Instructables
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This instructable will show you how to create a deck plate and sides for your Harbor Freight utility trailer frame. While this example is for the model/item no. 42708, the techniques may be applied to all models, with appropriate dimensional revisions.

Materials needed:
Harbor Freight trailer
1/4" Diamond plate x 41" x 48"
(12) 1" x 4" x 8' pressure treated boards
(40) 1/4" x 2" galvanized carriage bolts
(8) 1/4" x 1" galvanized lag screws
(8) 1/4" x 1-1/2" galvanized lag screws
(56) 1/4" galvanized washers
(48) 1/4" galvanized nuts

Tools/equipment needed:
Waterjet CNC cutter
Miter saw
Drill press
Drill
Socket wrench
Large bar clamp
C-clamps
Carpenter square

Step 1: Deck

This trailer had previously been assembled, painted black, and had a plywood deck installed, so the first step was to remove and discard the old plywood.

The frame rails are assembled with three hex head bolts on each side. These will be used to fasten down the new deck plate. Also, the wood side stakes fit into slots in the side and end rails, so measurements need to be taken for the overall deck width and length, locations of the bolt holes, and size and locations for the stake slots.

If you are using the model 4278 trailer frame, you may download our .DXF file

Using the Flowjet (Waterjet CNC cutter) cut the deckplate from 1/4" thick aluminum diamond plate. The Flowjet allows you to "drill" all of the mounting holes, as well as cut the overall shape, including the stake pockets. (see attached videos)





Attach the deck plate using the 6 stock hex head bolts along the frame rails. You may also add additional bolts in the center of the end rails and center cross member.
 
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cglaw20131 year ago
outstanding
weldor2 years ago
As scary as it may seem to some, I have been cutting Aluminum using a CARBIDE blade on either a circular saw or my table saw for years. You can also clean up the edges quite nicely using a carbide tool bit in a router.
For those that question the validity of these techniques I would like to point out that your "typical Aluminum is softer than a lot of hard woods that are cut/shaped with these same tools. Remember to follow ALL shop safety practices when using power tools. Especially eyes and ears (Incredibly loud and lots of chips.)
skylane weldor1 year ago
Me too.
I've used my miter saw to cut aluminum and copper tubing on numerous occasions.
The first time, I was thinking that I was just saving time and thought at the price of the blade... "what the heck". The blade just didn't seem to care.
The carbide blade works ever so nicely.
l8nite2 years ago
no tailgate ? maybe it's just my old back talking but it looks fairly deep to load or unload heavy objects over the sides, other than that it looks really nice
danzajax l8nite2 years ago
I agree. All that effort and not an easily removable rear gate?

I would have made the rear gate latch in place with butterfly latches or draw latch. Hinge the bottom and reinforce the timbers from the backside. Instant foldown ramp. Just makes it more practical for moving lawn mowers, carts, anything on wheels.

Nice build! Lets see a folding tailgate now!
lime3D (author)  danzajax2 years ago
Don't need it, don't want it.
lime3D (author)  l8nite2 years ago
Nope, its only 17-1/2" deep. I hauled a full load of patio blocks last weekend, no problem.

However, since each side is only held by 2 lag bolts at the bottom, and 2 at the top, you can take off any or all sides with a socket wrench in about a minute.
chancefour2 years ago
I really like the look of your "new" trailer. I would have to use pressure treated plywood for the floor. I wish I had the plazma cutter ... but not now ... most likely not ever. I question the use of lag bolts for corner stability. I feel the thread grip on wood can't stand up to the sway, vibration, and jolting a small trailer gives such a joint. I would substitute a 2 X 2 placed all the way down the inside corner with bolts and thread lock nuts through all the 2 X 2, side, and end boards for true stability. If that wasn't something someone would like to do, I would at least put a properly sized metal corner bracket on the inside of your wooden triangle and use a bolt and thread lock nut with washer ... slightly recessed ... on your wooden triangle for extra strength. Just thoughts ...
lime3D (author)  chancefour2 years ago
This first time I used it after the 'finishing' was to haul a full load of patio blocks from the big box retailer to home. (This is why I made this.)

It worked perfectly.
Real pretty.....but to what purpose? That 800lbs load rate on the tires sounds like a lot until you start carrying stuff around. Solid wood walls might be good to keep in your pig but they are definetly not aerodynamic and deadheading all that weight in these oh so cheap gas prices time does not bode well for your pocketbook LOL
I went with 2X12 oak flooring(no frame wracking now) and eight 2X4 X4 pine stakes with a 1/2X4 pine half way up and another along the top.Then stapled plastic garden fencing all the way around for the 'walls'. Rear gate was easy too.Cut the 2X4's at 45 degree angle about three inches up from floor then use six inch strap hinges to put them back together.Makes a nice load ramp for lawnmowers etc.....
lime3D (author)  prince-of-weasels2 years ago
This trailer frame is by definition, 'light duty'. It is not intended for heavy loads.
actimm2 years ago
Just a couple of comments.

First of all, I noticed in Step 3 you show the Lag Bolts as being put in with the button head on the outside. While that makes for a pretty appearance, when I built mine I put them on the inside to prevent me from scraping up the back of my hands, arms, and stuff in the trailer on the end of the bolt.

Second, my trailer has 3 hasps at each corner with a long rod running down through all of them so they are easily removable. It allows me to take off a side or end for loading but still keeps the rest of the walls intact. The hinge base is on the side and the loop is on the end so that the hasp wraps around the corner and holds everything in place. Since I fold mine up and store it in a corner of the garage when not in use, it is very convenient. It also allows me to take the sides off without the use of tools when I need to.
I had the 4x8 model that folds in half. We made sides that were very similiar to this. The 8' sides we made with two 4' sections so they were easy to store when the trailer was folded. I was driving a Jeep Wrangler at the time to they were perfect together and fit nicely in the garage.
veryken2 years ago
The CNC cutter is, of course, impressive, especially on 1/4" thick aluminum. I'm only confused by your wood. It looks like regular kiln-dried 1x4 pine or hem fir (or even generic "white wood"). Pressure treated would instead look dark red or dark green and usually done on 2x (reads "two by") stock instead of 1x stock (note that dimensionally calling it 1" x 4" x 8' is extra confusing if it's not 5/4 stock planed to those dimensions). So was it a special colorless pressure treating process at your workshop?
lime3D (author)  veryken2 years ago
Not all pressure treated lumber is red or green. The boards are 1" x 4" x 8' as I described:

http://www.lowes.com/pd_201711-152-LBR-201711_0__?productId=3020106&N=0&catalogId=10051&langId=-1
At my local Big Box I recently prices some PT 1X lumber for a fence. It turned out the 5/4 low grade decking was much cheaper (in 12 foot lengths) than the 1x PT dimensional they had. The only difference was the rounded edge of the decking material. (plus greater width and thickness, but that was a positive). This probably would not matter for this project. I recommend cross check those prices every time!

for example in the link provided 1"x4"X8' pt was $3.97 for my location.
I paid $4.97 for 5/4"x6"x12' pt decking.