Cutting straight lines with a jig saw; help!

[Ken Sington]

How do you do this? I need to cut four rectangular holes into a fixed horizontal surface and the blade is running all over the place, so I am having to plane or chisel after cutting to get the cuts straight which is a right faff. The only thing I can think of doing is using a batten screwed into the sections that will be cut out to act as a guide for the blade. Any suggetions (other than getting someone in to do it who knows what he is doing)?

[tr7v8]

I use a batten or even better a piece of aluminium angle.

[miniman]

If you fix the batten to the bit that you're removing, it will most likely move when you get close to the end of the cut. Fix it with a couple of grip clamps / g-clamps instead. Nice and slowly with the jigsaw.

[odyssey2200]

batton and some G clamps

[Big Al.]

If you can't use clamps double sided carpet tap can also work to hold the batten/angle in place.

A reciprocating jigsaw will have less tendency to wander.

Take it slow.

[miniman]

Big Al. said:

A reciprocating jigsaw will have less tendency to wander.

Is there another kind?

[odyssey2200]

miniman said:

Big Al. said:

A reciprocating jigsaw will have less tendency to wander.

Is there another kind?

a circular saw

Edited by odyssey2200 on Sunday 16th October 20:46

[miniman]

Surely a circular saw is less likely to wander than a jigsaw?

[CedGTV]

You can not keep a jigsaw blade in a straight line, it will always wonder or try to do it free hand but slowly.

Better to use a circular saw run along side a clamped straight edge or maybe use a router alone side a straight edge with a long cutout bit.

[odyssey2200]

miniman said:

Surely a circular saw is less likely to wander than a jigsaw?

thats what i thought too

[Simpo Two]

CedGTV said:

You can not keep a jigsaw blade in a straight line, it will always wonder or try to do it free hand but slowly.

Better to use a circular saw run along side a clamped straight edge or maybe use a router alone side a straight edge with a long cutout bit.

This. Jigsaws are designed to cut curves!

When I cut holes for a kitchen sink and hob it was much quicker and more accurate to use a circular saw + battens on a 'plunge' basis and finish off with a jigsaw.

[PoleDriver]

Get the widest blade you can for the jigsaw, they don't wander so much. Use battens either clamped or double-sided taped and keep the speed down!

[Simpo Two]

You can still end up with an angled cut depending on the grain direct. The top looks straight but the underneath isn't! (worst in thick wood going with the grain). Then again, it may not matter what the underneath looks like..

[CunningPlan]

As said above - use a guide to run the saw along, and if you can use another type of saw, do so as jig saws are awful and even with a guide the blade can bend and deliver a messy, unstraight cut. Also as above - going slowly helps reduce this. But jig-saws are the last port of call - I have one and there are times when it is the only thing that can do the job but it only gets used when all other options have been exhausted.

[Big Al.]

miniman said:

Is there another kind?

There are, one the old type where the blade just goes straight up and down, the second type is where the blade not only goes up and down it also has an orbital action which allows the blade to clear swarf on the up stroke of the cut.

http://cordlessjigsawreviews.com/reciprocating-saw...

A jig can cut straight lines, choose your blade according to your cutting parameters/material. Cut slowly and take care it's not easy but it can be done.

[dickymint]

Just drill holes in the corners and use a hand saw.

[Blakeatron]

Practice makes perfect!

Or like has been said, use the biggest blade you can fit.

For a perfect job you could undercut the hole and then use a router and template to get them perfect, square off corners with a chisel.