Hemingway Kits Knurling Tool

[Mr Bowcat]

Cheers Steven.

[Mr Bowcat]

Morning all.

Just a quick update, I took most of the unwanted material off on the mill, then hand filed down to the buttons.




The buttons worked perfectly. I did have to stone the sides a little, the sections where I had milled the slots were a little tight in the main body, I will clean these up with sandpaper before final assembly.

[Mr Bowcat]

Morning all.

Getting close to the end of this now, finished some more parts over the weekend.

I started with the pins for the arms and knurling wheels, these were turned from 1/4" drill rod, with the two for the knurling wheels tapped through for M3 hex bolts. These still need to be heat treated before final assembly.



I then moved on to the parts that ride in the scallops machined in to the arms earlier. This starts of as round bar and has a 5mm hole drilled through. The middle was then milled out and one hole opened up to 1/4", the other tapped for M6. The stock was then put in the lathe and the two parts parted off.





The last part of this weekend was the leadscrew which is just 1/4" rod, turned down to 6mm in a couple of sections and threaded M6.



And this is how it looks now. What cant be seen is a spring between the two arms that goes around the lead screw. When the nut is tightened the spring allows the arms to move together the same amount and the scallop parts allow everything to move without binding. The nut is just temporary as the next part is the adjustment knob, but the tool will function in it's current form.

[stillp]

I had access to various lathes in previous jobs, culminating in a very nice Myford Super 7 with the Tri-Leva speed selector and screwcutting gearbox. I supplied a local model shop with small parts and made some special tools for the local car club. One thing I could never get to work though was knurling, so I'm hoping you have more success.
Pete

[Mr Bowcat]

Morning All.

Got this tool finished up over the weekend. There were only a few more parts to make, starting off with the adjustment knob. This was just turned to the desired shape and hole drilled and tapped M6 for the leadscrew. I couldn't resist adding some knurling with the tool with the temporary nut, which was completely unnecessary as it has a tommy bar through it to apply torque.





The final part was a simple brass washer that goes between the adjustment knob and the rounded parts made earlier, presumably to avoid wear from steel on steel contact. However I decided to improve the design and also made two dished brass washers for either end of the spring.



And this is all the parts. They were then given a cold blueing to protect against rust (I think my cold blue solution is at the end of it's life as it came out quite patchy, but should be good enough for now) and the tool assembled.





Couldn't resist a quick test, and I have to say these are the best knurls I've ever done. No doubt I will be able to improve even more with some practice.

[stillp]

Excellent knurls Bob. What speed did you run at?
Pete

[Mr Bowcat]

Fairly slow, didn't actually look at the readout but I would imagine around 250-300 rpm.

[Steven000]

That's looking amazing ? very impressive, well done!

[Mr Bowcat]

Cheers gents.