This jig allows me to make rings out of round or square bar, or even flat bar if needed.
It uses the classic pyramid rolling bender setup but allows for thicker stock bending than the harbour freight basic machine. Idea for this concept, that features a quick release mechanism, comes from https://www.youtube.com/watch?v=XTIzU_ITvhg so all credit to him.
Improvements on the original concept above include a guiding base for the bar to prevent it from twisting when rolling as well as adjustable guiding blocks to prevent the bar from sliding up the rollers. It also features a more compact base and a wheel to roll much easier than a simple (yet effective) 90 degree pipe.
The key points of this build are
- A sturdy base, or VERY sturdy depending on the material thickness to bend. Mine is made of Jarrah wood reinforced with angled steel. Go for steel if required.
- 2 solid and strong rollers. Mine come from (I suspect) some automotive parts. Original concept is designed using casters so that's another way to go. Some people make their own, but I don't have the tools and skill to make rollers that would be straight and balanced enough.
- Thick pipe of 2 diameters that can be slid into each other. In my case, the bigger diameter pipe I used was too thin and so I had to reinforce it by welding an extra layer. 4mm thickness or more is best.
You will also need some threaded bar and matching nuts, and a jack for ease of use, then some other parts for the rotating pipe and the base.
The stuff I build requires me to make ring of round and square bar of 10 or 12mm. Before making this roller, I used a different jig that was way too ineffective. Now, I can easily make all diameters of rings, as small as 12cm.
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Step 1: Plan Your Work
Get your parts
- Base material (wood/metal)
- Threaded bar + nuts
- wheel (for ease of use, can be substituted with a single bar)
Make a plan, draw, measure what needs be, have a clear picture of what you are about to build
The wheel is a really nice addition to the this jig. You can build one, or salvage one (like I did) from an old chair.
Step 2: Build the Parts
Start with the base, weld the bushings to the threaded bars, add the rollers, prepare the wheel and back plate.
The threaded bars need to move freely in their guiding holes. I opted to have the rollers in a fixed position.
At that stage, I was using a simple threaded bar with handle to apply pressure at the back. I replaced this with a jack later on, as was the plan all long.
Step 3: Complete the Assembly and Test
Try with some stock and notice what parts need to be adjusted.
At that stage, I had managed to make a decent ring already but the pressure system was inadequate and the bar needed extra guiding when rolling.
Step 4: Improve on the Build
Major improvements that I applied then included the jack and guides above the rollers.
Later on I reinforced the base with steel to prevent the rollers from bending to the side (not pictured yet).
I also had to reinforce the bushings and the jack support at the base.
Rolling 12mm square bar is really tough for a wood assembly so if I were to do it again, I would most certainly design the base in metal. That being said, with the improvements and reinforced parts, it does an excellent job.
Step 5: Final Words
This rolling bender does a great job once adjusted properly and with a bit of practice. It must be clamped on a sturdy bench for best results.
Pressure should be applied gradually, starting small. The jack must used carefully, as it applies more pressure for the same amount of turns as it expands (mostly due to its design to, well, lift a car). Using it quarters of turns or less has proven to be good practice.
The bar will have the flat ends as expected for pyramid roller. This can be mitigated by pre-bending the ends. I prefer over-rolling so that the flat ends are crossed, then I cut off both ends and weld on the rounded ends.
There will be some twisting involved and the ring is not (or rarely) a perfect circle. Providing more guiding and support for the bar as it is rolled helps a great deal, and a hammer fixes a lot of issues. I also tend to re-roll a welded ring to help perfect the curvature where needed.