Creating a spiral

[Chris Cooper 5Participant @chriscooper5]

Anyone got the first idea as to how I go about creating this spiral?? Cheers

[HopperParticipant @hopper]

I’ve done similar by marking it out and filing it to shape, after first making a hacksaw or Dremel cut for the driving face of the dog. Use a piece of emery tape wrapped around the job to mark out the spiral part. Then hacksaw or Dremel the slot to full depth. Then file with a 10 inch flat file. If they are just those common locking levers etc, spiral does not have to be any kind of perfect.

Same technique used to make special counter boring tools and the like from silver steel. It’s not hard.

You could mill it but its a lot of faff, requiring a dividing head geared to the longitudinal movement of the milling table and a second set-up to mill the sharp corner at the base of the driving dog face. Not worth the hassle for such an application.

 

 

[Tony Pratt 1Participant @tonypratt1]

Hopper is about right with his reply and I’m thinking the original was cast.

Tony

[Speedy Builder5Participant @speedybuilder5]

isn’t it a job for the rotary table / dividing head which is set at the angle of the slope?  A bit of careful milling as the face of the slope is perpendicular to tilted axis. This is one I made for the start dog of a vintage car.

[HopperParticipant @hopper]

Yes machining it as one flat face like that is much simpler than dividing head geared to the table travel. It won’t be a true helix, but neither is the filed version so it will work just fine for this application. Looks like a nice job there too.

[bernard towersParticipant @bernardtowers37738]

In a lathe with toolpost milling attachment and lathe in threadcutting mode, turn lathe mandrel by hand.

[Les Jones 1Participant @lesjones1]

You could a setup like this that I used to cut a helix.

 

The right angle drive was for a drill.  You just need to work out the gearing to get the correct pitch helix.

I also used this type of setup to make this drive dog.

To get a sharp corner you would need to use a small diameter end mill and undercut the end slightly of finish the radiused corner with a file.

Les.

 

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