Thread: Noob (measuring/layout) question!

Hi Keano and congratulations!

Just doing the maths will give a spacing between 55 and 65 mm - I will not be more precise.

There are safety rules concerning the spacing of slats on a cot - you will not want your baby to get caught between the slats. We don't want to hurt his/her hands or feet - or frighten the hell out of mum and dad.

May I suggest that you do some googling or, probably better, go down to a baby supply store and measure the gaps in safety approved cots.

Originally Posted by GraemeCook

Hi Keano and congratulations!

Just doing the maths will give a spacing between 55 and 65 mm - I will not be more precise.

There are safety rules concerning the spacing of slats on a cot - you will not want your baby to get caught between the slats. We don't want to hurt his/her hands or feet - or frighten the hell out of mum and dad.

May I suggest that you do some googling or, probably better, go down to a baby supply store and measure the gaps in safety approved cots.

Thanks Graeme!

The gaps on the store bought cot for our first born are 70mm. My slats are narrower so I am including an extra slat so as to not have too big a gap. So your maths of 65 sounds about right. I'm more worried about how I measure/space them out repeatedly and accurately.

Divide the total gap space, 790mm by the number of gaps, 13 to give the width of each gap, 60.77mm.

You could also make the gaps an even figure and take up the space with a couple of wider stiles which would add a feature to the sides

You could then machine or plane a scrap to that exact width of the gaps to help with marking out the rails.

Have you checked the Australian standard for cots as there are definite rules for space between stiles, etc to prevent accidents?

Hope that helps

I see that Graeme and you have posted while I was typing.

Here is how I would calculate it.

Imagine a 13th stile so you can do a division for 13 pairs of stiles and gaps. Add the width of this imaginary stile to the overall length then divide that by 13. This gives the width of each stile/gap pair with a gap left at the end. If you start at the left side then the right hand edge of the first stile will be at that measurement and the others will follow as that measurement is added to the previous position.

Cot stile spacing diag for WWF post.JPG

As far as I can see by info on the net this will give safe gaps but do check for yourself as Graeme advises.

Good luck with it.

I know you have good answers above for your current problem, but in the future you can turn to this site for lots of calculators when you can't get your head around something.

Originally Posted by labr@

Here is how I would calculate it.

Imagine a 13th stile so you can do a division for 13 pairs of stiles and gaps. Add the width of this imaginary stile to the overall length then divide that by 13. This gives the width of each stile/gap pair with a gap left at the end. If you start at the left side then the right hand edge of the first stile will be at that measurement and the others will follow as that measurement is added to the previous position.

Cot stile spacing diag for WWF post.JPG

As far as I can see by info on the net this will give safe gaps but do check for yourself as Graeme advises.

Good luck with it.

This idea will mark the right hand edge of each stile.

So just teasing it out. I could cut a scrap to be the required width (95.8mm) and use this to mark the right hand edge of each stile. From there I could take another scrap piece 17.5mm wide (half the width of the stile and use the line I have already marked to mark back to half the stile width for domino placement.

Does that sound like it would work? Or am I over complicating it and introducing more possibility of error?

Originally Posted by Keano

....
Does that sound like it would work? Or am I over complicating it and introducing more possibility of error?

That should work, Keano, but, as always, mark it out before you start cutting. Any error might then be cumulative....

One trick is to mark the middle of your rail; mark the middle slat there, and then mark out both ways from the middle.

Thanks Graeme

And thanks everyone else too for the input. It really is a great community.

I'll update with some pictures when it is all built.

I made a similar style cot a little while ago. Chesand is on the money - I used the same method to calculate the gap.

I used a story stick and started marking from the centre of the rail. That way if the marking on the actual piece varies a little bit you don't have an additive mistake and have a much larger gap on one side of the cot than the other. I used a thin scrap from one of my rails and cut it to half the rail length and marked out the mortise locations. Then placed the edge of the story stick at the centre mark of each rail and marked off the mortise limits. Happy to say this gave excellent results as the top and bottom rails for each side lined up very nicely and the opposing sides lined up as well.

I think your layout will be even easier because you're using a Domino. You could do it the story stick way but you're only really interested in marking out centre points and you could do a jig of some sort both for the stiles/slats and for the rails. Ideally you don't want to be 'measuring' at all, just using a known length and a reference point - for the rails I'd think something like a piece of scrap that you put a domino in, cut one mortise in the rail, then use the scrap with the domino to reference the location of the next mortise.

For safety info do indeed have a google, but make sure it's Australian information. I used this Vic site for safety information. There is also AS/NZS 2172-2003 but this deals with things that are more relevant in a mass production environment.

Edit: Sorry if I doubled up on any info, I've had this open and been adding to it most of the day and didn't see the additional posts.

Originally Posted by GraemeCook

One trick is to mark the middle of your rail; mark the middle slat there, and then mark out both ways from the middle.

I should have added that - much better to have a slightly smaller or larger gap at each end rather than at one end only.

When I do balustrades, I do the calculations slightly differently depending whether I am nailing slats or drilling dowels. For slats I want a mark on which to align one side of the slat, when doing dowels I want a mark that is the centre for drilling the dowel. If you are Dominoing, a centre mark might be convenient. There are two important measurements you need. One is 790/13 +35 = 95.77mm. This is the centre to centre distance (or right to right or left to left if you prefer). The other is 790/13 +35/2 = 78.27mm. This is the right to centre (or left to centre if you prefer)

To mark the "side" mark, I fasten a tape measure to the inside of your left stile (its right side) and draw it right across the full work. Then I make a mark at 95.5mm (close enough). Then I use a calculator and do 95.77 "+ +" 95.77 = 191.5mm. This is the next mark. Subsequently, simply pressing the "=" button (adds another 95.77mm) returns the next measurement and continue until finished. I allow the calculator to add the finer measurements together but round the answer. This allows the calculator to take care of the summation of fractions and minimizes the cumulative error.

To mark the 'centre' mark, I make my first mark at 78.0mm (close enough), then use the calculator and do 78.27 "+ +" 95.77 = 174mm. This is the next centre mark. Subsequently as above, pressing "=" (adds another 95.77mm) and gives the next centre to centre mark.
I've always found marking from one point and doing the fine summation on the calculator but rounding the answer always overcomes any chance of cumulative error. And if you make a gross mistake with any one position, it doesn't throw out the rest of the marks.

A spacer block is also a good idea since you are making the stock and can control the dimensions. But if you are using bought timber of nominal dimensions which might be plus or minus a couple of mm, the result can ask awkward questions of you once you have set it all out!
cheers
Easier done than said!

**Edit as Alkahesic said above a story stick is a GREAT IDEA! You can do all this measuring work once on the story stick

Dry fit of a side panel. Gaps are even and everything is square.

Gluing it is going to be a nightmare. Any expert tips from you experienced crew on the easiest way to approach the glue up?

20200924_170756.jpg

Use the titebond liquid hide glue or titebond III for a bit more open time. I used titebond II and it was a rush but not the end of the world. The first rail is relatively easy but the second can be a pain, I had my wife help me out by lining up the slats as I fit them into the second rail. You don't need a ton of glue either since you're gluing so many slats to the rails. I tried to avoid any squeeze out and the end result could be used for a ladder (for me, not the kids).

Don't take any shortcuts on the dry assembly, check everything, have all your materials at hand you'll be right.

Originally Posted by Alkahestic

Use the titebond liquid hide glue or titebond III for a bit more open time. I used titebond II and it was a rush but not the end of the world. The first rail is relatively easy but the second can be a pain, I had my wife help me out by lining up the slats as I fit them into the second rail. You don't need a ton of glue either since you're gluing so many slats to the rails. I tried to avoid any squeeze out and the end result could be used for a ladder (for me, not the kids).

Don't take any shortcuts on the dry assembly, check everything, have all your materials at hand you'll be right.

I have Titebond II so I will just go with that.

I'm planning to have the dominoes pre-glued into the slats so then on final glue up I'm only dealing with glue in the rails. I only have enough clamps for one glue up at a time. Just gonna take me time and do one each evening.

Good call on using the wife, I've told her she'll be the foreman.