Variable Adjustment Grow Light Build for Plant Starts and Microgreens

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This is an ambitious build that connects all the dots of aesthetics, practicality, and uniqueness that results in an awesome little light temple for your plant starts or microgreens to thrive under. Even if you’re not into woodworking or are deterred by all the miter joints, you could easily modify the design to use straight boards and apply the magnetic adjustment mechanism to whatever new designs you come up with.

I have a cheap fluorescent grow light that didn’t come with anything to hang or stand above plants, so it was the perfect opportunity to design something. My guiding principles were as follows: a) it has to look more decent than two stacks of books which was my previous grow light stand; b) adjustment has to be variable without set levels; and c) it needs to reflect light back to the plants to maximize efficiency without being an eyesore.

I wrote this Instructable with customization in mind; I provide exact measurements of what I did, but I really focused on the process and proportions so you will be able to customize this project to suit your needs. This is also why I haven’t provided an exact “Cut List” as is usual in most woodworking plans. There’s also so many bits and pieces that I think it’s easier to cut as you go instead of all at once in the beginning.

Materials Used

Lumber:

(This is a scrap-friendly project, so hopefully you have some to make some of the smaller pieces. The estimates below assume purchasing everything new).

(3) 1x2x8’ – I used common boards, so I skipped over some knots which ended up using a little less than 8’ per board.

(1) 1x3x8’

(1) 1x3x6’

(1) 1x6x6’

(2) 2x2x6’ (the project uses just over 8’ of 2x2, which means (1) eight-footer won’t quite make it. If you want to reduce costs, skip the diagonal braces which are optional. Then you would only need (1) eight footer.

Drawer Slides:

(1) pair 12” ball-bearing, full extension drawer slides. These will be taken apart and used as a track for the magnets. If you want more or less adjustability you could get a different size; remember, this project uses the middle track of the slide which is shorter than the actual drawer slide length. On 12” drawer slides, the middle track is about 11 1/8.” I got the Everbilt brand at Home Depo.

Magnets:

(2) 1 ½” x ½” x ¼” neodymium block magnets, with countersunk holes.

I recommend ordering directly from a magnet supplier such as CMS magnetics because it was cheaper than Amazon, even with shipping. They only cost $1.50 each. Plus it’s easier to find magnets in the size you want.

Here is the exact link to the magnets I purchased: https://www.magnet4sale.com/n42-1-1-2x1-2x1-4-neo...

Strong magnets are necessary for this project, but not too strong; I tried three different sizes of magnets, and these gave the best hold and easiest adjustment. 1” by 2” by ¼” magnets were too strong and made adjustment nearly impossible, while any smaller contact surface than the ones I chose was too weak and would slide down gradually.

Sheet Metal:

(2) 1' by 2' aluminum sheets. I got mine at Home Depo near the windows/doors. Aluminum is cheaper than steel and easier to cut and work with.

Eye Hooks:

(2) 1 7/16” eye hooks (that’s the length from bottom to top; the actual “eye” has an outside diameter of 5/8”).

Grow Light:

Mine measures 21 7/8” long by about 2” wide at the plastic base. It’s a fluorescent, so it gives off very little heat and can be very close to plants without damaging them. If you have a different kind of light that produces heat, that will change how close you want the closest setting on your build to be, so keep that in mind.

Tools:

Circular saw

Miter saw

Cordless drill

Kreg Jig + pocket hole screws: 1,” 1 ¼” and 2 ½”

Wood glue

24” bar clamps (or longer).

Other clamps (never too many clamps…)

Tin snips (or some other way to cut aluminum sheet metal).

5/8” wire nails

5/8” flat head wood screws (for the magnets; must be flat head. Need 4 of them).

Supplies:

Step 1: Cut and Glue Pieces for Reflector Sides and Top

You may want to customize the size of your build to the dimensions of your grow light/windowsill/other variables. Be sure to oversize the width of each board a little bit to leave room for squaring-off and beveling the edges.

To achieve a desired board width with the 45 degree diagonals, cut the length of each diagonal piece to 70% of the desired board width. For example, I cut my diagonals to 4” long because 4 is (just about) 70% of 5 ¾, which is the width in inches that the board will be once the pairs are together. 5 ¾” wide is my rough size for both sides and top, and it will be trimmed down square and beveled later.

Sides and Top --Make 3 boards using the following procedure:

• Cut 16 diagonal pieces of 1x2 at 45 degrees on both sides at 4” long.

• Cut the 4 triangles you need by placing a pair of diagonals on the edge of a 1x6 board and tracing the triangle. The angle won’t fit precisely with the corners of the 1x6 and will overhang resulting in an imperfect triangle, but it won’t matter because the edges of the board will be squared off later.

• Glue each pair of diagonals together for a total of 8 pairs. Let them set, because the fewer things that can move during the final glue-up, the better.

• Using two long bar clamps, lay out all the pieces with glue between all the joints and twist each clamp evenly so the pressure is consistent. Clamp the top face down or put something heavy on a block of wood to distribute the weight over the area. ***Use wax paper under and over the project while gluing so nothing sticks to it***

• I added wood filler and sanded the boards at this stage, but in retrospect it makes sense to wait until after assembly because inevitably during the pocket holes and assembly, little dings and glue marks show up. I had to re-touch it later anyways, so sand when you think its right.

Step 2: Bevel and Square the Edges of Reflector Top and Sides

When beveling the boards, pay attention to which side will end up being the outward facing side according to how the bevel will join to the other. I left all the dried glue residue on the “bad” sides of my boards because it’s just going to be covered with sheet metal and never seen again, so the orientation of the bevel matters.

When ripping down the boards, split the difference of how much you want to remove and take it off both sides to keep the pattern centered. If you remove all of it from one side lengthwise or widthwise, it will offset the pattern in relation to the others and it won’t be as centered.

I wanted the final width of each board to be 5” so I ripped off 3/8” from each long side. Lengthwise, I removed as little as possible and only enough to square off the edges using a miter saw because I want the reflector to comfortably accommodate the grow light (final length= 22 ¾”) My method to mark the cut lines was to cut a perfectly 5” wide rectangle out of poster paper and place it as centered as possible on the board, then trace the long sides. I found it easier than attempting to measure in from inconsistent edges.

Reflector Top: Bevel both long sides at 22.5 degrees. The cuts should be angled towards each other (i.e. not parallel) so a trapezoid face is created at each end of the board. To make sure the widest side of my board is 5” wide, I cut into a piece of scrap wood at 22.5 degrees and measured the distance from the edge of the guide I was running the circular saw against to the widest side of the bevel. On my Dewalt it is 1 15/16” so I would place my guide board that distance away from the line I traced.

Reflector Sides: Bevel one long side at 22.5 degrees.

Step 3: Drill Pocket Holes

Top:
  • · Drill 3 pocket holes on each short end. Make sure they’re on the inside face!

Sides:

  • · Drill 2 pocket holes on each short end (not shown in picture, I took the pic before doing this)
  • · Drill 5 pocket holes on the bevel with the Kreg Jig and stop collar set for ¾” stock. When assembling, use 1” pocket screws instead of the usual 1 ¼” screws recommended for ¾” boards.

Drilling pocket holes on a bevel is not really an official way to use a Kreg Jig, but I didn’t have a good way to clamp a joint that is purely glue, and I don’t have any other tools. So I messed around with the Kreg Jig settings on some scraps beveled at 22.5 degrees and found that normal ¾” settings with 1” screws works best. As long as you don’t over drive the screws at all they will not poke out to the other side.

Step 4: Trace and Cut Metal Reflector Pieces

Before assembling the reflector, trace out the inner face dimensions of the sides and top on sheet metal, so you have the perfect outline to cut out.

All 3 Sheet Metal Pieces: Drill small holes (1/16”) along the edges for the wire nails to go through when the metal is ready to be installed.

Don’t attach the sheet metal yet, because we need to access the pocket holes to attach everything.

Step 5: Assemble the Reflector Sides and Top

Use 1” pocket screws to join the sides to the top, being careful not to overdrive them. Put some wood glue in the joint for extra strength.

I gave the joint a little hand sanding with 220 grit sandpaper to round it slightly.

It makes sense to make the short sides after assembly because it’s easier to just stand the reflector on one end, trace the exact dimensions of the end, and cut it out.

Step 6: Make Short Reflector Sides + Sheet Metal for Them

The short sides will have magnets attached on the outside to slide the reflector up and down inside the track on the main frame.

I made a diagonal grain board using the same process as the reflector sides (except using 1x3 instead), then I traced the profile of the reflector and cut it out.

***After tracing out the wood sides, use the same process to trace out the trapezoid sheet metal pieces needed to cover the ends on the inside. Be sure to trace the inner edge for these since the sheet metal has to sit under the joined edges.***

Make two boards:

Cut and Glue:

· Cut 8 diagonal 1x3s at 4” long, with parallel 45 degree miters on both sides

· Cut one triangle to fit the bottom (optional; makes clamping easier).

· Glue each pair of diagonals together for a total of 4 pairs

· Use one bar clamp to clamp the whole thing together, with heavy stuff on top to hold it flat.

Trim down and Square the edges:

· Trim down each lengthwise side equally. I did this because I like having straight edges to reference when I’m centering the trapezoid shape I need to cut out.

Trace the Reflector End

· Stand the reflector on its end and place it where you want on the board.

· Trace the outside edge of the reflector, and draw a line across the bottom to complete the trapezoid shape.

· Remember the sides will fit over the edges of the reflector sides/top, so trace the outside edge and not the inside.

Cut Out the Trapezoid

· I used my circular saw and clamped guide boards to get a perfect cut.

Step 7: Attach Short Reflector Sides

Attach the trapezoid sides to the reflector with 1 ¼” pocket screws.

Step 8: Attach the Sheet Metal Interior

It’s time to make the reflector actually reflective. Use 5/8” wire nails to tack in the sheet metal interior.

Step 9: Mount the Light

I wanted my light to be flush to one side so there was extra room around the switch for me to use it later on, so it’s not centered lengthwise.

  • · Position the light how you want it and use a sharpie to mark where the holes need to be to allow the eye screws to get through.
  • Drill those holes through the metal and into the wood just a little bit, maybe an 1/8” or so. The eye screws thread in easy and it makes sense to give them maximum grab.
  • · Thread in the eyes screws so the “eye” is sitting almost right on top of the surface, with hardly any shaft. (I had to go to this depth because otherwise the “eyes” would hit the light bulb. Yours may be different). Orient them in the direction that will allow you to slide the light housing over them.·
  • Slide the light housing over the hooks. Give the hooks another quarter turn or so to lock the light into place, so the light can’t slip off the hooks.

Step 10: Attach Magnet and Spacer Blocks to Reflector Ends

The neodymium magnet I used measures 1 ½” long by ½” wide by ¼” thick. The track is wider than ½” so I cut a block of wood to fit the rest of the track to help keep it riding evenly up and down.

Make the Spacer Block:

  • · Cut a ¼” sliver off a piece of 1x2 (1x2 makes it easy because it is already 1 ½ inches long, same as the magnet).
  • · Use a handsaw to cut about 1/8” or a tad more off the ¾” thickness, so it measures 5/8” or slightly less.
  • · Mine still fit very tightly at 5/8”, and the track actually shaved some off when I was forcing it through initially. But that’s okay, because I want the wood to contact the track side as closely as possible.

Attaching:

  • · Use 5/8” wire nails to tack the spacer block in first, and put it on the right side of where the magnet will attach. That way, when the drill turns clockwise to tighten down the screws through the magnet, the spacer block will stop it from moving in that direction.
  • · Use #6 5/8” screws to install the magnets.

Step 11: Cut Frame and Drill Pocket Holes

2x2

Main Vertical Beams – (2) at 22 ¼”

Base Boards –(2) at 12”

*Top Beam –(1) at 25”

Diagonal Braces (optional) – (4) at 7 ½” long, on the longest side. Each side should be cut at 45 degrees, with the cuts facing towards each other (i.e. not parallel). The longest side will measure 7 ½” long.

1x3

*Bottom boards –(2) at 25”

*For the top beam and bottom boards, I recommend setting up the reflector between the main frame and measuring these out exactly. I installed the bottom boards at 25” first, and I found it ever so slightly moved the main beams apart so the magnet was losing hold. So I cut the top beam to a hair shorter (maybe 1/16”) than 25” so it would pull it back together at the top, and it worked good.

Pocket Holes:

Main vertical beams – two on one side. Make sure Kreg jig is set for 1 ½.” These will be screwed into the 12” long 2x2s.

Bottom Boards – two on each end. Kreg jig set for ¾”

Top beam –two on each end. Kreg Jig set for 1 ½”

Step 12: Attach Vertical Beams to Base Boards

Use 2 ½” pocket screws to attach the vertical beams to the base boards. Clamping helps keep the joint square.

**You know, it probably makes more sense to attach the bottom boards to the base boards first, then work up from there so the vertical beams are not in the way when trying to screw in the bottom boards... I was getting so excited about finishing that I was just throwing it together before other life obligations could get in the way of me finishing it, so you may want to assemble it a different way than I have listed.**

Step 13: Prep the Magnetic Track

The adjustment mechanism is made of a drawer slide track with the ball bearings removed and a heavy-duty magnet (~20 lbs pull force) that rides up and down in it.

You’ll notice I used the middle track of the drawer slide, when there are two others that are flat inside without a raised middle like the middle track has. During my experimentation, the flat tracks provided too much magnetic force, and sliding the magnet up and down was harder than I wanted it to be. By using the track with an uneven surface, the 1/2” wide magnet has slightly less contact area and an easier adjustment, but still retains more than enough hold to support the fixture.

My original plan was to keep the bearings, but I found operation was actually smoother without them because the magnet wasn’t constantly trying to pull to the different poles in the ball bearings, which caused little wobbles here and there. Surface contact wasn’t as good either, so I removed the bearings. I added some silicone grease to assist the magnet in sliding smoothly.

Repeat for Both Drawer Slides:

  • · Separate the two members of the drawer slide by pulling it to full extension and lifting the release lever that becomes revealed at full extension.
  • · Remove the rubber stopper at the back of the main track and hammer down the metal tab that sticks up.
  • · Pull the middle track off of the main track by sliding it down and off. If it won’t go, hammer the tab down a little more.
  • · Remove the bearing track by hammering down the metal tabs that stop it from sliding off the bottom. Hitting a big nail head on the tabs with a hammer can help pinpoint the force. Make sure these are flat enough, otherwise adjusting the reflector later on will be difficult.
  • · Drill two holes for mounting the track: one in the black plastic at the top, and the other through the metal at the very bottom. These locations are the least intrusive on movement of the magnet and do not reduce available length.

Step 14: Attach Track to Frame

I used ¾” Kreg screws because I had them, but any self-tapping pan-head screws will work.

· Mark a line 8 ½” up from the bottom of the main vertical beam (not from the bottom of the base to which it is attached).

· Line the bottom of the track up with that line

· Clamp them together

· Use 2 pan head screws to attach, using the pre-drilled holes you created earlier.

Step 15: Attach Bottom Boards to the Frame Sides

Use 1 ¼” pocket screws to attach the bottom boards between the frame sides.

Some manner of clamping helps keep this tidy. I used the Bessey clamp for joining each board on one side, then I stood it on its side, pressed down, and screwed the bottom boards into the other side.

Step 16: Attach the Top Beam

I found it easiest to mount the reflector in the track before installing the top because then you can push it in at the middle. The pan head screws used to mount the tracks get in the way if you try to slide it up from the bottom, plus it’s a tight fit because it is sized that way.

Install the reflector, see how it’s fitting, then cut the top beam to just where you need it, whether it be a hair shorter or longer to give the magnet good grab.

I left the reflector in while clamping the top beam to the sides, pressing down, and screwing it in.

Step 17: Glue in Diagonal Supports

I chose to glue in the diagonal supports, which are really just for looks at this point since it's stable without them. I didn’t even clamp them or anything, since the angle holds them pretty good.

Step 18: Use It!

To adjust the reflector up, grab the side beams and put your thumbs under the reflector, about center. Move one side up a little bit, about ¼”, then the other, and keep doing that until it’s where you want it, then level it out. Add some silicone grease to the track to help things along.

It’s not perfect, but not bad for a first go at this design. I’d love to see your improvements on it!

To move it down, orient your hands the other way and move one side down about ¼”, then the other, until it’s where you want.

If your wood block is slightly oversized, you may encounter a lot of resistance when trying to adjust it. As long as it’s not too bad, you should be able to push past it, even if it’s a little hard the first try.

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    8 Discussions

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    faustr

    9 days ago

    Would it be possible to use led lights and what kind would I need for photosynthesis?

    1 reply
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    knottwoodfaustr

    Reply 9 days ago

    Yes, LED grow lights are becoming more popular nowadays. Any light that is marketed for growing plants will work for a home set-up, but blue light waves (cool light) is especially good for plants.

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    JohnM623

    10 days ago

    This is definitely a project that I am going to try. I might change a couple of things, but it will be basically the same invention.
    This is an amazing project !!!!

    1 reply
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    knottwoodJohnM623

    Reply 10 days ago

    That's awesome! I'm so glad to hear that it can be a starting point for your own designs. Have fun!

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    HeatherK105

    11 days ago

    Wow, this is great!