Tire Hammer Build

[Michael Cochran]

I have no experience building a hammer yet but I am in the planning stages so take my comment however you want.

if it were me and I was placing it outside, I'd go for the long and skinny. Dig out a hole several inches larger and deeper than you need and put a bed of sand and gravel. Pour a few inches of concrete with some rebar sticking up and after its set up set the 'anvil' in place and fill the hole the rest of the way with concrete. While you're at it you might want to pour a pad for the rest of the hammer. I'd probably go 8"-10" deep on top of the same sand gravel mix as the bottom of the hole. I'd also put some more rebar around the avil in the hole and in the pad. I'd also make sure the pad is a little bigger than the total footprint of the hammer.

hopefully if I'm wrong someone will tell us but right now that's what I'd imagine would be the best way.

[Leeknivek]

that sounds good enough. I have a slab already, it's about 3' wide off the edge of my shop. I could dig a hole beyond the slab, however. I'm hoping the first piece isn't cast, I think ill only be able to tell with a spark test. More work for the long skinny one, if the first is steel. I'll just have to wait and see I guess.

[arftist]

http://www.littlegianthammer.com/resources/50 LB FOUNDATION.pdf

http://www.littlegianthammer.com/resources/100 LB FOUNDATION.pdf

[Leeknivek]

26" of concrete? geez. That'll have to be a later addition. I don't actually know how thick the slab is (I have three hydraulic in-floor vehicle lifts with a maximum height of about 6', so who knows really). That's a very good reference though, for the future. I wouldn't have guessed that much but makes a lot of sense. 


I had an epiphany, also. Many people complain about tire hammers being wobbly at the top - and I guess this would hold true of any power hammer with a giant crank 6 feet up in the air - so what if the drive and linkage was reversed and instead was on the floor? I think the working principle of the spring-toggle linkage would still work, though it may need some modification. 

I made an new animation to help me understand it, it will probably help illustrate what it is I mean:
 

 

assuming the linkage principals still work the same, the end result would be a hammer where all the momentum happens low to the ground and is less affected by violent, heavy, off-center-of-gravity swinging. Less material. Less top-heavy.

This also opens up not only having the drive opposite the user, but while retaining the few parts needed in the original, front-facing design. This is hard to illustrate with a 2D animation, so i'll try to explain... 

Imagine that instead of a ram directly connected to the linkage, instead is a piece of thick plate that measures, say, for sake of argument, 7"w x 15"H x 1"d (30lbs, for reference). The ram, 5"w x 10"H x 4"d (57lbs), is attached to the plate, so that the top is flush with the top of the plate. The bottom 5" of the plate are empty, all for a 5" stroke. (note: these figures are arbitrary)

The ram is in line with the anvil, while the plate can be used as a guide - maybe set into the flange of an I-beam. I don't have this part exactly figured out yet, but ideas are welcome. I think this is a much more practical design, again assuming the linkages will still work in the same manner. I'm still wrapping my head around it, but I'm very excited...


EDIT: thinking more on this, I think the working principal would have to be the same, because the toggle arms and links are a mirror image and the spring keeps them apart. The spring should be compressing on every up and down stroke either way. This may require a stiffer spring to overcome gravity, however. 

Edited April 7, 2015 by Leeknivek

[KRS]

Many people complain about tire hammers being wobbly at the top - and I guess this would hold true of any power hammer with a giant crank 6 feet up in the air

With a counterweight and the right balance its not wobbly.

This reversed linkage would at best be inefficient,

the toggle link should be level in idle, since this is not possible unless your the spring has a force of  F=∞ the ram will pull the linkage down.

The ram is supposed to go down, so thats not a big problem

If you reverse it you need the same force as a regular linkage only to be in neutral position- and then even more to make it hit.

Pulling it down makes a soft hit, instead of the snap you would normally experience- so much energy lost.

I don´t think it would work. Lots of the homemade power hammers are crap, that´s why they wobble.

[arftist]

Have you looked at the rusty style hammers? They have the works down low and are a simpler geometry as well. 

[Michael Cochran]

Arftist, that's what I was just thinking. Well, sort of. I was thinking that there would have to be a pivot and an arm instead of just pushing the hammer up and down. Rusty (and the other one, krusty?) both look like good hammers I could build much easier with what I have access to regularly.

[Leeknivek]

I have, and that's always an option however the Rusty style hammers need a larger footprint. 

the toggle link should be level in idle, since this is not possible unless your the spring has a force of  F=∞ the ram will pull the linkage down.

​The entire weight of most vehicles is held up by four coil springs. I don't think holding 50lbs with one coil spring is that far out of the question, the problem I see is that a sufficient brake would be needed to keep the crank/tire from rotating. This will likely require rigging up the drum brake on the spindle to work. Maybe the e-brake, because hydraulic brakes are pushing it for me.


If you look closely at these linkages, the toggle links are level both in the top dead center idle position and the bottom dead center idle position. Presumably, the snap works in both ways as the spring compresses and allows the "elbows" (where arm meets link) to come closer together. The ram should travel further in both directions. 


​With a sufficient brake, too, I can present the next idea I have - I've seen a lot of complaints about spare tires wearing out. I think a simple solution might be to fit a heavy canvas liner around the tire. It might need some sort of friction material added to it, but since the tire is a difficult to find consumable at best, this would, potentially, save a lot of time and effort. 

Edited April 7, 2015 by Leeknivek

[turbo7]

IMO a heavy canvas liner wont last as long as a spare tyre mate, I also believe heavy canvas would be harder to come by than a tyre. Depend on what is available to you though.

[Leeknivek]

I meant for heavy canvas over the tire, so that the tire remains intact and the canvas can be replaced. It wouldn't add much to diameter and could be made to be fairly easy to replace. 

It is available at most craft stores - and Walmart.

[KRS]

​The entire weight of most vehicles is held up by four coil springs

​

mg is your hammer, F is the resulting force of the spring that holds the hammer up.

This is in no way comparable to a vehicle suspension.

A regular DuPont idle force diagram would like the image above- flip it and you have a situation like you would get if you flip the hammer.

If you look closely at these linkages, the toggle links are level both in the top dead center idle position and the bottom dead center idle position. Presumably, the snap works in both ways as the spring compresses and allows the "elbows" (where arm meets link) to come closer together. The ram should travel further in both directions. 
 

​The physics of a flipped animated image is not real world physics

Edited April 7, 2015 by KRS

[Leeknivek]

​​The physics of a flipped animated image is not real world physics

​...obviously. I wasn't trying to prove anything with the animation, only illustrate what I mean. 

That diagram doesn't hold true to a DuPont style linkage, either, because it leaves out the very working principle of the DuPont linkage - the toggle arms and coil spring. With the toggle links and arms being specific lengths and attached as they are, the coil spring holds them in place. The coil spring absorbs the outward force on the toggle arms. 

On a lighter note, I did find a suitable anvil. They didn't have anything REALLY big, the biggest was 362lbs, 6 1/2" round by 38 1/2" long. Because it isn't 500+lbs, I opted for a smaller ram - 25lbs. I guessed the weight by holding it, I would have liked 35 but this should do just as well. This gives me something like a 1:14.5 hammer-anvil ratio. 

I also bought a small i-beam, it's about 70" tall. Same as me.

I didn't have enough for a hefty piece of plate today. They didn't really have much. I paid $160 even for everything, 471lbs. $0.34/pound. That yard is still stuck at last years prices... Interestingly, they are actually a thrift store that, in addition to selling typical thrift store stuff, they have a steel yard and are a used lawnmower/motorcycle dealer. 

Edited April 7, 2015 by Leeknivek

[jeremy k]

"I" beam? I would suggest heavy "H" beam.

[Leeknivek]

Too late.

Rather than orienting it like an "I", however, I will be orienting it like an "H". My ram is a 4 5/8"D x 6" cylinder, with a 5/8" square groove machined into one side. Not sure why. I have a piece of 5/8" x 2 1/2" bar stock that I will be welding into this groove, and on either side of the bar stock I will be using some angle iron to create two parallel vee ways to act as the guide.

The I-beam i have isn't particularly strong, but I will be trussing and gusseting it up. This design will have the ram and anvil relatively close to the I-beam, and I will later enclose it all in plate and pack with sand or iron dust or something for added weight and rigidity - as well as aesthetic reasons. 

Here's a picture of the anvil:

[jeremy k]

The sand or iron dust will do nothing for the strength or efficiency of the hammer.

[Michael Cochran]

http://www.littlegianthammer.com/resources/50 LB FOUNDATION.pdf

http://www.littlegianthammer.com/resources/100 LB FOUNDATION.pdf

Thanks for the links arftist, I didn't see them earlier.

[arftist]

Too late.

Rather than orienting it like an "I", however, I will be orienting it like an "H". My ram is a 4 5/8"D x 6" cylinder, with a 5/8" square groove machined into one side. Not sure why. I have a piece of 5/8" x 2 1/2" bar stock that I will be welding into this groove, and on either side of the bar stock I will be using some angle iron to create two parallel vee ways to act as the guide.



 

​You want at least 12 inches of stroke. There should be room for it to stroke even further. 

[arftist]

​...obviously. I wasn't trying to prove anything with the animation, only illustrate what I mean. 
That diagram doesn't hold true to a DuPont style linkage, either, because it leaves out the very working principle of the DuPont linkage - the toggle arms and coil spring. With the toggle links and arms being specific lengths and attached as they are, the coil spring holds them in place. The coil spring absorbs the outward force on the toggle arms. 

On a lighter note, I did find a suitable anvil. They didn't have anything REALLY big, the biggest was 362lbs, 6 1/2" round by 38 1/2" long. Because it isn't 500+lbs, I opted for a smaller ram - 25lbs. I guessed the weight by holding it, I would have liked 35 but this should do just as well. This gives me something like a 1:14.5 hammer-anvil ratio. 

I also bought a small i-beam, it's about 70" tall. Same as me.

I didn't have enough for a hefty piece of plate today. They didn't really have much. I paid $160 even for everything, 471lbs. $0.34/pound. That yard is still stuck at last years prices... Interestingly, they are actually a thrift store that, in addition to selling typical thrift store stuff, they have a steel yard and are a used lawnmower/motorcycle dealer. 

​Before you decide on the tup weight add the weight of the base to the weight of the anvil then divide by 10. Anything past 10-1 is lost to the law of declining returns in the hammer you are building. You want the plate to be as thick as possible. Mine is 1 1/2" plate (1.5") It is not excessive in any way. Even thicker would be better but 3/4 or 1" will work and even half inch will work but not as well. 

[Leeknivek]

12" of stroke? On such a small hammer? I was thinking more like 6-8" as I won't be trying to work anything bigger than like 3", and only then for drawing. If I start working on stuff that big I'll make a bigger hammer. 

Speaking of which, how does one calculate stroke/eccentric shaft position? Is there a good rule of thumb? I was figuring 1/3 of 'maximum' stroke, assuming that if there were a static stroke you'd want half. In a variable stroke, I want the linkage to provide the extra length of stroke. 

The tup weight is going to be about 30-35lbs, once all the engagements are made. I've read that 10:1 is minimum and 20:1 is maximum practical. I don't expect that it will make a huge deal of difference.

I'm looking for the biggest piece of plate out there, didn't see it today. I don't know where it is but I'll find it... All I need is the base plate, some thinner 1/8" plate (for giving profile and suave to my machine when finished), a coil spring and some hardware. I've got it mostly figured out in my head, too. 

The devil is in the details. 

[Leeknivek]

 

Here ​is an example I found of the principle I'm trying to express... The anvil is small and the ram is "10-20lbs", looks very light duty, but I think I can work within this design and amp it up some. 

Some evidence that it does "work"!!!

[arftist]

The faster she runs the longer she strokes and the harder she hits. That's why we use clear space over the dies. My 75 pound hammer has a 3.5" crank offset. I can't help you determine anything else, except to point out that you don't seem to be taking whip into account. You don't make shorter swings when you are using a lighter hand hammer do you?

[jeremy k]

Reference to the about posted video:

For being such a low center of gravity - there sure is a lot of movement on top even when he's holding it. - Hence another good reason to spend the little amount on the plans, so you can understand the counter balance that is needed.

[Michael Cochran]

Reference to the about posted video:

For being such a low center of gravity - there sure is a lot of movement on top even when he's holding it. - Hence another good reason to spend the little amount on the plans, so you can understand the counter balance that is needed.

If he had a solid base on that hammer and it was properly secured it would probably be much less wobbly. It looks as though this one specifically was meant for traveling and as such is too light.

i think it's a pretty cool set up just unsure of the usability.

Edited April 9, 2015 by M Cochran

[Leeknivek]

Jeremy, that's true, but to be fair that hammer has no bottom plate and the frame isn't bolted down. 

arftist, you're right. In my setup, with the ram in the front and the linkage in the back on the bottom, I'll have room for up to 24" of stroke. The linkage will cut that down significantly, depending on how big it is, but I think 12" is good like you suggested. 

I did some sketches of a full mock up, but I left my notebook at the shop. I did take some pictures, though: 
 

Everything in place


Wire mesh, used to be a grill for the back window of a pickup. I set my anvil on it since one side has a curved face and bent it by hand. 




Foot treadle, used to be the side of a fish tank stand. 1" angle iron. Real stiff. 


Potential motor candidate... Only 1/3HP, but she's big. What do you guys think? The ram will be about 30-35lbs. I can always upgrade later.

Almost time to put it all together. Another couple weeks and I think we'll be up and running, need a base plate, the linkage, and some hardware. 

Oh, and some paint! 

What color should I paint it? I don't want to do green or gray, because 75% of all hammers I've seen are British Racing Green or LG gray. The other 15% are red, 6% blue, 4% something else.  

Edited April 9, 2015 by Leeknivek

[Michael Cochran]

According to a chart I saw elsewhere I don't think 1/3 hp will drive that much weight. I would share the chart but the site is down and I didn't save it when I saw it  I'll keep an eye out for it and post it soon as I find it