Bloomin' cheap Jigsaw!

Ok, the story is that I needed a jigsaw because I'm doing a lot of tatting about and chopping bits of wood. Most of the work isn't vitally accurate so I just went for a Ferm (Screwfix 11932) with blade pack 17632, though I did also get a pack of down-cutting blades (41316?)
This is ok for most cutting-to-length jobs, but I have had *real* problems when I need to get anything like an accurate cut. Yesterday, for example, I completely ruined a knotty pine door when trying to take 1/4 inch off the bottom - I clamped up a straight edge, fitted a new blade, ran the thing without too much forward pressure and noticed after a few inches that the cut seemed to be wandering *towards* the straight edge!
Well, that wasn't really a problem because I was taking off slightly less than needed and intending to finish off with an electric plane I'd borrowed, but when I pulled the saw out of the cut and checked, on the bottom side - where I couldn't see what was going on - the darned thing had bent so much that it was some 3/4 inch away from the edge of the door. I was extremely surprised that the blade hadn't snapped with this much bend on it.
So, one door ruined (it might come up ok with some glue and filler), but that's better than ruining the kitchen worktop which is the next item on the list - one straight cut to size (will be going against a wall, so no need for absolute accuracy, but the straighter the better), and two holes to cut for sink and hob. These latter *will* need to be quite accurate. It's a block wood worktop by the way.
So:
1: Is this "blade wander" something all jigsaws suffer from, or is it just the cheap Ferm thing?
2: Could I have done anything to prevent the wander? Different technique, different blades?
3: I know a circular saw would probably be best for the straight cut, but I will really need a jigsaw for the holes, so any recommendations? Don't worry about price for now because I want to know what you think are useful features, but I will have a budget when considering buying.
I'll probably go for a mains saw, but so long as it's not ridiculously expensive I'd consider a battery saw too.
Any advice greatfully received!
Hwyl!
M.
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Martin Angove: http://www.tridwr.demon.co.uk /
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On Sat, 03 Jul 2004 13:04:27 +0100, Martin Angove

All jigsaws suffer from this to some extent, though the better jigsaws have a better blade guide with rollers close to the cutting surface.

Not really anything to prevent totally but jigsawing with a straight edge clamped in place makes it worse. You need to sort of rotate the whole baseplate to steer the cut to somewhere near straight.

You'll never get a decent straight cut from a jigsaw for a end of worktop cut, you'll need a circular saw with a high toothed blade.

Well, a cheap circular saw will cut a worktop much straighter than an expensive jigsaw. For your sink hole as long as the top of the cut is relatively straight you'll get away with a little wandering below as you'll never see it, but you'll need to use the method described above and definitely not use a straight edge as a guide.
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On Sat, 03 Jul 2004 13:04:27 +0100, Martin Angove

It is a function of cheaper jigsaws. I used to have an old B&D one and thought that they were all like it until I tried out a Bosch GST100 (costs about £110). Totally different. Very good speed control and either free hand or with a straight edge I can get a very good result with no wandering of the blade. The guides are extremely good.

Not really. It is largely a function of how well the blade is supported.

A circular saw is an option for a long straight cut or a router run against a clamped straight edge using a 1/2" cutter and cutting a depth of no more than about 10mm at a time. A decent router to do this kind of job would be something like the Freud 2000 at around £160. Anything less than that - don't bother.
You can use a router for cutting a sink hole as well, again using a straight edge clamped to the surface although a good jig saw will be perfectly fine.

A good speed control and a good blade guide. Some way to hook up dust extraction is also helpful so that you can see where you are going, but not essential.

I would go for the mains one. I can't see that much value in a cordless jigsaw.

.andy
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Jigsaws have a small thin flexible blade. They're designed for cutting round corners. To cut a straight true line you need something with a rigid blade - like a circular saw.
So saying, a poorly designed jigsaw will be much worse than a decent one - which will support the blade rather better. I don't know which camp your one falls into.
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--------------- I discussed this very problem with a joiner yesterday as I too have had the same thing happen to me. I was using a decent Bosch not a cheepy jigsaw but the effect was as you describe. My joiner chum tells me that the problem lies with using the straight edge as a guide. He too has that problem if he uses one, so he doesn't anymore. Having butchered a perfectly good melamine faced board I think he has a point.
I suspect that what happens is that as we strive to stay against the guide we are making many little corrections to the position of the saw. This produces only minor deviations on the top, where we are looking, but each 'correction' is not corrected on the bottom due to the flex inherent in the blade, so off it wanders.
What he does instead is to freehand cut a little shy of the desired position and then either plane or route for the final finish.
I think it may be possible to use two guides and effectively trap the jigsaw between them so that there is no deviation or twisting but I haven't tried yet, but I might as I now have some 'scrap' to practice on. Doesn't help though if you just want to trim off an edge.
So no I don't think it's simply down to your saw being cheap.
HTH
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the
but
he
melamine
I agree. As I posted here a while ago, I had this problem with an old Bosch jigsaw and was surprised to get the same problem with an expensive new Bosch too. While I am sure that other posters recommending a circular saw are quite right to do so, I have subsequently had some very acceptable results using my new jigsaw to cut a sink hole in a 38mm worktop without a straight edge: cuts which would be good enough to use as they are abutting a wall or which would be perfect with another 1-2mm taken off with a power plane. It's indeed the use of a striaght edge which seems to cause this wander problem.
Others are also quite right to suggest best quality blades you can get, changed frequently.
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RRH

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Martin Angove wrote:

More or less yes. Let the blade carve itself a path - that helps. But if it neets smetyhung like a knot, it can always happen.
Soft blades don't help. All are not created equal.

Less forward pressure.

No jigsaw is radically different from any other in this repsect. Some are bigger, some have better guides and speed controls - get the stiffest blade, and be patient and check it as you go.

Learn to use what you have properly. ;-)

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Hmmmm...
I read all the posts on this and thought: if it isn't the blade biased what is it? If it was the natural tendency to wander it would wander in any direction or rather in more than one.
So since I have never used a straight edge with a jigsaw, I imagine it is something to do with the frequency of the machine rattling the blade and causing it to flex. Take away the straight edge and the blade and recipricating mechanism are free to flow at their own frequency.
Anyone care to devise a way of monitoring this phenomenon? If such a thing there be.
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Hmm. The front of the blade has bits cut out of it. When bent, this might induce a twist into the blade that tends to cut in such a direction to increase the bend.
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Haven't the time to reply to everyone else yet (thanks guys :-) but this one is interesting. I have noticed the wandering phenomenon previously, though not as disasterously, and no, it doesn't always wander in the same direction. Not that I've done exhaustive tests, but I can think of one occasion recently where for some of the time I was having to re-do cuts because it was wandering left, other times right. Both against the same straight-edge, though come to think of it I did swap blades at some point...
Hwyl!
M.
--
Martin Angove: http://www.tridwr.demon.co.uk /
Two free issues: http://www.livtech.co.uk/ Living With Technology
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Of course not - it wanders in the direction you're least expecting it to ! :-)
(Nobody expects the Spanish Inquisition)
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Martin Angove wrote:

I have noticed that you get more wander when rip cutting (i.e. with the grain). The choice of pendulum setting can also make a difference on some materials. Blunt blades and excessive push are also more likely to cause wander.
You can also make up a saw guide for a jigsaw in the same way as you can for a circular saw. This tends to work better than a straight edge.
--
Cheers,

John.

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I'd guess it depends on the grain.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Ian Stirling wrote:

Actually I forgot - I had a jigsaw that used to do this - the blade was NOT parallel to the straight edge of the guide frame. I can't remember why not, or how I fixed it.
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On Sat, 03 Jul 2004 13:04:27 +0100, Martin Angove wrote:

I have used a circular saw to all but the corners of worktop cutouts. Start of with the depth adjuster set so the blade is completely clear of the workpiece, then lower the blade. In my case, this was with a cordless circular saw, so not sure how safe it would be with a more powerful, higher speed saw.
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My advice is buy a Bosch jigsaw and the most expensive blades you can afford. You will be amazed at the difference as this will cut most things very well. But at the end of the day, cutting doors isn't a jigsaw task.
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Believe it or believe it not I have got a very old Bosch Jigsaw (MIN 12 Years old)with no pendulum, no speed control BUT it cuts very nicely streight using Bosch economy blades (I do tend to cut along a line and not using a guide though)
HTH Phil
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things
task.
Just proves that tools are getting worse, not better. Cost is everything nowadays and even top brands don't last, whereas I remember my dad's old Wolf drill went on for most of his career.
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strung together this:

One of my mates has several old Wolf drills that are a good 20 years old and are used mainly for core drilling.
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SJW
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I bet lots of us have old B&Ds from the 60s and 70s still going fine. Its handy having some extra drills, saves a lot of bit changing sometimes, and features arent really needed for that. Those oldies are a much better bet than a cheap new one. And come almost free now.
Regards, NT
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