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Clamping ?

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Dog

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Fed up with paying thru the nose for wooden garden planters I decided to make my own. I designed something easy to do, involving routing and dowelling and this is the result :-


The only problem I've come up against is clamping. I make two sides first, clamp them up with alu sash clamps but when putting the planter together and using four alu sash clamps to clamp it up I'm finding that the planter sits unevenly after the clamps are removed. How can I correct this ?
 

Chris Knight

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Dog,

It could be due to a couple of reasons:-

1. The joints aren't square and the clamps pull the shoulders up tight which results in a non-level condition

2. You are putting the clamps on in a non-square way and that pulls everything out of line (very easy to do! DAMHIKT)

You can easily cut the legs to be flat on a level surface when it is all glued up if you wish BUT:-

Why bother? I bet your patio is not flat and level and after filling the thing with peat and whatnot then watering it, nothing will be square again. With its soil and plants, it is not going anywhere.
 

Dog

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That is true about non-flat surfaces, my patio especially, but I just like to get things right so I'll pay more attention to how I'm clamping them up in future, thanks for your advice.
 

Keith Smith

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Very nice planter, only trouble now is you'll probably have to make dozens as everyone will want a couple. :wink:

As for cramping up, the first two sides are relatively easy, I use a framing square to ensure it is still square after applying cramping pressure; these are sometimes called rafter squares, they are only about £5 and are pretty useful.

When dry ensure both sides are identical; then I see you are using sash cramps to cramp the whole thing together. Although they are alloy if they protrude much beyond the work they will tension the workpiece and when removed the piece will sort of pop back out of square.

I use multifix clamps (bar clamps) for this as they are much lighter and don't tend to cause this problem. One other point is that the clamps need to be at exactly 90 degrees to the work or they will pull it out of square.

Hope this is of some help.
 

Dog

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Thanks Keith, some good advice there, I'll get me a framing square and see if I get this minor problem sorted and think about different cramping methods. I'll also think about the glue I'm using. At the moment it's rapid dry PU but with only five minutes before setting I'm not giving myself much chance to make adjustments. I've tried TiteBond II but found this very poor compared to the PU glue. Any suggestions for a good strong glue that will last outside would be much appreciated :)

As for making more, it has already happened, 25 to date, most worked out ok though, no rocking :roll: :D Friends, family, family of friends etc etc :)
 
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Dog

Yep, familiar story with me. Everything nice and square and a perfect fit then it comes to glue-up. I hate glue ups and have begun to get a bit of a phobia.
Anyway, I find that when using aluminium clamps if you over tighten they will flex and hence exert pressure at an angle on the faces of the clamp heads (if you see what I mean). Run a straight edge along the clamp to see what is happening.

Nice useful items by the way.

Regards

Roy
 

Chris Knight

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Dog,

This is a book I found useful http://www.amazon.co.uk/exec/obidos/ASIN/0762102004/ref=sr_aps_books_1_2/026-9300866-6994858

You may have a bit of trouble finding it but it's worth getting hold of if you can.
Don't forget the old trick of measuring the diagonals of rectangular assemblies - which should be the same if the frame is square. Also, if your bench is flat as it should be, you can use that as a reference surface and make it part of the clamping operation.
 

Keith Smith

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Dog,

If you've made 25 you should be getting the hang of it soon :D

It is actually an excellent way of improving your skills; making lots of the same thing, trying to make each one better than the last.

Yes the 5 min P/U glue is a bit quick sometimes, Gorilla glue is a well known P/u glue with an open time of about 20 minutes. I have used Titebond P/U glue and wasn't too impressed seemed brittle when set and I am using a trade P/U at the moment but it isn't so easily available and only comes in large sizes.

Of course there is always Extramite which IMHO is better than P/U but it is a lot more fiddly as you have to mix it with water.


Keith
 

Dog

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Thanks all, lots of helpful tips in my eventual perfection of planter building :D

I'll keep looking for that book but for now I'll try something similar to this tip in this link http://www.woodworkingtips.com/woodtips/sntip56.html for the individual glue up of the two sides and no doubt ideas will arrive for something involving the bench surface, as suggested, when glueing up the whole box :)
 

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