Frequently Asked Questions . . . FAQFrequently Asked Questions @ Mechanical Elements

The best customers are the ones that ask questions.  So, along with all the articles in the The Mechanic’s Post, here are several answers to some common questions.

We understand that many questions are specific, and some answers just spon more questions.  If that’s the case, please Contact Us, and let’s talk about it.

After you purchase plans, they are immediately available for you to download.  We think the process is good, but occasionally we get questions wondering where are the plans?

If you have placed an order, but have not yet downloaded the plans, then definitely, read the full answer about downloading plans.  There are several ways to get to the links, and there are some hiccups that can cause trouble -- especially if the computer isn't always your friend.


This is a question we get a lot, but it's kind of an impossible answer.  It depends on choices you make when building.  Here are some reasons for saying that:

  1. Cost of raw materials change all the time -- Especially because of COVID.  For instance, steel prices fluctuate with markets and world demand.  We can't guess what the cost is for you.
  2. The plans have options.  The options you choose will certainly affect the cost.
  3. There are many levels of components.  If you buy cheaper parts, it will obviously cost less than if higher-end products are purchased.
  4. Some people have access to deals or even some free parts or materials.  We don't know what discounts you might negotiate in the purchase process.  Always ask for a discount.

Though we'd love to tell you just how much, we just don't have enough information.  Follow this link to read more about the Cost To Build including ways to save money doing it.

All the plans at Mechanical Elements are fully engineered at Synthesis Engineering Services, Inc. -- an Engineering Services Company in Colorado Springs.  Read more on the About Us page.

Another good question we get a lot -- with two parts to the answer.

First, the plans are fully engineered at Synthesis Engineering Services, and products made from them will perform as stated -- when built as defined with proper materials, skill, and care in construction.  Because materials, component choices, and construction skill are beyond our control, we cannot provide an advance certification.

Second, in most jurisdictions, certification comes after construction is complete -- when the trailer is inspected for road worthiness and adherence to local laws (axles, tires, lighting, wiring, chains, etc.).  They inspect the actual trailer, not the plans.  The trailer is "Certified For Highway Use" by the inspector.

Side Note:  For tiny houses, we recommend that you do the trailer inspection and get it licensed before you build the house on it.

In summary, the plans do not have a DOT or other government certification, because your build quality, your options and components will all go into the final inspection.  That inspection, for most jurisdictions, is the point of certification.  Build the trailer well, and you won't have any trouble with inspection.

Each Product page in the Plans Store explains abilities to build the project.  For instance, it might say "Welding and Steel Cutting Required." If you can do the things listed, then you have the skills to build the project.

One note, however. Some of our projects require welding that is critical to safety.  Please assure that you are sufficiently qualified in welding, or take those portions of the project to a certified welder.  We don't want you or anyone else hurt due to build problems.  Thank you.

Also to help you build, and to answer other questions, we have a whole library of tips and helps from the mechanic.

I'm sorry, we don't have plans specifically designed with metric dimensions or for metric materials.   That would be wonderful, we agree, but that's a bit harder than it first sounds.

The biggest reason is that different materials are available in different parts of the world.  Certainly it would be a ton of work to make several versions of the plans with materials that are easily available in each country.

Read more in our article about DIY Plans in Metric.  There is always more to it than meets the eye.  Though it's a great idea, we just haven't done it.

There are issues with CAD files not immediately apparent.  The most important --What CAD to provide?  DXF's of the drawings?  3D's maybe?  But in what software?  And for what version?  Are we responsible if files don't load properly in your CAD?  Sure, translations like IGES or STEP usually work, but not always, and not in every system.  What settings do we use for translation?

Then, the paradigm issues.  Which plans options do we include?  What options do we leave out?  Or, What if we don't use the parts you'd choose?  Or detail the purchase parts in a comprehensive way you want?  (Axles, hitches, lights, wheels, etc..)

We decided a long time ago that we're not going there.  I'm sorry, we don't sell the CAD files.

What we do offer are the best plans available -- with lots of details and options -- including both drawings and instructions.  They come in PDF, which is readily viewed with Adobe reader.  Other readers usually work too, but we know they open with Adobe, and that's free for everyone.

Best of luck with your project.

For this question, like the one above about cost, it's kind of an impossible answer.  It always depends, and here are some reasons for saying that.

  1. We do specify certain materials, but there are also material options.  Choices change the weight.
  2. The plans have options.  The options you choose will certainly affect the weight.
  3. Most of the plans descriptions have a weight range for the base trailer.  That gives some idea, but again, see the two points above.

These kinds of questions are tough because they deserve and answer, but until you build with the options you want, it's really only a guess.

This is a great question with one simple answer, which brings up a ton more questions.  The easy answer is No, these are not designed to be made in Aluminum.  So, the obvious questions are "Why Not?"  "Do you have any plans for trailers in Aluminum?"  and many more.

All of these questions deserve good answers, so here are 2 articles that discuss the topic in a lot more detail.  First, Advantages and Disadvantages of Aluminum for trailers, then the second article, "Why No Plans For Aluminum Trailers?"

Enjoy the reading.

Trailer axles come in a lot of different sizes, types and configurations.  Overall it's not that complicated, but there are a few things you should know.  Fortunately, the article "Trailer Axles 101" explains the details and also gives lists of things to consider when shopping for an axle.

While there are many types, the article focuses on the two most common -- Leaf Spring style and Torsion.  For more about that, read the article comparing Springs & Torsion axles.  Then, Choosing Multiple Axles for Tandem and Triple axle combinations.

If you want to explore a different axle style completely, please check out the separate article discussing Axle-Less Trailer Suspension.

Axles in the Trailer Plans

Axle sizes with details to order the correct parts are contained in each set of trailer plans.  Most plans have options for straight axles or drop style.  Some plans also have options for capacity, so the axle differences are explained for available option.

If available, torsion axle specifics are in the plans as well.  If you have any questions while building your trailer, please ask.

A great question.  In fact, that question is so important, we wrote an article about it -- including the engineering equations you'll need to calculate it.   (It's not that hard).  Please read  Where Does The Axle Go?  and get it placed right.

That first article wasn't quite enough (or we missed some things when writing it), because we've had even more questions on the topic.  That stimulated the second article "Calculating Axle Position".

The first has a focus on building a new trailer, and the second is more about existing trailers.  We hope you will take some time and read both.

Torsion axles apply forces to the trailer frame in a little different way than leaf springs.  (Read about selecting axles.)  Both types work great, but because of the differences, we design trailer frames specifically for the type of axle.  You can see the specification in the trailer plans description.

We recommend that you follow instructions about using either Leaf Springs or Torsion axles in all our plans.  Please don't substitute.

That said, we do recognize some of you will substitute anyway.  Read this example of Making Changes to the Plans.  On of the examples explains how to make the right adjustments if you really want to.

Plans are available in the shop for both Leaf Spring style axles and for Torsion Axle trailers.

These terms, "Overslung" and "Underslung", are descriptions of how springs are attached an axle.  Basically it's attaching the springs above (over) the axle or below (under) the axle.

Usually these words reference leaf springs, but the they also apply to some other styles.  For pictures and a much more complete explanation, read the post on Overslung and Underslung axle springs.

Great question.  Some stacks have many, and some have just a few -- or maybe even just one.  Normally the leaf stack is made to vary the stiffness of the spring as it gets closer to the axle.  That's because the bending moments get higher toward the axle.

The ideal leaf spring is a continuously changing section from thin at the pivot with the frame, to thick as it cross the axle, then back to thin at the other end.  However, that is a expensive, and it doesn't provide some of the natural hysteresis of multiple leafs.

OK, that's a long way of saying No, it does not really matter.  Sure, there are some differences, but as long as the spring is rated for the load you intend to carry, then a lot of leafs or just a few don't really make much difference.

This question is related to the one above about trailer axle position.  And, we have an article about Choosing The Right Tongue Length to answer the question.  We recommend using both articles to select the right balance of both for the best, most stable trailer towing.  Good luck with your project.

Need help with wiring diagrams for your trailer?  Not sure about what connector to use or how to wire the lights or brakes?  Electrical questions are common.

We have the answers all spelled out on our Trailer Wiring Diagrams page with explanations on wire size, wire colors and choices for connectors.  Also, this short article about trailer lights and wires tells more about routing, splicing and other details.

The Frame is the base of the whole trailer, so make it right first, and that helps everything else.  It is important, so we have a few articles about just that.

  1. Start with "How To Set Up A Trailer Frame Build".
  2. Next, read "Tips To Strengthen A Trailer Frame".

First of all, yes, we do custom engineering and design.  Our parent company is Synthesis Engineering Services.

Cost to design is obviously a function of complexity and the base for which we can start.  Our custom projects range from a $200 USD for minor custom bits, on up for complete new plans.

For example, A Tiny House trailer design to meet your specific needs is likely to cost something in the $3000+ USD range.  Other specialty trailers are similar with prices going up as complexity rises.  That said, the best way to find out is to ask.

Another good resource for information is the Case Study of Custom Trailer Design from Synthesis.

Yes, we now have plans for the smaller trailer "Walking Beam" style suspension that includes tandem torsion axles.  Plans are available in 2 sizes:

  1. A 2000# up to 4200# version.  (Capacity set by the twin axles combined capacity.)
  2. A 5000# up to 8000# version.  (Capacity set by the twin axles combined capacity.)

For explanation about the suspension and tips to build it, check out the Walking Beam Suspension For Smaller Trailers article.  Then, to see the suspension in action, watch the video here.  Enjoy.

We are in the business of Engineering and Design.  Trailers -- and the other DIY projects -- are there for you.  That said, we want you to experience the pleasure of building success.  There is a great pride of ownership when you build it yourself -- even if it's not absolutely perfect!

Though we do build things frequently, we are not a fab shop so our work is not as fast or as skilled as a full-time fabricator.  If you want help, we recommend finding a local, skilled shop.

More Questions?

Questions are good, and we’re listening.  Please feel free to ask them by visiting our Contact Us page, and we’ll respond as quickly as practical.

Also, if you have something to contribute, we’d love the input.  Again, use the contact page, or leave a comment below one of the articles, or submit on our Customer Stories Submission page.

Thank you for visiting.