Thanks for the info.

    Well, here we go again. The split dogs are wobbled out and not driving the vise, again. I see that my feed screw shaft has worn at the rear end as has the bushing, so it wobbles. Front bushing not much better. The feed dog split nuts are always the first thing to wear out. As usual, the only place that stocks these parts is HP Lapidary. The good news is they actually have the parts for 18 inch Frantom saws, in stock. Was not cheap until you compare it to the cost of a used saw that actually runs good. Yep, try and find one of those. Screw shaft, 2 bushings, two sets of feed dog split nuts was about $275, free delivery.
   I called Cigar Box just to be safe. They are great to work with when you are in a pickle. They are glad to help those that need it but they do not stock many parts, so I went to HP Lapidary. AND, I ordered a second set of split nuts to put on the shelf as those are frequently not in stock.
WARNING:  I have always been told that the HP 18 inch saw is almost identical to the Frantom and uses the same parts. So many of these old saws have been modified that there are no guarantees parts are the same. I have no idea how many people owned my Frantom over the years. It has been modified and I am hoping the bushings and shaft will fit.
****   I watched numerous YouTube videos on rebuilding lapidary saws. Fun to watch other people make mistakes I have made. Should have watched them years ago.  The one thing I do that I have not seen in the videos, " I take the top off my saw". Four little screws hold on the hinges and one screw on the lid arm. 5 minutes of work and now I can get to every part so easy. Just a thought. More later after the parts arrive.
PS:  HP Lapidary just got a new shipment of parts in and are unpacking them to see what showed up. If you are in need you may want to check with them. SOON.

Ok, many thanks again.
Have a nice day!

Yes it is quartz. Your lap is the problem.Try Gearloose faceting laps. They have a chart so you can see what works best for quartz.

Many thanks for your reply. I've youtubed a thousand of videos but I've never found someone who told: "do this and you'll be satisfied!". Every video I've seen, shows someone who moves the stone left and right. Beeing honest, I started with a quarts because I own several pieces but the truth is I want to facet amethists and with a bit of experience, kunzite and rubies.
With amethists, will I have the same problems of quartz?

Not dyed.

Quartz may be the very worst stone for beginning facetors.Since quartz is inexpensive people tend to make a big stone and quartz simply does not like to be polished and gigger surfaces make it much harder. Do some research on the darkside laps for instance. Try searching for faceting quartz on you tube and you may luck into one of the good faceting lap review sites. The modern specialized laps  are much better for quartz. Yours is a very old and common problem, many of us have faced it when starting out.Good luck.

Hi everyone, I'm new in this forum and quite new in polishing rocks. Until now I've done many cabochons using calcite and other low mohs rocks. Two weeks ago, I bought a lapidary machine in order to create faceted gems. I've started with a quartz creating my first brillant faceted gem (right now, only the pavilion) using at least a 3000 grit lap.  The problem arrived when I tried to mirror finish the facets. I used a mix of allumin and chrome oxide (80% Al2O3 and 20% CRO) on several supports (cd rom, back of a lap, alluminum support) and moisturizings such as water and WD40 but the "cream" just disappear in few turns even at low speed and the facet just remain the same.
Can anyone help me use this powder in the correct way?
Many thanks in advance,
Andrea

This link might interest some of you. I found it recently when I was trying to decide what protective equipment I really should be wearing ( I’m new at this). I probably have all of it but I can be lazy or in a hurry and pass it up. I found it interesting.

https://www.asbestos.com/blog/2020/04/20/asbestos-jewelry-mesothelioma/

I’m concluding the same. I have a hard time believing that someone could dye and get the variations in the blue while maintaining unaffected areas such as the white and quartz. Doesn’t seem that the blue has pooled anywhere either. Other pieces I have found online do have some of those characteristics so buyer beware. None of the regular dealers I use (and trust) have this material so that was an additional worry on my part. Supposedly this material comes from Madagascar.