Internal threading tool

[Jmanb13]

I have collected quite a few used HSS tool bits from ebay including a bit already ground for external threading. However I am in need of an internal threading tool.

In my previous questions I ended up going with HSS tool bits mainly due to the speed my lathe is capable of achieving (500 rpm) as well as wanting to learn how to grind my own tool bits.

The part I'm going to be internally threading has a bore around 1" diameter.

I've been looking at late tools on the various places, MSCDirect, Shars, CDCO, Amazon, etc.

It seems that about the only tools available for internal threading are tools with carbide inserts.

Are these the only options I have?

Is there any issue with using this with my slower lathe? From my watching of videos and reading, it doesn't seem that threading is done at super high speed anyway.

Any other suggestions or things I don't even know?

 

[DAT510]

Little Machine Shop has internal treading cutters made from HSS. Both ones that accept HSS inserts and ground HSS cutters.

http://littlemachineshop.com/products/product_view.php?ProductID=1895&category=-147164245

http://littlemachineshop.com/products/product_category.php?category=-147164245

I bet Shars also has HSS treading tools.

Hope this helps.

 

[mikey]

Check out the internal threading bars from Micro 100. Their carbide bars are very solid, sharp and cut beautiful threads. I use them for anything small - up to about 1/4-20 or so. After that, I use a Circle Machine inserted tip carbide bar.

 

[Charles Spencer]

I use a carbide insert bar on my SB 9 at slow speeds (back gear engaged). It works for me.

This is the Chinese boring bar that I bought:

http://www.banggood.com/SNR0016Q16-...urning-Tool-Holder-with-Wrench-p-1061082.html

 

[Tozguy]

Mesa tools, versatile, good quality, good people.

http://www.mesatool.com/products/threading-tools/

I have been using their 1/2'' internal threading tool for external threading too. It allows me to run the lathe in reverse and cut on the backside of the work, going away from the chuck.

Also, when running in reverse for internal threading I can see the cutting more easily.

Their inserts don't have to run any quicker than HSS ones. All my threading is done at 65 rpm (slowest available). You do have to start the work turning before the insert touches it (or the insert will chip).

 

[brino]

You could easily make your own boring bar.
1) find a bar that works (ie. fits the hole with clearance and you can hold onto it), 3/4" or 1/2" dia, maybe 6 inches long
2) drill a 1/4" hole clean thru the diameter near one end
3) file that hole square to fit a 1/4 HSS tool bit
4) drill thru the end of the bar into that first hole and tap for a set-screw to hold the tool bit

With these you only need a short threading tool, so one HSS blank could make a couple threading tools.

Above is the simplest version with the tool bit square to the axis of the bar; great for internal threading.
For boring a square bottom hole into a workpiece make the tool bit hole on a 45 deg. angle to the bar axis and put the set screw thru the side of the bar above it. In fact you could put that on the other end of the same bar.

I'll try to remember to get some pics of mine when I get home......

-brino

EDIT: of course you could also save all that filing by using a round tool-bit like a broken drill bit.

 

[MozamPete]

Plus 1 on the Chinese boring bar with an internal threading insert.
Threading is about the only thing I exclusively use carbide inserts for. I mostly use home ground HSS for turning (only using carbide for tough stuff), but for threading - both internal and external - I now use the preformed carbide insert as my go to tool. I'm just using the cheap Chinese stuff (Banggood.com) but it does the job for me with the minimum hassle. And they are cheap, $5 to $10 each is all I paid.

 

[Kevin J]

I also use the boring bar offered by Mesa Tool and I am very pleased with the results.

Kevin J.

EDIT
Forgot to include "in my opinion"

 

[Jmanb13]

Thanks for the suggestions everyone. I ended up going with the Mesa Tool's bar. It cost a little bit more than the chinese ones, but it also has a grooving tool on the other end, which will help with another project I have planned.

 

[kvt]

I purchased a few boring bars that hold 1/4 inch HSS tools, The bar, with the insert cut short to where it just sticks out works great. I have even done a few backing plates for chucks, and also, spindle spiders using them. My problem was I needed to do 8tpi which the inserts I found would not do. So I found my own way. I even ground my own HSS for it. Fun trying to get that to work the 60degree fishtail properly. If I can do it most should be able to do it.