Flexy Rack (with MDF Staining Tips)




Introduction: Flexy Rack (with MDF Staining Tips)

I was looking into buying a rack for a new audio system I'm putting together for my home office, but the cost of 'audiophile' racks made me choke. I was looking for a nice looking, decent rack without breaking the bank, and decided to build one. My total cost to build was probably about $250. If you don't go the spendy route I took buying stainless steel hardware, you can probably make one for about $75-100.

I had to buy more MDF than I needed, because my lumberyard only stocks 4' x 8' sheets, so I actually have extra material. Also, the great people at the fastening supply store I bought the hardware at gave me 6' all-thread rods instead of 3', which means I can build a second equally sized rack for the same amount of money.

You have probably seen Flexy Racks all around the web. My inspiration was a dual rack found at http://www.tnt-audio.com/clinica/flexye.html. Full credit to the folks at TNT Audio for the great idea.

I decided to post clear instructions for a dual rack with measurements, since it's mostly a guessing game, and I love clear instructions.

Disclaimer: I make no warranties, express or implied, about the process laid out here. Always use safety equipment, don't hurt yourself, etc. Most of all, have fun with your cool new rack. :)

Step 1: Materials, Consumables, and Tools

The main materials are (for a 5 shelf rack):

- 1 ea. 4'x4'x3/4" sheet of MDF (medium density fiberboard)
- 5 ea. 5/8" all-thread rods (3' length recommended)
- 30 ea. 5/8" nuts
- 30 ea. 5/8" flat washers
- 30 ea. 5/8" rubber, neoprene, or santoprene flat washers
- 10 ea. 5/8" acorn nuts
- 5 ea. 1/2" x 8' edge molding (I used white oak. Any type of molding that covers most of the edge of the MDF is fine. Make sure it's unfinished.)

The consumables are:

- wood filler
- wood glue
- 120, 180, and 220 grit sandpaper (no need for wet or dry)
- 1/2" and 4" chip brushes (go for the cheapo ones!)
- mineral spirits
- any brand gel-type wood stain (dark colors are probably better)
- fast-drying spray polyurethane (I used clear satin)
- nitrile gloves
- lint free rags
- plastic drop sheets

Required tools:

- table saw (or a friendly lumberyard that will do cuts for you)
- drill (drill press is recommended)
- miter saw (so you can get that nice finished corner on the molding)
- 5/8" and 1-1/2" spade bits
- hammer
- nail set (used to hide the nail heads)
- 3" plastic putty knife
- two 8" adjustable wrenches

A few notes:

- Since I live in a hot, humid salt air environment, I chose to use 304 (also known as 18-8) grade stainless steel for the hardware. Aside from the aesthetics of the SS, the corrosion resistance was a requirement for me, but I must warn that there is a cost difference between the two. I suggest you go to McMaster-Carr (http://mcmaster.com) and price it out. My local fastening supply store had a great selection and I was able to get a better price (if I factored in shipping, plus they gave me some freebies).

- With a 4'x4' sheet of MDF, you can have up to six shelves. I chose five because of my spacing requirements between the shelves. If you wish to have a sixth shelf, add 6 each of the nuts, flat washers, and rubber washers.

Step 2: MDF Preparation

First, you must cut the MDF sheet to size, or your lumberyard can cut it for you. I had access to a table saw, but I cut it at the lumberyard with the help of one of their employees. It was easier since I had to buy a 4'x8' sheet and I couldn't fit it in or on my car.

A 4'x4' sheet of MDF will give you 6 shelves, with some scrap left over. DON'T TOSS THE SCRAP! You'll use it to test your MDF staining skills. Also, wear a dust mask - MDF has all kinds of binders, waxes, and chemicals that are not good to breathe in. You might also want to wear a long-sleeved shirt.

The dimensions for the shelves are 24" long by 15" wide. See Fig. 1.

The next step is to drill the holes for the mounting rods. I added two pass-thrus for wiring and cables, since my rack is mainly for audio components. These can be left out.

All this drilling can be done with a hand-held drill, but I highly suggest a drill press. The precision afforded by one gives you a much cleaner result.

Also, do not drill in one direction only. Drill in from one side until the tip of the spade bit pokes out the other side - then come in from the other side. MDF is prone to breaking chunks off if you drill in from one direction only. A hole saw might work if you drill in from one side, but I make no guarantees that you won't screw up your shelves.

The two holes that are on the same side are 1" to center from both edges. See Fig. 2 & 3.

The single hole on the opposite side is also 1" to center from the edge, and centralized on the 15" side, so 7.5" from the other edge. See Fig. 4.

If you want to do a mock up, go ahead at this time. I suggest that you do. I did because I wanted to know how to put it together before doing the final construction with finished shelves . Use the shelves to hold the all-thread rods in place while you mount other ones. See Fig. 5 and 6.


The two 1.5" cable pass-thrus are 8" from the edges to center and 1.75" to center from the back edge. See Fig. 7.

Step 3: MDF Edging and Filling

Ok! You've got your shelves ready to finish. Now it's time to put the edge molding on.

Because of minor inconsistencies in cutting the shelves, your best bet is to measure each shelf, and cut the molding pieces for them individually. I used 1/2" white oak, and cut them on a miter saw set at 45 degrees. See Fig. 1.

Cut slow! If you don't, you will have bad miter cuts, and fitting the edges will be a little harder. You still might have to adjust the corners with a bit of sandpaper to get the best fit. See Fig. 2

Make sure you lay out your shelves so 3 work in one direction, and 2 in the other (or 3 in the other if you want a 6 shelf rack).

Install the molding with 1.5" finishing nails.

When you install, line up the molding as best as possible with the top edge of the shelf. See Fig. 3.

The shelf will stick out a bit on the bottom of the molding. This is normal, and since it's on the bottom of the shelf, you can't tell it actually sticks out.

Make sure you miss the shelf mounting holes where the rods will go. 3 or 4 nails will be fine for each piece of molding.

Since the molding isn't exactly straight, you can put 1 or 2 nails in and align the molding to the MDF as you go. Use wood glue where the molding will join the shelves, and also on the corners. Use your nail set to hide the nail heads into the molding (only a bit is necessary).

Ok, by now you've got your shelves ready, but you've noticed that there might be gaps, the molding might not be even with the shelf itself, or the corners might be a bit off. This is where wood filler is your friend.

With wood putty and a plastic putty knife, fill any gaps, inconsistencies, etc. where the MDF meets the molding. Also remember to fill the holes to hide the nail heads you sunk into the molding. See Fig. 4

Let the wood filler dry well. You don't want to sand semi-wet wood filler, you'll just clog up your sandpaper.

Start with 120 grit sandpaper on a sanding block. I like the rubber ones, and you will get 4 pieces per sandpaper sheet using them.

Sand the wood filler to get the surface, edges, corners, etc. as even as possible. You can see in Fig. 5 where I had to fill a LOT in order to get the molding and MDF even.

Fig. 6 shows what you really want to aim for when installing the molding. This corner only needed minimal filling and sanding.

Step 4: Staining and Finishing

Now, you've finished the edges of your shelves, and you're happy with your results.

However, you're not done sanding yet. MDF needs to be roughed up a little so it will take the stain well. See Fig. 1.

Pull out your sanding block yet again, and sand the entire shelf - top, bottom, edges, corners. I started with 180 grit, and then use 220 to get a finer finish. You don't need to kill yourself sanding, just get a nice surface before you stain. The stain is quite forgiving.

Once you've finished sanding and gotten most of the sanding dust off (you WERE wearing your dust mask, right?), get some mineral spirits, some lint-free rags, and your nitrile gloves.

Wet the rag with the mineral spirits and wipe them down. Get all the dirt, crud, etc. off the shelves. You want them as clean as possible. See Fig. 2.

If you want to test your skills, get some of that scrap MDF from Step 2, and follow the staining process below. It's actually quite easy to do, but practicing will let you screw up before you go on to staining the shelves themselves. See Fig. 3.

Now, on to the stain! MDF does not stain like regular wood does. Normal liquid stain will soak in and give you a strange finish.

I used Minwax Gel Stain in Brazilian Rosewood, and a cheap 4" chip brush. The trick to this is simple. If you've ever stained anything, forget about what you did then. The best way I can explain it is to treat the stain like paint.

Use long strokes, but do it unevenly. Lay the stain on thick in some areas, thin in others - you want to approximate real wood as much as possible, which means: be uneven! See Fig. 4 for a general idea of what you will get as you stain.

I did the shelf tops and edges first. Since the 1.5" holes for the cables are not finished, I just took a small brush and smeared them with stain to they'd have coloration similar to the rest of the shelf. Now let the tops dry.

One important note: this will take time to dry. A long time. I'm in a tropical climate, with average temperature of about 80 degrees, and I let the tops of the shelves dry for at least a day. See Fig. 5.

Next, I repeated the same process for the bottom of the shelves. If you ding or scrape some stain off, don't worry. Touch-ups are very easy with a small brush.

One good trick is to use one of your all-thread rods as a hanger to let the stain dry without anything touching the stained parts.

I have to repeat: let the shelves dry for at least a full day. This will get you the best results in order to put on the polyurethane finish.

Now it's on to spraying the polyurethane. I used spray cans of  Minwax Fast Drying Polyurethane in Clear Satin.

The biggest problem with the polyurethane is dust and dirt getting into the finish as it dries. I solved my problem by converting one of my bathrooms into a spray booth. If you have a significant other or roommate, don't do this without getting consent first!

"Spray Booth" Prep:

I lined my bathroom and the tub with plastic drop sheets. They're cheap, and indispensable, unless you want to get polyurethane everywhere. Tape them up, cover everything, and you're good to go. Oh, and get yourself a respirator. You don't want to breathe in polyurethane fumes. They can kill you.

Use a couple of your all thread rods as hangers - I hooked them on to the shower curtain rod (which is screwed into the wall) and to the window. Check out Fig. 6. Follow the directions on the can regarding spraying. You don't want to lay on too thick a coat, or it will run.

Spray on 2-3 coats, depending on your preference. The fast-drying polyurethane requires no sanding between coats, and I didn't do it. Let the shelves dry for at least a day, or you might get some ugly fingerprints on them.

Step 5: Rack Final Construction

I hope you mocked up the rack before you started on the staining! It gives you a good understanding of how to put it together. If not, here is how to put it together.

1) Lay out your 5 pieces of all thread in this pattern on your bench or floor: 2-1-2.

2) Sort out your hardware. For each shelf, you will need 6 ea. nuts, flat washers, and rubber washers.

3) If you're building a 5 shelf rack like me, you have a left over piece of MDF with all the holes drilled. Use this as a helper stand to keep the all-thread rod level while you install it on the shelves. You want to avoid having the all thread torque the shelves. In the battle of steel vs. MDF, steel wins, and your shelves will get busted up.

4) Put a nut, flat washer, and rubber washer on the 3 all-thread rods that you will use to mount the bottom shelf.

5) Slide the bottom shelf (whether it's to the left or right - it was to the right on mine) onto the all-thread rods with nuts already installed. Make sure that the lengths of all-thread that are sticking out of the bottom of the shelf are equal in length. Install the hardware in this order: rubber washer, flat washer, and then nut.

6) Repeat for the bottom shelf on the other side. You have to make sure you install the hardware on the central (common) rod from what would be the top, with the nut first, then flat washer, and then rubber washer.

7) Install acorn nuts as 'feet' to your shelves. At this point you can stand up the rack on its feet to avoid any damage to your nicely stained shelves.

8) Repeat for all shelves. Please see Fig. 4 for dimensions. These are the dimensions I used, but you can choose any dimensions that suit you.

9) Note that I used acorn nuts for the highest shelf on the right to get a more finished look. You can cut the other all-thread that sticks out of the other side's top shelf and finish with acorn nuts. I haven't done so because I'm expecting a different amplifier than I have, and I want the adjustability.

Step 6: You're Done!

Congratulations! You have built yourself a nice new rack for cheap!

There are also other things you can do to make the look cleaner. Painted PVC pipe covering the all-thread rods is one idea. I like the shiny stainless I used, so I left it as-is.

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    15 Discussions


    9 years ago on Introduction

    OP here, if you have any comments or questions, I'd be happy to respond.


    6 years ago on Introduction

    I built a variation on this using unfinished pine boards.


    8 years ago on Introduction

    Awesome post, I am definitely going to be making something similar for my amp and turntable. Thanks!


    9 years ago on Introduction

    Beautiful result and very clean 'ible. Thanks for sharing. I actually found myself thinking about how to make the shelves adjustable so you could resize each section depending on what you decide to put in in. Might be a fun version 2!


    Reply 9 years ago on Introduction

    You mean the shelf size being adjustable?


    Reply 9 years ago on Introduction

    The shelf height, not the shelf footprint; basically make it so the shelves can slide up and down on the poles and then tighten down when the get to where you want them. (it may already work that way and I just missed it when I skimmed the instructable...).

    Anyway, great project.


    Reply 9 years ago on Introduction

    The shelf height is infinitely adjustable, I just put in the measurements that I used to fit all the LPs that I have.

    The all-thread rod allows complete adjustment - if you see the mock-up picture and then the completed component, the heights are different.

    Thanks for the compliments!


    Reply 9 years ago on Introduction

    Oh! I read 3' all-thread rods and saw 3"! After that I just assumed you were slotting the rods into pipes that you had cut to pre-determined lengths. Shows what I get for skimming.


    9 years ago on Introduction

    I'd never thought about staining MDF before. I'll have to experiment a bit.


    Reply 9 years ago on Introduction

    I found it to be pretty easy. You don't wipe off the gel stain, you just let it set for a while, and it comes out with the faux wood grain finish I got. You could experiment with different types of brushes or with maybe a graining tool.


    Reply 9 years ago on Introduction

    I've painted miles of MDF, and stained several fiberglass doors, faux-woodgrained many stage props, and I'm currently duplicating 100 year old faux-woodgrain finish in a historic home for a client, but for some reason it never occurred to me to stain MDF. Right now, duplicating the historic finish, natural sea sponges are working quite well, as they are much more subtle than the graining tool.


    Reply 9 years ago on Introduction

    Yeah, I considered using a sea sponge, but once I tried the chip brush method I discarded that idea. The important part is using gel stain. It sticks and stands up well, instead of laying down. Maybe a more detailed instructable on the MDF staining process is in the works. :)


    9 years ago on Step 2

    Ooh, good tip about drilling. I always wondered how to avoid splintering and breaking in chipboard and MDF.


    Reply 9 years ago on Introduction

    Debo decir muchas gracias, en vez de thanks! Saludos desde Puerto Rico.