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Old 2nd Jul 2020, 10:50 am   #1
vinrads
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Default Making new push buttons

I need to make some round push buttons for an American auto tune radio, I can get them turned, they have a rounded end ,I was thinking plastic , it needs to be hard so as to get a smooth finish ,any suggestions welcome, Mick.
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Old 2nd Jul 2020, 11:22 am   #2
GrimJosef
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Default Re: Making new push buttons

Do you mean smooth-matt, or smooth-glossy ? Not many plastics can be machined smooth-glossy. Acrylic (e.g. Perspex) can be polished glossy quite easily though, and there's a wide range of colours available. The downside is it's brittle and can be prone to cracking in use, especially if it's got machining stress left in it. Resins can be cast to a pretty good finish, but for that you need a mould of course.

Cheers,

GJ
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Old 2nd Jul 2020, 1:00 pm   #3
vinrads
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Default Re: Making new push buttons

Hi Smooth mat would be OK , I asked because I have found some plastics don't respond very well to sanding , Mick.
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Old 2nd Jul 2020, 1:46 pm   #4
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Default Re: Making new push buttons

Copolymer acetal is lovely to machine and can take on a good shine by merrily buffing with a soft cloth while on the lathe.
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Old 3rd Jul 2020, 9:52 am   #5
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Default Re: Making new push buttons

If you have an original you might try moulding and casting it with resin.
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Old 3rd Jul 2020, 10:07 am   #6
vinrads
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Default Re: Making new push buttons

I did think of that ,but the ones fitted were wooden replacements ,they have a hole down the middle, so I thought some rod turned in the lathe and drilled in the lathe was the way to go , some pictures of the complicated mechanism. Mick.
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Old 3rd Jul 2020, 10:34 am   #7
David G4EBT
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Default 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.
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Old 3rd Jul 2020, 11:06 am   #8
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Default Re: Making new push buttons

Good morning David , as usual you have come up with some good ideas , there are some lovely material out there , as for the colour I was looking for a brown /bronze ,the dimensions are eight at 12mm and eight at 9mm Thank's. Mick.
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Old 3rd Jul 2020, 3:57 pm   #9
David G4EBT
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Default Re: Making new push buttons

Three polyester options from Turners Retreat come to mind which might suit your needs:

1) 'Alternative tortoiseshell', which is 20mm diam x 140mm long:

https://www2.theturnersworkshop.co.u...ternative.html

2) 'Alternative horn', which is 20mm diam x 130mm long:

https://www2.theturnersworkshop.co.u...ternative.html

3) 'Briar', 20mm diam x 130mm long:

https://www2.theturnersworkshop.co.uk/briar.html

Not expensive at 2.25 for the first two and 2.45 for the last.

Polyester turns well with light cuts and sharp turning tools, and will polish to a high gloss if desired, but like any plastic, will tend to chip at lower speeds or too heavy cuts. The main problem with any plastics is that the waste comes off in ribbons so you can soon be festooned in it.

I appreciate of course that the micromesh pads and polishing compound I mentioned in me earlier post are expensive for a one-off project, but given that you need 16 buttons in all, and that they'll be a prominent cosmetic feature of the radio, maybe not that expensive per button.

Every success with it.
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Old 3rd Jul 2020, 6:04 pm   #10
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Default Re: Making new push buttons

For polishing look at "Nail Buffers" a bit of flat foam with very fine abrasive on each side.
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Old 4th Jul 2020, 6:46 pm   #11
David G4EBT
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Default Re: Making new push buttons

Gary Tempest - who will be well known to BVWS members - isn't a member of this forum but reads threads from time to time.

He spotted this thread and as he's a member of the American Antique Radio Forum he posted a query there in this thread:

https://antiqueradios.com/forums/vie...26870#p3226870

The responses might be of interest:

Quote:

The push-buttons can be seen here...

http://www.tubularradio.com/featuredtabletop.html

The small ones are like flat headed golf tees (pan-head in the world on engineering).
The larger ones are like organ-stops...

Renovated Radio sell some nice looking repros:

http://www.renovatedradios.com/productlist.php

Unquote.

But as Gary said in the ARF thread, with Customs duty, handling, VAT, before you know it, the best part of 80 is racked up.

Hope it's of interest anyway, especially the repro parts for American radios at the 'Renovated Radios' link.

The 1938 RCA knobs at the link below look identical to those used on some Portadyne radios.

In 2017 I needed two for a Portadyne 'Princess'. Couldn't find any anywhere so ended up using the one that I had to cast two replicas:

http://www.renovatedradios.com/product.php?product=222

Every success to Mick in his efforts with a such complex radio - not for the faint-hearted!
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Old 4th Jul 2020, 10:35 pm   #12
vinrads
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Default Re: Making new push buttons

Thank's again David ,looks like I need a rethink regarding the style of the push buttons it's nice to see what they looked like originally , I must say the repro ones don't look very substantial , I think I could live without the recess for the station names , the good thing is we have some measurements to work with , thank's again to David and Garry for doing the research , Mick.
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