Jigsaw help

[Will-I-Am-Not]

I'm a newbie, trying to build a simple box out of 18mm ply and not having the space or the ££ for a saw bench thought I'd try working with a jigsaw and a workmate. But the jigsaw cuts are all curving away from my line, though I'm cutting slowly, with a steady hand (!) against a firm straight edge as a guide. I've tried several different drill speed settings and thicker blades, but can't stop it happening. Have I simply got the wrong tools for the job, or am I doing something very wrong?

As you can see, the cut below is typical. Within 100mm, the cut has deviated away by about 5mm; though the guide has followed the line, the blade has bent away to the left. Any tips gratefully received.

 

[footprints]

Not uncommon, I used to use a circular saw for that kind of cut (till I was given a saw bench, OMG what a dream to cut timber now!) I have had similar trouble with a jigsaw. Firstly any wear in the tool (or a cheap tool) and you are on a hiding to nothing. Use a new blade, cut slow, let the tool do the work and if you have a pendulum adjustment on your saw set to longest setting. Trouble is if you cut freehand and start to run out you can turn the saw back on line but with the fence you can't, all you can do is tilt the saw which just results in an even bigger mess.
A circular saw is pretty cheap these days, go on treat yourself!

 

[endecotp]

Jigsaws do that. Get rid of the straight edge. Draw a line, follow it by eye.

 

[big-all]

yes never ever use a strait edge with a jigsaw
blades can have a bias any slack in the clamp or blade will cause the blade to wander
just work out your jigsaw watch the blade and only the blade ignore any guides unless you have worked out where the guide should be as in 1.5mm above /below the line to put the blade strait and on line
most jigsaws will crab to some extent or orther

 

[Will-I-Am-Not]

Thanks. Appreciated.

 

[geraldthehamster]

My jigsaw does that. It's a De Walt; despite that the blade fitting has gone so far off straight that it diverges visibly from the foot. However, I do find that I can do a reasonable job cutting straight by going freehand.

 

[Will-I-Am-Not]

(Not trusting my freehand, I hired a circular saw instead).

 

[footprints]

Put one on your Christmas list!

 

[Chud]

(Not trusting my freehand, I hired a circular saw instead).

If you can be patient you should be able to pick up a decent circular from gumtree/ebay for less than the price of hire - I got an Evolution Rage (http://www.evolutionpowertools.com/uk/build/rage.php) for c. £30

 

[footprints]

Treat yourself to a new one, nice new blade fitted and 12 months warranty!

http://www.screwfix.com/p/evolution-rage-1b-185mm-multipurpose-circular-saw-230v/84664#_=p

Good for old timber in particular as it is undamaged by nails.

My own policy is never buy used tools unless you know the seller personally, a lot of the stuff is nicked from sheds and tradesmen's vans.

 

[big-all]

My jigsaw does that. It's a De Walt; despite that the blade fitting has gone so far off straight that it diverges visibly from the foot. However, I do find that I can do a reasonable job cutting straight by going freehand.

yes my old dewalt 933 18v is like that by perhaps 3 or 4 degrees lol
it is very accurate if you follow the blade i use it the most over all other jigsaws i have [all battery] bosch 10.8v and ryobi 18v
they are less out off true but you need to adjust your brain to the saw now this may take perhaps 3 or 4 cuts so on less accurate work i choose the saw to match the kit i am taking as it wont matter
as most off my work is construction off furniture in my shed with the odd bit off fitting i choose the old faithful dewalt first