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

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.
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

Subject

See abpw for a similar unit I made, but without metal balls.

Lew

On 2/18/2014 12:40 AM, 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.
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


Looks good, but I would agree with Martin, also I might use lead shot to
increase the weight with less fill.

--
Jeff

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

On 2/18/2014 1:50 AM, 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




So I was wrong, I thought Martin was talking about the bounce back.
With a full head, you gain mass, but I don't think it gives you the
deadblow, that is desireable. That's why I would go with less fill, but
lead, to gain back the mass.

--
Jeff

On Tuesday, February 18, 2014 1:55:33 AM UTC-5, woodchucker wrote:
On 2/18/2014 1:50 AM, 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









So I was wrong, I thought Martin was talking about the bounce back.

With a full head, you gain mass, but I don't think it gives you the

deadblow, that is desireable. That's why I would go with less fill, but

lead, to gain back the mass.

No. Substitute the mass for lead in my equations above. You are still better off with a full head of lead than 1/2 full head of lead. It's the same equations.







--

Jeff

With a full head, you gain mass, but I don't think it gives you the

deadblow, that is desireable. That's why I would go with less fill, but

lead, to gain back the mass.

No. Substitute the mass for lead in my equations above. You are still
better off with a full head of lead than 1/2 full head of lead. It's the
same equations.

What you are describing is a weighted mallet. For a deadblow hammer to be
effective, the shot moves to the back of the hammer as you start to swing,
then crashes forward at impact, thus reducing rebound. It can not shift if
it is full. See the definition, here.


http://www.hgtv.com/home-improvement...dex.html#dname
dead-blow hammer
Strikes blows without damaging the work's surface. The tool's hollow head is
partially filled with small metal shot, which reduces rebounding.
--
Jim in NC


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

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: ---

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

Nice looking mallet!

BUT with no internal loose mass, your answer about " deadblow?", would be
no, not until the bb's slowly deform the cylinders and have more room to
move to give the secondary amount of force to help counteract bounce back.
The more movement the more counteraction to bounce back you will have.

Having said that, walnut being significantly softer than maple might itself
cushion/absorb some of the impact and lessen the bounce back if you don't
strike squarely or until the walnut rounds off or splits off.

If you are building these for a conversation piece, the walnut looks very
nice. For actual use I would recommend that the striking faces be of equal
hardness. As the softer material mixed with a harder material wears away
faster the striking surface naturally becomes smaller and the force is
concentrated in a smaller area. This might leave an unwanted impression on
a wood surface if you are using the mallet for adjustments. That particular
use is what deadblows excel at.

If you used a heavier material, walnut is pretty lite weight, with less
loose mass internally you benefit more with more counteraction to bounce
back.

Now let me throw you a curve on your "force calculation". First off your
equation does seem logical.
BUT an impact driver delivers more efficient force than does a
drill/driver with the same available power supply. It's the multiple
impacts of the impact driver that wins the contest of loosening the stuck
screw vs. the constant force of the drill/ driver..
So while loose shot in a dead blow hammer might seem to have less force at
initial impact the amount of work being done is probably close to the same
given the second impact force of the loose shot. That is going to be hard
to formulate given some loss from the secondary force counteracting the
bounce back. Maybe if the entire mallet striking surface was walnut the
bounce back would be diminished. Whew! :-). Something to think about.
LOL

Consider this:

A large force that is delivered in smaller doses is not as efficient at driving a joint home as one force all at once.

Each smaller force would have to first overcome the coefficient of friction before it can move an object. Any small fraction of the force that is below the coefficient of friction is a loss.

Consider the extreme : dropping 100 kg of lead weights on a stuck joint at a 1g at a time versus dropping the 100 kg all at once. If the 1g force doesn't break the coefficient of friction you will have very little net joint closure.

On 2/18/2014 9:15 AM, wrote:
Consider this:

A large force that is delivered in smaller doses is not as efficient at driving a joint home as one force all at once.

Perhaps in theory. but in real life, the impact driver works with
multiple lighter strength impacts. Its the multiple impacts that
produce more work in a given period of time. A larger single force may
be way too much or simply not enough.







Each smaller force would have to first overcome the coefficient of friction before it can move an object. Any small fraction of the force that is below the coefficient of friction is a loss.

Agreed there is that, but addressing the deadblow that you mentioned,
the loose shot works more to dampen the bounce back rather to increase
force. There are all kinds of factors to consider here. The loose
shot's main function is really not to increase the driving force. Your
adding of the loose BB's to fill the void was more of a convenience to
add mass than to add the feature of a dead blow mallet. You have to
have the second impact of loose shot to tweak the mallet to have dead
blow characteristics.





Consider the extreme : dropping 100 kg of lead weights on a stuck joint at a 1g at a time versus dropping the 100 kg all at once. If the 1g force doesn't break the coefficient of friction you will have very little net joint closure.

That is correct however in a dead blow hammer the loose shot weight does
not have that extreme of a difference to the rest of the hammer head as
the 100 to 1 ratio.

I think your reference to the mallet possibly acting like a deadblow was
whet most of the replies were questioning.

I was just throwing the countless possibilities to be factored in to get
different affects depending on the size of the shot, weight of the shot,
shot weight ratio, size and shape of the shot chamber... ;~)
Just something to think about. ;~)

Either way your mallet looks really cool!

In article ,
Leon lcb11211@swbelldotnet wrote:
oN 2/18/2014 9:15 AM, wrote:
Consider this:

A large force that is delivered in smaller doses is not as efficient
at driving a joint home as one force all at once.

Perhaps in theory. but in real life, the impact driver works with
multiple lighter strength impacts. Its the multiple impacts that
produce more work in a given period of time. A larger single force may
be way too much or simply not enough.


I believe the flaw to that argument is that an impact driver in fact
does NOT use multiple lighter strength impacts, but actually, due to the
nature of impact, uses momentarily HIGHER forces than the static tool
torque spec would imply.




--
There is always an easy solution to every human problem -- neat,
plausible, and wrong." (H L Mencken)

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

On 2/18/2014 6:09 PM, Larry W wrote:
In ,
Leonlcb11211@swbelldotnet wrote:
oN 2/18/2014 9:15 AM, wrote:
Consider this:

A large force that is delivered in smaller doses is not as efficient
at driving a joint home as one force all at once.

Perhaps in theory. but in real life, the impact driver works with
multiple lighter strength impacts. Its the multiple impacts that
produce more work in a given period of time. A larger single force may
be way too much or simply not enough.


I believe the flaw to that argument is that an impact driver in fact
does NOT use multiple lighter strength impacts, but actually, due to the
nature of impact, uses momentarily HIGHER forces than the static tool
torque spec would imply.






I don't know, I can hold the impact with a large enough socket, with my
bare hand, with a little slippage.

On Monday, February 17, 2014 10:34:56 PM UTC-6, 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

It looks great but I think a solid head where you drill, fill, and cap on both sides would be more useful. Also, why not taper the mortise and insert the handle end first so that it gets more snug the further you pull it through?

Here's Roy Underhill getting it done.

http://video.pbs.org/video/2365021538/

I hate to keep kicking this horse but... I just received my electronic issue if Popular Woidworking today. An article on mallets was on the inside. What a coinkydink.

On the topic of dead blows the cabal says:

"Minimal rebound makes better use of the applied force"

How do I get a better use of force here? How did this myth start? I want to blame someone. Norm? Can I blame Norm?

Again if F = ma. And I apply the m a little at a time apposed to all at once, how is this a better use of the applied force? I think we officially debunked Leon's hammer driver explanation

On 2/20/2014 10:47 AM, wrote:
I hate to keep kicking this horse but... I just received my electronic issue if Popular Woidworking today. An article on mallets was on the inside. What a coinkydink.

On the topic of dead blows the cabal says:

"Minimal rebound makes better use of the applied force"

How do I get a better use of force here? How did this myth start? I want to blame someone. Norm? Can I blame Norm?

Again if F = ma. And I apply the m a little at a time apposed to all at once, how is this a better use of the applied force? I think we officially debunked Leon's hammer driver explanation








Probably thinking one thing and saying another. With a dead blow you
don't have to worry about the the hammer bounce back coming and hitting
you in the head. ;~) Consequently you can bang harder and not worry
that so much.

On 2/20/2014 10:47 AM, wrote:
I hate to keep kicking this horse but... I just received my
electronic issue if Popular Woidworking today. An article on mallets
was on theinside. What a coinkydink.

On the topic of dead blows the cabal says:

"Minimal rebound makes better use of the applied force"

How do I get a better use of force here? How did this myth start? I
want to blame someone. Norm? Can I blame Norm?

Again if F = ma. And I apply the m a little at a time apposed to all
at once, how is this a better use of the applied force? ...

You _really_ don't want to get more into the physics of hammers, trust
me...

But, besides the conservation of energy, there's conservation of
momentum to be considered and the transfer of energy from/to the target
is also a dependent on the characteristics of both the driver head and
the target.

And, the actual force is an impulse wherein the motion of the hammer
comes to rest in a distance that is dependent on the resistance of the
target--the more resistant, the shorter the distance moved and the
higher the delivered force because that resisting force times the moved
distance must be the same as the kinetic in the hammer to balance the
energy.

A well-designed dead-blow hammer has most of the mass in the head in the
innards so the actual head has essentially come to rest when the
internal mass then delivers the blow. The effectiveness comes from the
more effective transfer and less recoil energy that doesn't go into the
target with a conventional hammer head.

And, that's all I'm going to say and I'm _not_ going to go into a
full-blown analysis...if I still had access to a nonliner FEA system I
might be inclined to set up a couple or three examples that could show
what happens w/o having to actually set up the detailed analytical
solution, but having returned to the farm from the consulting gig I
don't. It's a lot like a simplified case of the collision analyses the
major auto manufacturers go through where they actually use such to help
design survivability into their vehicles...

--

What I don't understand in particular are these two phenomena that would seem to reduce the effectiveness of the applied mass:

1) when the deadblow is accerated toward the object the mass (majority) is in the rear of the cavity (from inertia). After the deadblow makes contact the mass leaves the rear of the cavity and travels to the from and as it does, it decelerates. (Loss of a thus loss of efficiency)

2) there is still bounce back inside the deadblow head. After the shot is thrown against the front inside of the deadblow it will bounce back. The energy that is lost to internal bounce back should equal any energy lost to the bounce back of a non-deadblow mallet of equal mass. Correct?

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

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

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.

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.

On 2/20/2014 1:29 PM, wrote:
What I don't understand in particular are these two phenomena that would seem to reduce the effectiveness of the applied mass:

1) when the deadblow is accerated toward the object the mass
(majority) is in the rear of the cavity (from inertia). After the
deadblow makes contact the mass leaves the rear of the cavity and
travels to the from and as it does, it decelerates. (Loss of a thus loss
of efficiency)

2) there is still bounce back inside the deadblow head. After the
shot is thrown against the front inside of the deadblow it will
bounce back. The energy that is lost to internal bounce back should
equal any energy lost to the bounce back of a non-deadblow mallet of
equal mass. Correct?

Both, essentially, "no" with a proper choice of materials and
construction. 1) doesn't decelerate except by hitting the head (albeit
some indirectly thru the elements ahead of them) to any appreciable
extent. The benefit comes from the marked difference in recoil energy
lost. The internals don't act as does a solid; it's that
elastic/inelastic thingie again...

--

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.