Aussie Lapidary Forum

LAPIDARY => Cabbing and More => Topic started by: Dihusky on February 01, 2019, 06:11:38 PM

Title: Gemmasta Gem Grinder
Post by: Dihusky on February 01, 2019, 06:11:38 PM
Interested to see if anyone here has any knowledge of these machines. Picked one up off an Opal miner last weekend as it looked interesting, he didn't want it and the price was right. Love to get my hands on a copy of the user manual and find out a bit more about the different cams and rollers it's supposed to have, also going to be looking for some different grit wheels as the one with it is a 120 which I would consider a roughing wheel.
Title: Re: Gemmasta Gem Grinder
Post by: Bucket on February 01, 2019, 06:14:41 PM
I haven't used one of the grinders myself, but the club has a couple of Gemmasta saws and faceting machines, they are robust and operate well. I would imagine that the grinders would be of the same caliber.
Title: Re: Gemmasta Gem Grinder
Post by: Dihusky on February 01, 2019, 06:19:27 PM
I learnt to cut on a GF4, great machine. This Gem Grinder is a serious piece of work, weights around 50kg and beautifully engineered. I found the patent papers which are 1970, but that's all I've found so far.
Title: Re: Gemmasta Gem Grinder
Post by: Bucket on February 04, 2019, 10:38:59 AM
Other than the motor burning out, the bearings are pretty well the only other thing that can go wrong with a grinder. If the wheels and arbor turn freely with no play, it should be OK. Even if they are shot, they can be replaced relatively easily.
Title: Re: Gemmasta Gem Grinder
Post by: Dihusky on February 04, 2019, 06:49:45 PM
There's a bit more to this machine than wheels, arbor and bearings, there's the 90 degree reduction box, a series of helical ground gears, a series of offset cams of which I only have #4 so will have to make the others, a vernier adjuster for offset rotation settings and so the list goes on.

Once I strip it I recon there'll be somewhere between 100 & 150 individual parts to be cleaned, labelled and their configuration/position photographed.

I'm really looking forward to doing it this winter.
Title: Re: Gemmasta Gem Grinder
Post by: Rusted on February 05, 2019, 06:51:17 AM
Before you dismantle it show us a photo, I am intrigued what this machine is.
Title: Re: Gemmasta Gem Grinder
Post by: Dihusky on February 05, 2019, 05:51:50 PM
Grab the PDF on my opening post, that's the photo. Doesn't appear to be any other way of putting up pictures on this forum.
Title: Re: Gemmasta Gem Grinder
Post by: Rusted on February 05, 2019, 06:03:11 PM
That's an amzing looking beast, I'm none the wiser though. looks like a fantastic project for winter.
For pictures use the gallery and copy the link to your post.
Title: Re: Gemmasta Gem Grinder
Post by: Dihusky on February 05, 2019, 07:14:21 PM
This is what's under the lid and controls the primary shape/girdle:

(http://aussielapidaryforum.com/forum/gallery/9/82619-050219190252.jpeg)

Then there's a cam which mounts on the spindle above the nut with a hole in it that's under the quill in the image. There are 4 different cams I believe, I only have #4. This controls the dome profile. Going to be fun making the others and working out the cam profiles. Could be some interesting results :-[ when I get to that stage.

A few other things going on here that I'm not sure about quite yet, got some ideas, but..... ???
Title: Re: Gemmasta Gem Grinder
Post by: Bucket on February 05, 2019, 08:10:20 PM
I see what you mean, haven't seen one like that before. From the quick look I've now had, it would appear that you do have some control for grinding the dome of the cabochon rather than using your own hands to guide the dop stick. Have you thought about contacting Gemmasta to see if they can give some advise. I know Shellap have shut down in Adelaide, but maybe Gemcuts (the new owners) could help you out.
Title: Re: Gemmasta Gem Grinder
Post by: Dihusky on February 05, 2019, 09:54:35 PM
Been in touch, they know nothing about the machine.
Title: Re: Gemmasta Gem Grinder
Post by: MakkyBrown on February 05, 2019, 10:03:05 PM
I wasn't reading the thread as I thought it was about a standard grinder  ::)
Gee that looks pretty impressive, would be great if you could share more photos.
CheersMB
Title: Re: Gemmasta Gem Grinder
Post by: Dihusky on February 05, 2019, 10:26:29 PM
Let me get it cleaned up a bit first mate. It's been well used but looked after, just hasn't had a good clean for I don't know how long, the original owner passed away a couple of years ago so it's been sitting and is screaming out for some TLC which it will get once I have a few other things off my plate.

Need to finish servicing the Hall 2000 first so I can get back to cutting, then there's the 8" grinder polisher to finish building so we can get some opal finished then it's this beast's turn.

Thought I'd put some posts out early to see if anyone would come out of the woodwork that new a bit about this machine, but so far drawn a blank unfortunately.
Title: Re: Gemmasta Gem Grinder
Post by: Rusted on February 06, 2019, 07:14:26 AM
That is an amzing machine, I bet it wasn't cheap to buy new, and I bet they didn't sell many.
Title: Re: Gemmasta Gem Grinder
Post by: CSSDOP on July 26, 2019, 01:09:26 AM
Hello Dihusky,
I came across your request for information regarding a Gemmasta Semi Automatic Cabbing Machine, while looking for another topic. I don't know if you still have interest in knowing more about this machine but I am sure I can help you. I have the instruction sheet for this machine and having  owned several of them at different times, am familiar with its operation. Ask and I will do my best to answer your questions. The machine you have is the "split case" model. Two models were manufactured. Yours is the later, preferred model. 
Regards, CSSDOP
Title: Re: Gemmasta Gem Grinder
Post by: Dihusky on July 26, 2019, 05:01:12 PM
CSSDOP, great to hear from you, and yes I would love to get some more information on these machines. I have managed to work out a bit but to see or even possess a copy of a manual would be awesome.

I have been able to discover that there are several different models of cam profiles, I only have #4, none of the others, I do have the skills to make them though if I can discover the patterns. The items I am at a loss about are the rotating cams that mount on the end of the drive shaft, how they engage I can see, but their shape I know nothing about, let alone how they work in with the operation of the machine. I am assuming part of the cyclic drive system has to be disengaged.

So any information would be of immense value, thank you.