Bloomin' cheap Jigsaw!

[Martin Angove]

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.

[Lurch]

On Sat, 03 Jul 2004 13:04:27 +0100, Martin Angove strung together this:

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.

[Andy Hall]

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

To email, substitute .nospam with .gl

[Dave Plowman (News)]

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.

[gandalf]

--------------- 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

[The Natural Philosopher]

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. ;-)

[John Armstrong]

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.

[Michael Mcneil]

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.

[Ian Stirling]

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.

[G&M]

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.

[N. Thornton]

If you cut it clean and level with a circ saw and plane, you could glue on another strip of pine. Or maybe you could put draught excluder strip over the damage. Maybe.

yep, you could have binned the stupid thing. Cheap jigsaws cost you in damaged workpieces. Of all the power tools the jig is the one I rarely use.

battery stuff costs more, performs worse, and NiCds dont last well.

You could do it with the old jig, but keep a close eye on the blade! Top and bottom. And steer by turning the saw, never use any sideways pressure, nor a straight guide rail.

Regards, NT

[Steve Firth]

No it's common to several makes of saw. The worst that I have had for it was a Black and Decker "scrolling" jigsaw which was truly crap. The blade was unsupported. I have a cheap B&Q Performance Pro mains jigsaw which I bought as a replacement and a B&Q cordless jogsaw. Both of them work much better than the B&D but on both the blade will wander if you let it.

Different blades would help. I found that several companies (Bosch, Piranha) make jigsaw blades for cabinet work where the teeth are formed without any offset. i.e. the blade cuts flush. Put the blade on a polished surface with largest surface area in contact with the surface and push the bade around and it won't scratch the surface at all. Try this with a standard blade and it will leave a mass of scratches.

They make an excellent smooth cut that doesn't need planing or sanding. And the blades themselves are thicker and harder than the standard jigsaw blades. They are almost useless for cutting curves, but will cut a true vertical though material up to a thickness of approximately 3/4 of the length of the blade (I have used them to cut kitchen worktops satisfactorily).

Piranha part number (Black and Decker type) is X28802, blade length 9cm.

As to mains vs cordless pay your money, take you choice. I bought a set of cordless 18V tools from B&Q because I work on my boat at weekends. The cordless tools are ideal, and every bit as good as their mains equivalents. Also not having a cord makes a jigsaw and circular saw very easy to use. OTOH cutting time is limited and you really need to buy a set that has a one hour charger and at least 3x batteries.

Mains tools of equivalent quality are cheaper.

[Martin Angove]

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.

[G&M]

Of course not - it wanders in the direction you're least expecting it to ! :-)

(Nobody expects the Spanish Inquisition)

[Quddus]

Dont rely on a jigsaw to make accurate cuts in anything thick. if you have no other option then use it without a straight edge guide and rotate the saw towards your mark rather than push the blade towards it.

When i fitted my kithen and hob unit the way i overcame this was to plunge in the circular saw by pivoting it from the front of the base plate and SLOWLY lowering it into the straight cut. Assuming your holes have straight sides and are not circular then this would work ok. Please only do this if you are confident in using the circular saw and are able to control it in this manner.

My sink hole had rounded corners and these are notorious for blade wander in thick material. the way I overcame this was by drilling holes right through the worktop every cm through the curve with a drill bit just bigger than the blade of the jigsaw. this allowed the blade to be rotated and corrected and and the result was a pretty accurate curve. And by the way my Jigsaw is a 4 year old B&D and

I'd go for a mains if I were you. More power, no fade but cables do get in the way. As advised go for something that has the guide roller close to the cut

Also for the sink hole cut i made sure the worktop was sealed against any water seepage which can ruin the worktop. I also put silicone sealant under the rim of the sink because the rubber seal it came with was rubbish and was letting in water.

[The Natural Philosopher]

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.

[John Rumm]

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.

[Dave Plowman (News)]

I'd guess it depends on the grain.

[Phil]

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

[rrh]

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.