Measuring instrument storage.

Almost certainly temperature swings Gray. Doesn’t have to be moisture in the workshop, wood ‘breathes out ‘ moisture as it warms up.
regards Martin

Some plastics are what's known as a hygroscopic material and can retain and release air borne humidity much like wood. So all plastics aren't created equal. And I have the exact same boxed set of Emco ESX 25 collets as you do Gray. I also remember what they cost almost 35 years ago. So I'd be quite upset having that happen. But my shop is climate controlled and I'm in a fairly dry climate area. So I've had no marking from the plywood they used. I think machining your own aluminum bushings for collet storage would be hard to beat. A fair amount of work, but there's no moisture issues and it's more than soft enough to not mark the collets.

Hi Pete,

You make a valid point and one which led me to choose ABS for my collet rack. This plastic being one of the lowest for absorbing moisture, and commonly available. The old RS catalogues here in UK used to have a very good page entitled the "Properties of Engineering Plastics". This told you almost everything you need to know about plastics. I have not looked to see if this page is available in their on-line catalogue. If it is then maybe someone could provide a link?

Regards

Gray,

Not had time to go through the entire list, so don't know if there's anything about engineering plastics - a better search facility would help - but this would be a start to finding RS Guides to various things.

Links to https://uk.rs-online.com/web/content/discovery/ideas-and-advice

Rob

Ultra high molecular weight polythene (UHMWPE) has notably low permiability to water and other vapours. Many plastics have quite high absorption and transmission of vapour. However, silicones including RTV are particularly bad, an order of magnitude worse than common plastics.

Edited By Macolm on 22/09/2023 15:01:10

I use IKEA chopping boards when I want machineable flat plastic. They are about 8mm thick from memory. SWMBO actually like going there, I absolutely hate it. The way they try to make you go through the whole store is maddening.

Chopping boards are generally made from the Ultra high molecular weight polythene (UHMWPE) mentioned by Macolm. Also useful as neutron moderators

Robert.

Edited By Robert Atkinson 2 on 22/09/2023 16:58:44

My son was quite shocked when I bypassed a large part of an Ikea store by nipping through the café.

George

Purely by coincidence it was announced after tea that I had to go to IKEA to look at a bed for #1 son. Talk about the outer circle of hell! I am going to do my utmost never to go again, but if I am instructed by senior management I'll take the dog, it will be good exercise for him. At one point I threatened to just follow the fire exit signs, opening the fire doors along the way, but was talked out of it. They should realise that their ploy of making you go through the entire store actually puts people off. I'd willingly pay extra to a normal department store where I can go straight to the bit I want, and then leave. I thought the Trafford Centre was bad, but at least you can escape.

There's some woods, glues and sealants that continue to produce acidic fumes even after fully curing. Oak is just one of those wood species that does. British or European oak may or may not be different than American, but I haven't checked there exact properties. Part of engineering is understanding the positives and negatives for anything that might be unfamiliar that your using. And yes like it or not, were not immune from having to know about those as well. Fortunately for us, the internet makes doing so fairly easy today. And the more you learn, the easier it is to understand what to look for and how to find it. There's no such thing as the perfect material, everything we have available will have built in compromises involved. About all we can do is chose something that has the least amount of those verses there expected life span and cost against what it's intend for or to do.