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Posted: Fri Jul 08, 2011 8:31 am
by mjmills
Setting Out.
Am complete novice, and looking to set out my patio using string lines. Theory all makes sense, but how do i measure off the individual lengths.
I locate 1 pin as a starting point, and i know 1 side of the rectangle is 3050mm, the other side is 3640, so
i have also established the hypotenuse.
What is the technique for measuring off lengths of string to set the right angle out? I can't just put the pins in and
then run the string around it as that defeats the object of setting out the right angle. Cutting lengths of string doesn't
seem appropriate as when it is attached to the pins and knocked into the ground the level/height of the string may differ and additional tension or slack appears in the string.
A bit of guidance as to the 'grass roots' of setting out with string lines would be appreciated. Once i know the
'right way' to do this bit the rest should be fine!
Thanks
Posted: Fri Jul 08, 2011 8:47 am
by Carberry
Posted: Fri Jul 08, 2011 8:53 am
by mjmills
Thanks, i had read this beforehand.
The difficulty i'm having is getting the measure of the line between pins correct. i.e. how is it done - measure string first then tie, or set pin out manually (which appears to defeat the purpose when trying to set out aright angle)
The linked page seems to suggest the pins are set out and the string then tied to each, however surely the measured string is needed first to enable the pins to be placed?
Posted: Fri Jul 08, 2011 9:24 am
by seanandruby
??? Is this a wind up? You set out your pins to where you want to, then determine the height and tie the line to the first pin and pull to the next pin and loop it around. Alterativly tie to first pin pull to last pin and tie a tindle ( short piece of string ) around the pin and line to hold line at correct level. The tindle allows you to free up your pins easier by untying piece of string. Hope that's clear.
Posted: Fri Jul 08, 2011 9:38 am
by mjmills
Thanks
Posted: Fri Jul 08, 2011 10:13 am
by London Stone Paving
MJ.
I think you are going a bit too deep into this. Setting strings out is a really straight forward process.
Set out 1 string line at the correct height which runs parallell along the highest point of the patio. Then set a line parallell to the first line at the lowest point of the patio. All you need to do then is to run a string line between the highest point and the lowest point and you willl then have a surafce level to work to.
You dont need to worry too much about the lines being in a perfect right angle to eachother. As long as the first line is square to the property and you lay your first course accurately to this line
Posted: Fri Jul 08, 2011 12:28 pm
by seanandruby
lsp is right. I just assumed you had a major contract, imagined your patio to be the size of a football pitch, ha ha. We always work to 0.5 of a milimetre :;): :laugh:
Posted: Fri Jul 08, 2011 4:40 pm
by lutonlagerlout
3:4:5: is your friend here
set your lines up then mark say 4 m along the house wall from the line and mark
measure 3 M out from the house and put a piece of ply or something similar under the line and mark 3 metres
now on the hypotenuse put your tape to the mark on the house and measure it at 5 M where the 3 metre line is
where they cross is where you line needs to be for a 90 deg angle
it is very important to get this right as a little bit out can cause all sorts of problems with racking and joint width
hope this helped
LLL
Posted: Fri Jul 08, 2011 5:30 pm
by peg basher
0.5 of a mm??? i find that very hard to believe on a building site! I am a setting out engineer and in my experience if everybody worked to an accuracy of 5mm then 99.9% of everything on a job would go to plan perfectly. after all its generally only a bit of concrete and steel not a swiss watch!
Posted: Fri Jul 08, 2011 5:40 pm
by lutonlagerlout
:;): this is a wink peg basher
it means hes having a laugh
most stuff is + or - 5mm over 3 metres
LLL :;):
Posted: Sat Jul 09, 2011 7:15 am
by cookiewales
peg basher wrote:0.5 of a mm??? i find that very hard to believe on a building site! I am a setting out engineer and in my experience if everybody worked to an accuracy of 5mm then 99.9% of everything on a job would go to plan perfectly. after all its generally only a bit of concrete and steel not a swiss watch!
have had a few bad experence with site peg bashers so now allways check myself and make them put in datum marks and nails then photo graph them after being caught for a few thoushand pounds it makes you wise 
ps we work to spot on :;):
Posted: Sat Jul 09, 2011 9:23 am
by seanandruby
Correct LLL. Keep up peg basher :laugh:
Posted: Sat Jul 09, 2011 10:45 am
by peg basher
cookie i can believe that. If i make a mistake i will always take it on the chin, as its the only way, you will ever get any respect from the lads working for you. And most of the lads I work with understand that if your setting out all day every day that you will make a mistake sooner or later. They will do their best then, to rectify it or get round the issue.
However you would not believe the amount of times i hear "i only worked to your lines and levels" (But have since pulled out all your pins and covered any lines you gave me)!
Posted: Sat Jul 09, 2011 12:36 pm
by lutonlagerlout
or cut the top off the datum :;):
the best one is when the bison floors come and they dont fit,
seen that happen, and heads rolled that day 
LLL
Posted: Sat Jul 09, 2011 2:26 pm
by peg basher
kerb layers favourite is to lay their kerbs and then go round and adjust the pins to suit them!