It Bends Where?

When I was bending these spikes I thought I was witnessing a violation of an axiom I learned as a beginner - steel bends where it is thinnest or hottest. In this case neither was true. The axiom needs an amendment. Steel also bends where the bending force is isolated.

This story is a progression of the “picture or 1000 words” post. To complete the spikes I needed to bend the kink point to a right angle. I could have used localized torch heat to do this and if I only had a couple to finish that’s how I’d do it. In this case there was a pile, I had a bending jig and I had other forge work to do so using the coal fire was quickest. The way I was working it wasn’t possible to get a heat localized at the desired bend point like a torch heat. However, the jig effectively did that isolation of the bend point.

I used the power hammer to draw out the spikes in a single heat and did the 90º bend in the second heat then ran them through the tumbler. Now they are ready for welding into a tripod base, This is a component of what I would call a functional piece and isn’t particularly artful, but, the subtle stretch-buldge of the 90º bend is a tiny detail which appeals to me.

http://www.persimmonforge.com/

A Picture or 1000 Words

Last week I downloaded a few images from my old shop camera then it expired. New batteries couldn’t shock it back to life. So after many years of service in a harsh environment I let it go to R.I.P. in the realm where expired electronic devices go.

I understood immediately that this was not a crisis since it seems like almost everything with a battery is now capable of taking a picture. My older son, Keith, tells me my iPhone has a better camera than my camera. That sounds circular but you get he idea,

My actual solution was to take my wife’s old camera which she never uses as she prefers the one on the iPhone and I traded her a newer camera which I have used to take “professional” images in my mini photo studio. Incidentally, that camera was obtained at Stapes in response to my request for their “least expensive Canon camera.” I will never take the time to figure out anything more complicated a don’t use most of the features built into the inexpensive one.

Today, I took several images of the steps used in preparing some spikes for tapering. It was a pleasure to look in the viewfinder and actually see a large clear image of the target, It was also neat to hear the click sound which indicated the image had been captured. It gave me a comfort sensation similar to the old days when I picked up the phone receiver and an operator asked. “number please.”

I don’t know if a picture is really worth a thousand words or how anyone would know. I do know that the images I take are a great help in documenting my work processes. They save time and provide more information than my written notes.

http://www.persimmonforge.com/

Making Small Rings

Last week I needed six rings for a chandelier project. I made them by tacking a 5/16” round rod to a 1.25” round mandrel then wrapped a coil with torch heat until I had 8 or 9 rings. I generally make a few extra in case I misplace one or one doesn’t look just right. The extras are handy to weld on things as hangers.

I removed the rings from the mandrel by slicing the coil with a zip disc and opening each ring with a tweaker until it slipped off.

Sometimes it is important that a ring not be able to rotate so an ellipse is preferable. I have made several mandrels with crank shafts like a windlass to make chain links of different sizes. The principle is the same as the round rings, torch heat, wrap, sever and release.

http://www.persimmonforge.com/

That’s a Swell Hole

For the past couple of weeks, besides trying to get the lawn to recover after the terrible hot and dry summer, I’ve been finishing a chandelier. I’ve never made one of this style before and have found it to be interesting and challenging. At this point the frame and pendant elements have been constructed and I’m just working on finishing details.

This detail, if not trivial, is at least a very small one. In my opinion I still think it is worth considering and in other cases can create a much more striking visual detail.

In this design the power cord traverses most of the distance between the ceiling canopy and the candelabra pendant inside a tube with rings at each end instead of winding through the more common vernacular chain. After making the rings from 5/16” round and flattening 1” of the tube ends with the hydraulic press, I sunk a center punch mark and then drilled a pilot hole. Working over a narrow vise opening I heated the hole perimeter with the torch and used a handled opening punch to enlarge the hole so that the 5/16” ring could pass through and swing easily. That process necessarily creates the slight bulges along the edges of the flattened area.

It may take a blacksmith to notice a change this subtle but an accumulation of such little details in the design can eventually add up to interesting.

http://www.persimmonforge.com/

Hot Punching

I like to design projects which use hot punching as a technique. There is a little bit of a learning curve to climb before it gets easy but when mastered it is fun to do and the swell around the hole looks nice.

In the earliest days of my metal working experience I visited a smith who owned a historic shop and he offered some advice based on his 30 years of working. I still remember some of those things and one was to keep my punches sharp. I really didn’t understand the significance of that at the time but I became a believer through practice.

Usually I try to set up punching work when I have an assistant to either strike or to hold. Most of the holes I punch are 5/16” or 3/8” round by design. With holes smaller than 5/16” there is more risk of the small diameter punch drawing so much heat it reaches forging temperature and deforms. With holes larger than 3/8” a lot more force is required to create the hole.

If hole position must be very precise I will make a light mark and check the position and make adjustments and eventually set a shallow depression which can be seen of felt at punching heat.

A six pound sledge is my tool of choice for striking. I try to avoid placing the hot workpiece on the anvil until the punch is ready to place so the anvil doesn’t suck heat away prematurely. When the punch is in proper position, vertical and still it is time for a firm blow with the sledge. The punch is rotated about 90º while the hammer is lifted. The the punch is held steady and struck again once of twice until it is felt to “bottom out” against the anvil. Then the punch is cooled in the quench tub.

If the work piece is turned over the darker, cooler, circle is visible if the punch sunk deep enough to form a very thin area which will be the slug. This is where it gets interesting to me. If the punch face is flat and the edge sharp and the workpiece is cool enough when the punch is centered on the dark circle and struck the slug will fall out. In other words, if every thing is just right, it works perfectly.

If the punch is not sharp it acts like a fuller and moves metal back and forth without creating a stress riser perimeter which will break in shear. If the workpiece is too hot the slug mass perimeter will stretch and not shear. With enough practice this gets easy but, for me, never uninteresting. I just notice smaller and smaller details.

It seems like a trivial thing to rotate the round punch but it is an important detail if the hole is to turn out close to perfectly round. It’s sort of hard to dress a round punch so that it is perfectly round. Usually it is a little bit oval. If that is the case the hole will still be round if the punch is rotated while the workpiece is at a forging heat. If the punch is too oval it will be too difficult to twist so there is a limit to the our-of-round which is tolerable.

The body of the punch has a slight taper so the finished hole may have a very slight hour glass shape and each hole may not be quite the same diameter. Finishing holes with carefully made drifts corrects those imperfections.

I own a couple of square handled punches but have rarely used them to punch holes. I don't use many carriage bolts or make many square passthroughs. If I need a square hole I usually make a round one and use the square punch as a drift. Or can it really be called a drift if the tool doesn’t pass all the way through? Maybe it's a mandrel. It could be an opening punch but that sounds like a segue to boxing.

http://www.persimmonforge.com/

Pretty Side Down?

It occurred to me that over time there has been a change in my thinking about forming. This is something akin to the gestalt of seeing positive space or negative space.

It seems I used to think mostly about the forming process as how the work piece would have to move rather than how the radius of the tools would move the work. Today I spend more time thinking about how I want the surface too look - emphasizing the process marks or eliminating them.

The anvil is usually smoother and flatter than the hammer face. And too move metal quickly a short radius hammer such as a ball peen or rounding hammer is used. As the final form is approached a long radius forging hammer is useful if the chunky surface is to be worked to a smooth surface. Finishing the presentation face with a nearly flat planishing hammer can leave a very smooth surface.

I was taught that because the anvil face was the flattest and smoothest the surface toward the anvil was the “pretty face”. Today I often prefer more visible texture so the interesting side is up and the plain side is on the anvil face. Pretty side up.

The surface facets can be accentuated by hand sanding with 60 or finer grit sand paper or light filing and I do some of that but not much. Like with other surface accents of brass brushing or Guilder’s paste, I think a little goes a long way. I have spent a lot of time studying how I can use fire scaling followed by light tumbling to create the surface appearance I like best. I don't commonly use a wire brush to remove hot scale unless forge welding.

In the final analysis what shows in the work should be intentional so carefully picking the tools and making sure they are well dressed so they don’t leave unintentional marks is good craftsmanship.

Check out Care and Maintenance of a new or old anvil at:

http://www.blksmth.com/care_and_maintenance_of_anvils.htm

http://www.persimmonforge.com/

Pedal Hammer Seat Improvement

Over the summer I started using the pedal hammer in an auxiliary manner and now think I should report it. The one I’m referring to sits right beside my design table. Sometimes I just felt like sitting down for a few minutes while making notes or sketching some drawings so I made a simple angled drawing surface from a piece of angle and 10 gauge sheet that fits where the anvil ordinarily would. It rotates and is very comfortable to use. It is just flat enough to also use as a platform for photographing small items with my digital camera. It should go without saying that, like every other nearly flat surface, it attracts items which gather into piles.

The time sitting there apparently led to some other contemplation and I became aware of the kludge beneath my feet. The seat mounting could be improved a lot. First, the placement of the horizontals and verticals could be shifted to leave the space where a leg swings through more open.

Next, the seat bracket could be fitted with one or two cam locks to replace the locking bolts which would allow for quick changes in seat height or distance.

Also the vertical could be changed from square tube to round to allow rotation. Now that I’ve thought of how nice those changes might be all I have to do is find the time and energy to actually make the changes.

http://www.persimmonforge.com/

Too Short? Not a Problem

From time to time I have an experience which reminds me of my woodworking days and why I like ironwork better.

Last week I was assembling pieces of textured flat bar for a chandelier frame and found one of the vertical pieces to be short by a strong 1/16”. If this was a wood frame I would cut another piece and that would be a hassle to set up because both ends are cut on a 14º angle. However, in this case it was just a matter of running the piece back over the texturing die in the power hammer without heat. Two passes did the trick and the bar was then full length.

The ability to adjust length by subtle drawing is nice property of iron working. Shortening by upsetting is possible occasionally but usually trimming is easier. It takes a while to really understand forging dynamics but eventually it is intuitive.

Mentioning the chandelier brings up another issue. I don’t do wiring. I’d do it for myself but when dealing with clients I make all the components and let them arrange for their electrician to finish the work. They are the professional experts in that field.

http://www.persimmonforge.com/

Get Convenience First

I’ve had some interest in time and motion study since I read the book, Cheaper by the Dozen, sometime in the 1950’s. So, when I am planing a forging session I attempt to plan it heat by heat.

When working with small blanks or short material I want to form them into shapes I can easily pick up as early in the process as possible. Sure as can be, some pieces will find their way to the floor and as long as they are short and flat they will be difficult to pick up. At the very least this wastes time and motion and the distraction may risk losing something else to overheating in the fire.

In the image, Repoussé Sunflower center volume.JPG, I show how it may be possible to establish useful initial volume with the fly press. In the image, Sinking heart volume.JPG, the rounding hammer and swage block are used to establish some volume. Granted, if these pieces land on the floor concave side down, they may still be difficult to pick up (think magnetic pickup), but I’ve improved my chances of easy grasp to at least 50/50. I can skew the favorable odds more by working that initial volume more toward a potato chip shape, dome and bowl, rather than just the bowl or dome shape. I’ll just admit I don’t know the proper topological names for those shapes.

In the image, Various Handle Lengths.jpg, I offer the example of how I first drew out some of the 3/8” round handle length from the 3/8” x 3/4” flat bar blank so I had more to grasp and could do without tongs for the remainder of the forging of the cane bolt slide.

Those two techniques are rather obvious. Using the convenience bend is less obvious but becomes intuitive with some experience. As forging processes become more sophisticated and complicated the issue of obstruction comes up more and more. Planning convenience bends is usually the solution.

Sometimes the bend is just a fold-forge-fold back type. Sometimes it is a bend and twist-forge-bend and twist back type. Sometimes it is difficult to use the bend without leaving a trace of the process in the finished work. Planning a bend of long radius in which the stretching/compression deformation is subtle is often helpful.

Formulating general strategies, such as these, for my work has been helpful.

http://en.wikipedia.org/wiki/Time_and_motion_study

Back from a week vacation to southern California to see kids and granddaughter, it was disappointing to find the 106º heat still entrenched. The long anticipated break my come next week. In any event, it looks like head down work ahead for several months. It’s nice to begin feeling rested and full of new ideas.

http://www.persimmonforge.com/