Anyone built a power hammer?

[paulmowers]

Hi All

I am thinking of building a small power hammer for drawing down mainly 30 x 6 flat into tapers, its hard going with a hand hammer, one or two is fine but when I need 20 all the same.
So just wondered if anyone has built something that works.
I have seen a big one where a car axle has been mounted up high, with drive going into where the prop came off, and an eccentric on one hub end driving the hammer, with a cable to the foot pedal operating on the brake still fitted to the other end of the axle. So once motor is running the braked end spins and the hammer is stationary until the braked end is slowed or stopped then the drive goes through the diff to the hammer eccentric. simple and ingenious.
Far too big for what I need, so I was thinking of utilising an old ride on mower transaxle to the same effect, plus I will have 3 or 5 gears to select for various hit rates apart from slipping the brake to vary speed.
Obviously I will need to arrange a spring shock absorber on the pushrod at the hammer so it can obtain full travel even if the hammer head is on top of a bit of metal.
Any advice or obvious pitfalls pointed out would be appreciated.

Cheers Paul..

 

[wyn]

Have you had a look on metalmeet loads of home built stuff on there.

 

[irondarren]

when i actually get my rear end in gear and get some spare time, thats what i intend to do. One that uses a rocking leaf spring seems to be the best idea. the rear of the spring is lifted forcing the hammer down. basically a crank shaft on the back of the spring lifting and lowering as it goes round.

 

[chunkolini]

I spent a couple of years in Ghana on an aid project in health care and made friends with a bunch of blacksmith engineers. They had a power hammer made of a rear axle.

It looked fantastic, real heath robinsonesque stuff. It worked, but it didn,t look like a long term prospect. As a nonengineer but qualified bodger and fixer it looked as though it would tear itself to pieces in no time. Long levers, lots of movement and violence. I had the feeling that it was a 'nice idea' rather than a serious contribution to the country.

But the locals made an improved version, which if I remember went like this.

there was a flywheel mounted upright, with an arm that curved in the same radius as the wheel and coated in brake pad material, with the hammer mounted onto it. Press a pedal to apply the brake and BANG. It was 17 years ago so memories are a bit vague.

Get too it, drive the neighbours mad.

And keep us posted.

Chunko'.

 

[paulmowers]

Hi Guys

Thanks for the input, re the rocking leaf spring, it does look like it will work, but am a bit concerned that the spring clamp on the arm could work loose and also if anything breaks you end up with quite a long push rod flailing around!! But thats only my opinion.
With the axle thing, the only way the push rod can go if it breaks is downwards, so safety wise it looks like if it does fail it will fail safe.
Thanks for the link wyn, I will have a look.

 

[wyn]

A couple of nice pics of the front workings of a "yoder" type hammer here.

 

[madkayaker]

what about building a tilt hammer?

 

[astro_al]

Go to Iforgeiron.com and ask there - they have a whole section on power hammers.

I'm about to build a pneumatic power hammer, but the simplest and cheapest would be the type already suggested.

Cheers, Al.

 

[paulmowers]

Thanks guys

This is a bit of a long term thing, maybe sometime this year between work jobs, but thought I'd ask .

Cheers.

 

[irondarren]

Paul mine has been even longer term than that, i had the idea about 3 years ago. So far i have the anvil unit of it built and thats about it. For making the top and bottom tools ideally a hardened steel would work. I was looking at 50mm square EN9 (which i understand is what hammers are made from) but when i get to that point i will take advice of tech'al as he seems to be the resident metaligist