Matrax Aluminum Runner Sled Design and Precautions

This (RNZ) is the style that I have sold and used for around 25 years with Matrax runners.

RNZ 2716 is stainless steel 5/16-18 thread

QN 2716 would also work; it is a style with the 4 projections that distribute the load better than RNZ and I see now it is available in stainless as QNZ 2716.

QNM 080125 is the metric thread version, but no four tab metric *stainless that I can find here.

If the metric nut is used with 5/16-18 fastener the bolt/machine screw will jam as it reaches the bottom of the nut thread. If the fastener is exactly the right length to jam and clamp the assembly together there will be no risk of loosening. Similar for the corresponding metric bolt and 5/16 thread fastener.

How they should be used on Matrax aluminum runners:

The weld nut is installed with the nipple (dimension F) up in the lower track of the aluminum runner. The corresponding bolt or machine screw is attached through a hole in the web of the aluminum runner. If a new hole is drilled it must be done carefully to avoid nicking or gouging the load-bearing flange of the runner.

High strength aircraft alloy aluminum is extremely strong for its weight but is sensitive to cracking, crack propagation, and breaking at stress raisers: discontinuities, sharp corners, cuts and notches. Metal fatigue is an another important cause of failure in high strength aluminum after thousands or hundreds of thousands of loading cycles.

Cracks typically propagate under tension. In some structures a part of the material may be loaded only in tension or in compression, or there may be cycles of only stress or compression, or cycles of stress reversal, that is, alternating tension and compression. If there is only compression in an area or member of a structure that part can better tolerate the existence of notches, deep scratches or similar defects. So, an aluminum runner with a notch in the top/inside forward part of the runner curve or in the tail on top behind the foot board will be unlikely to break. Other low stress or compression-only areas can identified depending on the sled design and the loads applied/experienced. That is the field of stress analysis which in which I worked during my brief career at Boeing on the 747-C project.

*Read about the catastrophic De Havilland Comet aircraft disasters:

“Stress around the window corners was found to be much higher than expected, while stresses on the skin were generally more than previously expected or tested.[102] This was due to stress concentration, a consequence of the windows’ square shape, which caused levels of stress to be two or three times than that across the rest of the fuselage.[103]

The primary stresses/loads on a well-designed sled runner, wood, aluminum or any other material, are a result of bending when the runner is high centered coming over a bump on the trail, or bridging between two bumps. Under bending loads the inside surface layer or skin of the material being bent is in compression and the outside is in tension. Crashing into a tree or obstacle will also result in bending of the runner but other structure members such as stanchions that are truss elements experience axial compression or tension loads. Many fail at the attachments. A well-built sled with aluminum runners is most likely to have the runners permanently bent without any fracture/breakage.

The web of the runner profile is the unstressed neutral plane in bending up and down as well as sideways; it was designed for this, therefore holes in the web are not a problem. In the web of I-beams and similar profiles there may be large holes that are machined to remove unnecessary material and save weight. They are called lightening holes. The joke in conversation with non-engineers is that they are created to allow lightning to pass through.

The length of the bolt or machine screw is critical so that it is fully engaged in the weld nut but does not project so far through it to interfere with the plastic rail or the plastic runner dovetailed into the track.

It is safer to have/use a plastic strip between the angle or channel or other part attached on top of the runner and the aluminum runner top flanges. This will protect the stressed top flanges from damage from fretting and wear if anything loosens and moves under loads. It is not a good design to clamp a  straight length of angle or other stiff component on the top of a curved part of the runner. The only exception is at the front of the runner where there are no large bending stresses.

The nipple (dimension F in the diagrams) should be up and when tightened it will be pulled into the hole (23/64″ or 11/32″) in the web of the aluminum runner. The weld nut is deformed when sufficiently tightened. The weld nut will remain bent/deformed if the bolt/machine screw is removed; the weld nut will stay in place for repairs or replacement of parts attached to it.

It is possible that 8 mm metric thread fasteners can be used with the US thread 5/16-18 weld nuts. 8.8 is a harder stronger metric fastener. It would be ugly if the machine screw snapped off in the weld nut. High grade high strength metric or US thread (grade 5, grade 8) bolts/machine screws must be used that will strip out the weld nut thread (fail-safe mode of failure)  before they break.

Although the metric threads are not identical to US there is enough tolerance for the screw to fully enter the weld nut. It will be tight! Be sure that the tightness or torque used to tighten it is more than what is needed to overcome the misfit interference in the threads so it is also sufficient to clamp the parts together and avoid any movement in use/operation that could damage the flanges.

Another thought: If zinc or magnesium strip, tabs or washers could be attached in several places in contact with the aluminum runners that would serve to protect from corrosion especially in salty wet environments. Sacrificial anodes are used for this purpose in many marine applications (ship or boat hulls, outboard motors.) I have not yet found any good source.

See also:

Boreal Access Web Mailer

Racing Alaskan Sled Dogs, the book

The single review at is on target. Now in the Internet online booksellers era you can get your copy for the same price I paid when it was new: $8. I don’t see any copies of the WWII US Army Field Manual, Dog Transportation, that I reprinted the same year this came out, 1976.
Wow, 11 copies from $7.96!
5.0 out of 5 stars Mushing advice from several people who know their stuff, January 22, 2012
DJ “Donncadhf” (Sterling Heights, MI, USA) – See all my reviews
This review is from: Racing Alaskan Sled Dogs (Paperback)

This is a collection of articles by 23 mushers compiled by Bill Vaudrin shortly before his death in 1976. Many were the “Great Ones” back in the 1970s and here they tell how they do it. Often there are as many viewpoints as there are contributors.

Since there’s no peek available and no publisher’s description, here is what is inside:
Introduction by Bill Vaudrin
Early Day Sled Dogs by Robert Kennicott, H. M. Bannister, F. S. Pettijohn and Gus Jensen.
History of modern sled dog racing in Alaska by Earl Norris.
Breeding and conformation by Dick Tozler, Natalie Norris, Gareth Wright, Bill Taylor and Orville Lake.
Care and Feeding of Racing Dogs by Dr. Roland Lombard and Dr. Charles Belford.
Training Pups by Joe Redington Sr., Issac Okleasik and Orville Lake.
Training Leaders by Lloyd Haessler, Natalie Norris and Joe Redington Sr.
Training Teams for Races by George Attla, Shirley Gavin, Joee Redington Jr., Bill Sturdevant and Dr. Charles Belford.
Building the Sleds by Ed Moody, Darrell Reynolds and Nels Hedlund.
The Development of the Sport by Jimmy Huntington and Gareth Wright.
Famous Sled Dogs (brief bios of 18 dogs; Togo is here but Balto ain’t).
Race Statistics (for several races covering the period 1946-1976).
Glossary (of mushing terms).
Selected Bibliography.

Several black and white photos and illustrations are interspersed throughout the book.

Bought my copy back when it was first published and I’ve learned a lot from it. It’s sad that this book is no longer in print. I believe it belongs on every dog driver’s bookshelf; if you can get a copy somewhere, go for it.

Let Them Eat Dirt

Maybe it’s okay to let your toddler lick the swing set and kiss the dog. A new mouse study suggests early exposure to microbes is essential for normal immune development, supporting the so-called “hygiene hypothesis” which states that lack of such exposure leads to an increased risk of autoimmune diseases. Specifically, the study found that early-life microbe exposure decreases the number of inflammatory immune cells in the lungs and colon, lowering susceptibility to asthma and inflammatory bowel diseases later in life.

The finding, published today (March 21) in Science, may help explain why there has been a rise in autoimmune diseases in sterile, antibiotic-saturated developed countries.

To fully appreciate the value of this and similar findings it is important to understand that much of the damage and the symptoms of infections and autoimmune disease are the result of the immune response, somewhat like the damage done to your house if you went on a rampage to kill flies and mosquitoes indoors with a shotgun.

Psyllium and other dietary fiber sources

Update 4/25/17

stingingnettlewildfoodism   Plantago_major

Plantago/plantain leaf is more valuable for many purposes than the seed husk. Achtung! This is the vilified plantain weed which like dandelion grows in gardens, waste areas and lawns around the world, not the banana analogue growing in tropical climates.

This investigation shows that the P. major and C.
tetragonoloba contained important biologically active
compounds and P. major leaves had the highest total
phenol, flavonoid and tannin content. In addition, ethanol,
cold and hot extracts of the same plants showed
antioxidant activity, but the highest antioxidant activity
was found in ethanolic extract of P. major leaves .Also,
ethanolic extract of P. major leaves had the greatest
effect on tumor cell growth followed by hot water extract
of P. major leaves.

This website generated from three French high school students’ science project gives a good view of the medicinal “virtues” of plantain starting from its value to treat nettles sting. Here for the reductionist-minded a table of constituents and their properties:

Psyllium husk, the mucilaginous outer husk of a particular species of Plantago, is the most documented by scientific research for health effects and has been sold as a commercial product for many years under the brand name Metamucil in North America. Except for the capsules, the commercial products including the lower priced generic versions (Walmart Equate Fiber Therapy) are mixed with sugar, artificial sweeteners, and/or flavors. They are marketed to treat constipation, although psyllium has a normalizing effect rather than only laxative like some products not discussed here for that reason such as senna. $6 a pound is a reasonable price for psyllium husk from an herb store or an animal feed store. Compared to other specific dietary fiber sources psyllium is the most effect for the price (except where the fiber benefit comes collateral to a food source such as oats, barley, brown rice, cabbage…)

In herbal medicine these foods or supplements would also be classified as mucilage, demulcents, etc.

Herb suppliers like Mountain Rose Herb and San Francisco Tea and Spice sell many of these; price estimate per pound is given in parentheses.

Kudzu root, also know as the vine that ate Georgia. You think it should be cheap because so many people in the South would be happy to get rid of it.


Marshmallow root. Yes, there are real marshmallows; the roots were eaten similar to carrots or parsnips in ancient Roman times and the boiled-down thickened mucilage was mixed with honey and whipped up to make a medicine for sore throat and digestive problems.

Chicory root

Slippery elm bark

The following two foods also have good nutritional value as sources of protein and the omega 3 fat, alpha linolenic acid.

Flax/linseed has been studied for specific phytochemical or phytoestrogen effects. There is a small amount of cyanide in flax but has been shown to be harmless for normal consumption of cooked and raw seed. Flax must be ground to get the full nutritional benefit of the food. One or two tablespoons can be easily processed in a home electric coffee grinder. Larger amounts are a problem because the high oil content makes the meal stick to surfaces and gum up the grinder. I sometimes got around that by mixing in the grinder with a less gummy grain.

Chia does not have the bitter almond cyanide taste of flax

Nauseum, Add Psyllium!

Intestinal Bacteria Found to Protect Lungs from Infection

Graduate student Iris Pang (Immunobiology), working with former postdoctoral fellow Takeshi Ichinohe in Professor Akiko Iwasaki’s lab, has shown that helpful or, at worst, harmless “commensal” bacteria in the intestines actually play an important role in fighting flu infection in the lungs.

Her recent publication about this ground-breaking research in Proceedings of the National Academy of Sciences has attracted much attention in the scientific world and led to the publication of articles in American Scientist , Nature, and Scientific American.

Iris’ study is the first to demonstrate that commensal bacteria provide a signal to the body that prepares other organs, in this case the lungs, to mount an immune response against viruses. Antibiotics, which suppress bacteria in the gut, seem to impair the body’s ability to send those signals. The specific mechanism by which the microbes help mount an immune response is still unclear, but Iris and her colleagues suspect it might involve cytokines, cell-signaling protein molecules known to activate immune cells.

Parsley, Sage, Rosemary and Time for Essential Oils

In fact, a better list of useful herbal or aromatic oils would be Lavender, Wintergreen, Rosemary and Thuja.

Rosemary should be at the top of the list as an effective treatment for skin problems and muscle soreness. It is an ingredient of the commercial product Algyval at the level of about 10%. My impression is that the other ingredients are not active.

Lavender is a powerful antifungal. Both Lavender and Rosemary are not strong irritants and in many cases can be used directly on the skin without dilution.

A constituent of Wintergreen is methyl salicylate, related to acetyl salicylic acid, ASA, aka aspirin, the first commercial anti-inflammatory drug. Wintergreen oil should not be used internally and with caution on the skin. Salicylate the name is derived from salix the botanical name for willows; the original aspirin ingredient was isolated from willow bark. There are reports that  excessive topical use of methyl salicylate in a commercial counter-irritant like Bengay has caused death, but also that the synthetic form is a mixture of isomers different from those in the natural oil.

Breathing Wintergreen oil can help headaches and respiratory congestion.

Many of the home made foot ointments used and sold by sled dog veterinarians were concocted using as a base a commercial pink ointment with artificial cedar or Thuja oil and zinc oxide. There are warnings about Thuja oil; one constituent, thujone is also present in Wormwood and blamed for the toxic effects of Absinthe, although some believe that the primary toxin in Absinthe was alcohol and that when it was banned and replaced by Pernod or Pastis or other alcoholic drinks, the working men and their families for whom this done suffered no less than before.

Thyme oil is a strong irritant and I don’t know any uses that are not better fulfilled with something else.