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Warren
12-26-2005, 09:17 AM
I am looking to upgrade my threading tool. right now I use a 60 deg standard brazed carbide bit or a hand ground HSS bit in an aloris style holder. I was thinking of maybe one of the inserted type holders or maybe an Aloris type insert threading holder.

What do you folks use for external threads & why?

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Warren

vinito
12-26-2005, 09:42 AM
Most of the time I use a "top-notch" type insert tool for threading. You can check the net to see the configurations. The reason I use it is for economy and laziness. The inserts are common and can be found on eBay cheap - economy. They are easy and quick to set up since inserts are already ground to do threading - laziness.

When I'm not feeling lazy I usually get a better finish if I just grind my own HSS cutter. Since manual threading is usually more comfortable at slower RPM's, the HSS performs better in that range. The geometry of insert threading tools is set up for high rpm CNC applications and leaves a little rougher finish than one tailor-made for the job, but I find it acceptable for most work (still better than a die).

$.02

big-dipper
12-26-2005, 10:04 AM
At the speeds mostly used for "manual" threading HSS might be your best bet. I use an Aloris threading holder with the HSS "blade". The hard part is already made (the 60*), all you have to do is grind the top side, and it can be resharpened many times.

R.Johnson
12-26-2005, 11:23 AM
Get the book, Screwcutting in the lathe. If you make the grinding jig for shaping the tool bit, plus the tool holder, threading is just another turning job. The book is written by Martin Cleeve.

Warren
12-26-2005, 12:02 PM
In years past I have used those preformed bits like Big dipper mentioned but they were on an Armstrong type holder. They are so 20th century..LOL

Lazy is me Vinito, especially today!

I was looking at the Aloris #8 threading tool holder & preformed cutters this morning. Looks like that is the way I am gonna go.

I will also look into the book R Johnson mentions. I like to read.
Maybe there is hope for me yet. You gents may turn this old welder into a machinist yet! Thank you for the help

Luke55
12-26-2005, 12:32 PM
What about HSS true form tools. I've got a batch of them for pennies. For inside threads they are like boring bars and outside are like an exentric with a 5/156 mounting hole. Never use something else since

ACF
12-27-2005, 11:27 AM
A friend gave me a top notch holder for OD threading and some old inserts that kennametal no longer listed. These inserts didn't give a very good finish at slow speeds. I called kennametal to see what they recommended and tried an insert with the number NT2RK grade KU25T. This gave nice looking threads even at the slower speeds.

I've tried making a threading tool from HSS but came to the conclusion that without some kind of fixture to keep the angles correct I wasn't going to make a good tool.

Just my experience, your mileage may vary.

Chris

R.Johnson
12-27-2005, 03:23 PM
ACF: With the grinding jig Cleeve discribes, you can grind the tool first time, every time. His book is the best I've seen on thread cutting, and the jig, and tool holder are easy to make. The tool bit comes out razor sharp, with all angle's correct. With his jig, and tool holder, set-up is a snap.

flatlander
12-28-2005, 12:06 AM
I started cutting external threads with the same top notch inserts already mentioned. They don't give a very smooth finish on CR steel, but have done better on several different SS alloys I've used - including rifle barrels made with 416R. For internal threading, I got a Carmex 3/4" bar for laydown inserts, and have had mixed results with a couple of grades of AG60 inserts - running slow, threading to an inside shoulder in CRS, the thread's finish looked pretty ragged; doing the same job in a rifle receiver at the same speed, the threads had a better appearance. It'll take quite a bit more practice before I gain enough skill & confidence to run at high enough speeds while truing receiver threads to make much difference with carbide inserts, but so far, the threads I've chased/trued have been a good, smooth fit with barrels threaded with the top-notch inserts.

It sounds like reading Cleeve's book would be a good step though.

Warren
12-28-2005, 05:51 AM
I orderd Cleeves book from Blue Ridge Machine. They are the first US outlet I found that seemed to stock it. Hopefully it will be here in a few days. I have recently purchased two other Workshop Series books, Laws Gear cutting & one on Dividing. Both were helpful. I hope the thread cutting book is of the same caliber.

JPR
12-28-2005, 08:51 AM
Also the book is available on amazon.com for $9-10 (new).

Spin Doctor
12-28-2005, 09:23 AM
For most manual lathes the sppeds required for carbide IMO can't be safely reached in most cases. An exception would be a lathe with an automatic kick out system that disengages the leadscrew while the spindle is still running. The type of system used by the Hardinge HLV for example. But for the normal manual lathe where one has to open the half nut HSS is the why to go. But I don't hand grind threading tools anymore. I cheat and use a surface grinder (or did when I was working, I'll eventually have to get one for the home shop, now I just have one of the guys grind one for coffe money during his lunch) with a jig like this

http://img.photobucket.com/albums/v19/markandannie/Thread%20Blocks/P1010339.jpg

http://img.photobucket.com/albums/v19/markandannie/Thread%20Blocks/MVC-005S.jpg

http://img.photobucket.com/albums/v19/markandannie/Thread%20Blocks/MVC-010S.jpg

Between the three shown and an additional acme block I know the angles and clearances will be right. Which is a good thing with my eyes