Thread: Problem with jig saw

Jigsaws are useless at cutting straight lines. The blade will follow the grain and go pretty much where it wants.
If you only have a jigsaw, cut outside the line and refine with a hand plane. Or use a guided router bit and a straight edge to get down to the line.

Pressure may affect the cut but as mentioned, jigsaws aren't a great choice. They not only follow grain, the nature of the beast means they easily go off course. I can never get a cut to be vertical through material either.

How thick is the timber you are trying to cut? It may be better to get within a few mm from the line freehand (no straight edge) and then use a hand plane to get you to the line


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Some brands of jigsaw will take extra thick wide blades specially designed for ripping thick timber. Check to see if yours might be one of the good ones.

There is skill in using a jigsaw, and even then the results may not be perfect.

Basically, you must let them cut under their own weight. As soon as you force the cut (push it a tad too hard), it will cause the blade to bend. This will happen more easily with wild grain. Take it very slowly.

Regards from Perth

Derek

Seconding Derek's comment Dalpets.

Also, freehand follow the line, far better than trying to use a jigsaw with a fence, that's like trying to herd cats.

then as someone said, plane down to the line.

(try cutting tight curves, that's fun (the problem to me there seems to be more that we don't sense that the pivot point is the very cutting edge of the blade, not the centre of our handhold. We then inadvertently apply sideways pressure on the blade, encouraging it to both bend and wander.

Scraps of wood and lots of practice!!!!

Hi guys-thanks for your contributions.

This is 9mm MDF I'm trying to cut straight. It's for a base to fit into rebates in the 4 sides of a stereo valve amplifier cabinet. It needs to be pretty square otherwise it's going to work against the four 89mm high mitred corners.

This cabinet was supposed to be just incidental to the main electronics project but has turned into somewhat of a nightmare. It comes across to me now that unless you have relatively expensive purpose built powered equipment, that a modern carpenter's shop would have, you are pretty much behind the 8 ball. I never thought for a moment that I would have resort to using a plane to achieve this.

It's really a one off project so i couldn't really justify the purchase of the above mentioned equipment. Except for powered items (a router, jig saw, rip saw & planer) everything else I have are hand tools.

I think that you can do this with a jigsaw against a guide/fence as there is no grain to worry about. Just go very slowly.

Regards from Perth

Derek

I think if it's only 9mm mdf you'd get a lot better results by using a hardpoint hand saw from bunnings. They are really cheap (ie. ten dollars or less). Keep the angle fairly flat and cut to one side of your line. I think you'd be pretty happy with the results.
Good luck.

9mm MDF? More practice and as stated, cut near the line and sneak up on it with other tools. If the lines are straight a hand plane is perfect. If curved a sanding block with 80 grit then 120 will work

find your local men's shed - take it down there - gent them to cut it on their table saw - slip them $20 or so and go home - no pain, no hassle

Originally Posted by dalpets

This is 9mm MDF I'm trying to cut straight. It's for a base to fit into rebates in the 4 sides of a stereo valve amplifier cabinet. It needs to be pretty square otherwise it's going to work against the four 89mm high mitred corners.

This cabinet was supposed to be just incidental to the main electronics project but has turned into somewhat of a nightmare. It comes across to me now that unless you have relatively expensive purpose built powered equipment, that a modern carpenter's shop would have, you are pretty much behind the 8 ball. I never thought for a moment that I would have resort to using a plane to achieve this.

It's really a one off project so i couldn't really justify the purchase of the above mentioned equipment. Except for powered items (a router, jig saw, rip saw & planer) everything else I have are hand tools.

Hi dalpets

what you need is a longish piece of timber with at least one straight edge and some clamps.
The piece of timber with one straight edge can be purchased from Bunnings -- look at their D4R timber -- or produced yourself with your hand planner.

mark out the square shape you need to cut on the MDF, then cut a little outside the line with your jigsaw. I don't know what blade you have, but your "quality fine tooth woodsaw blade" may be designed for cutting curves rather than straight lines, or designed for material thinner than 9mm. And the Bosch blade numbering system can be confusing -- there must be over a dozen different blades labeled T101(something) each with a slightly different purpose.

anyway, once you've cut close to the line with the jig saw, use the straight edge piece of wod and your router (with a straight cutter) to trim the MDF to the exact size and shap you need. Run the router base against the straight edge. The base on most routers has one flat edge, run this side against the straight edge.

Also, re your miter problem, if your router will accept a 1/2" shank bits, you could use a 90 degree V groove bit you can use a similar technique to achieve accurate and straight 45 degree miters. Look up Carb-I-Tool bit number T 1230 1/2