Recommended Posts

On 10/7/2019 at 1:39 PM, FlatLiner said:

I for one am intrested in seeing how this powerhammer build ends up, and seeing how well it funcions.

Me too! Thanks for your interest.

 

On 10/7/2019 at 12:36 PM, ThomasPowers said:

The California Artist Blacksmith Association lists several members/officers in Sebastopol; have you contacted them to see if anyone is closer to you?

Thanks, I'll look into it.

I'm definitely putting horns on it. I'll make them as a first project on the hammer.

Share this post


Link to post
Share on other sites

Ted, I believe I suggested this in the swage block experiment, but especially here you might to look for some expanding grout to go between the concrete and steel (at least at the top and bottom).  This would allow for some mechanical preload that would help avoid a gap opening between the two.  Either that, or find a way to mechanically prestress like they do for concrete structural members.  I think the larger/longer the pieces  are the more likely it is that you'll run into problems with keeping the hybrid structure acting as a single unit.

Share this post


Link to post
Share on other sites

The way I built it I don't think I'll have any trouble with the concrete. As I mentioned above, the concrete is not load bearing and merely serves as a dampener and stiffener. Here is a picture of the rebar config.

UP1wUTq.jpg

There is also a solid 1"square bar in the middle on each side to support the point of impact.

Here it is after the pour:

7v4HDNU.jpg

When I hit the top with a hammer there is no ring at all, just a thwack. Concrete is a wonderful noise suppressor.

Share this post


Link to post
Share on other sites

How tall is that? It looks a lot taller that the power hammers I’ve been around...

Looking forward to seeing how everything works out.

Share this post


Link to post
Share on other sites

It's 34 inches high. That's a good working height for me. I figure another inch or two for the die. 

Share this post


Link to post
Share on other sites

I'm in the process of building the drive train for this hammer and was wondering how heavy of a hammer this motor can support, so I did some calculations.

The 1.5 hp motor produces 2.2 ft /lbs of torque. Converted to inch pounds: 2.2 x 12 = 26.4 in / lbs

The speed reducer is a 10:1 ratio. The speed is reduced by 10 and the torque is multiplied by 10. Therefore: 10 x 26.4 = 264 in / lbs on the output shaft.

I will be using a 2" cam which will half the 264 in/lbs to 132. So, I have 132 lbs of force when the cam is at 90 degrees to the load, which represents the maximum load on the motor throughout the cycle. 

Then the ratio of the distance of the drive point on the leaf spring with respect to the fulcrum, and the distance of the drive point of the hammer need to be considered.

A 2" cam will travel 4" vertically. If I want 8" of travel for the hammer, that represents a 2:1 distance differential which will cut my force in half. 132 / 2= 66 lbs

In this configuration a 66 lb hammer is my theoretical maximum. In the real world we have mechanical losses and other inefficiencies, so I'm thinking a hammer around 30 lbs would be reasonable. 

I'm also thinking that the more travel I have on the hammer, the more velocity I can develop. I would rather have a lighter hammer with more potential velocity to play with. Discovering the properties of the spring (springs) will determine the best configuration. 

Just some thoughts...

 

Share this post


Link to post
Share on other sites

If you have issues with the concrete cracking and spalling you could always weld flat plate over the sides and fully encase it.

Share this post


Link to post
Share on other sites

I got the "transmission" part of the build pretty much done. This includes the pulleys, belt tensioner (clutch), and cam.

M9BAowz.jpg

HGqES1e.jpg

I'm not entirely happy with this belt tensioner, but I'll see how it works.

Here's the Cam. I built it from two pieces of 3/4" square bar. The reason for this was so that I could mill a key slot in the 1" hole after I drilled it. I then pinned and welded the two halves back together. 

v9LzGev.jpg

bNf3SYc.jpg

I'm using two of these 3/4" rod ends with a turnbuckle for the link to the spring. These things only come in fine thread (3/4-16) so I'll have to build a turnbuckle for them, as most turnbuckles are in course thread.

Share this post


Link to post
Share on other sites

Most of the lighter duty hammers back in the day had hollow anvils. I commend you for giving it a whirl. 

Come to think of it the stand on my smaller hammer had a hollow base. It has since been filled with lead.

 

 

Share this post


Link to post
Share on other sites

Thanks for the vote of confidence, precious few here.

I was watching a video of an old power hammer today and it  also had hollow anvil. 

I'm not worried about it, but it seems to bother some folks. 

Share this post


Link to post
Share on other sites

Note that their "hollow anvils" probably weighed hundreds of pounds more than yours.  As sourcing heavy stuff is generally easy; why skimp on something you can do better on?

Share this post


Link to post
Share on other sites

My blacker stand was #275 pounds I think, the anvil 500 ish. So it had a 775 pound anvil by design with a hollow base.

Share this post


Link to post
Share on other sites
2 hours ago, ThomasPowers said:

As sourcing heavy stuff is generally easy; why skimp on something you can do better on?

I have had some difficulty trying to find heavy solid steel in my area. I don't own a truck, so whatever I get has to fit in my wife's minivan. Besides, I still think this anvil will work just fine. If I'm wrong you guys will be the first to know, and you can all take great satisfaction in telling me "I told you so". Until then, I'm moving on...

Share this post


Link to post
Share on other sites

Why did you go with a 2 inch crank offset? 3.5 is what most hammers use.

 

Marcus B, your anvil isn't hollow and has at least a 20 to one anvil to tup ratio. 

Share this post


Link to post
Share on other sites

The base supporting the anvil is hollow. Well it was, its now filled with lead. I would say similar concept to my former little giant, solid top, hollow cone but that was a one piece frame so I guess that's apples and oranges.

 

Share this post


Link to post
Share on other sites
On 10/17/2019 at 12:05 PM, marcusb said:

Whats the BPM going to be?

 

About 180. If it's too fast I'll adjust the pulley sizes to slow it down. 

 

3 hours ago, arftist said:

Why did you go with a 2 inch crank offset? 3.5 is what most hammers use.

What difference does it make?

Share this post


Link to post
Share on other sites

Well, it will reduce the acceleration of your tup by almost half. 

Since force is crudely acceleration squared x mass and since you are running your hammer very slowly it will strike with very little force. 

25 pound hammers usually run at 400-475 bpm.

Even my 75 # runs at 220 and should be faster.

Share this post


Link to post
Share on other sites

Well, thank you for the information. It's easy enough to swap pulleys if I need to. I'm still going to try it out at this speed to see how the whole mechanism works. I don't know how heavy the hammer is yet, so I'll have to see how all that pans out.

Just for the sake of discussion, BPM does not necessarily dictate velocity. The velocity is dictated by the geometry of the lever times the BPM. The closer your drive arm is to the fulcrum, the more distance your hammer will travel. More distance equals more velocity at the same BPM. 

Also, raising the BPM rate requires more power for any set configuration, since more work is being done. So, I could shorten my stroke and raise my BPM, but the same amount of total force is being delivered to the work in any given time span. It comes down to a preference between big heavy thumps or a bunch of lighter thumps. 

Share this post


Link to post
Share on other sites
39 minutes ago, Ted Ewert said:

So, I could shorten my stroke and raise my BPM, but the same amount of total force is being delivered to the work in any given time span. It comes down to a preference between big heavy thumps or a bunch of lighter thumps. 

This is true within certain parameters.  However, if the lightest blows aren't forceful enough to cause deformation of the material then it doesn't really matter how many of them are applied in a certain time frame.  When working some larger stock with hand hammers I'll choose a heavier hammer sometimes even though I can't swing it as fast or as long as a lighter hammer because I can move more metal of that thickness with the heavier hammer. 

In some ways it's similar to burner output.  The same total btu's over a given period of time for two different burners does not necessarily equate to the same maximum temperature achieved during that time.

Unless I misunderstood, arftist was pointing out that with a shorter stroke and reduced bpm you could not expect the hammer to hit very hard.

Of course the other potential drawback to a shorter stroke is the limitation on the thickness of stock that can be worked unless you have a way to adjust the height of the crank in relation to the anvil.

Regardless, I'm watching with great interest so I can learn more about the particulars as I embark on building one of my own.  Please keep us posted with the results.

Share this post


Link to post
Share on other sites

I agree with the above, that's awful slow, unless it hits like a freight train to compensate I fear you may be disappointed with its performance.

Share this post


Link to post
Share on other sites

In theory practice and theory are the same. In practice they are not.

Mainely Bob

The difference in velocity between 172.5 bpm and 475 bpm is almost is almost 3-1 regardless. Then when you cut the stroke in half you again diminish the velocity by almost half. 

Just for discussion sake.

FYI 1.5 hp is plenty for you to run a 30 at full stroke and speed. One thing you may not be aware of. When working heavy stock one needs to hit hard enough to move more than just the surface. Otherwise piping, fishmouthing,  cold shuts and other issues can occur, so no, the same amount of work is not necessarily done.

The other difference between hand forging and power forging is that a properly striking hammer will keep the work hot. So much energy should go into the work that the work is heated, which greatly increases the amount of work one cab perform in a given time.

My master has demonstrated making a 3 " ball in a single heat. 

Since the joy is in the journey, carry on merrily. 

At my age it is more important to me to build a machine which fires right out of the gate, so I researched until I found all the known knowns and utilized them in my hammer build.

I see that you are on a different path, to each his own and more power to you. 

 

Share this post


Link to post
Share on other sites

Thank you all for the input. I'm sure I will make many changes once the thing is up and running.

I just got through building the drive linkage. I had to build a turnbuckle since none are available in fine thread. I used a couple of pieces of 5/8" square stock and a couple of nuts welded together. Works good. 

04GvUn3.jpg

The turnbuckle will allow me to adjust the height of the hammer, and the clamp on top will allow for stroke length adjustment.

6L4v4A8.jpg

The core of the hammer is going to be four 12" pieces of 1-1/4" square stock which weigh 20 lbs. Adding the end plate, connecting rod and other pieces should make it close to 30 lbs. I can always add weight if desired.

Share this post


Link to post
Share on other sites

I should have asked some questions.  I had incorrectly assumed you were building a DuPont style linkage hammer like a LG.  In the worst case if the stroke isn't long enough you'll only have to make one new part to change  that anyway. 

Thanks for posting your progress.  I'm looking forward to seeing it beat some hot steel.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.