Does anyone have any tips for cutting external threads using a die? I’ve been trying to create my own thermal barrier tube for my stepstruder mk7 based on this tutorial ( http://www.mastersketchup.com/qubd-extruder-jam-fix/). Instead of bolts I got some 6mm brass rod, and while drilling it out by hand isn’t bad trying to thread it is proving difficult. Any tips on how to make this easier on myself would be appreciated.
Replace it with one of the new all-metal hotends. PFTE and PEEK based hotends are a world of pain (and jams). If that is out of reach, add active cooling to the top part of the hotend (a fan).
Use it like a tap. Make sure it’s straight and back off every so often to break the chips. If you have a drill press, you may be able to use it to help keep the work straight while applying force to get the cut started. I can’t remember if cutting oil is a good idea on brass.
No cutting oil needed on brass
@Shachar_Weis what would you recommend?
@Dale_Dunn / @Tony_Hine_Nifty_Acce Thanks, I’ll try a better vise next time I try
Make sure your outer diameter is only just what it needs to be to get complete threads, maybe even very slightly less (the material will push and deform a little bit to make the peaks of the threads). Driving a die onto a rod that is too large introduces A LOT more pressure. Even if oil is not required for the kind of brass you’re threading, it won’t hurt certainly.
@John_Davis thanks, should I look into getting a surfur based cutting oil, or could I get away with WD-40?
If this is the only thing you plan on threading I wouldn’t buy anything special. Wd-40 or 3 in 1 should work fine. If you see yourself doing more of this then pick up Tap Magic or something similar.
I use a touch of whatever oil is lying around, sometimes special purpose trefolex cutting compound for important stuff.
I teach 12 year old kids to use taps and dies almost every week! (Teacher by day, E3D by night…)
Number 1 tip, is to file a slight cone or chamfer onto the end where you are starting your threads, this helps the die start, and also means your threads have a slight starting taper which means they thread into female holes more easily - commercial bolts have this feature too. Even a tiny 0.5mm taper helps a lot here.
Look carefully at your die, you will probably find one side has a slightly funelled entrance, which along with the taper trick above helps start the die. The other side wont have a taper and will just have full size teeth which is harder to start the cut. The full size teeth side is also handy though, if you need threads right up to a shoulder but the taper side is stopping you cutting down far enough you can start with the taper side, then unscrew and flip the die to get threads that go that last mm or so.
Final tip is that you need the die and bar to remain totally perpendicular during the whole process, or you’re going to rip up threads. I have my kids clamp the bar in a vice, making sure it is pointing truly straight upright, put the die onto the bar, and twist the die not by turning it with their hands but instead by holding the die handle and walking around the vice to produce the turning force. Arms and hands are pretty rubbish at creating accurate rotation, but this method just relies on the floor and die being kept parallel by the childs hands, and the bar being clamped upright in the first place.
Anyway… Teacher mode over! Good luck