Aussie Lapidary Forum

LAPIDARY => Ask a "Silly" Question => Topic started by: Campbellpotter on April 16, 2015, 04:16:01 PM

Title: Hot to use mini-flexodiscs?
Post by: Campbellpotter on April 16, 2015, 04:16:01 PM
Hi, beginner here. I am carving some greenstone from New Zealand and am struggling to find good advice on the finishing and polishing.

I have just bought a 400 grit and 800 grit diamond bands for polishing and these are pretty straight forward but still leave the stone rough.

I have also bout a 1800 grit mini-flexodisc resin pad with the mandrel to go with it. This is where I am stuck, how do I use this I have found reference to usng compounds and lube that I have no idea about, and what sort of results can I achieve or should I be using a different tool.

Fi, I am doing all this with a Drexel on a 3 mm shank size.
Title: Re: Hot to use mini-flexodiscs?
Post by: Lefty on April 16, 2015, 07:31:40 PM
Not a carver but #14 000 grit should put a reasonable shine on your piece. I use #60 000 on some cabs and occasionally even #100 000 but a polishing compound that fine shouldn't be necessary I would think.
Title: Re: Hot to use mini-flexodiscs?
Post by: Aussie Sapphire on April 18, 2015, 03:48:05 PM
Not familiar with the flexodiscs but 1800 is pre-polish stage only.  You need to go to #14,000 at least to get a good polish on most material.

The #400 and #800 stages are for shaping and sanding - you are going to need to pre-polish before going to final polish in most cases.

Is the #1800 pre-charged with diamond? You could use with a light drip of water similar to the diamond bands?  Or if like crystal pads which need to be charged, then can use diamond compound and any suitable diamond extender (singer sewing machine oil, baby oil, Snake Oil or the like). Some people use various oxides but a quick google search indicated that diamond was most reliable.

One of our members (MickB) carves a lot of jade and gets fantastic results with high grade diamond.

cheers
Leah


Title: Re: Hot to use mini-flexodiscs?
Post by: mick B on April 19, 2015, 07:23:41 AM
NZ green stone can be either nephrite jade or Bowenite- gem serpentine, most New Zealand carvers prefer a satin finish, they finish on 1200 or 2000 silicon carbide dry - wet & dry paper, its a matter off personal choice how high the polish will be, some jades look better with satin finish and others look great with either, I do prefer diamond polishing but Linde A - alumina A can also work. One polishing method will not work on all jades as they all have differences in hardness, some undercut more than others, I do not think miniflexo disks are a good polishing option with jade - greenstone, most rotary tools pull the fibers causing undercut in the final polishing stages.     
Title: Re: Hot to use mini-flexodiscs?
Post by: nssian on April 19, 2015, 08:22:24 AM
This is great information and just what I have been looking to find out.
Some of the stones I have found are some type of Jade :-)
Title: Re: Hot to use mini-flexodiscs?
Post by: southerly on April 28, 2015, 06:09:20 PM
I use the mini flex disks a lot and like them. I find the various pre made pads for them mostly useless and a waste of money. I have about 8 disks and use half for sanding, i buy diamond belts or diamond sanding strips and cut them to size and contact glue them to the disk in 600, 1200 & 3000 grit. Tbey work really well but wear out after 10 minutes of use and a new pad has to be cut and glued on. I have also glue cirles of leather onto 4 of the disks and use diamond powder in 3000, 8,000, 24,000 & 50,000 for final finishing and polishing. The leather lasts a long time and only gets changed if it gets contaminated. I have used both diamond pastes and loose diamond grit and perfer the diamond grit. I have tried tin oxide etc on the disks with leather but results have been poor as i guess the tiny disks do not create enough friction.