Reciprocating saws and blades

[JohnW2]

Yep, you only need to read some of the ads for tools, especially those intended for the DIY market. I have in mind some of the adaptors and attachments commonly sold for B&D drills, to make them into jig-saws, and etc.. Absolutely deadly!

Do you mean 'in the past', since I don't think such things have been available (new) for a long time?

'Back then', I had a wide range of those attachments, and I've probably still got most of them (and occasionally even use some, with equally ancient drills!) - jigsaw, circular saw, table saw, orbital sander etc., and even a lathe (which I still use occasionally!).

Although you say 'absolutely deadly', most of them could be used pretty safely ('as safely as anything else'), provided one had common sense and was sensible- at least for me!

Nothing you do can be without any risk at all - all you can really do is assess the risk and minimise it. I habitually worked and still work live, it frequently mitigates the risk of something unexpectedly becoming live.

All true, for me as well as you!

Kind Regards, John

 

[Deleted member 174758]

...whilst you may well be right in suggesting that the move from grinders to reciprocating saws (for the sort of tasks being discussed) in the construction industry has probably been largely the consequence of "H&S" considerations, I don't think that "H&S considerations" are behind what I have been hearing and reading.

Recip saws have been used in construction since at least the 1930s and I have UK publications showing them readily available to the trade in the UK in the 1950s.

Modern demolition blades evolved from/into (depending on who you talk to) F&R (fire and rescue) blades in the USA. AFAIK they started to become widely available here in the early to mid-1990s.

Over the last couple of decades developments in blade technology has seen the introduction of carbide tooth blades, I believe first for blockwork (I first came across them 20+ years back), later for metals and demo work. Diamond is a more recent introduction. So my contention is that the more widespread use of recip saws and specialised blades has trickled down into the DIY field from trade.

In the construction and industrial fields risk reduction has been a partial driver to the greater adoption of recip saws with specialised blades over abrasive cutting, even though a 9in angle grinder or a Stihl saw with a metal blade is actually far quicker than a recip saw, whilst a small 4-1/2in grinder is often no faster than a recip saw and can be slower - but that all depends on tooling (ever tried using a diamond wheel on an angle grinder, or using a carbide bladed cordless metal cutting saw? I feel both would open your eyes)

All of the suggestions (that recip saws are preferable) I have seen were directed at "DIYers", and all majored on the saws being an easier/nicer/quicker/less messy method, without any mention of safety advantages, and certainly no mention of fire risks with grinders.

Then that probably suggests pure ignorance on the part of the authors and maybe they should have mentioned these things because fires and grinding wheels breaking and causing injury aren't unique to building sites

... if my upcoming job entails making, say, a dozen or less cuts in CI soil pipes, would an appreciably cheaper) non-carbide blade be likely to last long enough for that?

Yes, with the caveat that not all blades are equal. @^woody^ mentioned Lennox blades which have a good reputation, I mentioned Milwaukee Ax. I can say from experience that the Ax blades are generally thicker and more durable than equivalent Bosch blades I have used, although I am yetvto.use their carbide blades. DW demo blades are OK, but not as durable as the Ax blades in my experience

 

[Harry Bloomfield]

Do you mean 'in the past', since I don't think such things have been available (new) for a long time?

In the past, yes..

'Back then', I had a wide range of those attachments, and I've probably still got most of them (and occasionally even use some, with equally ancient drills!) - jigsaw, circular saw, table saw, orbital sander etc., and even a lathe (which I still use occasionally!).

You missed out the circular saw blade, which just bolted to an arbour centre, then clamped in the chuck - absolutely lethal.

 

[JohnW2]

You missed out the circular saw blade, which just bolted to an arbour centre, then clamped in the chuck - absolutely lethal.

Mine didn't (still doesn't ). One removed the chuck (which had a male 3/8" end in those days) and then bolted the blade into the female threaded hole thereby exposed. Whatever else might have gone wrong, there was no way that the blade was going to become 'detached', or even loose.

Kind Regards, John

 

[JohnW2]

Recip saws have been used in construction since at least the 1930s and I have UK publications showing them readily available to the trade in the UK in the 1950s. Modern demolition blades evolved from/into (depending on who you talk to) F&R (fire and rescue) blades in the USA. AFAIK they started to become widely available here in the early to mid-1990s.

I don't doubt any of that.

Over the last couple of decades developments in blade technology has seen the introduction of carbide tooth blades, I believe first for blockwork (I first came across them 20+ years back), later for metals and demo work. Diamond is a more recent introduction. So my contention is that the more widespread use of recip saws and specialised blades has trickled down into the DIY field from trade.

That surely has to be the case? It would be very odd if DIYers were being advised to use, and were using, something which was 'better' (in terms of effectiveness/convenience etc. and/or safety) than what was being used industrially. That would be a bit like production road cars having state-of-the-art' safety features which were not yet used in Formula 1 cars!

I merely commented that everything I have read that was directed at DIYers, and everything I have been told in conversations, has said that recip saws are now considered preferable (for the sort of tasks being discussed) because of effectiveness, easy of use, less mess etc. etc., never with any mention of them being 'safer' (or 'less dangerous') than grinders.

In the construction and industrial fields risk reduction has been a partial driver to the greater adoption of recip saws with specialised blades over abrasive cutting, even though a 9in angle grinder or a Stihl saw with a metal blade is actually far quicker than a recip saw, ...

I have no problem in believing that ...

whilst a small 4-1/2in grinder is often no faster than a recip saw and can be slower - but that all depends on tooling (ever tried using a diamond wheel on an angle grinder, or using a carbide bladed cordless metal cutting saw? I feel both would open your eyes)

I have no experience of the latter, but I use diamond blades in a 4½" grinder 'all the time' for cutting bricks, paving slabs, concrete etc - so my eyes are already open to that experience

Then that probably suggests pure ignorance on the part of the authors and maybe they should have mentioned these things because fires and grinding wheels breaking and causing injury aren't unique to building sites

Perhaps - but, even if they were not 'ignorant', maybe they didn't feel the need to mention the 'safer' aspect - since they were already strongly advising people to use recip saws, rather than grinders.

Yes, with the caveat that not all blades are equal.

Thanks. That's useful advice.

Kind Regards, John

 

[Deleted member 174758]

...everything I have been told in conversations, has said that recip saws are now considered preferable (for the sort of tasks being discussed) because of effectiveness, easy of use, less mess etc. etc., never with any mention of them being 'safer' (or 'less dangerous') than grinders.

Just what do you mean by effectiveness? Speed? Speed is one thing that recip saws are not noted for.

...I use diamond blades in a 4½" grinder 'all the time' for cutting bricks, paving slabs, concrete etc - so my eyes are already open to that experience

Tried one on steel yet?

Perhaps - but, even if they were not 'ignorant', maybe they didn't feel the need to mention the 'safer' aspect - since they were already strongly advising people to use recip saws, rather than grinders.

But why were they advising that especially given that recip saws are much slower?

 

[JohnW2]

Just what do you mean by effectiveness? Speed? Speed is one thing that recip saws are not noted for.

I really used 'effectiveness' as a vague general term meaning 'related to function, not related to safety issues'. 'Much less messy' was one of the main things mentioned - but also see below.

Tried one on steel yet?

No, I haven't. In fact, the diamond blades I use on masonry etc. are usually 'segmented', and (rightly or wrongly) I would be rather nervous about using one of those on metal. If I did try, what would I experience?

But why were they advising that especially given that recip saws are much slower?

As above, 'less mess' and (vaguely) 'easier to use' are frequently mentioned. Perhaps more to the point, although the 'speed of cutting' may be appreciably slower than with a grinder, the 'speed of 'getting the job done' might be better with the saw. When, as is commonly the case, a ~4" cast iron pipe is close to a wall, one certainly cannot 'just cut through it' with a 4½" grinder (and I imagine probably not with a 9" one) - one therefore has to fiddle around with multiple cuts and, even then, it can be difficult to end up with a totally 'clean/straight cut'..

Kind Regards, John

 

[Deleted member 174758]

...the diamond blades I use on masonry etc. are usually 'segmented', and (rightly or wrongly) I would be rather nervous about using one of those on metal. If I did try, what would I experience?

I use segmented diamond blades quite a bit for small cutting out tasks such as removing embedded metal in floors (e.g. clout nails etc), joists, soffits, etc, also for trimming overly long bolt threads on steel fabrications and general trimming/tidy up work. I also buy carbide grit blades specifically for in-situ cement board cut-outs (i.e. after the board gas been fitted). These are the sorts of jobs which couldn't be done readily with a recip saw and for which a 115mm cordless grinder fits the bill. I find them quick and effective, plus metal blades can't shatter if, for example, they are twisted in a cut. Storage is also e asier, because the metal body cutting discs are less sensitive to water (traditional cutting and grinding discs need to be stored dry and flat - if stored on edge and in particular wet, abd on edge, they are unbalanced and can shatter when run up)

This is why we are supposed to have a grinding wheel ticket these days

 

[JohnW2]

I use segmented diamond blades quite a bit for small cutting out tasks such as removing embedded metal in floors (e.g. clout nails etc), joists, soffits, etc, also for trimming overly long bolt threads on steel fabrications and general trimming/tidy up work. I also buy carbide grit blades specifically for in-situ cement board cut-outs (i.e. after the board gas been fitted). These are the sorts of jobs which couldn't be done readily with a recip saw and for which a 115mm cordless grinder fits the bill. I find them quick and effective, plus metal blades can't shatter ....

Interesting. Thanks.

As I implied, I have always been nervous about using any type of 'segmented' blade/disc, through fears of the gaps between segments getting 'caught' on the metal. Do I take it that such are unnecessary concerns?

Kind Regards, John

 

[JohnW2]

You missed out the circular saw blade, which just bolted to an arbour centre, then clamped in the chuck - absolutely lethal.

Mine didn't (still doesn't ). One removed the chuck (which had a male 3/8" end in those days) and then bolted the blade into the female threaded hole thereby exposed. Whatever else might have gone wrong, there was no way that the blade was going to become 'detached', or even loose.

I could have added ... it rather sounds that you may never have owned/used any of those B&D 'accessories'

The way in which the blade of a 'circular saw attachment' was attached to the drill (as above) was no different from the way in which any circular saw blade or grinder disc is attached to whatever it is being driven by (in portable circular saw, table saw, radial arm saw, grinder or whatever).

In fact, all of those B&D accessories I had and used back in the 70s (circular saw, jigsaw, orbital sander, lathe) attached to the drill in essentially the same way, by being screwed into the threaded hole exposed by removing the chuck. ... I never saw any which were powered through the chuck.

On the other hand, what does personally make me nervous (such that I probably would be hesitant to use them), today, are some of the 'large things', potentially rotating at high speed, that people do (today) sometimes insert into (non-SDS) drill chucks (likw some "core drill bits".

Kind Regards, John

 

[Deleted member 174758]

I have always been nervous about using any type of 'segmented' blade/disc, through fears of the gaps between segments getting 'caught' on the metal. Do I take it that such are unnecessary concerns?

At 10,00 rpm a 3 or 4mm slot really can't catch on anything - it is effectively a solid disc, but with the advantages that the slots help remove some of the debris and help keep the disc cooler

 

[Deleted member 174758]

On the other hand, what does personally make me nervous (such that I probably would be hesitant to use them), today, are some of the 'large things', potentially rotating at high speed, that people do (today) sometimes insert into (non-SDS) drill chucks (likw some "core drill bits".

There is, though, an issue of using the appropriate equipment in an appropriate manner with appropriate tooling.

Unpacking that: dry diamond core drills absorb a lot of power, so they need a drill capable of generating sustained high torque (power in watts is actually less important, but even so it will need be 1000w plus as a rule). They need to be run at low rotational speeds (to ensure that the maximum peripheral speed of the drilling core is not exceeded - resulting in overheating and premature failure of the nickel brazing which holds the diamonds in place). They need to be fitted on a drill with an adequate clutch. This latter is extremely important. And ideally they need an extra long side handle, which gets used as a torque reaction bar. So no high speed - more like a few hundred rpm with the bigger cores

You occasionally read posts by people claiming it is "safe" to run something like a 127mm core bit in an SDS, whilst conveniently ignoring the manufacturers recommendation of 65 or maybe 80mm maximum. Like so many things in life they may get away with it, but if the core ever jams in the hole (which can happen), the result can be a sprained wrist or even a broken wrist. The consequences if you are foolish enough to have such an accident at the top of a tall ladder, where the risk is that you can be thrown off aren't good

They aren't dangerous if used correctly but even so there is always the risk of a "catch"

 

[JohnW2]

At 10,00 rpm a 3 or 4mm slot really can't catch on anything - it is effectively a solid disc, but with the advantages that the slots help remove some of the debris and help keep the disc cooler

Fair enough - I suppose it is just my (probably faulty) 'intuition' that has led me to that 'concern'!

Kind Regards, John

 

[catlad]

Cars did not even have seat belts, let alone air-bags & crumple zones.

Yes and just think if they still didn't people probably wouldn't be playing with their phones while driving! which is a menace to pedestrians and cyclists.

 

[JohnW2]

Yes and just think if they still didn't people probably wouldn't be playing with their phones while driving! which is a menace to pedestrians and cyclists.

Yes, there are plenty of swings and roundabouts around. Such is life.

However, I think the important thing for people to understand is, as I wrote before, that, in most cases, what has changed is not the risks, but the ('our') attitudes to those risks.

Taking the example you mention, to have a certain type of impact at a certain speed without seat belts, air bags or crumple zones today would have represented no less a risk (to life and limb) in the 1950s/60s than it would today - just as the sort of domestic light switches whose covers could be unscrewed by a 5-year-old (yes, I did ) would have resulted in no less a risk back then than it would today. However, in both cases (and countless others) what has changed is 'our' view of what levels of risk are 'acceptable'.

As has been said, there have been considerable improvements in safety (reductions of risk) in many/most walks of life (e.g. construction industry, 'on the roads' etc. etc.), very often as a result of regulations/laws. However, human nature and psychology being what there are, there is somewhat of a downside, in that the more people feel that they are 'protected by the system', the more likely is it that some of them will become complacent (hence careless) in relation to (the inevitable) residual risks.

Kind Regards, John