3M Radial Discs.
Traditionally, jewelers used sandpaper, Tripoli, and rouge to polish precious metals. But in recent times, the development of abrasives has really taken off. As jewelers, we now have a bewildering array of abrasives and polishes at our disposal. But one has taken the jewelry world by storm- The 3M Radial disc.
3M have long since held a world-class reputation for industrial abrasives. But with the release of these tiny little discs, a whole new world has opened up to the jeweler. Giving us faster and cleaner ways of working.
So what are they?
The 3M radial discs are small, flat, flexible discs the size of a small coin, with multiple arms radiating out from the center in a spiral. They are made from a flexible silicone rubber type material which is impregnated with 3M abrasives. The discs are attached to a special mandrel and are used with a flex shaft or other rotary tool. They can be used to polish jewelry, precious metals, and other small components. Their main advantage is that they are used dry without any additional compounds or polishes. This means that they make almost no mess and there's no greasy polish to clean up afterward. This makes them ideal for small touch-ups and repairs, such a polishing a jump ring you’ve soldered; without having to refinish the whole piece.
Photo showing Dave Wilson demonstrating the 3M radial discs.
Note the picture inset showing 5 discs stacked together on the mandrel.
The discs are color-coordinated to match other products in the range. Starting with coarse grits such as brown 36, green 50, and yellow 80 which are good for removing tarnish, oxides, and light scratches. The yellow 80 grit is particularly useful as a first stage. Moving on, we go up through medium grits white 120, red 220, and blue 400. The blue 400 grit is a good medium pre-polish. Finally, they move to the thousands with Pink 1200, peach 3000, and light green. The light green is 14,000 grit with particles of 1 micron. This gives the finest finish and with careful use can achieve results comparable to traditional rouge polishing. This is great for small, quick touch-ups to already polished items.
Chart showing the range of grits and corresponding colors.
You must use the proper mandrels that come with the discs. The head of these mandrels are a little wider and larger, which gives support and a better grip. The screw is also longer than normal, allowing for several discs to be stacked up together.
Tip. To avoid constantly changing mandrels, it is recommended to purchase at least one mandrel for each color. That way you can quickly swap accessories as you move up through the grits.
Begin by selecting your chosen grit/color. You can use the discs individually, but it is highly recommended that you stack three to five to get the maximum effect. Ensure that all the discs are the same grit (color) and all new. Do mot mix grits and do not mount old with new discs. It is vital that they are mounted the correct way wound.
note they are all the same grit and in the same direction.
Insert the discs onto the screw, as shown, and screw onto the mandrel. If your mandrel comes with a small red washer, place this next to the screw head, first, to protect the top disc when you tighten the screw.
As you thread the mandrel onto the screw, the discs should rotate in the same direction. The arms should sweep backward, rather like a galaxy as it rotates. To fully tighten, insert the mandrel into your flex shaft or rotary tool. If you have a lock feature on your tool, apply it and use a small flat blade screwdriver to tighten the mandrel screw.
When you first activate your tool, just check that the discs are rotating in the correct direction. Your flex shaft must only be used in forward. Using reverse will cause the mandrel to unscrew. Likewise, if your discs are the wrong way round they will get damaged on first use.
Wipe the piece clean of any dirt, grit, polish, etc. Oxide and tarnish are fine, but If the piece is dirty and soiled, then any such particles will simply get dragged across the surface and may not give a good result. Do not use the discs to remove dirt and debris. Clean first with soapy water and a brush.
Likewise, if the piece has been pre-polished with Tripoli or rogue, clean the polish off as remnants of polish may clog the discs.
It is recommended to use the discs between 15,000 and 20,000 rpm. Excessive speed produces friction, heat and may reduce the lifespan of the discs. If you are using a Foredom flex shaft, about half power will be fine. Note. As always wear eye protection when using power tools
Click image above to find out more.
Pepe also offer a set of 3M discs ,mandrels and the Foredom H20 quick change handpiece. The perfect combination for fast and efficient polishing with your Foredom Flex shaft. Click image to find out more.
As you polish your piece, keep the discs moving across the surface, this will help to ensure a smooth and even finish. Too long in one spot, could eventually create depressions and unevenness.
Go lightly. It’s a well-used phrase, but a particularly important one. “Let the tool do the work”. Excessive pressure will only create friction, heat, and reduce the lifespan on the disc. As long as the discs are in contact with the surface, they will work. Light fingertip pressure is all that is needed.
As you change from one grit to another, work each successive grit at 90° to the previous one, this will help to remove the scratches from the previous grit and help to achieve a better finish. Wipe the piece free of any dust before commencing the next grit.
Click the image for more information.
The 3M discs are very tough. Especially in comparison to other similar brands, so they do last a long time and hence represent better value. You may observe that the coarser grits will wear down faster, whereas the higher grit polishing discs appear to last longer. As the discs wear, you should not see any difference in operation. The abrasive is impregnated throughout the entire material of the discs, so they will continue to polish as they wear. In all cases, the discs will get progressively smaller in diameter as the arms wear down. They may also become tarnished and discolored due to oxides and contamination. Ultimately, arms may start to break off as they wear down. At this point, you should remove and replace all the discs in the stack with new ones.
When you’ve finished with the highest grit, there is usually no cleanup required. A simple wipe over to remove any particles is sufficient.
Keep a good supply. There's nothing worse than running out of a certain grit part way through a job. So maintain a good supply and replace them as they get used. That way you are always good to go!. See Pepetools.com for the full range, and great value kits.
…don't forget your mandrels!
Written and illustrated by Dave Wilson www.celticdreams.co.uk
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