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Zeb Camper

Power hammer build questions

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Hey guys! I decided I'm going to make a power hammer similar to the little giant. I'm going to use parts from an old belt driven saw for the drive shaft.

On one end of the shaft the motor will pull a belt attached to the flywheel. An intermediate wheel attached to a foot treadle will tension the belt allowing the shaft to turn. On the other end of the driveshaft, a piece of 10" diameter x 1" thick round will spin about its center axis. Offset from the circle's center, a piece of 1 5/8" round bar will act like a crankshaft for the hammer assembly (think pistons). The hammer will get shot down the race to the anvil. I figure the race will be T shaped (like a negative T) and the hammer will have a positive T shape welded on the rear. I think the action of this mechanism is self explanitory via the drawing below (which is to scale) 

My questions are: 

Should I get a 5hp 220v single phase motor, or will a less powerful one suffice? Would 1700 rpms be a good amount or more? Less? I figure it will have a 6" stroke without the whipping effect. More with it. 

I think I will need a bigger flywheel in order  to slow it down some. I think if the flywheel were 15x bigger than the pulley at the motor then 1700 rpms at the motor will be reduced to about 113 rpms at the hammer. Sound about right? 

Should I use needle roller bearings, or just bushings for the arm joints? I fear that this thing will beat the crap out of itself. 

For the T shaped "race" (if you will) that the hammer will be guided through; what should it be made of? Will steel on steel suffice? Or should I use some of that self lubricating bushing material? What's that stuff called? 

Do you think I will need a brake mechanism to stop the hammer in the open position? 

Thanks guys! Not sure what I'd do without you!

20180322_212245.jpg

20180319_185908.jpg

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5 Hp is probably more than you need, but if you have it, why not?   I have seen all kinds of things used for the guides.  I saw one that used the foot of a piece of RR track (which is pretty much what you are talking about), I saw one that used a bunch of roller skate wheels.  I saw one that used a large square tube with pieces of water pipe rolling on bolts as the bearings.  On mine we built a guide of heavy angle iron with four bronze wear strips.  That hammer has been running on just a bit of grease for 18 years.

We also didn't use any bearings for the toggle arms, we used 1 1/4 " wrist pins, steel on steel.  They get a shot of oil every so often.

Two things to think about.

1)  Be sure that the mas travel on the tup won't hit the spring on the up stroke.  You don't want that spring flying out.

2)  Be aware that that kind of spring arrangement can shatter at high speeds (known as a "Little Giant Grenade").  Imagine that spring exploding under stress, now imagine where your head is going to be.  A shield over the spring is a good thing.

Check out the tire hammer designs.  They use a spare tire  and a steel contact wheel on the motor.  You step on the pedal, which pulls the contact wheel against the tire.  The harder you step, the faster it runs.  Instant clutch!  You often see them with the tire up high, but by mounting the motor and tire at ground level and using a belt to a pulley (or a pitman arm) you can put most of the mass near the floor for better balance.

Many hammers use a band brake on the tup end.  I use a simple counter weighted scrub brake on mine.

Two things I learned from my build.

1)  The tub does not need to be a single piece.  It can be built up of pieces of what ever you have.  The anvil will work better if it is a single, solid, piece.  (ok, that's two things)

2)  The guys who built mechanical hammers, as far back as 2000 years ago, were not rocket scientists.  They were blacksmiths who needed more force.  Don't overthink things, but build as strong as you can.  

BTW, I have pics of most of the build of my hammer, if you want to see them.

 

g

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4 hours ago, Geoff Keyes said:

BTW, I have pics of most of the build of my hammer, if you want to see them

If he doesn't  I do .....!!!  :D

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6 hours ago, Geoff Keyes said:

 

BTW, I have pics of most of the build of my hammer, if you want to see them.

 

g

Yes please!!!

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and I guess I should drop the hammer down a few inches to be safe and build a shroud out of sheet metal. Thanks! I'll look into the bronze plates. Tractor supply sells bronze bushings; should i use those for the arm joints?

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This is the one i want to build.:P

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8 hours ago, Geoff Keyes said:

5 Hp is probably more than you need, but if you have it, why not?   I have seen all kinds of things used for the guides.  I saw one that used the foot of a piece of RR track (which is pretty much what you are talking about), I saw one that used a bunch of roller skate wheels.  I saw one that used a large square tube with pieces of water pipe rolling on bolts as the bearings.  On mine we built a guide of heavy angle iron with four bronze wear strips.  That hammer has been running on just a bit of grease for 18 years.

We also didn't use any bearings for the toggle arms, we used 1 1/4 " wrist pins, steel on steel.  They get a shot of oil every so often.

Two things to think about.

1)  Be sure that the mas travel on the tup won't hit the spring on the up stroke.  You don't want that spring flying out.

2)  Be aware that that kind of spring arrangement can shatter at high speeds (known as a "Little Giant Grenade").  Imagine that spring exploding under stress, now imagine where your head is going to be.  A shield over the spring is a good thing.

Check out the tire hammer designs.  They use a spare tire  and a steel contact wheel on the motor.  You step on the pedal, which pulls the contact wheel against the tire.  The harder you step, the faster it runs.  Instant clutch!  You often see them with the tire up high, but by mounting the motor and tire at ground level and using a belt to a pulley (or a pitman arm) you can put most of the mass near the floor for better balance.

Many hammers use a band brake on the tup end.  I use a simple counter weighted scrub brake on mine.

Two things I learned from my build.

1)  The tub does not need to be a single piece.  It can be built up of pieces of what ever you have.  The anvil will work better if it is a single, solid, piece.  (ok, that's two things)

2)  The guys who built mechanical hammers, as far back as 2000 years ago, were not rocket scientists.  They were blacksmiths who needed more force.  Don't overthink things, but build as strong as you can.  

BTW, I have pics of most of the build of my hammer, if you want to see them.

 

g

Geoff please do post some pictures of your build...I would be interested in looking at the design a bit closer

 

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Thanks Geoff! here are some revised plans (never mind the spagetti sauce). I can make this for aroun $1,000. 

1521828686669-1697250971.jpg

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Here is a short video of the power hammer i built. This was all put together for less than $100 and most of that was the welding rod. There is some major changes im going to make when I get my addition to the shop finished and it mounted on its base. Right now it is sitting outside. One change i have already made that is not in the video is i put in a large turn buckle in the shaft between the soring and tire to adjust for stock thickness. Other changes will include a new anvil and a new guide for the hammer. Right now it is metal on metal. I have some food grade UHMW plastic for the new guides.  And Changeable dies set at 45° 

Edited by Jeremy Blohm
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17 hours ago, Jeremy Blohm said:

I did some hard thinking about this last night... I wonder how well the modified helve design stacks up against a fairbanks or LG design. I wonder why the helve has to be so long? Why not compact the parts and lengthen the stroke at the motor side in order to make it take up less space? I gotta do some doodling. 

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If you don't have a copy, find one of this

 

Pounding Out the Profits

By

Douglas Freund

 

Mingus Mountain Machine Works

P.O. Box 532

Jerome Az 86331

 

It has pictures of and descriptions of most of the mechanical power hammers ever built.  It's a gold mine of ideas, and a cool bit of industrial history.

 

 Find a picture of a Bradley strap hammer.

 

Geoff

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You can indeed shorten and thicken the springs / solid helve. Google Kerrihard hammer for a small helve-type hammer.  And the Little Giant EZ hammer, another helve type.  The problem with shortening the spring helve type is that while you gain speed, you lose a little of the snap.  And get that book Geoff mentions.

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Thanks guys. I checked those out, and decided to just go look for junk and let fate decide my path.

I found a coil spring that fits perfectly in some well casing. I figure I'll make a couple sockets out of the well casing with a solid sheet metal back and some triangular gussets that will be welded from the socket onto the frame of a fairbanks type construction.

I found some potential wrist joints aswell. They are super old, but have grease fittings and just look professional, so why not? I will try to find some thick bolts to fit in them.

I like the tire design, because it is so cheap and simple, so maybe I'll stick with that. I already have some huge I-beam tracked down, but it may not be tall enough. I would almost prefer to start with new stock. Can probably pick it up at the dropshop for cheap. I just need to go to the dropshop and see what I CAN make it out of before I figure out how.

I am going to sit down today and reconfigure pricing on all the head components and order what I know I can't find.

Thank you guys a ton!!!

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Here Is my new head design made around the junk that I found. It should work good I think.

Next I need to go find a 15" tire and steel to build the frame and make the pins. After that I'll buy the right bearings to fit the pins and drill the right sized holes to fit the bearings. I'll give my best effort to "get er dun!".

 

20180325_171102.jpg

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This was the thread that inspired me to build mine even though i didn't build mine like it.

 

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Just a thought; if you can make rubber fastener-mount compression springs work I'd seriously consider it. Probably less of a chance of exploding than a regular spring, and McMaster carries ultra-high-load ones.

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I'm intrigued with this design.  First, a lot of it seems to be from a car or a truck.  This means that the rotating  and moving pieces are built for much harsher conditions than it will see.  You could repurpose the crank from a car or truck to provide reciprocation.  I like the use of broken anvils for the tup and dies.  Could you use a flat spring in the place of the strap, or find some off the shelf solution for the strap connection? 

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Yeah, Bradleys are (in)famous for their use of rubber to provide the springiness, both on that model and the larger guided helve models.  You have to have them custom cast when they wear out.  Of course, that takes 75-100 years...

I like that tire hammer!  That took some ingenuity.  The strap thingy is widely used on Japanese power hammers, and at least one American-made one.  Leather flat belting was the usual material.

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Bradleys were the basis for the ram design I came up with for my (to be built) power hammer. The black pieces are rubber compression springs, and the caps on the outsides will be held in place by threaded rods that pass through the springs and into a center block that does not move with the arms. I had to sketch the up position to make sure I didn't crash the ram into anything.

image.png

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5 hours ago, AJ Chalifoux said:

 

 

looks good! 

Have you sourced those rubber springs yet? 

You should probably give your hammer more room so it doesnt hit the arms when it gets to whipping. 

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16 minutes ago, Zeb Camper said:

 

looks good! 

Have you sourced those rubber springs yet? 

You should probably give your hammer more room so it doesnt hit the arms when it gets to whipping. 

Yep! Did a few calculations and arrived at this: https://www.mcmaster.com/#9732k18/=1a15229

The thing is it won't be able to hit the arms. The spring mounts would crash first. Given the arm lengths I don't even know if it would be possible for the ram to crash even without springs there to stop it, but I'd have to sketch that up again.

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You really think these will work? They just don't look beefy enough to me. I Guess they would though.... More to think about. 

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