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.  You can simply save them to your computer using one of the links we provide - on the Order Received page, or in the Email Receipt we send, or by Logging in.

Overall, the process works well, 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 with instructions.  There are several ways to get to the links, and there are some hiccups that may cause trouble - especially if the computer isn't always your friend.


We understand, and we're here to help.  If the article doesn't get you there, let us know.  We take care of our customers.

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

  1. Costs for raw materials change all the time - Especially because of COVID.  For instance, steel prices fluctuate with markets and world demand.  That drives the cost of materials up and down locally too.
  2. The plans have options.  The options you choose will certainly affect the cost.
  3. There are many levels of components.  Cheaper parts will obviously make the project cost less than higher-end parts.  Choose parts to meet your needs, longevity desires, and budget.
  4. Some people have access to special deals, or even some free parts or materials.  Sometimes you can negotiate discounts in the purchase process.  It doesn't hurt to ask for a discount.

Though we'd love to tell you just how much, we 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.

A great question - we get a lot.  Here is the short answer in two parts.

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, options, and construction skill are beyond our control, we are unable to 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.  They will look at the material, the welds, and all details of how you customize your trailer.  It 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 must 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.

The full long answer is in this article about Certified Plans.

Most of our product pages in the Plans Store explain abilities needed to build the project.  For instance, it might say "Welding and Steel Cutting Required."  If you can do the things listed, then you probably have the skills to build the project.  And, there are always things to learn along the way.

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

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.

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.  There are a ton of settings – though many systems don't allow users to easily adjust them.

So, What settings should we use for translation output?  What settings will you use to read them?  How much responsibility will we have to diagnose issues and make sure everyone can read the files in their particular CAD system?

Then, the paradigm issues:  Which plans options do we include?  (Most of our plans have many options, some mutually exclusive.)  What options do we leave out?  What if we don't use the parts you would choose?  Or detail the purchase parts in the comprehensive way you want?  (Axles, hitches, lights, wheels, etc., and various options for each.)

Next, there are differences in expectations.  For instance, once in awhile I get and ornery note about our PDF plans saying I took shortcuts, like not modeling the welds.  Well, level of detail is an issue for some people.  How would that explode if 3D CAD were available?

This may sound selfish . . . Yet we decided a long time ago it is a whole pile of issues we are not willing to deal with.  I'm sorry, we don't provide or sell the CAD files.

What we do offer are the best plans available - including both drawings and instructions - with a lot of build options.  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 is 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 different sizes, types and configurations.  It's not complicated, but there are a few things to know.  Fortunately, the article "Trailer Axles 101" explains the details and 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 it, read the article comparing Springs & Torsion axles.  Then, Choosing Multiple Axles for Tandem and Triple axle combinations.

If you want something different, check out the Axle-Less Trailer Suspension or this simple Low Profile Suspension.

Axles in the Trailer Plans

Specifications for the necessary Axle size are contained in each set of Mechanical Elements trailer plans.  Also, axle differences and various options are explained.  Most plans have options for straight axles or drop styles.  Some plans also have options for capacity.

Axles are ordered by dimensions -- spring center distance, hub face distance, and capacity + the options.  Springs and hardware are usually sold separate, so we let you know what you need for that too.

While some vendors provide "standard" axles to fit typical mass produced trailers, or sell axle "kits" with THEIR choice of springs and brackets, it is more common to special order them in the size and function you want.  That is what I do and recommend.  Please don't confuse common sizes as being "standards".  In fact, when you see "standard" axles, it just means they ordered a bunch of axles at THEIR size with the options THEY want.

Because there are so many options, and to make sure your trailer is perfect for you, we recommend special order axles with the options you want.  Read this article for more about special order axles.

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 for suspension in all our plans.  Please don't substitute.  Especially, please do not use Torsion Axles in Tandem (or Triple).  Read this Article about Torsion Failures to learn why.

— With the above said, we do have Torsion Axle Conversion Plans available for some trailers.

Now, we recognize some of you will substitute anyway.  Read this example of Making Changes to the Plans.  One of the examples explains how to make the right adjustments if you really must make the change for a single axle.

Plans are available in the Plans Store 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 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 are higher toward the axle.

The ideal leaf spring has 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 leaves.

OK, that's a long way of saying it does not really matter.  Sure, there are some differences, but as long as the spring is rated for the load you carry, then a lot of leaves or just a few don't make much difference.

Many of you have asked for a long time, so finally this answer is changing to YES !!

Rather than making plans for a full tilt top trailer, we've created plans for a conversion.  You can now convert the plans of many of our trailer to be a tilt top.  Read this full article about designing for Tilting Trailers.

As time goes on, we'll add more to the list.

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 important, so we have articles about it.

We have the answers all spelled out on our Trailer Wiring Diagrams page with explanations on wire size, wire colors and choices for tow vehicle 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.  Here are a few articles about that might help to achieve it.

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

First, Yes, we do custom trailer design through our parent company Synthesis Engineering Services.

The cost for custom work is a function of complexity and the base for which we can start.  Custom projects range from a $500 USD for minor tweaks, on up to many thousands of dollars for completely custom big jobs.

For example, A Tiny House trailer design to meet your specific needs may cost $4000 USD, $6000 USD, or even more if it is big or complex.  Other specialty trailers are similar with prices going up with complexity.  It boils down to the amount of work required to achieve the result.  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 do Engineering and Design, and we make plans for DIY.  Trailers - and the other DIY projects - are here for you to experience the pleasure of building success.  There is a great pride of ownership when you build it yourself - especially when you learn some things along the way - 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 fabrication shop to assist.

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.