A lot of what we offer here on the “DIY” blog is material information; however, as the hobbyist, you actually have to cut, drill, and machine the plastic yourself. It’s beneficial to educate yourself on practical fabrication matters. Most hobbyists grow up working with metal and wood; however, industrial plastic is only usually encountered when one knows to look for them – usually when one is a teenage “DIYer”.

The prevalence of CNC machines in recent years makes machining knowledge even more critical. In the video linked below, Instagrammer Tom Zelickman educates on issues he’s had with machining plastics and how to overcome various challenges including his stressing about one “aggressively” machining plastics and cleaning them.

You can view the whole video on YouTube here:

Ultra-High-Molecular-Weight Polyethylene (or “UHMW” as it’s commonly known) is one of the most popular industrial plastics. Unfortunately, due to its well-known reputation, people overestimate the properties of the material and their expectations of it are, frankly, too high. The plastic hold poor tolerances due to thermal expansion. This means that the tolerances of a part when machined may be much different then when the part is actually installed.

In addition, the part’s geometry will change due to thermal expansion once installed. This has created an odd paradox – customers try to impress on us that somehow due to wishful thinking these poor tolerance holding properties of UHMW will somehow ‘not exist’ if we just hope they won’t. That statement may not make sense but it’s actually what we often encounter at Redwood Plastics and Rubber with customers. They dislike the wide tolerances of UHMW and ask us if there are ways to account for the thermal expansion issues in machining. We can mitigate some effects but expecting UHMW to hold good tolerances simply doesn’t work.

This short YouTube video highlights some issues with UHMW and serves as a good primer of the challenges you will face with the material.

 

For some reason PVC plastic, DIY, and summer seem to be a magic trifecta! The plastic is strong, commonly available, and easy to work with. It has a disproportionate number of applications in the DIY community due to it being such a commonly available pipe. What are not so common are videos as good as this one we’ve found! Unlike many DIY videos, this one states exactly how the project was made even down to specific measurements for the drill holes for the spray nozzles. The video also includes a life test and troubleshooting of what would appear to be a common problem. Once the project is said and done it appears to work marvellously!

Don’t take our word for it, see for yourself:

Redwood Plastics and Rubber, the sponsor of this blog, offers many resources on their website to help their customers work with plastic. Some of these charts and information are ‘overkill’ for what the DIY community really needs, however. In this case, more basic information is best. The good news is their website actually has a page that links to several sub-pages that give general information on fabrication and care for plastics. These guides include some of the most common plastics used by the DIY community: UHMW, acrylic, polycarbonate, and acetal.

You can find the guide and the link to the sub-pages here: https://www.redwoodplastics.com/tools-data/fabrication-machining-guidlines/

 

 

“So do you have any of that neoprene?”
From the DIY community that is what most plastics and rubber companies hear from a customer. You can’t really blame them, they don’t know about the different types of rubber and what they need for their application. In addition, people don’t want to sound “dumb” – they want to act like they know what they’re talking about and often “neoprene” is all they know. The best thing to do is phone your trusted plastics and rubber specialists, let them know about your application, and they’ll help you find the best material. Here is a primer of the commonly available rubber types:

Natural:

Just because it’s the “natural” grade of rubber does not imply poor performance! Natural rubber, in fact, has outstanding wear resistance and “Redco Safeguard” natural rubbers has excellent UV-resistance.

EPDM:
Commercial and premium grades have excellent weather resistance including UV-resistance. All Redco EPDM has excellent temperature resistance 220-250 F (depending on grade). Functions well as a gasket or seal, especially outdoors, but is weak to oil, gasoline, and other hydrocarbons.
NBR:
It is an economy grade rubber and has the advantage of price. This comes at the disadvantage of mechanical properties and chemical properties.
SBR:
An economy grade rubber that does in fact have good mechanical properties as well as wear/abrasion resistance; however, this comes at the cost of poor UV/weather resistance and resistance to oils, gas, and other hydrocarbons.
Neoprene:
Name recognition combined with a wide variety of “good” properties. However, it has limited performance in the cold, doesn’t excel at any one property, and depending on your application you may be needless paying for a higher grade neoprene that you do not need!
Other grades are available. If you want to get in touch with a rubber expert, please contact Redwood Plastics and Rubber.

One new DIY application that’s started popping up on the internet in the past few years is what’s called a “water table”. This a play table where water is sprayed from the top and drains through small openings on the base of the tray(s). The table allows kids to splash around or use toys in it yet is constantly replaced by new, clean, water. This project is indicative of the types of fun and simple-to-make projects you can do with PVC pipe and fittings. While we don’t have any designs to offer you, we do have a couple videos that will provide tips and inspiration!

 

 

One of the most requested acrylic fabrication techniques requested of plastic companies is bonding (or more correctly, “solvent bonding). This is a process that most people would consider “gluing” acrylic together but it really is a different process chemically. In the case of a glue, two separate pieces of plastic would be held together by the solidified glue itself. However, acrylic solvent bonding goes a step beyond. The solvent actually dissolves part of the acrylic turning it liquid at the point the bond occurs. When the acrylic re-solidifies it is now truly one piece. This solvent bonding, while obvious a better bond then glue, has different requirements but the good news is it can be done at home.

The video below is a great approximately 5-1/2 minute overview of solvent bonding and how to solvent bond acrylic. The video is detailed and we recommend you take a look as there is no reason this bonding cannot be done by the home hobbyist.