Split (open) adjustable round dies

[seagull369]

Was hoping someone could explain the point of these apparently adjustable dies for cutting threads. In the past I usually just avoided 'em in favor of the fixed hex-shaped dies, but today ran into a Horror Fright Ti set at a flea market at a price I couldn't pass up which is chock full of them. If for nothing else, I don't like 'em since they force you to use the 3 screw stock handle, which can't really be turned if you're working in a tight area.

 

[1950mercury]

adjustable for different classes of thread fit.

 

[justanengineer]

^^^This. Being able to adjust your dies and/or taps as they wear or when you need a special thread fit is very handy at times. I often open them up a tiny bit to chase threads as well. JMO, but I find non-adjustable dies to be one of the tell-tales of low quality. If its non-adjustable and the packaging/advertising doesn't tell the thread class then buyer beware.

 

[Finky198]

Split dies tend to be more for thread repair at least that I have used them for in the past.

The adjustable dies like the Snappys are nice to. And perfect for... well adjust the tolerances of the fit

 

[larry_g]

http://tapmatic.com/tapping-questions/class-of-threads-h-limits

Above is a quick grab of thread H limits. If you understand thread cutting you will understand the split die. Not all screw threads are cut to the same tolerance and that is part of what separates a machinist from a mechanic.

Here is another chart showing thread limits http://engineersedge.com/screw_threads_chart.htm

lg
no neat sig line

 

[Steinmetz]

Was hoping someone could explain the point of these apparently adjustable dies for cutting threads. In the past I usually just avoided 'em in favor of the fixed hex-shaped dies, but today ran into a Horror Fright Ti set at a flea market at a price I couldn't pass up which is chock full of them. If for nothing else, I don't like 'em since they force you to use the 3 screw stock handle, which can't really be turned if you're working in a tight area.

We have different classes of threads. They are adjustable for that reason.

 

[seagull369]

that is part of what separates a machinist from a mechanic.

Guess that makes me a mechanic

Thanks for the info, guys. Didn't realize there was more to it.

 

[kunkernator]

I think to the general mechanic, non adjustable dies are fine. I have some nice ones (not cheap by any means), that are non adjustable. Then again, i use a die about every 10 times I use a tap....


Sent from my iPhone using Tapatalk