Hand Spinning Fenders

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Article By: Paul Wideman

Photos By: Nichole Grodski

The first time I looked into metal spinning, I was in complete awe. I was a young gearhead and had always heard the old timers talk about “spun” fuel cells on the front of their dragsters. Not long after, I saw the Mooneyes’ oil tanks in a catalog. Again, the term “spun.” I had no idea what the hell these guys were talking about, and over and over again I tried to figure out how they were spinning metal into cylindrical shapes. So I did some research on the Internet. Man was I blown away by what I saw. And the sound! There’s nothing cooler than a wheel on a scissor tool wiping across a large diameter circle of steel.

I was immediately hooked and knew I wanted to do this.

A few years later, we began sourcing our fender blanks in the spun form, but not cut, welded or finished. This was okay, but I never had much control over lead time, and I always feel more comfortable slapping my name on something that is born right in my shop. Plus, I knew I could improve on the quality of the material. I love US steel, if you hadn’t noticed, and it welds beautifully. There IS a difference.

So the search was on. Nichole and I tracked eBay and Craigslist for a couple years until we found one large enough up in Minnesota. The price was right, and I thought it would do the trick. Well apparently the guy we bought it from gets his tape measures somewhere else because it did not have the swing it was advertised to have. The simple construction of this type of lathe allowed me to build an 8” riser block for the head and the tailstock, so we bought it. By raising the spindle and tailstock up 8”, I can spin about any size fender out there (as a matter of fact, we are now spinning fenders for a large company that caters to the 30” bagger wheel guys. That’s a big damn fender!). So for the next few months, Nichole tore the machine down and stripped it of its paint and repainted it. Meanwhile, I built the tailstock ram with the Acme thread and the quick release. While I was at it, I replaced all the bearings and made the riser blocks. I also had to raise up the tool rest and I made most of the tools we use. My dad and I made the first few wood mandrels as well. So we kinda make the shit that makes the shit.

Other fender blanks we had used always had a fairly rough surface, as if the material was not planished properly, or the wheel that was being used was too small. There would be countless small ribs running the circumference of the fender. Knowing this, I made a series of different sized wheels, from 1/2” wide and 2” diameter, all the way up to 3” wide and 6” diameter. I will use varying sizes, depending on the project at hand. Being able to choose the right wheel allows me to minimize the ribs and reduce stress and work hardening.

As with most projects you might jump into with minimal (or no) experience, the learning curve can be rough. But the reward is unmatched. While speaking with seasoned spinners, they shake their heads when we tell them we spin 12 gauge by hand. Many don’t believe it. It is very labor intensive, but sometimes me and the other guys jump at the chance to spin. That is unless we’ve been spinning a lot, or the Missouri heat is in the 100 degree range. Both of those happened to be the case on the very day we shot and wrote this article. So, here we go; time to spin.

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This is an example of a mandrel that we use. This one my dad and I built, using hard maple boards. We waterjetted a 1/2” backing plate for the mounting on the back. This helps the wood keep in the same place.

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Here is a mess of blanks that have been waterjetted and await spinning. The fender in the forefront is one that is to be trimmed to its exact size. We start with blanks ranging in size from 27” all the way up to 40” diameter. All of our fenders are 12 gauge.

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This is how the whole get-up goes together. The mandrel attaches to the spindle, then the blank, then the follow block, and then the tailstock assembly. There is a quick release mechanism and a handle to crank the tailstock down tight.

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We are going to spin a 9” fender, so the mandrel we are using is right about 4 1/2” wide, and has the radius to match that of the tire it will cover.

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While the machine is spinning, I rub some wax on the steel and the large wheel on the scissor tool to help keep heat down. The wax comes off very easily and will not harm welding or paint the way petroleum based solvents will.

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To start, I only work the inside 1/3 of the area that needs to be spun. I will take the material all the way down to the mandrel behind it.

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Doing this allows the outer area to hold its shape and rigidity. As you can see, the outer portion is still straight and unaltered.

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After I am satisfied with the shape of the inner 1/3, I sweep the remaining material to the left to approximately 45 degrees.

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And now, using a 1-2-3 technique of stretching, forming, and shaping the material against the mandrel, I lay the rest of the fender down against its form.

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After adjusting my tool post, I load the trim tool onto the scissor tool. This is another tool we made. It is simply an indexable toolholder with a carbide insert. I actually intend to modify this soon for a cleaner cut.

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I mark out 4 1/2” with a framing square.

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You can see the way the tool aligns here.

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A few turns after I apply the trim tool and a deep V groove appears. Keep in mind this is 12 gauge, so it takes a minute to safely get through the material.

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The tools allow me to stand a few feet back for this part…

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which is good, because once I got too close. The glove came out far better than my left hand faired.

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Once through, the excess just pops off the back of the fender.

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I released the tailstock and with a little help from a deadblow hammer, the fender slides right off.

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Sexy; the fender that is.

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I send the fender over to Russ who made some of this contraption that spins the fender while he runs the plasma cutter to trim the inside diameter.

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Sometimes a customer will specify a certain amount of fender wall, and we can of course accommodate any size. For the most part, the fenders get a 2” wall.

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This one is getting the 2” wall.

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Russ uses two squares to very accurately mark the two cutlines that will split the blank.

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We have tried cutting these fenders in half numerous ways, but our bandsaw does the cleanest job possible. And there is no work hardening as if we used the plasma cutter.

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The trim tool leaves a very deep V groove, and Russ only removes the thinnest part and any burrs prior to welding.

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Now that the fender is back in my hands, I begin tacking it together using only fusion welds.

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After I have sufficient tacks, 3-4” welds are placed with even spacing between each.

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After I let it cool for a few minutes, the remaining spaces are welded. It is possible the entire circumference could be welded without any risk of damage or warping, but I have had great luck with this method, and it doesn’t take all that much longer.

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At the belt grinder I remove only the top side of the weld.

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Back in Russ’s hands, the corners are trimmed and radiused, and all the slag from the plasma cutter is removed.

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A quick trip through the E Wheel removes any irregularities and helps insure a perfect radius.

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There ya go; another finished fender. This particular one is going to a rather well known builder in Florida that said there was no way we were hand spinning 12 gauge fenders. Video soon.