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David G4EBT · 3rd Jul 2020, 10:34 am

Acetal (and polyester) is used extensively by pen turners and can, and is, polished to a high gloss.

Likewise, pens turned in wood and coated with medium 20 second CA glue ('superglue') can be/are polished to a high gloss. To remove all scratches that are visible to the naked eye it needs to be in stages to 12,000g. That isn't as onerous as it sounds because micromesh pads are used and it takes only a minute or two with each pad up to nine pads depending on how well the finish of the item is 'off the tool'. They're used wet and last a long time. (You can't miss out a grade as each one removes residual scratches from the previous one).

You can also get plastic polishing compound meant for the purpose.

You don't say what colour or dimensions your knobs will be, but pen blanks are usually 16mm diam (or square) and 150mm long so might fit the bill. They're not expensive but are generally mottled, though you might find a suitable solid coloured blank if you shop around. Turners Retreat at Blyth (near Bawtry) isn't too far from you Mick and are open so you could look at their wide range of blanks and choose something to your liking, but they do mail order too.

These are polyester blanks:

https://www2.theturnersworkshop.co.u...one-range.html

These are acrylic, and probably a bit too fancy:

https://www2.theturnersworkshop.co.u...ic-blanks.html

Countless blanks on ebay:

https://www.ebay.co.uk/b/Acrylic-Pen.../bn_7023468945

Micromesh polishing pads:

https://www.amazon.co.uk/Micro-Mesh-.../dp/B000H6EC4C

Plastic polishing compound:

https://www.amazon.co.uk/Plastic-Pol...2T3VQ73JBBAW3C

The smaller the diameter of any material turned on a lathe, to get a good finish 'off the tool' the faster needs to be the speed at which it's turned because there is so little material passing the tool with each revolution. On a woodturning lathe, acrylic (or wood) pen blanks are typically turned at 2,000 - 2,500 RPM, but metalworking lathes don't generally run at that speed, so the highest speed available is best.

Polishing is done at 100 - 250 RPM.

Without going too far of topic, as examples of the finish obtained with micromesh polishing pads and polishing compound, the pics below are of 'slimline' pens I've recently turned in wood, finished with ten coats of CA glue and polished to 12,000 G.

First pic: Ebony inlaid as a 'Celtic knot' with plastic veneer,
second pic: Laminated veneers,
Third pic: Walnut and plastic veneer in 'Celtic knot'.

Obviously no discussions on pens or turning, but I hope the info and links might help.

3rd Jul 2020, 10:34 am	#7
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,763	Re: Making new push buttons Acetal (and polyester) is used extensively by pen turners and can, and is, polished to a high gloss. Likewise, pens turned in wood and coated with medium 20 second CA glue ('superglue') can be/are polished to a high gloss. To remove all scratches that are visible to the naked eye it needs to be in stages to 12,000g. That isn't as onerous as it sounds because micromesh pads are used and it takes only a minute or two with each pad up to nine pads depending on how well the finish of the item is 'off the tool'. They're used wet and last a long time. (You can't miss out a grade as each one removes residual scratches from the previous one). You can also get plastic polishing compound meant for the purpose. You don't say what colour or dimensions your knobs will be, but pen blanks are usually 16mm diam (or square) and 150mm long so might fit the bill. They're not expensive but are generally mottled, though you might find a suitable solid coloured blank if you shop around. Turners Retreat at Blyth (near Bawtry) isn't too far from you Mick and are open so you could look at their wide range of blanks and choose something to your liking, but they do mail order too. These are polyester blanks: https://www2.theturnersworkshop.co.u...one-range.html These are acrylic, and probably a bit too fancy: https://www2.theturnersworkshop.co.u...ic-blanks.html Countless blanks on ebay: https://www.ebay.co.uk/b/Acrylic-Pen.../bn_7023468945 Micromesh polishing pads: https://www.amazon.co.uk/Micro-Mesh-.../dp/B000H6EC4C Plastic polishing compound: https://www.amazon.co.uk/Plastic-Pol...2T3VQ73JBBAW3C The smaller the diameter of any material turned on a lathe, to get a good finish 'off the tool' the faster needs to be the speed at which it's turned because there is so little material passing the tool with each revolution. On a woodturning lathe, acrylic (or wood) pen blanks are typically turned at 2,000 - 2,500 RPM, but metalworking lathes don't generally run at that speed, so the highest speed available is best. Polishing is done at 100 - 250 RPM. Without going too far of topic, as examples of the finish obtained with micromesh polishing pads and polishing compound, the pics below are of 'slimline' pens I've recently turned in wood, finished with ten coats of CA glue and polished to 12,000 G. First pic: Ebony inlaid as a 'Celtic knot' with plastic veneer, second pic: Laminated veneers, Third pic: Walnut and plastic veneer in 'Celtic knot'. Obviously no discussions on pens or turning, but I hope the info and links might help. Attached Thumbnails __________________ David. BVWS Member. G-QRP Club member 1339.