Product Spotlight: SBR 70

Posted: November 17, 2020 in Uncategorized

Today we want to highlight another product, this time SBR 70 rubber. SBR stands for Styrene-butadiene rubber and is essentially a synthetic alternative to natural rubber. It is made of up approximately 75% Styrene and 25% Butadiene. Styrene is a very inexpensive material and its large percentage in the product creates an inexpensive rubber. The product is popular for its low-cost and high availability.

It’s commonly used in tire type applications though they tend to be lower-duty types (for example aircraft tires are natural rubber, not SBR). SBR has similar properties to natural rubber but has limitations in some areas including heat-resistance (which often isn’t an issue in DIY) applications.

So, where do you use it?

If you need a light-duty, IE. typical of DIY, roller or tire application you won’t beat the price of SBR. In addition, it works very well as general purpose skirting or homemade gaskets. It is quite abrasion resistant and has decent flexibility at low temperatures, which is important to remember. It is also water-resistant which may be useful if you’re lining a trough or pond. Note that the product is not bio-compatible rated but may work well in a decorative pool.

For more information on rubber products download the Redwood Plastics and Rubber line card here.

Halloween Decorations From Recycled Materials

Posted: October 23, 2020 in Uncategorized

Something a little seasonal today…There’s a chill in the air.

We found a blog that lists a bunch of Halloween DIY decorations, many of them made from plastic, and all of them look either fun to create or look just plain good!

We’ll post a couple pictures below but you can read the entire article here.

Redco Acrylic is an attractive and versatile plastic used in a wide variety of functional and decorative applications by the DIY community. That said, it’s one of the less forgiving plastics to work with and mistakes can lead to a poor surface finish or even the sheet cracking. While it’s impossible to ensure nothing ever goes wrong, we’re offering some best practices to minimize damage and maximize the chances of a successful project!

One issue people run into with acrylic is cracking the plastic when drilling holes. While this is a risk, it can be mitigated by placing the holes at least 1″ in from either side of the sheet. More is better, if you can work with a design that can place holes 2″+ in on either side of the sheet, that is best. Another issue is cutting the plastic with a saw. Many people look up beautiful acrylic applications and objects on the internet that can only be described as “art”. However, in order to fabricate these pieces – sorry to say – takes professional skills and equipment you will likely not have. If you keep expectations in check; however, there are many DIY guides on YouTube for techniques such as flame-polishing, which is necessary to give the cut edges of acrylic a nice “glass-like” look.

Bonding acrylic is easier, though also unforgiving. There is not actually an acrylic “glue” but instead you solvent bond acrylic. What’s the difference? Solvent bonding actually chemically melts part of the acrylic which then re-hardens when the new piece is joined to it. This creates a very solid permanent bond; however, where the solvent touches will also create a permanent “stain” or “etch”. Similar to if you accidentally spread super glue on a surface where you don’t intend to. Acrylic bonding agents are widely available for purchase online.

So far this sounds like a bunch of warnings against acrylic fabrication but that’s not our point! Acrylic is a sturdy, beautiful, naturally UV-stable plastic that is versatile in so many applications. However, where people get disappointed with acrylic is 1.) unrealistic expectations based of projects they’ve seen online and 2.) making fabrication errors we’ve hopefully covered solutions for today.

If you have acrylic related questions feel free to contact us.

 

 

We have a saying at Redwood Plastics and Rubber that many customers know the rubber they use as “flat, black and stored out back”. To many people rubber is rubber and it’s all essentially the same. However, outside of the most rudimentary applications, that’s a dangerous assumption that could lead to premature failure in your application. in fact, many rubbers are “black” in color but have different properties – everything from chemical resistance, to operating temperature range, weather resistance, and, of course, price. The key is to match up with what you need. Not all rubber is covered in this short primer but the rubber most likely to be used by the DIY community is.

Natural Rubber:

This rubber type is typified by abrasion-resistance and in non-DIY applications is commonly paired with abrasives, especially in the aggregate or construction industries. The limitation of the rubber is that it typically does not have good weathering properties including resistance to UV.

EPDM:

Excellent resistance to bursting and pressure, EPDM works well as a gasket and premium grades can handle temperatures up to +250 degrees F. However, it is weak to hydrocarbons and oxidizing agents.

SBR:

Decent abrasion and impact resistance but is primarily known as the most economical grade of rubber. Good in applications without demanding requirements.

Silicone:

Excellent properties over a wide temperature range up from -76 F to +440 F. Is available in food-grade white or blue. Excellent release for materials paired with it.

Neoprene:

The “jack of all trades, master of none” rubber. Neoprene offers balanced properties in many applications but does not necessarily excel. The commodity grades can have poor resistance to some chemicals and the premium grade has reduced properties in temperatures below -15 degrees C.

As we mentioned there are other types of rubber available; however, the types listed above constitute the majority used in DIY applications. For assistance with the selection of your rubber please contact Redwood Plastics and Rubber. For a a PDF copy of Redwood’s excellent rubber line card, click here.

One of the easiest DIY applications for performance plastics is food grade surfaces, especially for outdoor kitchens. Several plastics are available that are compliant for direct food contact, with the ones you’re most likely to encounter being HDPE, UHMW(PE), and natural nylon. Specialty “cutting board” grades of HDPE in particular exist; however, for a DIY application you shouldn’t need to go that route. The question is – what to use when?

Unless you require a very hard plastic natural nylon is the most expensive of the three options and as a cutting surface is probably “overkill”. As a note, where nylon would be best is if you’re making a food grade part. Nylon will hold better tolerances and its hardness would benefit as say some sort of paddle or roller. In regards to choosing UHMW or HDPE for your cutting surface? Well, it depends really what that surface will be used mostly for.

For horizontal abrasion, such as using steel wool frequently to descale fish or perhaps skinning game, then UHMW would be superior. However, UHMW is so wear resistant it will eventually dull knife blades over time. If all you’re doing with your board is cutting or chopping, then HDPE would be superior as it will not dull blades. There is a trade off; however, in that HDPE is much less wear resistant than UHMW!

For assistance with your application or if you have questions on plastics available for outdoor kitchens, please contact us Redwood Plastics and Rubber today.

 

We found a pretty neat video on the YouTube channel of “Atomic Shrimp“. He previously made some homemade HDPE plate (though “plate” may be a stretch) from old milk jugs and other household HDPE items. In this video you see him cut out a pulley blank from the plate then machining it to specifications. Not too many tools are required and the ones that are needed should be owned by most home hobbyists. We like the simplicity of this project and how the techniques would be relevant to making pulleys from UHMW or other plastics.

What we would caution is that HDPE and other polyethylene plastics are quite soft and Atomic Shrimp’s keyway in the center of his pulley would not hold up to a lot of torque. However, for his Lego application it’s probably fine. Nylon plastic or nylon with a metal hub (in heavy duty situations) would be the way to go when the shaft going through the center is keyed and the pulley is driven.

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.