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Tooling for thread cutting

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Armourer

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#1
Hey all, dumb question from a newbie here. But I was going to purchase a carbide insert threading tool for my lathe, I have a QCTP and it will accept up to 5/8" bits. Am I better to purchase the largest tooling that will fit my tool post? Or should I go smaller? I would think the larger tool, the more rigid it would be. Are there any drawbacks to the larger tooling?

Next question, I am not sure if I am allowed to post links but I was looking at getting the Mesa Tools 5/8" threading tool that will thread external and internal threads. Has anyone used one of these before? Any opinions on it? Thanks for all the help!
 

Uglydog

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#2
I'd go with the largest tool holders your tool post will hold.
However, you need to be able to find the center-line of the shaft.
Factors including a tool post which is to large for your lathe will make it to high. Conversely it is also possible that you may need to shim up the bottom.
An old fashioned lantern gives you all kinds of flexibility as you merely grind your HSS to fit.

Daryl
MN
 

Technical Ted

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#3
I don't have much experience with carbide insert threading tools, so I'll let others more knowledgeable answer that question. But, have you considered grinding your own HSS tool for threading? It's a great skill to have in your tool belt...

Just a thought,
Ted
 

Wreck™Wreck

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#4
You can buy one tool that will thread from 60 TPI to 4 TPI 60 Deg. V, Acme, Whitworth, buttress and metric trapezoidal threads simply by choosing an insert intended for the application.

Be aware however that a small lead threading insert may not have the clearance angles needed for a large lead thread depending on diameter of course.

The answer to your question is that the holder size is unimportant but choosing the correct insert for the thread is, an excellent tool system is Kennametal Top Notch, threading, straight and full radius grooving internal and external. I do not work in the tool business I just find these tools versatile and the clamping system works well.

Started a job this past Friday, 2000 parts made from 10" lengths of ABS plastic tubing, OD finishing, grooving and parting with 1 tool at 300 per day, straight grooving insert with almost no corner radius. Works a charm yet the chips can get a bit out of control at times.

 

Chipper5783

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#5
I have the Mesa threading tool. It works well. They also offer a couple other shapes of inserts (square and round grooving). I recommend the tool.

This tool does not provide the "correct" thread form. It is really intended for fairly fine threads, of course being carbide and a small tip radius - they chip/damage very easily. I find you can repoint the insert a couple times (so long as you stop as soon as the insert is not fully sharp) and I will add radius to the insert tip if the thread root will allow it.

This is a good starting tool to learn with and will always be useful (of course just grind up some HSS - that works fine too). I have since gone to the Iscar SER system (the triangular insert that lays flat) to achieve the correct thread form and it works very well. Obviously the full form inserts are not nearly as versatile. The little Mesa tool is my second choice when it comes to threading.
 

BGHansen

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#6
I use 16 ER AG60 inserts. They are cheap (under $1 each from China) and work well. I've bought a number of things from eBay seller "zimi-hk" and have been pleased. The 16 ER are 3/8" diameter, External, Right hand thread. The AG60 bits thread from 8 - 48 tpi. Here's a current eBay item with a 16 mm (5/8") tool holder and 10 16ER AG60 inserts for under $20 delivered. Tons of other similar options on eBay.

The Arthur R. Warner (arwarnerco.com) sells HSS inserts with everything made in the USA. They have a number of options. Don't quote me on it, but you may be able to regrind their inserts for longer use. The carbide inserts are tossers.

Bruce

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benmychree

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#7
Personally, I would go with HSS tooling; Aloris makes a threading tool that has its own dedicated holder, and is easily sharpened by grinding on top; it is adjustable for helix angle. The cutters come in several sizes for different pitches of thread, I think there are three, and acme cutters are also available. Best thing, they last a long, long time, the ones that I use have been around for many years. Inserts make sense for CNC machines where speeds are high. Remember also that inserts need runout relief or they will chip and sometimes that does not fit your plans. The Aloris holder is made so that the cutter can be used upside down with the lathe run backwards in cutting left hand threads, cutting from tailstock to chuck.
 

Cobra

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#8

benmychree

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#9
The other option is to use HSS inserts and tool holder from Arthur Warner sold through the Little Machineshop.
They are similar in that the one holder will do both internal and external threads. The kit comes with two inserts, one for steel and one for non-ferrous.
I find them much less likely to chip at the tip of the tool.
Link to the site.
http://littlemachineshop.com/products/product_view.php?ProductID=3467&category=-147164245
For internal threads, I like Bokum Tool Co. form relieved tools, again, they are sharpened on the top, without changing the form, They come in many sizes, the smaller ones with integral shank, the larger ones with screw on shanks. I very much like their boring tools also, also form relieved, both in lead angle and flat bottom styles; I find them on E Bay.
 

f350ca

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#10
I was given a holder and carbide inserts as well as a boring bar that holds threading inserts. They work great on the Hardinge lathe with automatic thread stops. They cut incredible on my 16 x80, but make one slip and kick the half nut out a micro second too slow or fast and the insert is toast. For production they are no doubt incredible, I almost always use hand or machine ground HSS now. A honed edge on HSS will cut cleaner and is far more forgiving.

Greg
 
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