Making bearings at home with your own lathe is a classic DIY application, with UHMW, nylon, and acetal being the most common materials used. Sometimes though we neglect the basics just because we don’t think of them and press fit and running clearance on a bearing are two of those. A press fit takes into account the fact that a bearing is going to be pressed into an axle or shaft and therefore you need to ensure the outer diameter (“OD”) is slightly larger than its nominal design. This is because plastics are soft and with that slightly added diameter it can actually squeeze into the shaft. Of course, we’re talking about a truly slightly larger diameter – it’s not a big change.

Running clearance is just as important! This is over machining the inner diameter (“ID”) of the bushing to give a little extra space for the bearing to rotate. Not doing this or having negative tolerances on the ID could lead to the shaft seizing and that’s something nobody wants but it’s not something we always consider. How to know the press fit and running clearances for plastic bearings? Glad you asked – Redwood Plastics and Rubber offers a handy form you can download here.

Sometimes a DIY application’s requirement can be defined by purpose instead of any specific material. One requirement for certain applications is shock or vibration dampening to maintain the stability of the rest of the application. The key is you need a material called an “elastomer”. Elastomers are unique materials in that they can be impacted or compressed but will return to 90% of their original dimensions within a few minutes. The elastomers we will discuss here are rubber and polyurethane.

On the economy end of things rubber products are typical with natural rubber or all-purpose Neoprene being the most common materials. Widely available, cost-efficient, and easily fabricated into pads, gaskets, or rings these rubber products serve very well in everyday use. These products are available in sheet for and can often be purchased by the square foot.

For more aggressive applications polyurethane is used instead, in fact, Redwood Plastics and Rubber offers a polyurethane variety specifically designed for shock absorption called “Redco Deadplate”. This blue colored product can deaden incredibly high impact (it was designed to take log impact in sawmills). This product converts the energy of shock into heat which is then dispersed into the atmosphere. Redco Deadplate is cast-to-size and made to-order, and not cut out of sheet stock, so you will need to know the exact final sizes you need when you solicit a quote.

If you have questions about these elastomers for your application please contact Redwood Plastics and Rubber.

Previously on this blog we have been very specific to call plastic products traditionally called “phenolic” by the correct term of “Industrial laminate”. This is because many times customers call a laminate a phenolic when it actually isn’t. Phenolic is a specific type of resin system and only one of five primary resin systems used in industrial laminates. That said, one of the most popular and widely available industrial laminates used by the DIY community is called “CE grade laminate” or “CE grade phenolic” and, yes, in this case it is a true phenolic!

CE grade industrial laminate is a brown, extremely hard plastic with excellent physical properties. It stands apart from other plastics with its hardness, ability to bear load, and resistance to deformation. It also looks a lot like wood despite being significantly tougher and longer lasting. All these properties combine to make it formidable material in mechanical applications where it is destined. CE grade industrial laminate is used in DIY substitutions where high load strength, low deformation and precise tolerances are required. Some example applications DIY customers have used our CE grade industrial laminate for:

  • Sailboat mast stabilizers
  • Saw guides
  • Furniture feet
  • Work bench covers
  • Boat seating
  • Engine mounts
  • Equipment spacers
  • Circuit boards

Many applications requiring high strength will benefit from CE grade phenolic products; however, the one caveat is that working with it creates a lot of dust. You should wear eye protection and a dust mask while working with it and should have a dust removal system if possible.

For questions about CE grade phenolic, please feel free to contact us today.

A common question we receive is “what happens to my plastic when exposed to the sun?” This question comes from customers concerned about UV (“ultra violet”) damage to their application when exposed to the sun. As is typical, the damage depends on the type of plastic exposed and also where the exposure takes place – UV damage will be much greater in the Arizona desert than Alaska, for example. Therefor it’s impossible to give specifics on what damage will happen and when. In addition, the UV damage affects plastics differently depending on the type that is exposed. However, there are three generalities you can expect:

1.) Fading

Many plastic’s colors will fade when exposed to sunlight over a few years.

2.) Brittleness/Cracking

Most plastics exposed to UV light will become brittle and then show cracks of varying degrees. This is the most concerning damage that can occur to mechanical applications where the plastic bears load or performs a functional task.

3.) Bronzing

Glazing (“see thru”) plastics specifically will fade from clear to a bronze tint, eventually to the point that the plastic is no longer transparent.

So, when do you decide to invest in a UV stable plastic? First of all you need to temper your expectations. UV stability delays UV damage, it does not stop UV damage or otherwise make the plastic immune to UV exposure from the sun. Typically UV stable plastics buy you an extra 10 years of the plastic being unaffected by UV until damage slowly starts, one must see it as delaying the countdown, not stopping it. That said, certain plastics such as fiberglass reinforced plastic (FRP) will incur color fading but not take mechanical damage from the sun.

Where UV stability becomes an issue is when someone expects UV stability to be ‘forever’ or where distributors get told that a plastic must last several decades. Again, you must temper your expectations! However, if you have questions about the UV-stability of a specific plastic, please contact Redwood Plastics and Rubber.

3D printing is a booming area where plastics are used by the DIY community and it’s a topic we probably should discuss more on this blog. We’ve found a great video to start us off on YouTube! A channel several 3D printed wrench pieces and subjected them to a couple types of torque tests to see how they held up. The results were pretty interesting: ABS and Polycarbonate while rigid and held their form, broke catastrophically when the pressure got too high.

Nylon seemed to be the worst both with how soon it failed during testing but it was also soft and deformed quickly. The best plastic was clearly ULTEM, which while the presenter seemed surprised, is no surprise to us! ULTEM is a high performance plastic with excellent physical properties across most dimensions and we knew it would be the best before the test was even conducted.

Takeaway point? In a demanding application you need to consider high performance plastics. As the frustrating cliche so eloquently gets wrong, it’s not all “just plastic”.

Industrial laminates, commonly called “phenolics”, are a large family of plastic materials and one of the more confusing plastic types for the DIY community otherwise not familiar with plastics. The problem occurs when you have a project you think needs ‘phenolic’ and you walk into a plastic distributor asking for it by that name. They won’t know what you want, and even if they show you what you have on the shelf, you probably will just get more confused about getting what you need. Given that industrial laminates are such a wide family, it’s appropriate to define and drill down to what most people mean by “phenolic”.

An industrial laminate at its core is a plastic resin of one of five types: (true) phenolic, epoxy, melamine, silicone, or polyester – which is then reinforced by a substrate, typically cloth or canvas, glass, or paper. There are certain grades with more or less substrate so when you consider already five grades of plastic resin to bind it, there are hundreds of grades of “phenolic” available. So, how does one drill down to what you need?

The first and most accurate way is to find out what’s called a “Mil spec” which is what the U.S. military and others use to define industrial laminates. One spec for a common laminate, a true phenolic product called “CE grade laminate” is NEMA CE per MIL-I-24768 TYPE FBG. Were a plastics distributor brought that specification we would know exactly what to provide you with. Working on a DIY project, lots of our information comes from various online forums and it’s worth simply asking someone who has done a similar project what they used. If you cannot find a mil-spec, the next step would be to get a sample of what you’re looking for and bring it to the distributor for review. Some of the laminates, such as FR-4, are readily identifiable by their milky-green color, while others might not be – but it helps.

What is important is that unless you know your required product is a true phenolic, utilizing a phenolic resin, you shouldn’t call it that. Knowledgeable plastics distributors are geared to take requests literally and will default to a true phenolic product even though you may need a completely different industrial laminate for your application. We recommend you work slowly, consult with your distributor, and pull the trigger on a purchase when you’re fully comfortable that you’re getting the product and solution you need.

 

This is a really cool application for those of you DIYers that dream big. It’s a gentleman who looks to be located in Montana who designed and built a backyard hockey rink big enough for 3 on 3 “shinny” as it’s called. On a complexity scale out of 10 this one is probably a 9 as built; however, there are ways to simplify the application.

Firstly, building the lighting was an extra step where some adjustable tower torches might work almost as good for night hockey. Secondly, while we can appreciate what he did with his boards (especially the foam rim) you could just build with the HDPE puckboard plastic perimeter without the thicker interlocking plastic backing. Don’t get us wrong – having the backing is better and would result in a more structurally sound rink; however, it’s not required and this level of reinforcement isn’t common. “Puckboard” itself is available at many plastics distributors, ask for it by that name.

Perhaps the best touch is the hot water resurfacer used near the end of the video. This is an important component of a proper rink that may be overlooked by some builders. You can see the whole video below:

Buy Better!

Posted: January 2, 2020 in Basic Plastic Tips

Every once in awhile on this blog we like to educate our readers on how you as a hobbyist can be more efficient in your plastics purchasing. The idea is to get you the plastic you need at the lowest cost and like anything there are strategies to do that. Here are some tips to get the best deal on the plastic you need.

1.) Ask For Offcuts

“Offcuts” are pieces of plastic left over from fabrication jobs. Distributors who do fabrication work tend to have little pieces left over which just take up inventory space waiting for a future job to come in where they may be used. If you get in touch with a distributor, let them know the piece size you need but ask if there’s an offcut you can buy close in size. Any reputable distributor will be glad to check and they’ll price it for less than it would retail in standard sheet form. In addition, you might be able to get a higher grade of plastic for cheaper asking for offcuts! Just be aware that offcuts will not always be available though it never hurts to ask.

2.) Ask about a “generic” grade

Just like with other products, many plastics have brand names, which are more expensive than equivalent plastics from “generic” manufacturers. We can tell you the quality is almost always identical and you often cannot tell the difference even in how it looks. Often hobbyists hear brands such as “Delrin” on the internet or the DIY community and assume that’s what they need; however, that’s usually not the take! For example, “Delrin” is the brand name of a homopolymer acetal plastic. The plastic is called “acetal” not “Delrin”. If you get a quote on name brand “Delrin” it will likely be more expensive than generic alternatives. The best way to pose the question to your distributor would be “Can I get a quote on [brand name] or generic equivalent?”

3.) Do the fabrication work yourself

This might appear to be a no-brainer but it really isn’t! Even though we’re members of the DIY community and enjoy our home projects, lots of hobbyists ask for the distributor to cut their plastic to size or even engage in light fabrication. While the distributor will price you out on that – make no mistake, you’re paying for it. You may not realize that fabrication isn’t free yet also most plastics can be easily cut or fabricated at home with no special tools! Why waste money when you’re a hobbyist in the first place?

 

There are many assumptions people make with plastic and one of those is that the DIY community finds beautiful acrylic applications on the internet and thinks that acrylic “just comes like that”. Unfortunately, there is no “easy button” when it comes to acrylic – to make it look beautiful requires specialized techniques. In fact, most plastic companies will not provide these finishing services unless they’re an acrylic specialist. The disappointment often occurs when someone cuts into acrylic and finds the finish of the edges isn’t what appears on the internet. So how do you get that amazing edge?

Well, there’s two techniques only one of which we’ll cover today. To get the “smoked glass” effect you need to sand the edges; however, for the beautiful glass-like edge you need to do what’s called “flame polishing” which is exactly what it sounds like: you take a flame to the edge of the acrylic melting it and letting it reform in a glass-like appearance. Fortunately for most of us in the DIY crowd, home flame polishing where perfection isn’t required is easy to do and a quick run to a hardware store will give you all the “equipment” you need. We found a short video that gives some quick instructions on home flame polishing and you can view that here:

Do you like to look clueless and unaware?

Didn’t think so.

This is why so many customers trying to ask a distributor about a certain plastic or rubber get themselves into trouble. Being in the industry, it’s frustrating to see as we want what you want – success in your plastic or rubber applications. Errors in plastic selection or identification are more critical then many would think. After all, most plastics feel the same in their hardness and strength, right? Well…Getting it into an application might result in a nasty surprise. Despite how plastics or rubber may look or feel the same, the fact is their greatly differing properties could result in an under-performing application or even a failure.

So, in the case you’ve used a plastic or rubber in the past and need more of it, you need to make sure you request the right thing. There are several ways of doing this. Firstly, we’d recommend you keep the invoices for all plastics and rubber orders you make. The invoice will typically be detailed enough to identify the material. If you don’t have that, the next best thing would be to bring the distributor even a sample of your old material. They can either analyze it on site (sometimes) or send it away to get tested. That extra time and effort is worth it to avoid a failure!

You need to be aware that color does not equal type! It’s common when a customer doesn’t know the plastic they’re trying to purchase to tell us it’s red, or black, or brown, etc. This unfortunately does not identify the material – not only are many materials typically in those colors but many plastics can be supplied as custom colors which throws this option out the window as far as identification.

Rubber is an issue all its own. Most rubber is not colored and is black; however, this again does not denote the type of rubber or the grade. Many rubbers are available in inexpensive consumer grades as well as high-performing premium grades. As we joke internally, when you ask many customers what type of rubber they use the answer is “It’s flat, black, and stored out back.” More commonly, a customer will identify all rubber as “neoprene”. While neoprene is a good all-purpose rubber it has limitations and shouldn’t be assumed to work well in all applications.

The moral of the story is when it comes to plastic and rubber there is no shame in admitting you need help in identifying what you’re looking for. Ask an expert, don’t feel ashamed, and get the application right the first time.

SAMSUNG