Hey everyone, thought I might try my hand at Autocad. I made a quick drawing for making center punches with 60 degree points. It's a good beginner project, I'm thinking of making a set at the shop this coming monday. Will post pictures when I get around to it. Let me know if there are issues with the pdf or if drawing specs are a problem.

Booze23.

Hey, I've made some adjustments to the drawings and have a few pictures of a first trial piece I made earlier today. I will post up progress on the actual punches shortly…

Here is the trial blank that I "attempted" to turn down to 3/8 inch. The stock material is slightly oversize at about 15/32 inch. As an aside, I really love those Aloris quick-change tool posts. This is a Hardinge lathe at the shop at my university. I was blessed with having full access to facilities there.

Here is the compound rest set up to turn a 30 degree taper. The turned rod had inconsistent finish because my speed was too low.

Here is the result of a few passes using the compound rest.

The test piece brought to a single 30 degree point. I think I'm getting the hang of this. The finish on the taper looks much better too. You'll have to excuse the marrs on the left side of the image. I got the workpiece stuck in the collet and couldn't get it out. A little impatient, I used some 'physical persuasion'. Luckily I found out later that giving the spindle lock lever a good tap will pop the 5C collet open.

Thanks for viewing. I will post up the actual center punches as they are made.

Hello again, here is a pic of the (not fully) finished center punches. The third one needs to have the second taper turned. I will have to post up the updated drawings soon.

As far as hardening goes, there was a guy on Youtube who showed you can harden drill rod using a small propane torch. I live in an apartment so I thought it would be great to go outside and get these punches hardened. Gives me the opportunity to scare some of the neighbors' kids too! The instructions for these punches came from an old Workshop Series book, the author recommends using silver steel (ie: drill rod is the closest to that, I believe), heating until it is the colour of a boiled carrot, and dipping in oil. Then you need to place it in a sand bath (no idea what that is) and temper until the metal has the colour of straw. 

My only concern is what temperatures these finishes are achieved at, and how effective the torch would be at getting this work completed. The guys in the shop told me that I need to make sure it is drill rod (the material was in the drill rod rack, but unmarked so it could be something else). I think I'll use a piece of rough stock and heat it to see if it hardens. If not, the shop guys said they can get it vacuum-hardened (?) at a subcontractor. Unfortunately, I did not make the punches in such a way to allow for knurling at this point, so I will mill out some flats and punch out the size markings. Will update on how it all goes.

Hahaha, yeah I don't mind applying a little elbow grease on the job, so to speak. But for the sake of the workpiece not looking like silly putty, I will be using a gentler touch next time.

As far as knurling goes, I believe you need to turn between centers, so yes you would have to knurl before you make the tapers. The machinists I speak to say that the forces generated from knurling are so great that you should use a dead center (lubricated) in the tailstock, and a headstock that can take the punishment. I've never knurled but am planning on giving it a go in the near future.

There was a video where someone mentioned something to the effect that the diameter of the workpiece needs to be a multiple of the thread pitch of the knurling tool in order to get the even diamond pattern right (interesting quirk!).

If you want to avoid marring the knurl pattern, you could always cut up some paper or a soda can and wrap it around the part before chucking. You may need to true up the part if using a chuck, not sure how it would come up in a collet.