tool to ensure the guide clamp is clamp in straight

[amateurSparky]

how do i ensure the guide is clamped in perfectly striaght so my cuts are striaght

 

[big-all]

i am assuming you mean guide fence??
what machine are you referring too

 

[amateurSparky]

I used one of these http://www.toolstation.com/shop/p81...+clamp&pmt=p&gclid=CMTEvPPB7cgCFYydGwod-2gKBQ.
Like many casual diyers I can't cut straight to save my life.
The only machine I have is a evolution jigsaw and makita circular saw. Could I use a combination square?

 

[Burnerman]

Why not use a combination square to get the right angle, and then clamp a length of straight timber in place to guide your circular saw?
Mark and cut from the back to avoid splintering any surface finish.
John

 

[Chud]

Straight cut...make yourself a saw guide (he goes on about it for a bit but the instructions are clear (fyi I'd go for a chalk line rather than the square if you're not sure how straight the edge of your timber is) -