Posts Tagged ‘uhmw’

BRAXX Anti-Slip Sheeting

Posted: December 20, 2018 in Uncategorized
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Ever worked on a home project where you need a rugged anti-slip surface? Could be stair treads, maybe the side of a pool, a deck or anywhere slippery. One option is BRAXX anti-slip sheeting for an application that does not require load bearing material, IE. you are going to simply screw, nail, or bolt the anti-slip surface into a substrate. BRAXX comes in a standard 3′ x 9′ sheet that is 0.30″ thick and this is the only size available. There are two options, a blue UHMW plastic with sand surface anti-slip buttons or the more popular safety yellow UHMW with LUNS (clean coal slag) anti-slip buttons. See picture below for detail of each. This product is very strong as UHMW cannot break and it was originally developed for military applications such as the floor surface of naval tank carriers.

The product cannot be ‘glued’ using a liquid adhesive. Mechanical fixation is required but there is no special hardware for this…Nails, bolts, screws, whatever you have lying around will work. UHMW is easily fabricated with power tools found at home. This is a premium product, you can expect a cost of approximately $600.00/sheet US funds before freight is factored in. However, for a premium anti-slip surface from the demanding DIY individual, it’s the best there is.

This product is available from Redwood Plastics and Rubber: http://www.redwoodplastics.com

For those not very familiar with plastics, it is sometimes difficult to tell the plastics apart. A plastic rod feels like, well, just plastic and we don’t consider sometimes the nuances of each material. One major consideration for those of us in the DIY community is how a material is fabricated or machined. Acetal is a very hard plastic and machines very well and can be held to tight tolerances (+/- 0.005″) whereas realistically (+/- 0.05″) is the best you can get out of UHMW in a DIY setting. UHMW is much softer and less dimensionally stable; however, it is slicker and more economical.

A short video on YouTube we found shows both plastics being machined and offers a comparison, take a look below:

Sick of cracked, rotten, and unstable wooden jack pads for your RV? Want to do a little project that will make you feel accomplished and provide a long-lasting solution? The good news is making your own plastic jack pads is an incredibly easy project that virtually any member of the “DIY” community can do! Fabrication of a couple pads for your RV should take 15 minutes or less.

What you will need to start:

-(1) 12″ x 24″ x 0.75″ (thick) piece of UHMW black-reprocessed plastic.

-(2) pieces of rope 1/2″ in diameter 12″ long.

-Table saw

-Power drill with 3/4″ bit. The bit should be at least 1.25″ long.

Instructions:

  1. Measure with a colored marker or tape the halfway point on the UHMW plastic. You want to simply cut it in half to obtain two 12″ x 12″ pieces. One of the pieces may be undersized but that is not important for this application.
  2. Cut the UHMW in half.
  3. Find the midpoint on each pad again. Mark it.
  4. On either side of your mid-mark, 1″ in, make two points 2.5″ on either side of that line.
  5. Drill thru-holes with your 3/4″ bit in those two marks.
  6. stick a piece of rope through the holes. Tie knights on each end wide enough that the rope cannot get pulled back through the drilled holes.
  7. *Optionally you can then cut the corners off the pads.

There you go, you have two jack pads that should last as long as you have your RV! Estimated cost per pad would be $35.00 including materials but they would likely retail around $70.00+ for an equivalent pad were you to buy them.

Let’s let the dreariness of winter pass for a moment with warm thoughts of Spring shall we?

Outdoor living areas are becoming more intricate and popular these days. What was once just a barbecue and some furniture is now a full living space, often with a complete outdoor kitchen and lounge, with a fire place and so forth. As outdoor spaces have grown, the plastics world has grown with them and we want to highlight two excellent plastics for outdoor living areas.

The first is HMW PE 500 where the letters stand for “high molecular weight polyethylene”. This food-safe white plastic provides an excellent cutting surface for your outdoor food preparation needs. Unlike UHMW PE, HMW PE 500 will not dull your knife blades. The product is available as standard in 4′ x 8′ sheets. If you don’t have a use for all of that plastic, why not cut some of the extra into cutting boards for friends or family?

The second plastic might even be more exciting. It is “wood grain” HDPE plastic. This UV-stable and wear-resistant plastic has a faux wood grain finish. Strong and long-lasting, it replaces wood with a low-maintenance alternative for a wide array of outdoor living projects. Example applications include counter tops, cupboards, table surfaces, tree houses, or virtually anything else you can put your mind to. The sheets are currently available in a standard 4′ x 8′ x 3/4″ (thick) sheet. Currently the only color is brown but tan and black are being developed.

For pricing on these products please contact Redwood Plastics and Rubber.

For members of the public PTFE (polytetraflouroethylene) and UHMW (ultra-high molecular weight polyethylene) seem to be very similar materials. They’re both white, soft, food-safe, and widely available from plastic companies. But are they that different? Oh yes they are! The first thing you would notice is the price. PTFE is literally in another category of plastics called the “high performance” plastics. This means the cost is going to be much higher than UHMW. So when do you need PTFE?

It would be an application where slickness is important above all other factors. UHMW, while less expensive, will outwear, outbear, and outperform PTFE in tough mechanical applications like homemade bushings, cutting board, etc. PTFE is very soft, so soft in fact it suffers from something called “cold flow”. This means that PTFE slowly creeps like a semi-solid liquid almost just sitting at rest in room temperature doing nothing. What PTFE does have in addition to outstanding slickness (low coefficient of friction) is that it takes very high temperatures up to 500 degrees Fahrenheit. UHMW does poorly in high temperatures and cannot handle more than 180 degrees Fahrenheit.

To be honest, in most DIY applications that call for a white plastic with balanced properties UHMW is going to be your go to. It’s too available, too cheap, and too balanced to go with PTFE. But in certain situations where very low friction is required (telescope mounts for example) or high heat will be encountered – PTFE may be your only choice.

For more assistance with your application please contact Redwood Plastics and Rubber.

Are you a “DIYer” who makes plastic bearings at home or perhaps looking into doing some? Not sure how to calculate a press fit or a running clearance for your bearings? Fortunately there is a useful tool available from Redwood Plastics available¬† on their website: the machinist chart for plastic bearings found here.

This chart provides valuable information for bearing manufacturing using Redco 750 or Redco nylon bearing materials. While many in the DIY crowd like to use UHMW polyethylene for everything, including bearings, this is not a good bearing material and has large and variable tolerances. The bearing chart is not intended to be used for UHMW bearings. Acetal is similar to nylon and therefore nylon’s values can be substituted directly.

UHMWPE (Ultra-High Molecular Weight Polyethylene) often abbreviated as “UHMW” is one of the most popular and well known industrial plastics. UHMW is seen as a “Jack of All Trades” in many applications while being more available and less expensive than other plastic options. While this is true to a degree, UHMW has limitations that means it will not solve all problems in all situations. In fact, it has some properties which make it deficient and the “DIY” community should keep this in mind.

When to use UHMW:

UHMW excels at taking impact and it is virtually unbreakable, it’s also very slick and the colder the operating temperature is, the better it performs. This is why UHMW is so popular in applications such as toboggans or as rails on sleds: impact + cold + slickness are all important to the application, and it does really well in this application. UHMW is also easy to work with as it drills, saws, and lathes well. It functions as wear pads, sliding blocks, fenders, and in other impact absorbing applications.

When NOT to use UHMW:

The main application we here at Redwood Plastics see UHMW incorrectly used in is bearing applications. UHMW is a poor choice as a bearing for two reasons:

1.) it is difficult to machine to tight tolerances (+-) 0.02″ are the best you can usually hope for and

2.) UHMW has low load bearing capabilities (500-800PSI). In a DIY bearing application nylon or Tuffkast will be superior.

The issue with tolerances is important to hit home: UHMW is not a dimensionally stable material. Not just compared to metals but even compared to many other plastics. We regularly receive drawings and requests for UHMW parts where we cannot quote based off the requested tolerances (or have to get a written waiver for acceptable tolerances). This lack of dimensional stability extends to thermal expansion and contraction which is why it is so hard to guarantee tolerances: if the part is manufactured in 30 degree weather but used in 90 degree heat the dimensions of the UHMW will drastically change!

We hope this points you in the right direction if UHMW is or isn’t right for your project. But if you have questions, or might be wondering what an alternative material could be, please contact us and we’d be glad to help!