wrote in message
...
But you still have deceleration. A point that gets at the increased
efficiency claim. The magnitude can certainly be debated.

I'm not sold on the increased efficiency from a better recoil property for
the shot. It's still going to recoil. Bang into each other (energy loss)
and bang into the sides of the cavity (energy loss)

You also have a loss in energy via heat (from banging into each other)
that doesn't come into play on a solid hammer of equal mass. Again, this
gets to efficiency. Magnitude can be debated.

I don't think we get a free lunch here. More efficiency from a hammer
strike with the same amount of mass - not convinced.


Look at the swing as a closed energy system. If the hammer bounces back,
that energy came "from somewhere." It came from not driving the object
being struck. When there is no bounce, all of the energy (minus a very
small amount of friction of the shot heating up) gets expended driving the
struck object. That is the only way you can look at it.
--
Jim in NC


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There is bounce. That's my point. The "bouncing" is occurring on the inside of the cavity. A ball dropped from one end of a cavity to the other is going to bounce.

On 2/20/2014 2:59 PM, wrote:
....

I don't think we get a free lunch here. More efficiency from a
hammer strike with the same amount of mass - not convinced.

They're _not_ the same system and that _does_ make a difference in how
they behave.

--

On 2/20/2014 3:31 PM, wrote:
There is bounce. That's my point. The "bouncing" is occurring on the inside of the cavity. A ball dropped from one end of a cavity to the other is going to bounce.

The mallet head striking an object bounces. The shot hitting the
opposite end of the mallet when the mallet bounces back "helps" to
cancel out the head bounce back.

On Thu, 20 Feb 2014 16:06:50 -0600, Leon lcb11211@swbelldotnet
The mallet head striking an object bounces. The shot hitting the
opposite end of the mallet when the mallet bounces back "helps" to
cancel out the head bounce back.

Pretty much as I'd have explained it. But however one looks at it, a
dead blow mallet is a damned useful tool. You don't really realize it
though until you actually use one.

On 2/20/2014 4:46 PM, wrote:
On Thu, 20 Feb 2014 16:06:50 -0600, Leonlcb11211@swbelldotnet
The mallet head striking an object bounces. The shot hitting the
opposite end of the mallet when the mallet bounces back "helps" to
cancel out the head bounce back.

Pretty much as I'd have explained it. But however one looks at it, a
dead blow mallet is a damned useful tool. You don't really realize it
though until you actually use one.



Now I will say........ I had a dead blow mallet back in the 70's. It
eventually degraded and the plastic disintegrated and left the steel
handle and a shot gun shell sized capsule partially filled with the pellets.

I suspect that a lot of the bounce back is also absorbed by the plastic
material that is used to encase the steel parts.

For the past 20 or so years I have used one of those smaller hammers
with a red rubber face on one end and a yellow plastic face on the
other. The plastic face end is a similar plastic that is used on the
dead blow mallets. My current non dead blow hammer does not have much
bounce back either....

On Thursday, February 20, 2014 5:06:50 PM UTC-5, Leon wrote:
On 2/20/2014 3:31 PM, wrote:

There is bounce. That's my point. The "bouncing" is occurring on the inside of the cavity. A ball dropped from one end of a cavity to the other is going to bounce.



The mallet head striking an object bounces. The shot hitting the

opposite end of the mallet when the mallet bounces back "helps" to

cancel out the head bounce back.

It helps to cancel out the mallet bouncing back. I'm not arguing this point. We agree here.

There is bouncing in either case that results in an energy loss. This doesn't address the deadblow's claimed increase in efficiency.

Hundreds (arbitrary) of shots smacking into the bottom of a cavity or a shot filled cavity are going to bounce and bang around. The sum loss in energy from the bounce back (including any collisions between each other) of each shot is going to be significant.

If you were to compare the efficiency of a deadblow's strike and a mallet of equal mass and size (shot filled w/ no empty space), and take into account the above, I wouldn't expect an increase in efficiency from the deadblow.

On Thursday, February 20, 2014 4:41:10 PM UTC-5, dpb wrote:
On 2/20/2014 2:59 PM, wrote:

...



I don't think we get a free lunch here. More efficiency from a

hammer strike with the same amount of mass - not convinced.



They're _not_ the same system and that _does_ make a difference in how

they behave.

Agreed. They behave differently and I touched on the differences in length.







--

On Thu, 20 Feb 2014 16:56:54 -0600, Leon lcb11211@swbelldotnet
For the past 20 or so years I have used one of those smaller hammers
with a red rubber face on one end and a yellow plastic face on the
other.

This is the one I have.
http://www.leevalley.com/en/wood/pag...26&cat=1,53193

wrote:

This is the one I have.
http://www.leevalley.com/en/wood/pag...26&cat=1,53193
----------------------------------------------------------------
When it's time to replace, HF is your place.

About $5 for the equivalent.

Lew

On Thu, 20 Feb 2014 15:36:59 -0800, "Lew Hodgett"
When it's time to replace, HF is your place.
About $5 for the equivalent.

Yup, I could buy a cheap knockoff from Harbour Freight for a lot less
money. Then I could add on mailing costs, duty garbage and several
weeks time waiting for it to come across the border into Canada.

Good idea Lew. I'll keep that idea in mind the next time I want to buy
some cheap tool garbage.

wrote:
On Thu, 20 Feb 2014 15:36:59 -0800, "Lew Hodgett"
When it's time to replace, HF is your place.
About $5 for the equivalent.

Yup, I could buy a cheap knockoff from Harbour Freight for a lot less
money. Then I could add on mailing costs, duty garbage and several
weeks time waiting for it to come across the border into Canada.

Good idea Lew. I'll keep that idea in mind the next time I want to buy
some cheap tool garbage.


Oh man Dave - sucks that you don't have Harbor Freight up there.

--

-Mike-

On Thu, 20 Feb 2014 19:14:47 -0500, "Mike Marlow"
Oh man Dave - sucks that you don't have Harbor Freight up there

Well, we've got a Princess Auto which isn't too far removed. But, to
tell the truth, the main reason I buy from Lee Valley aside from the
quality of their tools is their service. I can search out cheap or
quality tools almost anywhere. I *can't* get top notch service if I
have a problem or complaint most places.

I'm just about to hit sixty and my wants have changed significantly.
Take food as an example. When I was younger I mostly had quantity on
my mind. That's changed and now I almost exclusively seek out quality.
~ That concept has transferred over to a significant portion of my
life.

wrote:


Yup, I could buy a cheap knockoff from Harbour Freight for a lot
less
money. Then I could add on mailing costs, duty garbage and several
weeks time waiting for it to come across the border into Canada.

Good idea Lew. I'll keep that idea in mind the next time I want to
buy
some cheap tool garbage.
-------------------------------------------------------------------
It's NOT buying cheap garbage,
it is the prudent utilization of ones available resources. wink

It's all a matter of perspective.

Lew

wrote:

I'm just about to hit sixty and my wants have changed significantly.
Take food as an example. When I was younger I mostly had quantity on
my mind. That's changed and now I almost exclusively seek out
quality.
~ That concept has transferred over to a significant portion of my
life.
------------------------------------------------------
Rookie!!

Can certainly relate to your change in perspective of life.

Lew

On Thu, 20 Feb 2014 16:23:14 -0800, "Lew Hodgett"
It's NOT buying cheap garbage,
it is the prudent utilization of ones available resources. wink
It's all a matter of perspective.

Ok, I'll let you get away with that one. But, consider a significant
amount of the comments posted here in regards to the cheap crap that
floods into our North American market.

The demand for all the cheap **** has destroyed much of the quality
goods markets that made us great in the first place. All that's left
is for us to spiral down the drain. It's a slippery slope that there's
not turning back from, at least not as far as I can see.

wrote:


Ok, I'll let you get away with that one. But, consider a significant
amount of the comments posted here in regards to the cheap crap that
floods into our North American market.

The demand for all the cheap **** has destroyed much of the quality
goods markets that made us great in the first place. All that's left
is for us to spiral down the drain. It's a slippery slope that there's
not turning back from, at least not as far as I can see.

I certainly agree with the thought Dave, but you've seen me post about
Harbor Freight. There's a lot of stuff that they sell that is just fine.
There's things I'd be afraid of buying but even that has changed over the
years. Used to be that I wouldn't buy anything with a motor from them and
now that's not true. Some of the stuff is cheap junk - can't escape that.
But - that doesn't paint the entire line of products. I too look for some
level of quality - I think we all do. But, I'm not going to pay 3 to 4
times as much for something that just isn't all that much better. The name
brand market has done a good job of marketing their names, and the quality
difference just isn't there in a lot of cases.


--

-Mike-

On Thu, 20 Feb 2014 19:39:06 -0500, "Mike Marlow"
times as much for something that just isn't all that much better. The name
brand market has done a good job of marketing their names, and the quality
difference just isn't there in a lot of cases.

Sure, I know what you're saying. Taking the dead blow hammer that was
under discussion, any cheap dead blow would likely do, I can't deny
that. For me, it mostly comes down to what's easier or less time
consuming. Cost often comes in third.

When it comes to tools, I like most of what Lee Valley sells. If I
ever have any problem at all, they take care of it right away. One of
their biggest stores is close to where I live. If I can't get there,
my closest friend lives very close to one of their stores.

I've got a driver's license, but don't own a car. Because of the
chair, for me to go running around or spreading my dollars a little
more judiciously, it takes me considerable time than most. I guess my
position is a little more unique that most, but it's what works for
me. I'll even admit that I'm probably mired in my ways and not so
inclined to change.

On 2/20/2014 5:19 PM, wrote:
....

Agreed. They behave differently and I touched on the differences in length.
....

Superficially and without proper conclusions, unfortunately.

A demonstration that isn't _exactly_ the same problem, but very closely
related is at...

http://neilatkin.com/2013/07/31/3-act-physics-momentum/

--

On 2/21/2014 9:40 AM, dpb wrote:
On 2/20/2014 5:19 PM, wrote:
...

Agreed. They behave differently and I touched on the differences in
length.
...

Superficially and without proper conclusions, unfortunately.

A demonstration that isn't _exactly_ the same problem, but very closely
related is at...

http://neilatkin.com/2013/07/31/3-act-physics-momentum/

Didn't intend that to sound as snippy as it does, sorry...but, the
problem has much to do with the differences between elastic and
inelastic collisions which is why I pointed out at the beginning of the
subthread you really don't want to get too deeply into the actual
physics because it isn't a trivial problem that can be correctly modeled
with only a couple of masses with linear springs. Hence trying to draw
conclusions on comparison to that as a model isn't fruitful.

While the example video shows an interaction between to solid objects
w/o the inner mass of the deadblow hammer, the difference between the
two shows the fundamental difference in momentum transfer between
(nearly) elastic and inelastic collisions. Therein is the key to the
difference in behaviors in the other as well altho it's yet more complex
to actually model given the second mass. But, for a first
approximation, think of the inelastic case in the video as if that were
the impacting interior mass of the deadblow hammer assuming you could
deliver the blow w/o the container and you've got the start of a
visualization.

--

On Thu, 20 Feb 2014 14:40:05 -0600, Leon lcb11211@swbelldotnet
wrote:

On 2/20/2014 2:23 PM, wrote:
*Should be "of equal mass and close mass distribution"

And please don't swap the terms. Recoil? Leon likes the term bounce back

Bounce back = Energy that is not entirely absorbed by the strike and
which is deflected.

Right. Energy that isn't absorbed is useless, however that which isn't
moving the struck object is just being absorbed uselessly as heat
anyway. I don't see that the lack of "bounce" necessarily makes the
hammer more "efficient". It just means it's absorbing energy, rather
than the user's arm.

Recoil is a good term. Not all of the energy spent inside a bullet is
pushing the bullet down the barrel, much is absorbed by the person
shooting the gun.

Newton's third law kinda makes this a given.

On Friday, February 21, 2014 6:22:15 PM UTC-5, wrote:
On Thu, 20 Feb 2014 14:40:05 -0600, Leon lcb11211@swbelldotnet

wrote:



On 2/20/2014 2:23 PM, wrote:

*Should be "of equal mass and close mass distribution"



And please don't swap the terms. Recoil? Leon likes the term bounce back



Bounce back = Energy that is not entirely absorbed by the strike and

which is deflected.



Right. Energy that isn't absorbed is useless, however that which isn't

moving the struck object is just being absorbed uselessly as heat

anyway. I don't see that the lack of "bounce" necessarily makes the

hammer more "efficient".


It doesn't.



It just means it's absorbing energy, rather
than the user's arm.









Recoil is a good term. Not all of the energy spent inside a bullet is

pushing the bullet down the barrel, much is absorbed by the person

shooting the gun.



Newton's third law kinda makes this a given.

On Friday, February 21, 2014 10:40:34 AM UTC-5, dpb wrote:
On 2/20/2014 5:19 PM, wrote:

...



Agreed. They behave differently and I touched on the differences in length.

...



Superficially and without proper conclusions, unfortunately.

No. Correct conclusions and efficiently in depth.





A demonstration that isn't _exactly_ the same problem, but very closely

related is at...



http://neilatkin.com/2013/07/31/3-act-physics-momentum/



--

In article ,
wrote:
On Thu, 20 Feb 2014 14:40:05 -0600, Leon lcb11211@swbelldotnet
wrote:

On 2/20/2014 2:23 PM, wrote:
*Should be "of equal mass and close mass distribution"

And please don't swap the terms. Recoil? Leon likes the term bounce back

Bounce back = Energy that is not entirely absorbed by the strike and
which is deflected.

Right. Energy that isn't absorbed is useless, however that which isn't
moving the struck object is just being absorbed uselessly as heat
anyway. I don't see that the lack of "bounce" necessarily makes the
hammer more "efficient". It just means it's absorbing energy, rather
than the user's arm.

Recoil is a good term. Not all of the energy spent inside a bullet is
pushing the bullet down the barrel, much is absorbed by the person
shooting the gun.

Newton's third law kinda makes this a given.

It also depends on your definition of what an "efficient" hammer blow is
and what its purpose is. If I remember my physics right, there actually
is a _greater_ transfer of kinetic energy to the strcuk object when the
striking object rebounds. Conservation of momementum demands it. On the
other hand, that's based on "inelastic" objects and and when there's
deformation then things are calculated differently.

Maybe the deformation is what you're after, rather than kinetic energy
transfer. I've been away from the math of physics for too long to
figure out or remember how this translates for instance into driving a
tenon into a mortise or other common tasks. I'm sure one of our
engineer participants will address this soon enough.



--
Make it as simple as possible, but not simpler. (Albert Einstein)

Larry W. - Baltimore Maryland - lwasserm(a)sdf. lonestar. org

In article ,
wrote:
On Thu, 20 Feb 2014 16:56:54 -0600, Leon lcb11211@swbelldotnet
For the past 20 or so years I have used one of those smaller hammers
with a red rubber face on one end and a yellow plastic face on the
other.

This is the one I have.
http://www.leevalley.com/en/wood/pag...26&cat=1,53193

Buy one here and you'll have enough money left over to get 4 pounder too.

http://www.harborfreight.com/2-12-lb...mer-69003.html

http://www.harborfreight.com/4-lb-ne...mer-41800.html

and don't forget your free worklight, screwdrivers, and tape measure while
you're there.

http://www.harborfreight.com/free-coupons2014.html



--
Make it as simple as possible, but not simpler. (Albert Einstein)

Larry W. - Baltimore Maryland - lwasserm(a)sdf. lonestar. org

In article ,
wrote:
On Thu, 20 Feb 2014 15:36:59 -0800, "Lew Hodgett"
When it's time to replace, HF is your place.
About $5 for the equivalent.

Yup, I could buy a cheap knockoff from Harbour Freight for a lot less
money. Then I could add on mailing costs, duty garbage and several
weeks time waiting for it to come across the border into Canada.

Good idea Lew. I'll keep that idea in mind the next time I want to buy
some cheap tool garbage.

I'd bet even money that the HF model is identical to LVs except for color.

--
Make it as simple as possible, but not simpler. (Albert Einstein)

Larry W. - Baltimore Maryland - lwasserm(a)sdf. lonestar. org

On Mon, 17 Feb 2014 22:50:28 -0800 (PST), wrote:

On Tuesday, February 18, 2014 12:40:22 AM UTC-5, Martin Eastburn wrote:
As I posted, I'd use a 50% fill of BB's - the video shows 100% fill.

You want the many hammer blows when you smack something.

Not convinced. Here's why:

F = ma : Half full gives me approx F = 1/2 ma

"Many hammer blows" : Force = ma (collission1) + ma (collisions2) ...
etc. = m(total)a

You only end up with approx 1/2 the amount of force as a full hammer head
spread out over multiple smaller collisions. The sum of which are still
1/2 a full head.


Martin

On 2/17/2014 10:34 PM, wrote:

I made a mallet (deadblow?) from walnut, maple and BBs. Incredibly fun
project.



The plans were taken from Shopnotes 1992 No2.



http://www.youtube.com/watch?v=t-j3UcfQ_rE



But you have ended up with a sledge hammer, not a dead blow.

A proper dead blow transfers all its force and no bounce back. You can hit
it as hard as you can on a concrete floor and it just "sits" there.

--- news://freenews.netfront.net/ - complaints: ---

On Sat, 22 Feb 2014 00:59:19 +0000 (UTC),
(Larry W) wrote:

In article ,
wrote:
On Thu, 20 Feb 2014 16:56:54 -0600, Leon lcb11211@swbelldotnet
For the past 20 or so years I have used one of those smaller hammers
with a red rubber face on one end and a yellow plastic face on the
other.

This is the one I have.
http://www.leevalley.com/en/wood/pag...26&cat=1,53193

Buy one here and you'll have enough money left over to get 4 pounder too.

http://www.harborfreight.com/2-12-lb...mer-69003.html

http://www.harborfreight.com/4-lb-ne...mer-41800.html

and don't forget your free worklight, screwdrivers, and tape measure while
you're there.

http://www.harborfreight.com/free-coupons2014.html

"Limit one FREE coupon per customer per day."

On Sat, 22 Feb 2014 00:52:14 +0000 (UTC),
(Larry W) wrote:

In article ,
wrote:
On Thu, 20 Feb 2014 14:40:05 -0600, Leon lcb11211@swbelldotnet
wrote:

On 2/20/2014 2:23 PM, wrote:
*Should be "of equal mass and close mass distribution"

And please don't swap the terms. Recoil? Leon likes the term bounce back

Bounce back = Energy that is not entirely absorbed by the strike and
which is deflected.

Right. Energy that isn't absorbed is useless, however that which isn't
moving the struck object is just being absorbed uselessly as heat
anyway. I don't see that the lack of "bounce" necessarily makes the
hammer more "efficient". It just means it's absorbing energy, rather
than the user's arm.

Recoil is a good term. Not all of the energy spent inside a bullet is
pushing the bullet down the barrel, much is absorbed by the person
shooting the gun.

Newton's third law kinda makes this a given.

It also depends on your definition of what an "efficient" hammer blow is
and what its purpose is. If I remember my physics right, there actually
is a _greater_ transfer of kinetic energy to the strcuk object when the
striking object rebounds. Conservation of momementum demands it. On the
other hand, that's based on "inelastic" objects and and when there's
deformation then things are calculated differently.

You just contradicted yourself. There is *not* a greater transfer of
energy if the hammer rebounds. The energy required for the rebound is
not imparted to the object, which is sorta the purpose of striking it
in the first place. There is no such thing as conservation of
momentum, in this case. There is *always* conservation of (matter
and) energy.

Maybe the deformation is what you're after, rather than kinetic energy
transfer.

Deformation is kinetic energy transfer. You're converting the kinetic
energy into heat (still kinetic energy with perhaps some potential
energy in a chemical/physical state change).

I've been away from the math of physics for too long to
figure out or remember how this translates for instance into driving a
tenon into a mortise or other common tasks. I'm sure one of our
engineer participants will address this soon enough.

It all turns into heat. ;-) You're trading the kinetic energy from
the hammer into heat from friction (heat/kinetic energy) of the
mortise into it's tenon.

wrote

You just contradicted yourself. There is *not* a greater transfer of
energy if the hammer rebounds. The energy required for the rebound is
not imparted to the object, which is sorta the purpose of striking it
in the first place.

What he said. Where did the energy for the mallet come from to make it
reverse direction. From the object being struck not soaking up all the
energy. Been saying that all along.

This horse is about dead, isn't it?
--
Jim in NC


---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

On Sat, 22 Feb 2014 16:28:52 -0500, "Morgans"
wrote:



wrote

You just contradicted yourself. There is *not* a greater transfer of
energy if the hammer rebounds. The energy required for the rebound is
not imparted to the object, which is sorta the purpose of striking it
in the first place.

What he said. Where did the energy for the mallet come from to make it
reverse direction. From the object being struck not soaking up all the
energy. Been saying that all along.

That said, because it doesn't rebound doesn't mean that it did its
job, either. If the energy is absorbed in the hammer's head (heat),
it's not doing much good either. Of course, if it dents the paint on
your just completed cherry table, it isn't doing its job either. ;-)


This horse is about dead, isn't it?

You're supposed to put the glue on the tenon _before_ pounding it into
the mortise.

"Lew Hodgett"
It's NOT buying cheap garbage,
it is the prudent utilization of ones available resources. wink
It's all a matter of perspective.
--------------------------------------------------
wrote:

Ok, I'll let you get away with that one. But, consider a significant
amount of the comments posted here in regards to the cheap crap that
floods into our North American market.

The demand for all the cheap **** has destroyed much of the quality
goods markets that made us great in the first place. All that's left
is for us to spiral down the drain. It's a slippery slope that
there's
not turning back from, at least not as far as I can see.
---------------------------------------------------
It's pretty simple.

To paraphrase a famous country/western song:

You got the money, honey,
I got the time,

You got no more money, honey,
I got no more time.

There will always be a high end market.

The question remains, "Can you afford it?"

Lew

"Mike Marlow" wrote:

I certainly agree with the thought Dave, but you've seen me post
about Harbor Freight. There's a lot of stuff that they sell that is
just fine. There's things I'd be afraid of buying but even that has
changed over the years. Used to be that I wouldn't buy anything
with a motor from them and now that's not true. Some of the stuff
is cheap junk - can't escape that. But - that doesn't paint the
entire line of products. I too look for some level of quality - I
think we all do. But, I'm not going to pay 3 to 4 times as much for
something that just isn't all that much better. The name brand
market has done a good job of marketing their names, and the quality
difference just isn't there in a lot of cases.
--------------------------------------------------------
I use H/F for consumable items.

Gloves, chip brushes, pneumatic quick connect fittings,
light weight bar clamps, bottle jacks, some pneumatic hand tools, etc.

Air hoses are strictly a consumable item, with Goodyear rubber hoses
being the possible exception. The price has to reflect the fact they
are
throw away items.

I have yet to find an electric hand tool that can handle the
fiberglass
dust generated when working glass.

For working in glass, you have Milwaukee and you have Milwaukee.



Lew

In article m, Lew
Hodgett wrote:

There will always be a high end market.

The question remains, "Can you afford it?"

And there are places for the cheap crap. My brother works as a high
steel welder. One of the companies he works for buys $40 angle grinders
for work on site. Why? Because they grow legs and trip into the back of
people's trucks.

But I think a lot of people simply have no clue that when a tool is
advertised as "just like the pros use" it doesn't mean "professional
quality work by people who are proud of their skill and craft", it
means "anybody who can convince somebody else to part with some money".

My $0.02...

--
³Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness
sobered, but stupid lasts forever.² -- Aristophanes

In article ,
Morgans wrote:


wrote

You just contradicted yourself. There is *not* a greater transfer of
energy if the hammer rebounds. The energy required for the rebound is
not imparted to the object, which is sorta the purpose of striking it
in the first place.

What he said. Where did the energy for the mallet come from to make it
reverse direction. From the object being struck not soaking up all the
energy. Been saying that all along.

This horse is about dead, isn't it?
--
Jim in NC


---
This email is free from viruses and malware because avast! Antivirus
protection is active.
http://www.avast.com


Check out the math. If we're talking about kinetic energy and conservation
of momentum, more will be transferred to the struck object in an elastic
collision, where the striking object by definition is free to rebound and
there is no permanent deformation of either object. Of course, most of
the time in woodworking, we're NOT talking about an elastic collision and
it's not what we want either.


--
Often wrong, never in doubt.

Larry W. - Baltimore Maryland - lwasserm(a)sdf. lonestar. org