Bed bolts, socket wrenches and covers

[Wood_workur]

I'm in the process of finalizing the design of a bed, and one of the things still left is the bolts that will hold the rails to the head and foot board. All of the covers for the bolts I've seen are in the range of 1.375" in diameter and larger. The largest Forsner bit I have is 1" so I would like to use that is my maximum diameter for the counter bore.

That said, there are 3 design criteria I have to meet:
1) Washer under the bolt head O.D. < 1"
2) Socket wrench to fit the bolt O.D. < 1"
3) Bolt of sufficient diameter to support load and safely transfer it to the wooden parts (Bed is to be made from pine). I'm going to use 2 bolts per corner, and lets assume the maximum loading per corner is not to exceed 300 lbs or so.

That said, I'm currently 150 miles away from my house in a college dorm. So I don't have access to socket wrenches or washers to measure their diameters, and I'm looking for some input on #3.

Also, as a side note, how much space should I allow between the bed frame and the mattress? Using the standard double mattress size of 54" x 75" I am thinking that 1" extra would be good so that the frame has an opening 55" x 76"

[LCHIEN]

a site like this has all the dimensional data on bolts and nuts. as well as strength info if you know how to use it. i'd guess 5/16-18 bolts would be plenty strong...

http://www.thb-inc.net/technical-data.html

i built a bed with these - they're mortised in slide fasteners and they come apart without tools and son't show holes or hardware, work great.
http://www.rockler.com/product.cfm?p...bed%20hardware

THere's a lot of other hardware choices (look at Rockler.com, search for bed hardware).
http://www.rockler.com/search_result...&Search=Submit

[JimD]

Alex,

You do not need 2 bolts per corner and don't need a very large bolt. This link will get you some safe working loads in shear for steel bolts:

http://dodgeram.org/tech/specs/bolts..._strength.html

If you use a bolt which is not threaded where the posts join with the rails, a 1/4 bolt can take 370 lbs. Loadings will not always be even but if they were, that means 4 of them could support around 1500 lbs. Maybe you will want to use a 5/16 but another bigger seems to be extreme overkill.

The other factor supporting this view is the fact that the bolt is largely there to provide clamping load between the wood members. The resulting friction will support even higher loads. I once had a kitchen cabinet held by one drywall screw. The cabinet was close to 3 feet wide and had all our every day dishes in it. The only way that happened is that the load was taken by friction (I didn't hang this cabinet, I found out when I took it down).

Hope this helps. Either a 1/4 or 5/16 washer will be safely under your desired 1 inch diameter.

Jim

[LCHIEN]

Actually its not clear if you are intending to use hex head bolts which are threaded fasteners intended to go into nuts, or hex head lag screws which are intended to thread into wood. You are not making your design clear so its clouding the answers.

if you are building a vertical leg and intend to put a through hole into it to fasten into a horizontal rail member (a classic bed design) then you will probably want a screw. A variant is to drill a large hole in the rail side to side and put a nut into the hole, then a bolt into the vertical member into a hole in the end of the rail that intersects with the side-to side hole and into the nut.

Either way, bolts and screws have two key measurements, tensile strength and shear strength. Tensile strength how much force it takes to fail the bolt/screw when pulling along its length. Shear strength is how much force it takes to fail the screw/bolt when its through a fixed member and a moving member, like a pair of scissors. THis is like the vertical leg and the rail.

Probably two number 8 or 9 or 10 screws will carry sufficient weight for a bed. THe phillips heads are under a 1/4" and you can plug them to hide them with plug cutters that will look much better than a plastic cover over a 1" counterbore hole (BTW that's plenty big for 5/16 or 1/4" washers). You will want at least two screws per leg/rail connection , to keep the rail from twisting and to spread the load on the screws. Mostly you need to keep the heads from digging in (in softer wood like pine you mentioned) with stress/motion to keep them from loosening up, esp. if you plug the holes so you can't tighten them periodically. If you use soft wood then some washers under the screws will help spread the head load - #8 or #10 washers will dictate the size of the plugs, then. Make sure that you have plenty of thread engagement in the rail so that the threads won't pull out. At least 1-1/2" I would judge offhand.

[Wood_workur]

My mistake, I am using hex headed bolts that will go through the leg into the rail, and in the rail I'm going to use cross dowels to anchor the end of the bolt.

I also intend to use two bolts instead of one because for the joint I would like to just have the two pieces butt, instead of a shallow mortise or similar joint, and with a butt joint I would need two to constrain any motion of the rail.

[vaking]

Alex,
I will second an advice from Loring to use hardware that allows bed to be dissambled without tools. I used these types from Lee Valley.
http://www.leevalley.com/US/hardware...842,41269&ap=1
These don't even need mortices, they just attach to the surface with screws. Does not get any easier.
If you use screws - you will need to tighten them up regularly because they will be getting loose from movement. I suggest to steer clear of woodscrews because those you cannot tighten regularly.
One more thing to consider. After you make the bed and put matress in it, you will need to put fitted sheet over that mattress and changing in will be regular process. If you make rails 1" longer than the mattress - putting that sheet on will be diffcult as you are leaving only 1/2" space between mattress and headboard/footboard. You need to be able to slip your hand between the mattress and footboard and headboard. I recommend making rails at least 4" longer. I have made a long twin bed (39"x80" mattress) and rails are 84".

[JimD]

One of my guest beds is assembled the way you describe. I used a single bolt but instead of rails and cross slats the mattress is supported by a platform. So the rails can't twist. In addition to one bolt, I added a piece of 3/4 wood under the platform. So in addition to the bolt I have the 3/4 thick extension of the post that would have to shear off for the platform to move. It's a double bed that occasionally sleeps 2 adults and works fine.

Jim

[JoeyGee]

I will third Loring's suggested on the rail fasteners. I ordered those same ones from Rockler. I have built 3 twin beds with those for my kids, and they have held up beautifully. They are very heavy duty, and do not work themselves loose.

[Wood_workur]

Thanks for the advice. I'll look into those bed fasteners some more, both the mortise style Loring posted, and the flush mount style Alex mentioned.

[jnesmith]

i built a bed with these - they're mortised in slide fasteners and they come apart without tools and son't show holes or hardware, work great.
http://www.rockler.com/product.cfm?p...bed%20hardware
[/url]

Those are what I use too. They work so well, I have never been interested in trying anything else.

[sscherin]

I also used the Rockler mortise in fasteners Loring posted in a bunk bed for my daughter.

They work great.. I built that bed in 2004.. It's been moved to 3 houses and taken apart at least a dozen times.. Still rock sold.. You'll want a rubber hammer to knock em loose. They lock tight.

[JimD]

I use these fasteners too. I've used them on the last 4 beds I've made. A plunge router and a jig is very useful for cutting the recesses for the hardware. You can do it different ways but if you make the jig and try it out on scrap first, you are almost guaranteed of not messing up. The easiest way to get the opening the right size is to split up some 3/4 wood with the center piece the size of the width of the opening. Glue it back together and you have your jig. A side fence can be braded on. A little hand work with a chisel will square up the corners.

Jim

[LCHIEN]

Going into detail, there's a couple of flavors you should really consider that I think will provide better results than your plan:

Here's my first choice:

the style above requires mortises in the ends of the rails. They work great, come apart easily and are completely hidden so I regard these as the standard of comparison. The trick is you have to mortise the ends of the rails, being typically 6-7 feet long then its a bit tricky, you have to make a jig. I used them and they work great/look great.


THe next style I would consider is this:

These mount on the surface of the rail and the side of the posts. They are visible if you look for them but aren't really visible at all because they're hidden on the backside of the rail. They are easy to use and only require locating them and drilling a few pilot holes. No complex mortising. They do come apart for transportability and like the previous mounts, are held in place by gravity.

Similar but locks:


Similar but uses heyholes instead of a hook.


THese are similar to the method of the bolt and cross dowel. But completely hidden


cross dowels and special bolts:


Fancy brass cross-dowel bolts and special allen head bolts for beds:


Anyway, my point is take a look at whats available - these are all from Rockler and its not complete.
If nothing else look at the text and the bolts diameters recommended - for single bolts (using dowels to align) these have 3/8" bolts, for two bolts per rail end it looks like they use 1/4 -20 hardware or 5/16-18 hardware.

Good luck on your project.

[Wood_workur]

Going into detail, there's a couple of flavors you should really consider that I think will provide better results than your plan:

Here's my first choice:

the style above requires mortises in the ends of the rails. They work great, come apart easily and are completely hidden so I regard these as the standard of comparison. The trick is you have to mortise the ends of the rails, being typically 6-7 feet long then its a bit tricky, you have to make a jig. I used them and they work great/look great.

I've searched around a lot, and these do seem to be the way to go. I saw a post you made here about them, and it appears that with more weight applied they lock tighter?

This style also seems fairly simple to install, I can easily make a jig to route them in place (I'd say routing the end of a rail is easier than trying to get holes aligned exactly on it), and they also seem to be the least obtrusive when the bed is apart (useful since I'll probably be moving a fair amount in the next few years)

[LCHIEN]

I've searched around a lot, and these do seem to be the way to go. I saw a post you made here about them, and it appears that with more weight applied they lock tighter?

...

the hook is initially tapered to allow it to start but the end is straight so there's a limit to how much it wedges in. You don't want a total wedge because then it'd be hard to get apart.

I actually had to take a file to the opening of the hook, I could mate them by hand (unmounted) but not get them apart. I filed each opening just a teensy bit so that I got a slip fit. I have to give the bottom of the rail just a bump to unmate them now - a bit of a awkward move so I actually made a support to hold the rail (with the bottom of the post about an inch off the floor) and you can give a bump down on the post with your fist to break it free. Tool-less disassembly!