Rocking box

[Gerard Scanlan]

How pleased I was with my latest handcut dovetailed box. However on the dry fit it rocked corner to corner. The elevated corner lifts 3mm off the table. I told myself it would settle down when I inserted the base ino the rebate groove. But that did not help either. I remember from woodworking classes in school ( a long time ago) that the teacher would tell us to plane the corrners until the box no longer rocked. All good practice with a hand pane but not an option here as the joints would no longer be evenly spaced (as well as bringing my rebates for top and bottom dangerously close to the edges. What have I done wrong? Is it just a question of paring the dovetails a little deeper? This box is the size of a large shoe box and slightly deeper. Or do I need to trim them off and start again :?

 

[MickCheese]

Are you sure your stock was cut at exactly 90 degrees?

To get a totally flat box it is imperative you start with totally square stock.

Mick

 

[Ian]

I will second Mick - but you will always find there will be a slight rocking (perhaps 0.5mm) and it should be removed on a flat piece of MDF covered with sand paper, A gentle circular sanding action will work.

One more thing is to check you are on a flat surface to begin with.

HTH

Ian

 

[Jeff Gorman]

Gerard might find that at least one of the sides was twisted slightly.

There's some more info about twist at http://tinyurl.com/3s5mmml

Apart from planing the corners as already suggested, its a bit late to do anything else.

Jeff
www.amgron.clara.net

 

[Jonzjob]

Probably not the most finness filled way but when you glue it up you could clamp it to your worktop with the corners that it's rocking on raised a couple of mil by putting some packing pieces under them? But first I would do assaid and make sure that the sides are square.

 

[marcros]

could you save it by putting it on feet?

 

[woodbloke]

How pleased I was with my latest handcut dovetailed box. However on the dry fit it rocked corner to corner. The elevated corner lifts 3mm off the table.

What this actually means is that you have two diagonally opposite corners that are 1.5mm high on each one which isn't too bad ...some careful planing on each of the high corners should be enough to bring the whole thing flat again...but make sure you check by sighting along the top that it's coming out of 'wind' ('cos that's what you've got at the moment). When both the short and long sides are sighted parallel, in theory, the box should be flat. Check also at the same time that the sides aren't humpy, convex as these need to be flat as well - Rob

 

[Gerard Scanlan]

Thank you all very much. I now have a whole list of things to do. I will see if I can turn this advice into an actual remedy for this box. I have had this problem before on occassion and remedied it by either planing or attaching feet. However alway felt this was cheating and I really wanted to know where I was going wrong as it something that just seemed to happen sometimes. I suspect something is out of square or that one of the sides has a slight twist. Once I have found the cause I will post the findings. I felt a bit embaressed about asking this question as I have never come across an explanation of how to fix or prevent this in an woodworking literature so I assumed it was a real beginners mistake.

 

[marcros]

I felt a bit embaressed about asking this question as I have never come across an explanation of how to fix or prevent this in an woodworking literature so I assumed it was a real beginners mistake.

Dont- you have asked it, many have benefitted from it, myself included.

 

[Gerard Scanlan]

I have checked all the ends for square against the lengths. I pared a couple of dovetails slightly deeped but this did not seem to make any difference. I dry clamped it with a short length of rope and this did not make any difference. I can see a slight twist in one of the sides towards one end but it is not much at all. Perhaps no more than 3mm! It looks as though that has translated itself into a 3mm rise in the corner. I proped the corner up with a chisel so that you can see the full extent. So I am going to have to watch out for a twist in my stock more carefully in future. I will try and rescue this one with taking down the high corners as suggested and adding feet. I bandsawed and planed all these pieces from a larger block and stacked them for a few days before proceeding with the job. I should have checked them more thoroughly before cutting the tails the wood obviously was not as dry as I had though it was.

At least I know what causes this and how important really flat stock is.