Thread Cutting on a Lathe In Prescott

Host  Doug Endrud

August 20th 2005

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Host - Doug Endrud

Demo - Neil Butterfield

Handouts and overheads - Gene Lucas

Photos - Bill "Beevo" VanOrden

Food - Almost everybody! Thanks to those that brought side dishes and drinks.


Members in attendance; Doug Endrud (our host), Owen Jeffers (Owen lives in Prescott and beat everyone there), Neil Butterfield (our demoer), Gene Lucas (handouts and overheads), Tom Davis, Eugene Niegoff, John Lea, Bob Harbour, Rick Sparber, Tim Coppage, Robert Riesman, Glen and Jeanine Lynch, Bill VanOrden, Earla Marshall and Scott Brown.


We began a bit late due to traffic or street numbering concerns, next time maybe we should put the white board out on the street. After we figured out that everybody was heading up the hill it was easy to reign y'all back in the right direction. Around 11:00 we started with introductions. 11:20 we began discussion on the basics of threading for the home shop. While many points had been covered I believe it went something like this. Some basics of threading were introduced through the use of overheads, handouts and group discussion. These covered but were not limited to; What is a thread and threading. What is a proper thread. The differences between tolerances in class 1 vs. class 2. (class 2 is hardened and half the tolerance specs of class 1). Clearances and failures due to improper clearances. A discussion of the different tooling for this operation and how each has its own advantages. 

Examples were passed around. Aloris setups, Armstrong/Lantern tool posts and the "Diamond tool holder" (Aussie invention I believe) and the "Butterfield Tool Holder" can be used for threading on the lathe. The later of course uses a collet system for holding taps or dies in the tool post to facilitate threading. This system has some distinct advantages if you thread as poorly as I do.


The importance of proper setup was stressed. The use of a thread gauge to grind the bits for your tooling as well to establish placement of the bit along the diameter of the piece to be turned was discussed. For HSS bits in Aloris and Aloris clones bits should be ground at 30% and your compound set to 29% to allow proper clearances when cutting threads.

When done properly this can reduce the stress on the machine and leave your with a much nicer finish. Also it is important to slightly round the end of your bits as any right or sharp angle can cause a fracture and possible failure of the part in question.

Pitch, Major Diameter and Root Diameter are all components of properly applied threading principles. But enough of this bookwork! It's time for some hands on. At this point we took a moment to admire Doug's lathe and have Neil show us what is so important about setup and which handles to turn to accomplish threading. After some discussion around the lathe Neil began to show us how it is done. After that he took the time to work with smaller groups while the others eagerly awaited a turn at the helm.

While this took place some of the others helped get things in place for lunch. Around 1:00 or so I believe we started the buffet even though Neil was still at the lathe answering questions about the days topic. A little after 2:00 we started cleaning up and heading for home.

Many thanks to Doug for hosting this meeting and all who helped out with it. Lot's of participation makes it much easier to continue to share knowledge with those who seek it.

Scott Brown