This is a simple steel brace frame for holding vertically oriented material sheets while working them with an industrial robot. The sizes of the members can be adjusted for your school or organization's robot room needs, and made stronger or lighter to fit. The connections are both welded and bolted and require basic mig welding and steel shop skills.
3 Main Stages of the Build:
- I. Modeling: Measuring for your space
- II. Fabrication: Steel shop time to cut and weld!
- III. Installation: Align and anchor into the floor
- 40mm x 80mm mild steel, ~3mm wall. (20m linear)
- M12x100mm bolts, lock washers, and nuts (x14)
- 12mm threaded rod for anchors (10cm lengths x 4)
Fabrication Tools (steel shop):
- mig welder
- drill press
- 13mm steel drill bit
Installation Tools (by your robot):
- hammer drill with 12mm bit
- anchor cement
Step 1: Model or Draw a Plan of the Frame Based on Your Robots Needs
The dimensions of the overall brace will be highly dependent on what you are using your robot for and what its needs are. This one is designed for holding sheet steel and aluminum for cold forming using a single-point incremental forming process (SPIF) and will also work for some light milling of wood and foam.
I've included the shop drawings for the legs and an overall perspective diagram of the full item.
There are 3 main parts:
1. The legs (magenta) - The two legs are fully welded, symmetric metal legs that will hold the material in the air, and take the lateral load and vibration of the tooling.
2. The frame (dark green) - The frame is a welded frame, but has an array of holes bolting it to the legs. This way it can move up and down the legs to accommodate the reach of the robot. The bolts are large carriage bolts with lock washers to prevent them from vibrating loose.
3. The removable struts (lime green) - These ribs are two arms that can be removed for a full sheet or added to mount a smaller sheet to. Also box steel with capped ends to be bolted it.
Step 2: Cut Steel Stock to Length and Weld Outer Legs
Here are the shop drawings for the legs. All of the pieces use 40mm x 80mm mild steel with about a 3mm thick wall.
The legs consist of long upright arms, an angled lateral brace, and discontinuous feet. The feet are long enough to get two anchor bolts each, but short enough to move the armature laterally without colliding with the electrical tails from the robots. The power and data cable for the robots run from their podiums all over the room and the brace has to straddle them.
These outer legs get fully welded at the joints, but not capped. For time and consistency our school sent these out to a professional steel shop and they were done within a few days for a few hundred dollars.
Step 3: Weld and Drill Inner Frame
The inner frame was a simpler task and I cut and welded it in one day in the school's steel shop.
Prior to clamping and welding, the vertical sides get the same array of bolt holes as the legs, to be able to mount to a few different positions. For the 12mm bolts I used a 13mm drill bit for a little play. I have 7 thru-holes spaced on center at 36cm. After drilling, soften up the holes with a counter sink.
The outer rectangle is seam welded but not capped.
Step 4: Cut and Weld Removable Frame Brace Arms
The two removable struts are simply two lengths of the same 40mm x 80mm box tubing.
At both ends of each strut, I cut out a rectangle from the 80mm side and weld it on the end with a 13mm hole through the center. This allows you to thread the bolt from the inside with your hand, and keep the strut as one full piece.
The first image shows the cut out, the following images show the piece welding into place and how it's used.
Step 5: Attach Removable Frame to Legs With Bolts and Lock Washers
We bolted the inner from to the legs with partial threaded M12 x 100mm bolts (at least 4 on each side). Each bolt has a lock washer and a plain washer. It probably won't move until the next big project, so we tightened them down pretty well with the lock washers.
Tighten in the removable struts with two of the same bolt sets. Since there is no welded connection, I would use as many bolts as possible to prevent vibrations from loosening the panel.
Step 6: Drill Anchor Bolts Into Concrete Floor
With the two legs welded up and the inner frame together, you're ready to bolt it to the floor. Think carefully about the reach of your robot(s) and if it should double function for any different types of tools/end-effectors and if they'll be doing any collaborative work.
I used two bolt holes in each foot, but only one anchor bolt each. This means the full frame can glide between two different spots (40 cm apart) to adjust to the project and reach of the robot. It is also possible to rotate the whole thing as well to be closer or further from each robot respectively.
The anchors are 10cm deep 12mm threaded rod with anchoring cement. Cut off any excess threaded rod to prevent trippinig (photo is pre-trimmed)
Step 7: Mount Working Material to the Frame. All Robots Go!
Once the frame is bolted together and anchored to the ground, you're ready to clamp some material up, and calibrate your robot! Grab some bar clamps and you're ready to go.
We designed this rig for a process called single point incremental forming (SPIF - seen in the photo) but have plans to use it for milling as well. Enjoy!