Putting casters on the narrow bottom of old bookshelves. Help?

July 3, 2009 8:47 PM

How do I put casters on the bottom of this bookshelf? The bottom looks like this. The bookshelf itself is of some kind of MDF or high density particleboard, i.e. not pure wood. I want to put casters on the bottom of the bookshelf, but the strip of wood that touches the floor is too narrow for a plate caster like this. Can I somehow put a screw into the end of the particle board to fit a caster like this? How? Details inside.

It was made my partner's late father (before she was born) and was headed for the rubbish heap but I've saved it to give it another life. The wood is sturdy but slightly warped - so if I was to put a strip of wood making the 1/2" section flush with the 3/4" section, I'm not sure if I could get it flush enough. Also -- the simpler the better here. I don't have a saw, clamps, heavy duty glue, etc.

I'm a little worried about the wood splitting if I was to put in a threaded caster like the second linked option. How do you even screw those into the wood? The bookshelves have lived a long life and I'm a bit worried that a screw through the middle of old particleboard will just eventually split up the sides.

Are there really narrow plate casters? I'm worried that the dimensions of the piece will overwhelm little tiny casters (visually if not structurally). I had another idea to put huge plate casters on the bottom of the bookshelf (they'd be taller than the small supports, making the casters sit on the floor) but that would just look stupid.

I have a decent power drill. No saw. They're too big for me to lug somewhere else to use a power circular saw.

I'm going for a combination of good looks and ease of install. I'm willing to buy whatever casters will work for this project. Any suggestions at all? Help me make a fantastic gift here!

posted by barnone to home & garden (21 comments total)

Can you glue blocks of wood into the corners of the bookshelf on the bottom before screwing in plate casters? I'm confused by the diagram. Is that the way the inside corners look when you're on the floor looking up? If so, can you either add a full piece of wood across the corner or cut a shape to fit inside those angles? Is there a lip where the casters are to fit under and not be seen or are they going to be on view? I have some furniture on casters (kitchen cabinet, buffet), but they are squat. How tall is the bookcase? Will it tip easily if it rolls?
posted by x46 at 8:54 PM on July 3

Assuming you want 4 wheels, you might attach two boards with short screws and glue, cut to to the right length to sit in that 1/2 inch step, across the width of the bookcase. Then just bolt the plate caster to each end of these boards.
posted by Flashman at 8:55 PM on July 3

Sorry for the confusing diagram. Here's a better one -- looking head on at the bookshelf (as though you were looking at the two shelves of books, trying to find one).

I've definitely thought about putting another board across the bottom or little blocks to make the supports more sturdy. But the wood isn't perfectly straight - it's a bit warped and wavy. Not noticeably so, but if you put a normal piece of wood against the bottom, it's definitely not straight.

Any ideas if short screws and a bit of wood glue would work? I don't have clamps...that's starting to get more expensive and time consuming than I'd like to spend on this little project.
posted by barnone at 9:08 PM on July 3

I had another idea to put huge plate casters on the bottom of the bookshelf (they'd be taller than the small supports, making the casters sit on the floor) but that would just look stupid.


Aren't the casters going to be sitting on the floor no matter what? How else would they work? Can't they be set back from the front and be of such a height that the shelves are only raised off the floor by a small amount? How tall are these shelves anyway? Will you really be able to move them with any casters without them tipping?
posted by orme at 9:15 PM on July 3

Ok, that new diagram helps a bit. What if you just got some furniture sliders that can be nailed onto the bottoms of the 3/4" wide area?
posted by orme at 9:19 PM on July 3

They're very long and squat -- only two short shelves high. About knee height. They won't tip over - they're already on these little tiny legs!

If the casters were inset -- i.e. beside the legs -- the legs would be floating off the ground, next to casters sitting on the ground. I just think it would look silly.
posted by barnone at 9:20 PM on July 3

Corner or Frame casters. I'd chisel away enough of the 1/2" section that the vertical part of the frame on the caster could fit up against the 3/4" section.
posted by Mitheral at 9:21 PM on July 3

You could shim the ends of boards if the centre is bowed down. Now I understand the diagram. I would avoid the corners if possible since the main part of the bookcase is inset not very much and attach either two boards across the width as Flashman says or use blocks in the corners. How short a screw? Don't put anything dinky in there as moving the bookcase on casters could move the screws if they're not buried deep enough into the wood. And, get screws made for MDF if that's what you're using as MDF doesn't have the same resistance as real wood. I'm very fond of the type of construction adhesive that comes in a tube. Being a bookcase, could you use it's weight to 'clamp' the blocks/boards to the bottom? I put up crown moulding up on a wall/ceiling that the prev owner had made from some type of fiber board (not drywall) that wouldn't take a nail or screw without crumbling. Just used a few finishing nails underneath to keep it in place while the glue dried. If I take it down, the wall will come with.
posted by x46 at 9:22 PM on July 3

How big is this book shelf?

Those castor's you linked are vastly bigger than is necessary to move around a moderate sized book shelf. Castor's installed on pianos are smaller in size by at least 2/3rd's than what you're attempting. Look around at furniture supply stores and you should find something suitable for your needs. You might simply need to fill the voids in the corners to mount these much smaller castor's.

What about these?
posted by Gravitus at 9:23 PM on July 3

haha mithreal posted what I was writing to post. /foiled again.. :)
posted by Gravitus at 9:25 PM on July 3

What about using the casters that would make it all floaty looking, but then attaching a narrow piece of trim across the front to hide them? You could get a matching bit of wood cut to size from a home center, then just tack it on. I think trying to get some casters onto the edges there like little feet or something is gonna be much harder.
posted by orme at 9:31 PM on July 3

Actual photos of the bookshelf:
- front
- bottom side
- side view
- close-up of bottom rails/legs

They just got primed and I'm going to take off the backboard to line it with nice wallpaper - kind of like this look, though not that exact pattern.

Thank you all for the good advice so far. I'm having a bit of a hard time imagining how those corner casters would work here.

I know the casters are bigger than needed. Those aren't the exact ones I'd buy, but it's the general scale that matters -- I'm going for more of this scale ratio not this scale ratio or this one.

Maybe casters are too much trouble... maybe we just need little legs instead. Basically the wood part that touches the ground isn't level (the wobble drives me nuts) and they're such basic pieces that they need a little something to stand out.
posted by barnone at 9:58 PM on July 3

You see those rails that run front to back undeneath the bottom shelf? Replace those with a couple of pieces of real wood that are as thick as those are high, and wide enough to mount your plate casters on. Put screws through the sides of the bookshelf and into the edges of the wood; use four per side, because those screws are now what's going to bear the weight of the sides and anything loaded into the top shelf. Also put a couple of short screws down through the bottom shelf and into the wood. Use screws with countersunk Philips heads, sink them in fairly deep, and fill over them before painting.

A worthwhile improvement, both to look and structure, would be to fit a couple of 19mm wooden rails on edge, below the bottom shelf at front and back, to conceal the caster mountings. The rails should be as wide as the distance from the bottom of the shelf to the bottom of the existing sides. Make the caster mounting pieces 38mm shorter than the depth of the shelf to accommodate these. You should be able to find timber that's close enough to the width you need that all you will need to do is cut it to length, which is easily done with a handsaw. Once again, fix these using screws that come down through the particleboard and into their edges. You should find that the screws will easily pull any warp into line.

Never put screws into particleboard when you have the option of putting them through particleboard and into wood. Never put any kind of pin fixing (screw, nail, or dowel) into the edge of particleboard, especially old particleboard. Get used to thinking of particleboard as weet bix and you won't go too far wrong.
posted by flabdablet at 10:43 PM on July 3

I've done this by simply fabricating a metal channel to fit over the wood, then drilling a hole and inserting the caster (you may be able to find pre-fab channeling at the hardware store - angle iron would possibly work as well). The metal channel should be snug fitting with the sides of the bookcase it is fitted over and as long as possible to stabilize the whole contraption. Use either glue/epoxy or small wood screws (or both!) to hold the channel in place. For bonus stabilization properties you could insert metal tubing (or a lead wall anchor for a threaded peg) in the hole you drill to accommodate the peg on the caster. Good luck!
posted by torquemaniac at 11:07 PM on July 3

Would these brackets work?

flabdablet - I like your idea of removing the piece of wood support and replacing it with something bigger and sturdier. But it's really glued/nailed on there. I don't know how I'd get it off without peeling away part of the particleboard...

I know they're not that attractive but they're meaningful to her and if I can get them in OK shape we'll all be happy.
posted by barnone at 11:13 PM on July 3

torquemaniac -- channeling over which part? The little support slat of wood beneath the shelf? Or the side wall?
posted by barnone at 11:15 PM on July 3

I don't know how I'd get it off without peeling away part of the particleboard

Destroy it carefully with a sacrificial chisel (i.e. a $2 shop purchase that you don't mind hitting the occasional nail with).
posted by flabdablet at 12:03 AM on July 4

And yes, if you don't mind the look of those bench dog brackets, they should work fine. You'd want to chisel four chunks out of the shelf support rails to let the inner brackets snuggle right up to the side walls.
posted by flabdablet at 12:07 AM on July 4

Mind you, at $50 a pop for bench dog casters vs $13 for standard plate mount swivels, I'd be going the extra woodwork route.
posted by flabdablet at 12:10 AM on July 4

The picture is very helpful. The bottom shelf isn't dadoed into the side so you don't really want to attach wheels to the shelf as it'll pull away from the side. You said you didn't actually need wheels in which case the conventional method to remove a wiggle from uneven surfaces (either the furniture or the floor) is with a rubber cushioned glide. They just hammer in like a nail though you may want to predrill a hole if you can to prevent a blow out. The rubber ring allows the glides that are proud to compress down until all four glides are touching the floor (within reason of course, though the nails are long enough that you can put a washer or two between the glide and the shelf if you need more levelling).

The Rockler price is 4 of the 3/4" for 4.29 however you can find these in most big box building and hardware borgs.
posted by Mitheral at 10:11 AM on July 4

Thanks for all of your very helpful answers. I ended up buying a nice handsaw, and sawing off the bottom legs (and little supports). This left a semi-flat bottom. So I then bought a decent sander and made it relatively flat. Got a piece of MDF cut to size at Home Depot, and glued it onto the bottom. I also put about 8 screws attaching the MDF to the bottom shelf and side walls. It's REALLY on there and not wobbly at all. Took off the old peg board backing, and put on nice new unwarped backing. The backing is going to be bright glossy yellow and the rest of it will be a nice warm grey.

Then I'll put some sexy plate casters on the bottom. Ahh...projects. I now have a saw, sander, lots of sanding discs, tons of leftover MDF, nail filler, primer, paint. I think this means another project will be heading my way... hopefully this time with a good excuse to buy a decent drill. No more of this 7 volt nonsense.

It's going to look GREAT and she is super duper excited to have them serviceable again. I'll post a photo when it's done. Thank you all!
posted by barnone at 1:29 PM on July 7