Introduction: Electric Ring Spanner

For a elective at school I had to make a product which is at least made of 3 different materials and use 3 different machines to make this product. The 3D printer and the laser cutter must be used.

So I thought that a mechanic will always have that one bold which can’t be reach good enough.

but why isn’t there an electric ring spanner? With this device you can fasten a bolt that is just reachable enough to get a ring spanner on it, but can’t be moved. Because the ring of the electric ring spanner is rotatable, the bolt can still be fasten.

For this instructable you will need a 3D printer, laser cutter, lathe, drill and a soldering iron.

MoSCoW list:

  • Must-have: An bevel gear, without this it would be hard to tighten a bolt.
  • Should-have: A electric motor so it is easy to operate.
  • Could-have: It would be handy if it is still usable without the motor.
  • Would-have: The possibility to tighten other bolts then M6 ( which has a hexagon of 10 mm)

The materials you need are:

  • 45 mm round bar POM (plastic) with a length of 250 mm
  • 40 mm round bar brass, with a length of 10 mm
  • 6 mm round bar of steel, the length depends on the distance you want between the bevel gear and the handle. I used a length of 180 mm
  • 13x1mm aluminum pipe, the length also depends on de distance between the bevel gear and the handle. I used a length of 160 mm.
  • motor with planetary gear (10 Volts or more)
  • 18 cm wire of 1 mm2
  • round button
  • round connector that fits with you power supply unit
  • power supply unit with the right voltage and amperage, in my case 10 volts and 1500 Mah

Step 1:

Step 2: Making the Drawings

This first step is one of the most important steps. Without the correct drawings is this project almost impossible. Before you start making the drawings you will need to find a good electric motor. I used the old motor including planetary gearbox from a cordless drill (10 Volt or more).

First the drawing for the handle.

  • At first you draw the dimensions of the motor and planetary gearbox. Be sure that you keep the same space between the motor and the gearbox. In this case, 5 mm.
  • The ring gear (of the planetary gear) needed to be fixed inside the handle. The ring gear that I had has some teeth on top of the ring. This is normally used to set the torque. I use it to fix it in the handle. I made a blocking ring with small holes that fits perfectly on top of the ring gear. This ring is with 4 bolts fixed to the handle and about 10 mm thick. (as you can see in the pictures)
  • On top of that ring comes another plastic ring, for the pipe that comes around the shaft (from the motor to the gear with hexagon) this is 10 mm thick. This ring stays in place by a circlip. This ring is also made of plastic and there needs to be a small cut in the handle. (as you can see on de drawing)
  • Now you now the length on the planetary gear side. All this rings have the same diameter as the planetary gear. This is one side of the handle.
  • The other side (where the motor comes) also comes a button and a connector that fits your power supply unit. These components need space, make sure you have enough space for this and the cables between them. I used 35 mm, I advise to do more space. After this space comes another plastic circlip. A small cap will be bolted to this ring with M3 bolts. In de cap comes a hole for the connector.

The drawing I made for the bevel gear will be probably remain the same for you. It was hard to make the right bevel gear because this needed to be 3D printed, which has some difficulties. In the first version where the teeth to small and did not work as a bevel gear at all. The next version worked gear great, but it was made of more different parts and not strong enough for tightening a bolt. The last version was a bit bigger, completely solid and was one part. This is strong and works well.

The drawings I made are made for a 10mm hexagon (bolt M6). You can just scale the model if you want another size hexagon. Check that the walls are thick enough so it won't break.

Step 3: Turning and Machining the Parts

There are a lot of different parts to make. The most parts need to be made on a lathe.

The handle

First you start with the handle. It is smart to start with the motor side, this easy to start with. If you have a steady rest, use it! This tool makes turning the long handle easy. The small cut for the c clip can also be turned.

The other side, for the planetary gearbox, can now be turned and again the small cut for the c clip can also be turned.

The motor is bolted to the handle with two M3 bolts. Two holes are needed in the wall inside the handle. When the handle is still in the lathe you can use the tool to mark the place for the holes. Drill and countersink these holes (the diameter depends on the motor, the motor I used needed M3 bolts, so the holes where 3mm).

Most motors need air for cooling, make sure that there are holes for cooling the engine.

In the handle comes an on/off button. A hole for this button comes just after the motor. Make sure that the button has enough space.

This part is made of POM (plastic), Polyoxymethylene.

Cap on the motor side

The cap on the motor side and where the connector comes can now be turned. 3 holes of 3 mm need to be drilled in this cap. Those holes should be on the exactly same place as the M3 holes in the cir clip. This circlip is actually a ring with a small cut. This ring has the diameter of the motor plus 2 mm. This ring has two holes, just like a normal circlip and 3 other M3 holes so the cap can be bolted to it. This part is made of POM (plastic), Polyoxymethylene.

Blocking ring

Now a very hard part to make, the ring that blocks the ring gear from rotating. This ring is 10 mm thick and has the same diameter as your ring gear. The diameter of the hole is just as big as the original shaft that comes out of de planetary gearbox. Mostly has the ring gear 8 teeth on the top. These teeth need to fall in to 8 holes if the ring you made. In my case where the holes 6 mm in diameter. Make sure that these parts fit in to each other. This part is made of brass.

Connecting ring (handle with pipe)

The last part for the handle is the ring that connect the pipe around the shaft to the handle. The drawing for this part is in the 3D file. The tube is threaded with M12. The circlip has the diameter of the planetary gearbox plus 2 mm. Just as the circlip on the motor side. This part is made of POM (plastic), Polyoxymethylene.

The pipe

The two ends of the pipe around the shaft needed thread M12, on the inside. The length of this pipe depends on the distance between the handle and de bevel gear. In my case, 160 mm. This part is made of aluminum

The shaft

The shaft is made of a 6 mm round bar of steel. The length depends on the distance between the handle and de bevel gear. In my case, 180 mm. One end of the shaft is Threaded M6. The other end has the shape of a square of 4 mm.

The bevel gear housing

The housing of the bevel gear is easy to make. If you keep the gear the same size as in the drawing, you can use the drawings in the 3D file. The cap of the housing is bolted to the housing with M3 bolts. I drilled the holes in the cap and housing with 2.5 mm at the same time so it will fit perfectly. The holes in the cap need to be drilled with a 3 mm drill after that. The holes in the housing are threaded with M3. The 3D printed gear should fit perfectly and rotates easily in the housing. Perpendicular on the housing comes a hole for the pipe and shaft. This hole is 15 mm from the closed side of the housing. The hole is threaded with M14. This part is made of POM (plastic), Polyoxymethylene. The cap can also be lasercut, it should be made of wood in that case.

Adapter socket

An adapter socket is needed to connect the pipe with the bevel gear housing. One side is over 5 mm threaded M14 and the other side is over 20 mm threaded M12. Between this parts is a thicker bit. This part is made of POM (plastic), Polyoxymethylene.

Step 4: 3D Print the Bevel Gear

The only thing that's need to be printed is the bevel gear. The STL file is added to this step. Check if the scale is right and if the printer prints it fully solid. If you have a better gear, feel free to use it! But keep in mind that it must be printable. The teeth and walls should not be to small (smaller than 3 mm).

Step 5: Soldering the Components

In this step is the motor, the button and the connector being soldered. Between the components is a flexible cable (1 mm2).

At first you solder two wires of 6 cm to the motor. Now you place the motor in the handle. One wire goes through the nut of the button and hole and solder the end of this wire to the button.

Solder another wire of 6 cm to the button. This wire goes through the hole and nut of the button. The wire and the other wire of the motor goes through the nut of the connector and the hole of the cap. This wires can be soldered to the connector. Put tape around every soldered part. Now you can check if the motor and the circuit works!

Step 6: Assembling All the Parts

The last step is assembling all the parts.

At first you fasten the motor to the handle with two bolts (picture 1). After this you can put the circlip on the motor side in. I used a special pliers for it. The cap can now be bolted to the circlip. Test the motor to make sure it all still works.

The planetary gearbox needs to be cleaned, degreased and put together. Use new grease on the gears and put the blocking ring on it. Now you can put it in the handle and fasten the blocking ring to the handle.

Next is the bevel gear. The bevel gear can be placed in the housing. The shaft and gear can be connected and put in the housing. The adapter socket can also be tightened to the housing. If the gears work and fit you can close the housing with the cap and tighten this.

The pipe can be connected to the housing and the connecting ring.

This piece can be put in to the handle and the shaft can be connected to the planetary gearbox. The last part, the circlip can be put in place and the assembling is done!