When is it Safe to Customize the Plans?

At Mechanical Elements, we encourage customers to modify and customize the plans.  That’s how you build the perfect project.  So, what things can you customize?  And what shouldn’t?

Searching For The Perfect Plans

You’ve been thinking about this new project for a long time.  You want a specific trailer, and you also have some great ideas for customizing that will make it perfect.  So, you search the web and find some good things similar, but not exactly what you were thinking.  At this point you realize the best way to get what you want is to build it.  That’s a cool too, because DIY is awesome.

Trailer Blueprints - Customize the PlansYou then turn your attention to finding plans, good plans.  And again, you don’t find the perfect ones.  Which plans to buy?  You could just make do and settle for something available, but what if you customize the plans?  What if you buy some plans that are close, then customize them to exactly what you want?

Well, that could be a lot more work, and what if you make a mistake?  What if you modify something that shouldn’t change?

These are valid concerns when you customize plans, so let’s talk about what matters.  The important things versus where you are free to make changes.

When To Customize The Plans

Do-It-Yourself is the name of the game here at Mechanical Elements.  We know that every customer has a little bit different idea about what is perfect, so we encourage you to customize the plans to fit your needs.  However, we always want you safe, so this article is a guide to safe customizing.

Of course, are all our plans are fully engineered to meet and exceed the limits stated in the descriptions.  And, we know modifications to the plans can change the engineering, so it’s important to understand what areas can change, and what cannot.  Here are some guidelines to help you make the right decisions — and to help you avoid potential issues.

Adapting the Plans For Metric

We do get the question a lot about metric conversion.  Yes, you can customize the plans for metric dimensions – both for overall size, as well as for the material dimensions.  Please follow the other guidance on this page, then read the article about Plans in Metric.

For plans that use special beam shapes, like various I-Beam shapes, may require a little more research for beam substitutions.  Not all beams are available in every area.  It might take some time for a conversion, but you can certainly do it.

In your conversions, look for beams that are the same size or slightly larger.  Look for wall thickness that match, or are slightly larger.  That will make conversion safe.

Areas Requiring Strength

In some plans, like the Speakers, there is not much to require strength.  Modifications to those plans will not likely affect strength.  Yes, some changes can affect the sound performance – like if the internal angles or volume changes – but they won’t change strength or make it unsafe.

Gantry Crane Top BeamHowever, when we consider structural projects like a gantry crane, or trailer, strength is super important.  For a crane, beam and leg strength are critically important.  Changes to these parts can drastically affect load capacity and safety, so be careful if you wish to customize the plans in areas of strength.  Calculate Safety Factors for the modification, and make sure it’s good for what you are trying to do.  Often the right material size change can make a modification work.

These are two examples of changes – one that does not affect safety, and one that might.  In general, it’s fine to modify the plans in areas that do not affect strength.

For areas where strength is important, like in the gantry crane example, it is almost always OK to shorten the overall dimensions or reduce loads.  For a crane example, if the design is a 10 foot length I-Beam, it can safely shorten to 9 feet if that is what fits in your garage.

Shortening the beams, or legs, or trailer frame members, etc. is OK if:
  1. The beam type does not change.  (If it calls for a steel 3″x 3″ square tube with 3/16″ wall, please use a steel 3″x 3″ square tube with 3/16″ wall.)
  2. Beam overlap and support members do not change.  Please don’t change overlap of beams (like how much of the upper leg goes into the lower leg on the crane).  Please don’t change supporting members like gussets or axle mounting bars.

Basically the same is true for any structural members.

Some Plans Anticipate Changes

Gantry Crane Graph To Customize The PlansIn some cases, we know are areas where you might want to customize the plans.  In our Upsized Gantry Crane we have included this graph to help understand the practical limits for changes in length, height and beam type.  You can choose the beam size, load, and length that meets your needs.

Another example. Our Car Hauler and Deck-Over trailers include plans for ramps, for driving a vehicle up onto the trailer.  We know each owner will have different needs, so the plans include a chart showing ramp strength as a function of length and material type.  You can easily choose what ramps to make based on how you plan to use them.

One Big Area Of Concern

People ask a lot about changing the axle type – from a leaf spring type to a Torsion axle – for instance.  This has some dangers as pointed out in this post.  The forces from these 2 axle types are different, so the design must accommodate the differences.  Not that one is good or bad, they are just different, so we must handle the forces different.  (For this situation, we have Torsion Axle Conversion Plans which solves the problem without guessing.)

Other options like changes from a straight axle to a drop axle for lower trailer deck height (or vise-versa) really are no problem since the loading to the trailer frame is the same.  (Note that some accommodations may be required in axle length to fit properly.)

Customize Trailer Plans Length Or Width?

Another common question is about changing trailer width or length.  For example, you want a 4.5′ wide x 8′ long trailer.  You see our 4′ x 8′ trailer plans, but is it safe to add 6″?  For this we recommend the 5′ x 8′, then customize the plans by narrowing.  This will give a safe design.  (Just remember to shorten all the parts – decking, axle, cross members, etc., so it all comes together right.)

4x6 Off-Road Jeep Trailer BlueprintsHow about a Jeep example?  If you want a 4.5′ wide x 6′ long trailer, you might find our 4′ x 6′ Off Road Trailer Plans and think:  “Hummm, that’s close, but I want it wider.  Perhaps I could customize the plans?”

We don’t have a 5′ wide similar trailer, so the above technique of narrowing won’t work.  For this, think about how the width is used.  If the loads are not near the limit, just make the trailer wider.  If you’re not sure, then up-size the cross beams.  Some added info on How to Make A Trailer Wider might also help.

In this situation, the cross members are angle iron (1.5″ x 2.0″, the 2″ leg vertical), so increasing the angle iron from 2″ to 2.5″ will make the beam stronger for the increased width.  Alternatively, you could add more cross members of the original size to increase strength.

General Rules Of Guidance

This method works for small changes, but is NOT good for big changes.  In general, changes going narrower and/or shorter are almost always OK.  Changes up to 6″ wider and/or 6″ longer are also almost always OK.  If it’s bigger, like a foot, don’t do it.

Read more examples in the article ‘Making Changes to the Plans‘.  It’s an easy read with examples from customer questions.

Loading / Axle Position

Another common customization is building the trailer for the way you will load it.  In most cases, this simply means moving the axle to a position for stable towing with your specific load.  Please read this post about axle position for details.

We also wrote an introduction to trailer loading and the engineering.  That’s worth thinking about if you wish to change the trailer loading.

It’s not rocket science, but it does require some thinking and reasoning.  Also, this method is NOT good for big changes.  If it’s something small like 6″, it works great.  If it’s bigger, don’t do it.  Contact us and we’ll help you figure it out.

Customize The Plans For Function

Functional changes are much easier.  Functional things include details like how tall the sides are, where the spare tire is located, or the type of crane trolley to use.  Almost always, you are free to make changes in these areas without constraint.  Use your head, of course.  The kinds of trailer lights you choose and where you select to install them, for example, will affect visibility, hence safety when towing at night.

Trailer Blueprints Page ExampleMany of our plans include options that are, of course, ways to customize the plans.  Adding certain equipment or using options that fit your needs are a way of creating the perfect and unique project.  A lot of these options are listed in the product descriptions, or are shown in the product images.  Many are highlighted in the animations.  Incorporate them as you see fit — or modify the ideas to make options of your own.

Another popular change is that for an adjustable hitch.  That is certainly an acceptable change, but do be careful with implications of ingress angles, even if your trailer is not particularly low.

What About Conversion To Off-Road?

At Mechanical Elements, we do offer a few specific Off-Road trailers – Jeep trailers really.  But, that does not mean others cannot be converted to use off road.  If that’s what you want, we have a full article about making the conversion to offroad.

This applies to trailer plans from Mechanical Elements only please.  I can’t speak for other designers and what will work or won’t.  We know our plans are fully engineered tough, but many others are not.  Please read that article to know what we recommend as you customize our plans.

The Perfect Project

When you finish building, and when you’re satisfied with the work you’ve done, that’s when the project is perfect.  Whether you customize the plans or just build it as designed, it does not matter.  What does matter is how you feel about it, and how it works for you.

So go ahead, customize away.  This is your project, so make it right!  If you have questions, let us know, and we’ll be happy to offer suggestions.


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