Micro chainsaw anyone?

[John Rumm]

ok

You seem to be trying to put words into my mouth... I use the blade jammed illustration simply as an example of one extreme of the various possible scenarios. The other extreme being saw held and braced, with the blade in free space. One will result in the minimum level of vibration likely to be experience, and the other the maximum. Normal use will be somewhere between those two extremes.

Of course. (lets ignore the trigger lock "on" situation for the moment).

Well having got the blade snagged, you now need to free it. Most I would expect will do as I do, adjust the position of the blade in the cut (if possible) and re-apply power.

They are IME quite difficult to break - certainly for wood blades anyway. It does depend a bit on how long the blade is and where along its length its snagged.

You said that above.

Well you *could* do that in the vice example, although the saw is going to be might unhappy!

I have not found this to be the case. Remember we are dealing with "normal" operation here - not a jammed blade. Applying similar levels of force against the rest as you are applying in the direction of cut is often adequate (in fact you can play one off against the other).

This is exactly the same situation as using a jigsaw - you get much less vibration if you keep the sole plate firmly in contact with what you are cutting. The moment you lift it away from the surface and try to cut with the body of the machine unsupported, you get a significant increase in vibration transmitted to the operator.

As with any tool, there are some use techniques that get better results than others. Personally I don't find it difficult to use in such a way as to control the vibration to a reasonable extent.

Now don't read into this that I am suggesting that these are particularly sophisticated or smooth cutting tools. I would not want to use one all day and every day.

I am a little confused by this... my initial comment on the subject was simply:

"The trick to controlling vibration on a recip saw is to make sure you push the blade guard firmly against the thing being cut"

That (to my internal voice at least) does not in any way amount to "such exception".

Whoa horse! You are now romping off at a tangent having your own argument. By all means do, but don't pretend its with me.

I have at no point suggested you don't get vibration from this kind of tool. I am also fully aware that vibration is harmful, especially with prolonged exposure. (read the power tools faq which I wrote many years ago - its a topic I pick up on frequently). I have spent many years here encouraging people to select better quality power tools, even if for occasional use, because you usually get a better quality result and more comfortable operation.

I gave a simple tip that helps reduce the impact on the user. I mention it because it does not appear to be self evident to some users IME.

For example, some years ago when de-tialing a roof. I passed a mains powered recip saw to my friend to cut down a row of tile battens nailed to the rafters. A good application for such a saw since its fairly blade hostile environment, and you want a cut flush to the side of a rafter - a recip saw will do it quickly and easily - and if you kill a blade in the process then who cares?

However he (an experienced builder) was struggling - the saw would snag quite often as not all the tile battens were well fixed - they could flex and pinch the blade. He was frequently getting the lions share of the reciprocation through him and not the wood. He passed it back to be and said "I have never been able to use those things". So I took over, and did the job with no drama simply by the expedient of doing what I suggested - engaging the rest against the top of the batten and applying some forward pressure, and cutting with the bit of the blade closest to the tool, rather than trying to use the end of the blade as he had done. This resulted in no snagging, and way less vibration for me.

Well this *is* standard practice and advice. You can read it in the handbook that comes with the saws, but then who reads those eh?

I am also not disputing that the more refined saws can better help control vibration than the cheap ones (especially that which results from the translation of rotational work to longitudinal, and balancing a somewhat variable blade mass). Floating and spring loading the mechanism also helps, as do vibration dampening grips.

However, the operator can still do a huge amount to influence the experience with any recip saw by their choice of technique.

[michael adams]

............................................................................................................................

But it's hardly that "extreme", is it ? According to what you posted earlier It's apparently quote common

" I am describing the problem many seem to have with recip saws where they end up with the blade snagging/sticking in the work and then the machine trying itself to reciprocate. There the more rigid coupling helps prevent it.

What you are describing is the internal vibration from the mechanism itself. (still undesirable, but not in the same league as when the machine decides it wants to move back and fourth rather than the blade!) "

There are two different things being discussed here.

To keep things simple assume inside the saw is a rod (attached to the free moving blade via the chuck) which moves forwards 1 inch, stops, and then moves backwards 1 inch, and then stops at say 2,000 times a minute. In simple terms this causes the body of the saw to vibrate; while in holding on to the saw, rather than allow it to move around on the bench the operator will absorb some of that vibration. That is the normal vibration (A) associated with reciprocating saws where the operator absorbs some of the vibration.

In addition if the blade is trapped, the entire body of the saw will move forward 1 inch, stop, and then move backwards 1 inch, and then stop say 2,000 times a minute. Which is (B). In this case its impossible for the operator to absorb any of this movement or more technically vibration. All that will happen should this be attempted is that the weakest link in the chain will malfunction or break, be it the saw blade, the chuck, the internal linkage, the motor, or the operator him, or her self

So the trigger is pressed rather than released.

However on the basis of your claim that (B) is such a common occurrence "the problem many seem to have with recip saws", I'd imagined there might have been a reluctance on their part to lock the trigger. Even if at the cost of losing the odd millisecond here or there,

What I meant was if they didn't stop the saw, and thus subjected themselves to a good dose of (B) the first time around, once having experienced (B) why would they do this a second time ?

In other words you stop the saw.

Previously you claimed if you remember that B) vibrations, those resulting from the entire body of the saw moving forward 1 inch, stopping, and then moving backwards 1 inch, and then stopping say 2,000 times a minute was a major problem. Whereas if you've immediately stopped the saw in such circumstances then clearly it isn't.

Indeed. Whereas in fact they don't. As you've just explained they stop the saw so (B) isn't as big a problem as you previously suggested it was.

Quite possibly but not enough to compensate for the fact that a reciprocating saw vibrates four times as far/much/whatever - 22 m/sec? when cutting chipboard as does a chainsaw 3.9 m/sec? Rear Grip

5.2 m/sec? Front Grip (task unspecified) . All Hitachi figures

This is the original point from Theo which I was responding to

"Out of interest, what would be a suitable alternative for cutting trees? Having a similar portable, relatively safe, battery-powered form factor - where a full chainsaw is not appropriate "

All I was seeking to point out, was that while with a chainsaw its possible to let the saw do the work some of the time, given the weight of the bar and the chain. IOW that it's not always necessary to apply maximum force, even if this is inefficient and will prolong the job to some degree. (here we go!) Whereas with a reciprocating saw which is usually suggested as the closest alternative, this simply isn't possible. Not only is it necessary to apply constant force on the blade but as I suspected and confirmed by the figures above, the level of vibration is considerably higher even in the most capable hands. So one must assume at least. Making reciprocating saws correspondingly that more tiring to use over extended periods

michael adams

...

begin 666 info_button.png MB5!.1PT*&@H````-24A$4@````P````," 8```!6=5SG````&71%6'13;V9T M=V%R90!!9&]B92!);6%G95)E861YWZ>WO:!"!70.B)G@9)%*4R6"IO*OAO#_$_'L225K M6!Y!&G%EBML1>_:>< M7MN-=

[michael adams]

The previous version included a graphic element inadvertently pasted from the Makita website which might lead to its rejection on some NewsServers.

............................................................................................................................

But it's hardly that "extreme", is it ? According to what you posted earlier It's apparently quote common

" I am describing the problem many seem to have with recip saws where they end up with the blade snagging/sticking in the work and then the machine trying itself to reciprocate. There the more rigid coupling helps prevent it.

What you are describing is the internal vibration from the mechanism itself. (still undesirable, but not in the same league as when the machine decides it wants to move back and fourth rather than the blade!) "

There are two different things being discussed here.

To keep things simple assume inside the saw is a rod (attached to the free moving blade via the chuck) which moves forwards 1 inch, stops, and then moves backwards 1 inch, and then stops at say 2,000 times a minute. In simple terms this causes the body of the saw to vibrate; while in holding on to the saw, rather than allow it to move around on the bench the operator will absorb some of that vibration. That is the normal vibration (A) associated with reciprocating saws where the operator absorbs some of the vibration.

In addition if the blade is trapped, the entire body of the saw will move forward 1 inch, stop, and then move backwards 1 inch, and then stop say 2,000 times a minute. Which is (B). In this case its impossible for the operator to absorb any of this movement or more technically vibration. All that will happen should this be attempted is that the weakest link in the chain will malfunction or break, be it the saw blade, the chuck, the internal linkage, the motor, or the operator him, or her self

So the trigger is pressed rather than released.

However on the basis of your claim that (B) is such a common occurrence "the problem many seem to have with recip saws", I'd imagined there might have been a reluctance on their part to lock the trigger. Even if at the cost of losing the odd millisecond here or there,

What I meant was if they didn't stop the saw, and thus subjected themselves to a good dose of (B) the first time around, once having experienced (B) why would they do this a second time ?

In other words you stop the saw.

Previously you claimed if you remember that B) vibrations, those resulting from the entire body of the saw moving forward 1 inch, stopping, and then moving backwards 1 inch, and then stopping say 2,000 times a minute was a major problem. Whereas if you've immediately stopped the saw in such circumstances then clearly it isn't.

Indeed. Whereas in fact they don't. As you've just explained they stop the saw so (B) isn't as big a problem as you previously suggested it was.

Quite possibly but not enough to compensate for the fact that a reciprocating saw vibrates four times as far/much/whatever - 22 m/sec? when cutting chipboard as does a chainsaw 3.9 m/sec? Rear Grip

5.2 m/sec? Front Grip (task unspecified) . All Hitachi figures

This is the original point from Theo which I was responding to

"Out of interest, what would be a suitable alternative for cutting trees? Having a similar portable, relatively safe, battery-powered form factor - where a full chainsaw is not appropriate "

All I was seeking to point out, was that while with a chainsaw its possible to let the saw do the work some of the time, given the weight of the bar and the chain. IOW that it's not always necessary to apply maximum force, even if this is inefficient and will prolong the job to some degree. (here we go!) Whereas with a reciprocating saw which is usually suggested as the closest alternative, this simply isn't possible. Not only is it necessary to apply constant force on the blade but as I suspected and confirmed by the figures above, the level of vibration is considerably higher even in the most capable hands. So one must assume at least. Making reciprocating saws correspondingly that more tiring to use over extended periods

michael adams

...

[John Rumm]

God I am glad we are finally in agreement, let's move on.

[Richard]

:)

[michael adams]

Indeed.

Taking into due consideration all those facts having any bearing on the matter in hand, the position you currently find yourself in, and the almost inevitable result should you choose to continue, were I called upon to do so, this is exactly the advice I would have given myself.

Try and move on, and put it all behind you; and in a while you'll most likely have forgotten all about it.

michael adams

...

[Richard]

FYPFY

YVW