Reproducing an antique scale pin, part 3

I thought all I had to do was cut 2 more parts to the same dimensions, but I was wrong. When I did the original design, the only factor was getting it to look like the master part, and I could go over the measured diameter, but not under. The measured diameter was  0.603″, so unless I made a custom collet for that diameter I was stuck with 1/16″ increments. So the design diameter was 0.625″.

After cutting the first one I weighted it to see how close Fusion’s calculation was to my reality. Turns out it was very close – 3.48 oz calculated, 3.5 oz weighed. I happened to mention this to the customer (my dad) and he said the original was actually a little too heavy for the scale – would it be possible to make it around 3.0 oz?

Back to Fusion.  A few quick changes showed the effect of various changes to the design on the final part weight.

Going to 0.563″ (9/16″) got as close to 3.0 oz as I could realistically expect – +/-0.001″ tolerance on the OD is +/-0.01 oz, and I’m not sure I can even hold +/-0.001″ on the OD. I could take it off the machine, weigh it, and drill out the center as needed, but that seemed obsessive for something that would probably never be used to actually weigh anything.

So I cut the new design hoping to hit 2.9 -3.0 on my scale. I was even able to turn down the 0.625″ diameter piece so I ended up with 3 good parts.

The first one I put on the scale was 3.0, the next 2 were 2.9. Success! Below, my 3 reproduction pieces are on top, then the original, then my steel test part. I think the 2nd one from the top is the one I turned down from 0.625″, it looks like some extra tool marks just to the left of center (I didn’t notice those before I took the picture). But these will probably be artificially aged to look more like the original anyway, so I’m not too worried about leaving a few minor tool marks.

Sharp eyed readers may notice the the small diameter “barrels” are a little shorter on one of the reproductions – I didn’t have quite enough stock thanks to the first epic fail. So the piece is 0.2″ overall shorter. Since there is only one of these per scale, there won’t be anything to compare it to so functionally and aesthetically it makes no difference.

Leave a Reply

Your email address will not be published. Required fields are marked *