Hydraulic Knurling Tool

With a small lathe like most of us have, a push knurl is a terrible idea, and a pinch scissor knurl in its normal configuration has a one-to-two disadvantage in applying pressure making it hard to get sugfficient pressure to produce a good knurl.

After looking through various alternative designs, Paul & I decided to go ahead building a hydraulic knurling tool. Based on Paul’s initial design I went off and refined the details to come up with a specific plan and draw the CAD design (which I’ll eventually publish when I get it all finished).



After that, I figured I would start on the easy parts (the arms) and leave the rest to Paul ;-)

You can see some photos of the work here and here. The final result is:



Not too bad, although a little rought, and perhaps not quite as accurate as I might hope. Still, at the very least they should work as a proof of concept and hopefully will work adequately for the finished tool.

Vice Clamps

I managed to spend Friday on my lathe, but ended up spending most of the time making some mounting clamps for my vice. One the bright side, I got to use the new low profile clamps we made as a group project, and they worked brilliantly except that they slipped a little because the clamping force is so strong it pushed the clamps back. Paul assures me he had the same problem and resolved it by tightening the lock down screw more - I solved it by placing some other clamps directly behind the low profile clamps to make it impossible for the to slip backwards.


The end result looks good and should work nicely. I took them around to Paul's on the weekend and polished (I really don't have the patience for that!) and blackened them so I should get to try them later this week.

Aussie Hobby Metalwork

I have created a joint blog called Aussie Hobby Metalwork to post these sorts of metalwork posts with other Australians. For the moment I will post my messages to both blogs and see which one I retire.

I made it back to my lathe yesterday and did another part of my engine, the second part of an airway elbow. The collet chuck really is easy to use, although I am a bit concerned it may actually have a significant runout (0.16mm), which presumably comes from the spindle, and if so I have no idea how to adjust that.



Part 1 fits nicely in to the new part making a nice elbow - now I just have to figure out how to soft solder.

I think my confidence and ability is finally starting to pick up as I knock out these parts a little easier than before, although the more complicated and critical parts (like pistons and cylinders) still await!

Airway Flange Elbow Part 1

The next part I have to make is an airway elbow which is basically two tubes soft soldered at right angles. This was a great opportunity to try out a collet chuck on my lathe, and I have to say “Why didn’t I do this before?!?”. Once the collet chuck was set up (which took a while, removing the four jaw, making a draw bar for it (I need to make a proper nut for it), figuring out how to lock the locking plate (turning the locking nuts around allowed the plate to be held solidly in place), and removing the safety cutoff screw on the apron (since the apron needs to travel further)) its use proved excellent.

I also sped up the spindle, up to 1000 RPM (2000 RPM frightened me too much) and dropped the tool down a little (as described in my Lathe Turning Finish article). This improved the surface finish no end!



The part was then fairly easy to make. Face. Turn 13mm down to 6mm external diameter. File a small chamfer. Center drill and then drill 3, 4, 5mm to a depth of 13mm. Cut off with a hacksaw and file clean.

Main Support Bush Completion

I snuck out of my nieces’ Birthday party (after the cake of course!) to finish off the main support bush.



The finish is a bit rough, and I will look in to possible solutions, but it is servicable, so I can move on to the next part.

I actually managed to get to my lathe today and make some swarf which was good. In the end I have a half made bush for one of the many parts of the hot air engine I am making:



I also found a slightly better way of removing the collet chuck from the mill head, namely by using the tailstock with a lump of wood on it to act as a rest for the milling attachment (of course, now I am hammering on the lathe ways, but you can’t have everything).

And I remembered a tip I should mention, namely marking 10mm marks on the tailstock sleeve, it makes it much easier to quickly judge the depth of drilling a blind hole.

I also attempted my first hack saw parting off, although I found it hard going and in the end simply hacksawed off the part - probably I should have just used the bandsaw. Still, it was a lot better than my previous real parting off attempts.