Tag: DIY tools

Background

In 2017 I worked with Nick Andrews and Heidi Noordijk at the North Willamette Research and Extension Center (NWREC) to help them develop a small wash and pack area to go with their Organic vegetable learning farm. The work was funded by a Clackamas Extension Innovation Grant. Part of the project was to design a few essential pieces of “furniture.”

I designed and built prototypes for three pieces and the spray table shown above is the first one I’m writing up here. You can find the packing table write up here and the harvest tote washer here.

The intention for the packing shed goes beyond just creating a functional space for packing vegetables out of the trial field, it’s also meant to be a testing ground for equipment, and a demonstration and teaching space for new and continuing farmers.

Basic Design

The initial request for this piece of furniture was something where vegetables can be sprayed down, cleaned and sorted. I based the design loosely on tables that I’ve built and used on several farms. Those tables were primarily made from wood, which is relatively inexpensive and easy to work with. It is unclear if it will be acceptable under the FSMA rules, thus the preference for this table was stainless steel. Stainless steel is a material that is definitely acceptable under any food safety rules. I also tried to incorporate adjustable height. Ergonomics is important and frequently farms have users of widely varying heights. I wanted the table to be quickly and easily adjusted to any users ideal working height. The table rolls so that it can be easily moved on a concrete slab allowing the work space to be quickly reconfigured and the floor beneath the table to be cleaned.

Tables I’ve designed and used extensively in the past have been 4’ wide which is roughly an arm span, allowing the user to reach both ends of the table without much movement. Usually I build shelves on the ends that allow the largest harvest totes used by the farm to sit flush with the table top, making it easy to move dirty product onto the table, and clean product off the other end. This table does not have the incorporated shelves (see Potential Future Improvements section for more on that).

I like to incorporate both a hanging hand operated sprayer and a hands-free, adjustable sprayer onto tables. The hands-free option allows the user to move product across the table with both hands while still spraying. With a hands-free sprayer, hands, or hand-held brushes, can be used to help rub soil and other debris off of the produce in addition to the spray without having to constantly pick up and put down the sprayer.

The hanging, hand operated sprayer is always conveniently located and never is in danger of touching the ground where it is easily contaminated. It is useful for spraying all corners of the table if the user prefers to dump a large pile of produce, or for cleaning the table after washing the produce.

For years I used mesh tables that just dumped spray water and mud at my feet and left me standing in a mud puddle. For the past 5 years I’ve been using tables that direct the water away from my feet. This table collects the water and pipes it away from the user. Because the table is mobile the pipe is not connected to a drain, but it can be positioned over a floor drain or a settling tub to help capture soil and debris before it goes down the drain.

One additional feature I find useful is a back splash. This prevents product (and water) from falling off the back of the table. I design tables for single users so they are one sided. I’ve found it difficult for more than one person to use a table at a time collaboratively so I design tables to work well for one user at a time and encourage farms to have more than one table if they need multiple users.

Because a sink is used in this design this table has the additional feature of a basin that can be filled with water for pre-soaking vegetables. I included two options of grates that can cover the sink basin so that the sink can be used solely as a spray table, in which case the basin of the sink just functions to catch the water and mud coming off of the vegetables and to funnel them into the drain pipe which comes out the side, or back of the table.

Construction Details

In researching the least expensive way to get a functional stainless surface that was appropriate I settled on using a single basin sink, double drain board restaurant sink. Because these sinks are mass produced they are relatively inexpensive and the dimensions are similar to the tables I’ve built in the past. The price of the sink isn’t much more than the actual price of the stainless steel so it’s definitely much cheaper than custom building a stainless table. There is also good availability of used restaurant sinks, although finding exactly the size you want might not always be possible.

For the sprayer I purchased a matching restaurant faucet and pre-rinse sprayer and attached a spray attachment with a quick on off trickle feature for the faucet. Pre-rinse sprayers are designed to hang above the sink and use a spring to keep them up out of the way, but easily in reach. The spray head for the faucet is a common retrofit for kitchen sinks. The quick on-off trickle feature is to save water, but it would be better if it shut off the water entirely (see photo in the previous section).

For the base of the sink I replaced the legs with a rolling adjustable height work cart. Like sinks, these are common enough that there are inexpensive versions available online. They are commonly used by mechanics for lifting heavy parts to a good working height, like engine blocks. The lift mechanism is operated with a simple foot pedal and it is lowered with a hand lever. Operation is quick and easy, and it will adjust to any height within a range.

I attached the sink to the cart with a wooden frame. That frame leaves just enough space for a drain pipe to extend out from the side, and the pipe could easily be extended to the rear, or redirected by attaching a drainage hose.

Water is supplied to the table by screwing in standard ¾” garden hose to the cold side. The hot water valve needs to be left closed, but can be opened to drain water from the system to keep it from freezing and breaking the faucet in cold weather.

Part	Description	Source	Price
Sink	Regency 54” 16 gauge stainless steel one compartment commercial sink with 2 drainboards – 18x18x14” bowl	webstaurantstore.com	$345 + $146 shipping
Pre-rinse Sprayer with Faucet	1.42 GPM wall mounted pre-rinse assembly with 8” centers and 12” add on faucet	webstaurantstore.com	$170
Faucet Adapter	Necessary parts for mounting the faucet to the sink	webstaurantstore.com	$15
Sink drain rack	Over the sink multipurpose stainless steel roll-up dish pot drying rack, 20.3”	Amazon.com	$29
Sink drain kit	Drain tail piece plus 90 degree angled waste pipe.	Hardware store	$11
Faucet spray nozzle	To replace aerator	Hardware store	$17
Lift cart	Goplus Hydraulic Scissor Lift Table – 500lb Capacity	Amazon.com	$176
2×4	(2) 17 5/8” rails (2) 21” rails (2) 5” legs	Lumber yard	$4
1×4	(2) 17 5/8” side plates (1) XXX” support for pre-rinse sprayer (1) 5” clamping piece	Lumber yard	$4
Angle brackets	Four 1×1/2” corner brackets to hold the frame down	Hardware store	$3
Screws	Assortment of 1 ½ “ to 2 ½” deck screws to hold it all together	Hardware store	$5
Pipe to hose adapter	½” FPT to ¾” FHT adapter	Hardware store	$6.50
		Approximate parts TOTAL	$931.50

Assembly Instructions and Required Tools

Assembly of the sink and its plumbing is fairly straight forward. The faucet, pre-rinse sprayer assembly and faucet adapter all screw together using generous wraps of Teflon tape on the threads. Make sure to slide the hook onto the riser pipe for hanging the pre-rinse sprayer when the sprayer is not in use. The hose thread to pipe thread adapter gets screwed onto one of the faucet inlets on the back side of the sink using Teflon tape. I hooked it up to the “cold” side, but it doesn’t matter which you use. For screwing these parts together I mostly tightened by hand, but it was helpful to have a pipe wrench and a pair of channel lock pliers to snug everything down. The faucet surfaces are chromed so use a thick rag, copper jaws or something similar to protect the finish.

The aerator on the faucet is unscrewed and replaced with the spray nozzle (without Teflon tape – there is a washer that creates the seal). The pliers make this job easy. The threads only need to be snugged against the washer.

For the drain, screw in the drain cup using the rubber washer on the bottom side to make a seal with the sink bowl. Trim the tail piece so that there is just enough room to fit the waste pipe to it. Pretty much any hand saw can be used for trimming the plastic plumbing pieces.

To create a platform for the sink to sit on I used some scrap lumber. I’ve put suggested sizes in the parts list but you’ll need to measure your particular sink and cart to make sure the measurements work for your parts. I used a basic skill saw and drill driver to assemble these parts (see the photos above for good views of the platform).

I sized my platform so that it fit around the leg brackets snuggly on the outside. The sink is not actually attached to this wooden platform, other than a friction fit and gravity holding it in place. Using screws at the outsides corners, and predrilling holes for the screws to prevent splitting the wood, provides enough bracing to keep it all from wobbling since the legs are very short. The 1x plates on the front and back keep the platform from sliding off and I used the metal angle brackets to keep the wooden platform from lifting off of the cart.

I attached a long scrap of 1×4 to the back of the wooden platform that extended up above the sink in the back. A second short scrap of 1×4 with one end cut at a 45 degree angle to shed water is screwed to the long 1×4 and clamps it to the top edge of the stainless steel backsplash. Near the top of the 1×4 I drilled a hole with a spade bit to allow the support for the pre-rinse sprayer riser pipe to slide through. I screwed the bracket for the support to the 1×4 and fixed the support in place.

Potential Future Improvements

Incorporated shelves for the ends could be built as separate low stands next to the table, or in a future design update it might be good to use two lift carts tied together on either end of the table that would function as the low shelves. The hydraulics on the two carts could be coupled so that they lift simultaneously, allowing the shelves to maintain their relationship to the table top. This would also help to stabilize the entire work surface as it would move the cart wheels out to the edges.

It would be better if the casters on the cart had higher quality locking mechanisms. The ones that came with this very inexpensive cart are difficult to lock and are only single locking, meaning they still allow slight wobbling when locked.

The one feature of the sink itself that I don’t like is that the sides have a rolled edge that sticks up. This works well for a drain board that is designed to keep water going to the sink but in this application it would be nice if it were flush with the drain board to allow product to be slid off the end and into a clean bin sitting next to the table. This is a modification that could be made by a sheet metal worker. It would likely require cutting off the existing rolled side and then re-welding it beneath the drain board with gussets to maintain the structural integrity.

One of the biggest problems I see immediately with this design is that the limited diameter of the plumbing on the standard faucet and pre-rinse sprayer  reduces the flow. This potentially saves water, but it also increases the time to wash very muddy roots or to fill the sink basin. There’s no easy way around this, other than building custom plumbing to replace these parts. On my own wash table I use a length of 3/4″ garden hose with a garden sprayer hanging over the table and an adjustable shower arm with a high pressure head (from a bathroom shower) instead of the more standard sink parts. This looks a bit funky, and takes some fiddling with parts to make it fit, but it does allow more water to flow when needed.

The current design in general is not super stable, due partly to the relatively narrow stance of the wheels on the cart in relation to the overall width of the sink. A second potential stability problem is that the sink is not actually positively attached to the wooden stand, and relies on a tight fit with the wooden stand and gravity to keep it in place. In most situations this should be fine but if the cart tips over due to uneven loading on the edges, or leaning too much against it the sink might separate from the stand and break the waste pipe. The single locking casters on the cart also don’t help the stability.

There are a number of ways the stability could be improved. As mentioned above adding a second cart would move the wheels out to the edges which would be a big improvement. The existing wheels could also be removed from the cart, or carts and replaced with an extra frame of either metal or wood that would extend the footprint. Higher quality double locking casters could keep the mobility high. Simply using fixed wheels on one end and feet on the other would improve stability with less expense, and would require that the cart be tipped up on the wheeled end to move, which would probably not be too difficult, especially for occasional moving.

On this version of the table the standard handle that comes with the lift cart is long enough that it prevents the table from fully descending. The handle is easily partially removed to allow the cart to be as short as possible, but without extra effort it cannot be completely removed as it incorporates the release lever that lowers the work platform. The handle could also be easily shortened by chopping it off a few inches and drilling new holes for the attaching pins.

Background

In 2017 I worked with Nick Andrews and Heidi Noordijk at the North Willamette Research and Extension Center (NWREC) to help them develop a small wash and pack area to go with their Organic vegetable learning farm. The work was funded by a Clackamas Extension Innovation Grant. Part of the project was to design a few essential pieces of “furniture.”

I designed and built prototypes for three pieces and the packing table shown above is the first one I’m writing up here. You can find the write up for the packing table here, and one for the adjustable height spray table here.

The intention for the packing shed goes beyond just creating a functional space for packing vegetables out of the trial field, it’s also meant to be a testing ground for equipment, and a demonstration and teaching space for new and continuing farmers.

Basic Design

The initial request for this piece of furniture was to develop a way to wash totes quickly and easily. The preference was for a feed through design and site limitations required a design with water flow limited to 12 gpm, and no power.

There are several commercial options available that fit the criteria of feed through, but they all have power requirements to run conveyor chains and pumps. Roeters Farm Equipment in Michigan sells two different chain conveyor washers for $4100-6000 that are designed for washing vegetables but are also being used by growers for washing totes. HarvestLugs.com sells a dedicated lug washer for about $18,500. They estimate it takes 2 people to operate the machine and it can wash 60-70 lugs a minute.

The prototype design for this simpler tote washer also requires two people to operate efficiently, with one loading the dirty totes and one emptying at the far end. There are PVC pipe rails that the totes slide on, upside down, and they pass through a tunnel where four spray nozzles are directed to spray all of the surfaces of the lugs before coming out the other end.

Below the rails and spray nozzles is a stock tank to catch and redirect the water and dirt coming off of the lugs. Water is fed into the system by a standard ¾” hose.

On a side note, this design could be used to pre-rinse vegetables in totes by running totes with good drainage full of vegetables through it.

The following short video shows the first trial of the tote washer.

Construction Details

The basic design is a light weight wooden frame that supports the stock tank, the rails above the tank, the spray nozzle manifold and metal hoops that hold up a tarp to contain the spray.

The frame pieces were cut with a circular saw but any saw could be used. Holes were primarily cut with forstner drill bits and a drill press which make some of the larger holes easier to cut, especially in the PVC which has a tendency to crack with other types of large drill bits, especially when they are fed too fast and the pipe isn’t solidly clamped while drilling.

Part	Description	Source	Price
2×2	Two 8’ lengths for frame	Lumber Yard	$5
2×3	Seven 8’ lengths for frame	Lumber Yard	$15
½” PVC pipe	20’ for sliding rails	Plumbing Supply	$9
1 ¼” PVC pipe	10’ for sprayer manifold	Plumbing supply	$9
1 ¼” PVC 45 fittings	4 for sprayer manifold	Plumbing supply	$5
1 ¼” PVC 90 fittings	1 for sprayer manifold	Plumbing supply	$2
1 ¼” PVC tee fittings	1 for sprayer manifold	Plumbing supply	$2
1 ¼” Slip to ¾” FPT PVC bushing	1 for sprayer manifold	Plumbing supply	$1
¾” FHT to MPT adapter	1 for sprayer manifold	Plumbing supply	$2
K-Ball Nozzles	Purple 0.129 orifice clip on nozzle	US Plastic Corporation	$33
½”EMT conduit	2 10’ lengths	Hardware store	$6
Spring Clamps	6 for attaching tarp to conduit	Hardware store	$3
Tarp	5×7’ tarp	Hardware store	$4
Stock Tank	Rubbermaid 50 gallon stock tank	Farm Supply	$80
Bath waste pipe	basic drain for bath tub	Hardware store	$20
Screws	2 ½” deck screws for framing, 1 ½” for attaching PVC rails	Hardware store	$5
		Approximate parts TOTAL	$201

 

I’m not providing the actual dimensions for the frame as it was built for a couple of reasons but I do think explaining the basic method might be useful so I am detailing that. The main reason I’m not providing the dimensions is that I don’t actually think the prototype is a good size now that it’s actually built. It is a nice, light weight, and feels very solid so the idea was good, but the outside rails are set to wide. (I have more recommendations for changes below in the Potential Future Improvements section.) Here are the basics of how I put the frame together.

Cut all of the frame pieces to size and then screw them together, drilling pilot holes to avoid splitting the wood. I used a circular saw and cordless drill but any saw and drill will work. Quick clamps and a square help with assembly, especially when putting the frame together solo.

I used a quick hoop bender from Johnny’s to make the two conduit hoops (these were actually just taken from an existing supply on the farm). A separate wooden frame could also be used, or a bender can be made from scrap wood. To clamp the hoops to the frame I drilled holes that approximated the diameter of the conduit into 2×2, then ripped the wood lengthwise and cut off the individual clamps. I also drilled holes for the screws to slide through.

The manifold is all set up with press fit joints and no glue. These could be glued if they start separating, but leaving them unglued allows the manifold to be easily removed and modified if needed, or even cleaned on the insides. I drilled the holes in the manifold for the clip on nozzles using a forstner drill bit and a drill press, and going slowly. PVC is prone to cracking when drilling holes so it helps to go slowly and steady with a drill press but it is possible to drill the holes manually with some care.

The tarp is just clamped to the hoops which makes it easy to remove.

Holes for the drain in the tub are drilled using hole saws and the tub simply sits in the frame. A standard bathtub drain kit can be installed in the bottom of the stock tank to provide drainage and direct the water away from the work area.

Potential Future Improvements

My hope was that this washer would be strong enough to clean the majority of dirt and debris off of used harvest lugs. The reality is that it will rinse them off well, but multiple passes and manual brushing is still required for totes with any significant soil and debris attached.

In limited testing it is still marginally faster than manually washing lugs, and much more ergonomic. It also contains the water well, allowing the wash water to be diverted away from the work area. The rails actually provide a good support for scrubbing out lugs, but the continuous water flow wastes water while lugs aren’t passing through.

A knee or foot valve would be an easy way to save water, but it would add significant expense, most likely in the neighborhood of $100 or more and it might reduce the water flow. A larger chain operated valve might allow more flow but would require creating a separate lever mechanism and would be more expensive.

This basic design could be easily modified to work with a single user. I think adding a foot, or knee operated valve, using a single fixed spray head directed down and slightly away from the user and into the tub would be a good set up. Using the sliding rails simply as a table to place the bin on while scrubbing and then manually moving the lug under the spray as the water is on would keep the water relatively contained, and allow access to all edges of the lug.

With the current configuration one design improvement might be making most of the manifold from smaller diameter pipe and reducing the amount of pipe above the bottom nozzles. The shut off valve should also be moved closer to end where one of the users can easily turn it on and off. This would reduce the amount of water and time that it takes to fill the manifold, not insignificant with the current design. It would also reduce the amount of water than drains from the nozzles between uses. Changing the nozzle types might also help. All of these changes would add materials costs.

 

 

 

Background

In 2017 I worked with Nick Andrews and Heidi Noordijk at the North Willamette Research and Extension Center (NWREC) to help them develop a small wash and pack area to go with their Organic vegetable learning farm. The work was funded by a Clackamas Extension Innovation Grant. Part of the project was to design a few essential pieces of “furniture.”

I designed and built prototypes for three pieces and the packing table shown above is the first one I’m writing up here. You can find the write ups for the adjustable height spray table here and the harvest tote washer here.

The intention for the packing shed goes beyond just creating a functional space for packing vegetables out of the trial field, it’s also meant to be a testing ground for equipment, and a demonstration and teaching space for new and continuing farmers.

Basic Design

With that audience in mind I designed the table based on feedback from Nick and Heidi and with my personal experience packing vegetables on small farms with diverse crops. Here are the basic design features of the table.

The first and most basic feature is a large, smooth, non-porous work surface. The table uses a 6′ plastic table top, but could also be fitted with a stainless work surface (or wood). The intention was to have a tough work surface that is easily cleaned to make the table acceptable for GAP standards and FSMA rules. The frame of the rest of the table is wood which is relatively inexpensive, durable and easy to work with. The same design could easily be built from steel or aluminum which would increase the cost but might make it easier to clean.

The table has a large shelf below the table top which is suitable for holding packing supplies like wax boxes or produce waiting to be packed.

There is a smaller, high shelf which is suitable for holding labels, marking pens, tape and other tools. This is a good place to clamp work lights to help illuminate the work surface to reduce eye strain if additional light is needed.

The table is on wheels making it easy to roll on a hard smooth surface. The packing table can be moved as needed allowing flexibility with the pack shed work flow. The rolling table can also be used to move packing materials from one place to another, rolled out of the way when not in use, or when the floor needs to be cleaned.

Different packing operations and different farm workers often benefit from different work heights. The table top height is adjustable with two pins on the ends. The pins can be set in holes at different heights to support the table at lower or higher heights.

The final consideration was cost and accessibility. I wanted to keep the cost as low as possible, while still offering good functionality, and I also wanted to make sure it was possible to build with some basic tools and skills. The materials costs for the project (detailed below) were about $240 for me. It took me a while to work out the design, but the actual construction only took a long day (hard to say exactly how long actually as I was still working out some design details in there). With the sliding table feature it pays to take your time and be a little fiddly with getting everything just so.

Construction Basics

Construction of the table starts with building a simple plywood and 2×4 platform for the bottom shelf. This is set up on the casters, using blocks on the corners to add extra surface to screw the caster plates to.

Two 4×4 uprights are attached to the base platform with plywood gussets and screws to keep them stable on the short axis. At the top of the 4×4 uprights is a 2×4 span that is reinforced with more plywood gussets to provide stability on the long axis of the table. On top of the 2×4 is a narrow plywood shelf.

A framework for the table top is built of 2×4 and plywood gussets. It is designed to slide up and down the 4×4 supports without wobbling. This frame supports the table top on the ends and in the center and it is attached with screws from the bottom so that it will not slide.

Heavy pins are made from ½” black pipe which insert into holes in the 4×4 uprights. The pins allow the table height to adjust by sliding the table top up or down on the uprights and then placing the pin in the closest holes below the desired height. The lynch pins and pipe caps keep the pin from coming out unintentionally.

The table surface that is used for the packing surface is a standard 6’ plastic folding table from National Seating. You can clearly see the underside of this table in one of the photos above. It is attached with four screws, so that it won’t slide out of place, but it can be easily removed and replaced, or used as a standard folding table.

Construction Details

I’m including a drawing of the table below with a few dimensions, the parts list and costs from the prototype, a rough cut list and more detailed step by step method for building the table. At the very end of this writeup there is a discussion of a few potential improvements or modifications I can see already.

I’m not giving a lot of dimensions, and you should double check the ones I do give. As I outline in the detailed step by step method, a lot of the dimensions should be checked against the actual dimensions of the table top you use.

Part	Description	Source	Price
Screws	1 ½” and 2 ½” deck screws for frame 1/4×2” lag bolts with washers for attaching casters	Hardware Store	$10
4×4	8’	Lumber Yard	$8
2×4	60’	Lumber Yard	$29
Plywood	One sheet ½” CDX	Lumber Yard	$22
Folding Table	National Public Seating 30×72” 1000lb capacity folding table	Amazon	$89
Double locking Casters	Two 3” non-marking double locking casters	Peachtree Woodworking Supply	$37.00
Fixed wheels	Two 3” non-marking	Peachtree Woodworking Supply	$25.00
Black pipe nipple	One 1/2×18” nipple	Hardware Store	$10
Pipe cap	Two ½” caps	Hardware Store	$3
lynch pin	Two 3/16 lynch pins	Hardware Store	$4
		Approximate parts TOTAL	$237

Approximate Cut List:

4×4

• (2) 48” uprights

2×4

• (2) 71.5” base shelf runners (these should actually be a hair over the length of the table top used)
• (3) 25” base shelf cross supports
• (1) 72.5” top bar (this should actually be the same length as the bottom shelf plus two gussets)
• (2) 79.5” table top supports
• (4) 8.5” upright side supports
• (2) 24.5” table top end cross supports (this is actually just under the width of the table at the very ends – mine had rounded corners so I only measured the straight part)
• (1) 29.5” table top middle cross support (this is actually  just under the width of the table)
• (10) 3.5” blocks

½” Plywood (dimensions match 2×4 pieces they support and can vary slightly)

• (1) Top shelf
• (1) Base shelf
• (2) Base shelf end gussets
• (2) Table top end gussets
• (2) Table center support gussets
• (4) Top rail gussets

Assembly Instructions and Required Tools

Start by laying out all of the cuts for the plywood gussets and shelf pieces (DRAWING). These will all fit onto a single sheet of plywood, but only if you’re smart about how you make the cuts. A long (4’) straight edge and a string line makes this easier. I also used a framing square, measuring tape and pencil. For the long straight cuts I like to screw or clamp a straight board to the plywood to use as a cutting guide to get the edge very straight and smooth. With all wood cuts I also like to quickly soften the edges and remove any splintering with coarse, 80 grit, sandpaper wrapped around a wood block after making the cuts. To make the cuts I use a circular saw, but any type of saw that will cut straight will work.

Cut all of the 2×4 pieces for the base. If anything, you want the ends of the 2×4 base pieces to be just slightly proud of the plywood on the short edges. This will make the 4×4 and gusset attachment easier to get tight against the 2x4s. The platform needs to be just a hair longer than the table top that you’ll be using, and could be as much as 1/16-1/8” longer without causing any trouble. If it’s shorter the sliding mechanism won’t work.

Screw the bottom frame pieces together. I only use 2 screws per connection and I pre-drill to prevent splitting. When I screw on the plywood I make sure the frame is square at the corners and then add screws every 12-16” around the edges and through the cross supports in the middle of the platform.

Screw the gussets to the ends of the bottom platform. I use two screws at the outside corners, and four more screws along the length, avoiding the area where the 4×4 uprights will go.

I attached the wheels at this point, which worked well for me. I was working in a very cramped space and it was convenient to be able to roll the table around as I was working on it. The wheels could also be attached at any point after this in the process.

To attach the wheels I added scrap 2×4 blocks to the inside corners of the platform (see photo above). I then used one set to mark the hole locations for the screws and drilled pilot holes. The two locking casters are screwed onto one end with the ¼” lag bolts, and the fixed wheels go on the far ends.

Cut the 4×4 into two equal length pieces. The actual length is less important than that they are equal in length, and that the cuts are square (especially on the top side). Make sure to select a 4×4 that is straight and has no twist. This is important because the table slides on the 4×4 and it will bind if it is not straight and true.

You can drill the holes for the ½” black pipe pin now, or wait until the table top is installed and check the working heights you want to use. I used a 7/8” spade bit to drill the holes. If you have a drill press that will make a 3.5” deep hole this would be a good place to use it to keep the holes square. I just used a cordless drill. With spade bits it’s best to drill until the point is just protruding from the far end and then to drill into the far end using the small hole to center the bit. This prevents major tear-out that happens when the bit comes out the far side but keeps the bit aligned so the two holes from opposite sides line up properly.

Cut the 2×4 top rail to match the length of the assembled bottom frame with the two plywood gussets, or just a hair under. If the top rail is too long it will be impossible to make the uprights square.

Attach the 4×4 uprights to the end gussets keeping them centered and using a square to make sure they are square to the base platform. I find that getting close with Irwin Quick Clamps, setting one screw, then readjusting and clamping before setting a second screw helps with many of these joints, especially if you’re building the table solo. The first two screws should go into the gusset above the platform, one close to the top of the gusset and the other low, close to the platform. Wait to put the rest of the screws in until the joints at the top of the 4×4’s are secured.

Again, using only two screws per joint, attach the top rail to the 4×4 uprights with the gussets. Check the square and use clamps to help adjust and hold the work as you go. Once all of the gussets are tacked into place and the 4x4s are square to the frame start adding extra screws to stiffen the frame. For the top gussets I use 4-5 screws per edge. For the gussets at the base I use 4-6 screws above the base and then another 2-4 long screws that go through the 2×4 at the base, through the gusset and into the 4×4.

Attach the top shelf, centering it to the top rail. I use two screws on the ends at the corners of the 4×4 and then zig-zag screws down the length every 10-12”.

Putting together the sliding support frame for the table top requires a bit of fiddling to find a good balance between sliding easily and not wobbling excessively. If you’ve already drilled the holes for the pins in the 4×4 you can make the pins now and use them to help with the next steps.

To make the pins, cut the black pipe nipple in half. This can be done with a hacksaw, or an abrasive wheel. If you have an abrasive grinder use that to soften the edges of the cut. Drill a hole through the pipe about ½” from the cut end of each half. Start with a small bit to drill a pilot hole, maybe 1/8”. Using a center punch to mark the start of the hole will help keep the bit from wandering. When drilling steel, use less rotational speed and more downward pressure than when drilling wood, and definitely use a sharp drill bit that is rated for cutting steel. Once the pilot hole is drilled use a ¼” bit to drill a hole that your lynch pin will fit into. I did this with a cordless drill and the pipe clamped firmly to a table. If you have a drill press this is another good place to use it. Finish the pins by screwing the caps onto the threaded ends.

Insert the pins in the corresponding holes and rest the long rails for the table support on them. If you haven’t drilled the holes yet you can make lines at the same elevation, close to an average table height you think you’ll want to use on both of the 4×4 uprights. Then use a Quick Clamp (or any other kind of clamp or even just nails or screws) clamped to the 4×4 at that level so that the rails have something to sit against. Put a thick piece of paper board, or even better, three thin pieces of paper board (from a cereal box for example) between one of the rails and the 4x4s to shim it out a bit and then clamp the rails to the 4x4s. Make sure the shim material sticks out the on the outside so you can pull it out when you’re finished with it. If you have three pieces the middle piece will be the easy one to pull out and then the other two should come out easily. Don’t let the shim material stick into the area where the gussets will go.

Fit the side gussets over the two 2×4 rails and clamp them to the 4×4 uprights to keep them vertical. Use a piece of paperboard shim behind one of the two gussets to set it off of the 4×4 slightly.

Using two screws and pre-drilled holes attach blocks to the rails, flush against the gussets. Screw another pair of blocks in the center of the rails. Screw the three 2×4 cross supports to both rails, making sure to put the longer one in the center and centering all of them. You only need to put one screw through each rail to support connection to hold these in place.

Next, screw the end gussets to the cross supports and the blocks and add the gussets to the center support. Use at least two screws per block and 3-4 screws per side on the cross supports.

Add the vertical blocks to the end gussets, using the same shim materials to maintain a good spacing. Screw those blocks to the gussets and then put a toe-screw at an angle through the bottom of the block into the end of the rail to keep the block from twisting.

At this point, if you’ve measured everything correctly the folded table should slide onto the cross supports and be snug, or at least close to the end gussets. Center the table on the supports and then drive screws that are just long enough for a few threads to penetrate the plastic through the underside of the cross supports and up into the bottom edge of the table. This will hold the table top from sliding off of the supports. Those screws can be easily removed to allow the table to be used as a regular table, or to replace it when the surface is excessively worn.

If you haven’t drilled the holes in the 4x4s for the pins yet, find your ideal working heights now and make marks. You’ll want to drill the holes far enough below those marks so that the rails rest on the pins when the table is at that height. Make sure the holes are square to the uprights. One clue when using a spade bit is that the when the large spade first contacts the wood surface it makes a full circle all at once. If the bit is tipped it will start scribing an incomplete circle when it first contacts the wood. You can use a speed square to sight against the bit. This is a fairly critical hole and because it’s so long there’s not a lot of room for error here. If you’re unsure of your ability to drill a square hole (meaning square to the surface), use a guide or a drill press.

Potential Future Improvements

Initially my plan was to have the black pipe pins go through both the 4×4 uprights and the 2×4 table top supports in order to positively capture the position. Drilling such a large, long hole accurately turned out to be tricky and so I fell back on just drilling through the 4×4. This means the table top sits on top of the pins but can lift. It’s unlikely this will create problems, but there might be an improvement to be made here for more positive attachment.

A wooden dowel might be less expensive than the black pipe for pins but it would likely not insert as smoothly. A tapered pin might be a good way to hold the table but it would be much more tricky to make.

The balance between sliding easily and wobbling with the table top is a delicate one and it will be interesting to see how the joints hold up long term. Making the table top a fixed height would greatly simplify the construction phase. I will be curious to see how the frame shifts through the year with temperature and humidity changes and as the wood cures. This may end up having a negative (or positive) effect on the adjustable height feature depending on how much the raw wood expands and contracts.

This cart has a lot of potential for customization for special needs, places to hang or hold tools specific to crops grown by different farms, special shelves or outlets for electronics or scales, and dividers below for different box sizes or packing materials.

I don’t usually find it necessary to treat or finish wood surfaces that I use on the farm. As long as it dries out regularly standard construction grade fir does not seem to rot or splinter in my experience. Finishing the surfaces might have some benefit but it also has drawbacks: it takes more time and expense to put on a finish (like oil or paint), the finishing materials are often somewhat toxic, both when applied and when manufactured, and potentially if they scrape off during use. When I do use a finish I prefer raw linseed oil, a finish that is relatively inexpensive, non-toxic, and easy to re-apply when needed.

For wheels I chose to use two fixed wheels and two double-locking casters. Double-locking casters don’t roll and also don’t pivot when locked, but there is still a bit of wiggle with them. Using four double-locking casters would make rolling the cart into position in tight spaces easier but means you’d need to lock four casters instead of two. Even locking one with this design keeps it pretty stable, not the case if you have four. The table, without anything on it, is light enough that two fixed wheels and two leg extensions would probably be enough to make the table moveable and would be less expensive. One end would need to be raised, to roll the table, a bit like a wheel barrow, and it would be stable when it was set back down. This would save money on wheels, and might add some stability, but would make it a bit harder to move, especially if the shelves or table top were loaded with materials.

 

If you build one of these and/or have suggestions for improvements I’d love to hear about it. Please e-mail me.