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Atlantic Motor build The Gears and Shafts

The Gears are made from brass they are 8.3mm in diameter and 6mm long.


The lathe I am using to cut the gears on is an old Drummond Round bed made around 1908. The main reason for using this machine is that a gear wheel can be fitted directly onto the end of the main shaft as can be seen further down.

The first thing is to turn a bar down to 8.3mm. Then the compound slide is set to 40 degrees and a point turned on the end.

The compound slide is then set to 50 degrees and a pointed tool on its side is drawn across a number of times each time taking a little more until the V is formed.

The position of the 16 cuts is set by locking a gear wheel in position on the back of the main lathe shaft.

Because there are no calibrations on this machine a Chalk mark is used to bring the horizontal travel back to the same place for each cut.

Once all the teeth have been cut the point is machined off and a 3mm hole drilled in the centre the diameter behind the gear is reduced and then it is parted off.


The next job is the shafts to get the dimensions of them right needs a working drawing.

The first shaft is the horizontal shaft it is made from 4mm stainless steel bar and turned down to 3.2 and knurled under the arrow and the rest is 3mm to go into the bearings or take a thread for the prop.

The brass bar on the right has a 3 mm hole in it and is held in the tail stock chuck to support the job once the end has been turned down to 3mm this is before the thread is added. It is also used to hold the die square when the thread is started.

Just before the shaft is cut off the gear is pushed on with the tail stock chuck.

 To help with getting the accuracy that is needed for the shafts the lathe has at DRO that is accurate to 1/100th of a mm  on both the cross slide and the compound slide

Here is the shaft with the case plug and a prop ready to be fitted in the main case.


The next shaft is the vertical shaft this starts by turning the end down to 3.2 mm. The bar is then pulled further out of the chuck and the 3.2 mm bit supported in a piece of brass while the other end which connects to the motor is turned down to the same size as the motor shaft. In this case 2mm as it is to go onto a 300 series motor the 400 series motors that I have been using upto now have a 2.3mm shaft.

Once the 2mm section is turned the shaft is put back in the chuck and the end knurled to take the gear.

The next stage is to fit the roll pin that will connect the shaft to the motor. This is the only way I have found of doing this, as the connection has to be made inside the vertical shaft case. The roll pin is pushed onto the shaft using the tailstock with the brass bar that was used to support the bar while turning.

Here is a close up of  the motor and the shaft ready to be joined together

Here it is with the outer case. One thing to note is that the bearing in the outer case is drilled out to 3.2mm

Here is the vertical shaft assembly put together with the gear pushed on unfortunately the shaft and coupling is not visible.

Here are all the parts put together.

The next stage is to make the motor mounting and steering  plate fit it and the motor and carry out some tests.


More Soon