Using Fusion 360 to Make Custom Parametric 3D Printed Dies for Harbor Freight Tubing Roller to Bend Metal Tubes for a TallBike

In this instructable I will show you how I made custom sized dies for my Harbor Freight Tubing Roller. I make a die setup for bending 1/2 and 3/4 inch steel tubing with a .060 inch wall thickness but this process is adaptable and could be used on a variety of different tubing sizes and cross sections. I made a youtube video that shows the process, you can watch that while following along in this instructable. These dies end up being used to bend some tubing for a collapsible tall bike.

Most of the time I use the tubing roller mounted to the hitch on my truck or the hitch welded into my workbench. To learn more about hitch mounted tooling check out the instructable I made Here. It is one of the best upgrades I've made to my small shop.

If you have access to a large lathe you could make dies out of metal easily. The process is a way to circumvent that for cheap for small jobs and prototyping. A metal set of dies will cost around 200 dollars and last pretty much indefinitely but you will only be able to bend that one size of tubing. I spent less than that on all of my dies and can make many more this way till I get anywhere near spending 200 dollars. While these will not last as long as metal ones I think a lot of makers could make use of this process.

Supplies

A Computer with CAD software, I used fusion 360
3D Printer with PLA or PLA+ filament
An automated way to cut steel/aluminum and the stock to cut
Assorted M6 or 1/4-20 Hardware
Harbor Freight Tubing Roller or similar style roller. The basic of these dies will apply to a lot of machines.
Tubing to bend that isn't supported by the existing tooling (1, 1.5, 2 inch)
A way to debur some metal: File, sander, ect.
A way to weld the driver roller plate tubing together, I used tig.
Drill and tap for the driver roller plate or nuts to weld on for the set screws to engage.

Step 1: Design Your Dies

I used fusion 360 to design my dies and chose to make them parametric so I can update them in the future. I am still fairly new to parametric drawing but thinking about the part like a math problem helped me to grasp it better. Our main variable is the tubing diameter we will be bending. If our tubing diameter is X then having a drawing designed around variable X input will give us dies for multiple sizes of tubing with very little work. The drawing is like a math equation that changes based on our X input.

A flat sketch is first drawn. The dies the roller came with are 4 inches in diameter so a box is drawn to show that as our boundary. Inside this box a profile to be revolved is drawn.
The Arc highlighted in the notes of the 2nd image will be our main variable X input.
This will be defined in our parameters in the 5th image as .75 and creates a tubing die for 3/4 inch tubing.
It is helpful to set your parameters first, then when you go to draw the sketch and dimension it you can type in the name of the parameter instead of the numbers into the dimension box.
The vertical redline in the 3rd image is controlled by the Center Pin Diameter parameter (The correct title in that image for that parameter should be radius not diameter).
By changing this input we change the size of the center hole by moving this line left or right.
This is useful since it allows me to use the same sketch for making dies for my Harbor Freight Roller and my Diacro No.2 Bender.
The horizontal redlines in image 3 are connected to the center pin line and move with it. On the other side they are offset .025 inches above/below the arc then are connected with another sketch line to complete the face. This gives just a tiny bit of clearance in the dies so the tubing doesn't bind. Im not sure what the best measurement to put here is but this worked fine.
The highlighted faces in the 3rd image will be revolved and create the grey solid in image 4. This solid will be the 3D printable core.
In image 6 I change the parameter to .5 and you can see in the 7-8th image a smaller die for bending 1/2 inch tubing is made.
The last image shows the bolt pattern sketch which will be push/pull command though to create the bolt holes. These are also based off parameters shown in images 5/6.
A circle who's size is controlled by the Through Hole parameter is sketched on the face on the die.
The Drive Bolt Pattern parameter determines how far the bolt pattern is from the center. It is set to a 1 inch radius making our bolt pattern two inches. This variable moves a circle sketched onto the plane in relation to the center of the circle.
This sketched circle can now be moved and resized all by changing the numbers in the parameters.
I selected this circle then used the circular pattern sketch tool and set it to 4 holes revolving around the center of the die.

By treating this part like a math problem with re-definable values you are easily able to get different dies by changing one number instead of totally redrawing the part. This takes a bit of work up front but once you have the "equation" down it is far easier to modify this than drawing a new one. I am having a hard time uploading the correct file here but if you shoot me message I can try and get it to you.

Step 2: Making the Plates

There are several ways to go about this step but I highly recommend avoiding plasma cutting. The plates are essentially giant washers, I cut mine out of 1/4 inch steel but I reckon you could do aluminum if you had a aluminum router table.

Cut the plates out one way or another. I had mine plasma cut out and ended up having to re-drill and machine lots of holes on them. Alternatively you could have them laster cut or water jet out, while costing a bit more it will be the least labor intensive.
Debur and file/sand away sharp edges. While this is a tool and it doesn't have to be perfect you will be handling them a lot as you build different die setups. I used a file, debur drill bit, debur hand tool, and air grinder with a scotchbrite pad.
Bearing Roller Plates:
These have a large center hole to fit the bearings.
You will need 4 of these to make a set of dies.
The bolt pattern I settled on is 2.5 inches x 4 holes hat are .25 inches wide. This is slightly larger than the driven roller plates to allow for the bolt head/nuts to clear the bearings.
Driver Roller Plates (The last two images in this step)
These have a smaller center hole and an additional tube welded to them
This tube needs to have holes drilled and tapped or nuts welded on for the set screws to engage with the crankshaft.
You will need 2 of these to make a set of dies.
The bolt pattern I settled on is 2 inches X 4 holes that are .25 inches wide. This is slightly smaller than the bearing roller plates to allow for the bolts to engage a little more in the 3D print.

Step 3: Print Your Dies

I am using an Ender3 Pro to print my dies but your printing setup/process will vary. The important bit is how I printed my dies.

They are printed solid with 100 percent infill.
They are printed in PLA and PLA+. While I've only tested these filaments I'm sure there are others that can do a better job but I was impressed with the results such basic filament gave me.
I had best results when I printed on a raft with no support structure. your mileage may very.
You will need to print 3 inner die cores for every set of dies you want to make since there are three rollers.

Step 4: Assemble Your Dies

I keep my dies and parts to assemble them in a tool box drawer, it takes a little bit to configure a setup so its easiest to have it all in one spot. The collection of washers and bolts is to help with the assembling/spacing that each setup might need.

The second image shows the view of a roller die unassembled. The metal plates form a sandwich that squeezes with the 3d print on the inside. Put the bolts through 4 of the holes and tighten them down, then insert the bearing into the outside holes.
Image 3 shows an assembled roller die with bearings installed. Two of these are needed to roll tubing.
Image 4 shows the assembled driver die. It is assembled the same as the roller dies but has no bearing and the outer plates have a spot for set screws. The shaft next to the die assembly has flat spots where the screws lock into.
Image 5 shows the 1/2 driver die installed in the tubing roller.
Image 6 shows the 1/2 roller die installed in the tubing roller. You can see there are several washers on either side of the assembly, this is to align the dies. The amount for each setup is different and I like to write down how many washers each setup uses. Some sides may be asymmetrical and that is okay as long as you match the spacing on the other dies.

Step 5: Roll Your Tube

Once your dies are set up you are ready to bend.

Set your dies so that the tubing feeds in and makes light contact with all the dies.
Crank the feed screw a little bit. This takes some getting used to but I was doing about half a turn on the feed screw then advancing to the next step
Spin the wheel to move the tubing back and forth.
Repeat step 2 and 3 until the desired bend radius is reached. It can take quite some time.
While I was able to bend two pieces of tubing at once I don't recommend it. While a good idea in theory it takes a lot more effort to crank. A similar result can be had by rolling one tube then marking the depth the feed screw was at when the right radius was achieved. Then bend another piece of tubing till the feed screw is at that mark again.

There is a lot of information out there on how to roll parts with these tubing rollers. I like to base my measurements when bending off of a centerline radius, more about that can be learned in The Art of Bending by Diacro, while that is for a bender not a roller a lot of it applies. Several other youtube videos are out there on how to use it and modify this roller by adding wings and using hydraulic jacks instead of feed screws.

Step 6: Make Something Awesome With Your Dies!

I made these dies so I could bend some thinner tubing on this collapsible tall bike I made. The rear seat stays and extra rear triangle were all bent using the dies designed in the above process. While this project was fun I look forward to making dies for tubing with a funky cross section or odd shape. If you do make some of your own dies please comment below with some pics with the I made it button!