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How would you bend this?


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Pulley broke on my treadle hammer. Thought id fix it by keeping the central wheel, replace the housing and O-ring to allow the pulley to handle the extra strain.

So i made my measurements and drilled my holes, everything was looking nice. Riveted the O-ring to the piece and then made my bend. Had a piece of square steel that was the width i needed for the pulley wheel to spin freely without touching the sides. I ended up making the left and right sides of where this steel piece would line up and hammer on this steel piece, with the idea that id be able to bend both legs of this piece at the same time. And it worked...mostly. i heated the steel, set it over the jaws of my vice that was opened to a present distance to accomodate the steel piece plus the thickness  of the steel  material. as you can see in the photo, one leg is longer than the other. I have no idea how that happened as i had marked where the edges of the steel was to line up on the bending metal. 

 

So id like to know, how would you go about making the same bend?

Let's say that it's a 5inch long piece of .75"W x .25"Thick flat stock, and you want to have a 1" inside gap. (The dimensions are close to what is shown in the picture)

20201112_154254.thumb.jpg.652ca9db50ab880b8be374385d8c63af.jpg

 

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You want to know how I'd make an uneven shackle? :huh: Well, okay I just wing it and they come out uneven.

Were I making your pully block I'd bend it, true it up even and square. Then drill it. I'd also put the eye on the same plane as the sheave.

Frosty The Lucky.

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In the pic the lift eye is laying at 90* to the plane of the Sheave. Most of the swinging forces will be in the plane of the sheave. The eye will swing on the hook or however you hang it but it's always good to minimize potential stresses on load bearing structures. Make sense?

If you make the eye swivel it'll be perfect as it can align with the load. 

Frosty The Lucky.

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Use a piece of pipe or rod the same diameter as the space between the legs for a mandrel. Measure the center of the stock and mark the edge with a center punch so you can see it at heat. If you have a vise lay angle iron jaw inserts flange outwards clamp the mandrel tight between them. Tap them down tight on the top of the vise, these will help keep things even as you bend. 

You'll need bending wrenches. Pipe wrenches work if you don't have large crescents. Slips to cover the teeth in the jaws will help prevent marring. However, if you get it hot enough it'll bend easily and not make to deep marks. This is also why you want to heat just the portion that will be wrapped around the mandrel if possible.

Heat the center of the stock to a high orange, place it mark up and centered on the mandrel and pull both ends around with the wrenches. When they're closed more than you want gently tap the spacer into the space. Lift it off the mandrel while still hot, stand it on the ends and tap them even, lay it on edge on the anvil face and tap them square. The spacer block will keep the space even while you tweak it. 

You might have to re-heat it and tweak on the mandrel but the spacer should prevent the need. IF that is, you don't HIT it evening up the legs. Tap tap. Hmmm?

Frosty The Lucky.

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4 hours ago, Frosty said:

If you have a vise lay angle iron jaw inserts flange outwards clamp the mandrel tight between them. Tap them down tight on the top of the vise, these will help keep things even as you bend

You'll need bending wrenches.

Two follow up questions

1) the bold, i kind of understand what youre saying, but not able to visualize it. When you talk of the mandrel, youre saying the cone mandrel? Or is there another type of mandrel im not aware of

2) why am i using bending wrenches? Is it for better control of bending the metal? 

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Dewn: A mandrel is anything you use as a form to bend metal to a desired shape.  A round mandrel can be a piece of pipe.  A square mandrel can be a piece of square stock or square tubing.  A cone mandrel is an infinitely adjustable round mandrel which saves having lots of individual round mandrels of different diameters.

A bending wrench is anything with 2 surfaces to bend against.  Adjustable wrenches are like a cone mandrel, infinitely adjustable.  A easy bending wrench is a piece of U shaped stock held in the vise with the 2 ends up so that you put the metal to be bent between them and use them as a base and a fulcrum to bend.  If you are doing a lot of the same shape with different diameter bends (think an asymmetric S shape) you can weld one up with different diameter posts or pipes to be inserted in the hardy hole or held in a vise.

"By hammer and hand all arts do stand."

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I know how I would bend it, heat it up bend it over the anvil with a hammer, mess it up and start again, second go similar to the first but this time using a mandrel, mess it up and start again. 

At some point I will have x amount of bad ones and I will loose my rag and bin the idea. 

A few days later I will go back, knock up a basic jig and bend it right first time. 

The moral of this story is if you take a bit more time to set up correctly it saves you loads of time in the long run. 

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I'd treat the "U" like a horse shoe. Mark your center and heat it up equally on each side of center. Bend one branch(side) over the horn. Then bend the other side. Straighten both branches over the heel of your anvil if needed. If one branch is longer than the other, then heat up around both sides of center. Then put the long side only on your anvil face. Tap the center to bring the short side down to the anvil face. This should even up the two branches.

Second way. Use your post vice and a set of bending forks and a scrolling wrench and do the whole thing in the horizontal plane. Clamp the fork in your post vice and use the wrench to make your two bends. You may not even need to heat it.

Third way, and my preferred way. Learn to make right angle bends to dimension. It's a simple process. Then I would lay out my bar while it is straight for the two right angle bends and where the two holes are at both ends of the bar. Then drill all holes. Now make your two right angle bends and you are done. This way you have learned a new technique as well. 

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On 11/14/2020 at 12:29 PM, anvil said:

Learn to make right angle bends to dimension. It's a simple process.

This way sounds interesting. Care to give me a nudge on where to look this up? Or perhaps know of a video that explains the process?

I ended up making this....its really ugly. 

20201116_105705.jpg

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I'm lazy and have a welder so i'd cut some flat stock and weld it to a U bar.

In case I wouldn't have access to a welder I'd wait with drilling the holes and make it a little bit longer so I can trim to lenght, swage about halfway through the material and knock it roughly into shape on the anvil and then further refine it in a vice like you described. It'd be a good idea to isolate the heat to the area that you want to bend with water.

Then get a 1 inch piece of steel, put it between the legs and make it level with the legs, clamp it in a vice and use a square to get the marks paralell.

Then drill/punch the holes 

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1 hour ago, Dewnmoutain said:

This way sounds interesting.

You should maybe stay with the least technically difficult method of achieving your desired results? 

You are looking for something that just isn't there. There is NO magic trick to replace basic shop skills and this project is first week shop class difficulty.

Frosty The Lucky.

 

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im not looking for a magic trick. Just trying to get help with something that may seem easy to you, but for me, is just eluding me.  And im frustrated because, as you said, this is something that is first week shop class difficult, only i never had a shop class, and the couple of blacksmith classes i did take didnt cover bending like this. 

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Sorry if I came across harshly, I get frustrated too easily. Bending like this wouldn't be something you'd encounter in a blacksmithing class unless you asked specifically. This kind of thing is more an intermediate skill. Accurately bending isn't easy, I've never cared for it myself so I leave myself room to tweak the end results and have extra stock ready. 

Perhaps do a little practicing with something easy say a stick of chewing gum and a pencil.  It shouldn't take long to see what happens if you don't pull it around evenly and how to tweak it straight and true if it is out. This is a serious suggestion, the dimensions of steel you wish to use aren't going to stretch or deform in a meaningful way being bent by hand, so the flexible but relatively inelastic stick of gum is a fair model. 

I don't know how much you expect to lift on that sheave but unless it's more than a couple tons 1/4" x 2" mild strap stock is more than enough. This runs into a little issue with the holes for the pin being a weak point. So, if you plan on lifting a ton or more then use heavier stock, say 3/8" x 2". 

I've used 1/2" strap stock for similar uses on 47,000 l. drill rigs and 70,000 lb. road graders. Not to lift them off the ground of course but to tow the grader and as part of the draw works of the drill and as a hitch to tow the service truck behind the drill. A piece of 1/2" x 2" mild steel strap stock is 1 square inch with a tensile strength of roughly 58,000 to 79,800 psi. I had to look that up just now, I haven't thought about it in a long time. 

So, unless you're planning on lifting foolishly heavy loads on a home made sheave, you can use much lighter and easier to work with stock.  1/4" will be fine but 3/8" will help satisfy the beginner's desire to be sure. Everybody and I mean all of us overbuild when we're not sure, it's better to be safe than sorry.

As a last tip, there is no good reason to cut a precise length of stock and try to bend it evenly. Figure a little more than half what it'll need and bend it on the end of the parent stock then cut it free and trim. 

I would NOT make a swivel eye, it's unnecessary if you line the eye and wheel in the same direction. 

Frosty The Lucky.

 

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9 hours ago, Dewnmoutain said:

This way sounds interesting

2020-11-16_21-14-49.thumb.jpg.51a834dfa513a78609044bf7bbe82e52.jpg

Sorry, I've been away. Right angle bends are relatively simple and to dimension is a no brainier. I suggest Francis Whitaker's book "The Blacksmiths Cookbook". He has a great and simple section on how to make them. It's basically a simple upset over the edge of the anvil. His book is a very good yet unsung book 

I believe that a forged right angle bend should be included in beginning blacksmith classes.

Actually this project you are doing, at least the "U" shape, is a first week beginner project. However you are most likely to learn it in a farrier school than a blacksmith class. Check out the first way I mentioned above. Also note how easy it is to even up the sides in my post above should your bend not quite be centered. It's kind of a no brainier to put the long end down on the face of the anvil and tap the other side down with a simple light blow on the center of your "U".

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I like to true up U bends by sticking a piece of the correct thickness plate between the legs and squishing it all together with my screw press; before the screwpress I used a large postvise. before the postvise I used the anvil and a large hammer to lightly tap everything true.

Note that the force on a sheave is concentrated on the axle and so using large diameter axles can make them stronger.

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Altho that works fine, and I still do that, minus the press, one of the real nice things about doing right angle bends to dimension is that all you need is a post vice, a forge, proper sized set of bending forks and scrolling wrench. This works even with a "U". 

The formula is very simple. Add half the thickness of your material to each side of the right angle bend. Then upset both sides til you hit your length. Also, the measurements are made from the Inside of the bend, not the outside.

As you can tell, I'm sold on the above. The beauty is in its simplicity and the absolute control over the problem in very small increments. For Instance, when trueing up a "U", if you place one branch on the anvil then tap the other, you get spring and perhaps both branches move. If you hit the "U" area, then both will close and the curve will change. With my forks, I can tweak from a 64th to whatever and only the part that needs fixing gets fixed. With my coal coal forge I can get a pretty precise localized heat and with the addition of my torch I can be even more localized, when it's too heavy to do cold.

I make these in sets and for specific size stock. As an example for half" the opening is just a bit larger than half. The less slop, the better.

Not meaning a critique, just expanding on the benefits of these two tools, from the simple to the sublime. 

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