Single point thread milling?

[mu38&Bg#]

Does anyone do any single point thread milling? I spent some time searching online for calculators and programs, but came up with a bunch of stuff that is unsuitable. Mostly either for multitooth tooling or proprietary to the company's tooling. Peter Smid's book goes into detail and I'll probably end up manually programming. My VisualMill has a threading function but the interface is incorrect. How are you doing it?

Greg

 

[John S]

Both my controllers, Mach3 and Ahha have thread milling built in.
Mach3 uses a wizard, fill the boxes in and it spits the code out.

Ahha has a G31 [ I think ] that does it all in one line.

John S.

 

[RonGinger]

I had to cut 3" NPT threads into a throttle valve and flange for a locomotive boiler. I used Mach3 to run the mill and a self-made single point cutter.

Scared heck out of me to make the cut- we had over $1k into the part when it was on my mill. I 'air cut' it a couple times, but finally had to push the Start button. It took nearly an hour, but it came out great.

I wrote a Mach wizard to calculate the code, but I never cleaned it up enough to release it.

 

[John S]

As well as single point threading you can use a tap with all the flutes except one ground off or a holder with a Coventry die insert in it.

This is an external thread done on the Ahha machine.

 

[toolsrul]

Some of the thread tool mfg's. have that info on their websites, Vardex, Kennametal, etc.
The multi-thread thread mills usually move 1 pitch in "Z" if the thread length is the same as the tool. If you get a thread mill program with your pitch, hole diameter, etc. I think all you have to do is edit the final distance or "Z" coordinate using a boring bar with a single point insert. Instead of going down 1 pitch you'll be going all the way to your needed depth, I believe everything else in the program is the same. Prove it out in plastic or wood first.

 

[mu38&Bg#]

I'm using EMC. The trouble with the manufacturers programs is that you can't specify the tool geometry, you pick from their product line. I have a Micro 100 TM250-16 mill but they were of little help.

I'm working on a Excel file to do the math, but metric threads have such complicated specs it's going to take a while.

 

[John S]

I know you are usng EMC but why not download the demo copy of mach, use the wizard to generate the code and copy paste it into EMC ?

John S.

 

[mu38&Bg#]

I finally sat down and made the Excel file to write the single point threading G-code for external threads, so far. The tool path is beautiful. I made a mistake on my test 11x0.5mm thread and ended up cutting too small a minor diameter. A screen shot from EMC is in order. The file calculates the number of full threads and the last partial thread depending on length of the thread. The lead-in is always at X a.bc and Y 0.00, the last thread can end at any angle so it figures where the lead out should be. I was going to record the machining, but of course the camera batteries weren't charged and my webcam doesn't reach that far. Internal threads will be much the same except lead-in and out are from the center and it's cut from the bottom up with G03.

 

[DFB]

Hi Greg,

I'm about to attempt my first thread milling. Is your Excel tool something you are able to share ?

I would also appreciate tips from anyone - I'm initially planning to do internal metric threads (M5, M6 and M10) into half inch 6061 aluminium plate. I have yet to buy the threadmills but considering parts from Threadmills USA - e.g. the M6 TM60100 with a TiAIN coating. I'm running an X3 mill converted to CNC with a CNC Fusion kit and using Mach3. The fastest spindle speed on my mill is 1800 RPM. Would appreciate views on feed rates, etc...

David

 

[kvom]

Is it correct to say that thread milling can be done on a mill that doesn't have a synchronized spindle?

 

[mu38&Bg#]

My sheet is for single point milling. The tool you are looking at is a multi point. As I understand it, Mach3 already has thread milling wizards. I'm using EMC2.

Thread milling is just a helical move, but getting the correct thread depth, lead in, out, etc takes a bit of math.

 

[atheras29]

Hi
I am using manual G programing at Mazak M32 control for ID thread with single point treading tool for years without any problem
If it is able to use G code programing i can help you if i know the thread / thread pitch, depth and OD of thrading tool

 

[shred]

My suggestion, after having done a bit of it, is to test the program spit out by the Mach wizards carefully before running it on a part. Once you get the idiosyncracies out of the way, it's really cool watching that little tool wind it's way around and make you a female M17x0.75 or male 3/4" GHT (Garden Hose Thread-- look up the specs on that one sometime ) or whatever you desire.

I've only ever done it with single-point tools (the frisbee-on-a-stick ones) as-seen here

With one 60' cutter, you can cut a lot of different threads (from female threads the diameter of the tool up to until you run out of tooth on the cutter). They aren't cheap, but ought to be a whole lot more popular amongst the home CNC crowd for larger threads. You don't need a synchronized spindle or anything fancy beyond a 3-axis mill.

It should be relatively easy to make them from drill rod for softer metals as well-- the geometry is a whole lot simpler than a gear cutter, but the basic idea is the same.

I found I had to fiddle with the final code & wizard a little to get the fit I wanted, so be prepared to make some test parts. Speeds and feeds wise, they say to run them like an endmill of the same diameter as the cutting edge, but I tend to baby mine..