with quote  
 Post subject: Re: Faceting machine question
PostPosted: Mon Dec 24, 2018 10:18 am 
Offline
New to the Forum or The Quiet Type

Joined: Sat Oct 27, 2018 7:01 pm
Posts: 5
Location: Россия, Урал
1bwana1 wrote:
CoreyB wrote:

I have no idea what "runout" is.

That's a variance of 0.25°, which is well outside the 0.1° safe zone.

Has anyone out there had a machine where the digital gauge isn't bouncing around by 0.25 or more? I use facetron which has a dial indicator, but all of the Ultra-techs with the digital head that I have seen bounce a little as well.


Станки с двойным контролем существуют, изготавливаются единично.
Очередной мой проект - зубчатые передачи отсутствуют, контроль угла через тягу. Этот проект сейчас на стадии изготовления.


Attachments:
File comment: Станок с двойным контролем - 1. транспортир, и электронный датчик. 2 лимб вертикального перемещения, и электронная линейка.
Проект станка - двойной контроль 2.jpg
Проект станка - двойной контроль 2.jpg [ 33.67 KiB | Viewed 1304 times ]
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 12 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: Google [Bot] and 25 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Gemology Style ported to phpBB3 by Christian Bullock