Facets in my 16 TPI Threads - Need some help!

[davidpbest]

I will confirm tool height this weekend per the Joe P. video shared by Jim F.

If you want to make a tool-height setting device like the Hardinge version Tom Lipton shows in his video, it's a fun project. I use mine often.

 

[Liljoebrshooter]

Nice work. What is your approach? Speed? Tool type?

I use a kennametal NTP2R insert. Usually at 110rpm(?). I also feed with the compound for most of the depth and finish with the cross slide the last. 005" or so to get to proper size.
I did have to do some work on the bottom of the compound. It was high around the bolts.

Joe

 

[qualitymachinetools]

These videos are taken on my 1440GT. This machine is known to turn out good threads. See results in the following messages.


1. The video titled: RH Thread 200 RPM DTI Tool holder. Ranged from 0.0005" to 0.0008" That cut looks like its supposed to. Cutting, not digging. What did the finish look like after that cut?

2. Something that I noticed, you used the cross slide and said you were taking .002". That is a huge cut for .002". Please see my attached videos showing what I am doing at .002" which would be .004 total, and then .004 which would be .008 total.

3. When you thread the normal way by putting the cross slide back to Zero each time and only advance the compound, how much are you advancing the compound each time? In this test, even .005 at that RPM was too deep. I had to make quite a few light passes to keep the finish nice.

 

[qualitymachinetools]

No good here, RPM Slow and cuts way too deep. Not cutting, its digging the material out. Seems like the same type of problem.

 

[qualitymachinetools]

This one moves with the indicatory on the machine, about the same results.

 

[xr650rRider]

I know my PM-1340GT came with factory installed DRO but the resolution of the scales was not set correctly and did not match the hand wheel movements, I had to change the cross-slide to .0001 uM.

 

[qualitymachinetools]

This is a good thread, same machine, material, and cutting tool

.005 DOC on the compound only. 29.5 degrees. 95 RPM.

When I got down in to the thread more, I backed off, .0025 per cut. This was 8 TPI, I made it a coarse pitch so its easier to see whats going on.

Ended up with good threads.

Proper chip. I did not use oil, I sprayed on some coolant. Id have better results with cutting oil at the slower speeds.

Notice the chip is smooth like it should be during these cuts. Not tearing like in the other videos.

 

[qualitymachinetools]

This is while cutting, before any finish work. Just a quick job to get a post here, with oil and finish it could be even better.

 

[qualitymachinetools]

With oil, .001" on the compound finish pass.
FYI this material is 1018 CRS. Not the best for finishes, but still turned out OK.

 

[TX COWDOC]

These videos are taken on my 1440GT. This machine is known to turn out good threads. See results in the following messages.


1. The video titled: RH Thread 200 RPM DTI Tool holder. Ranged from 0.0005" to 0.0008" That cut looks like its supposed to. Cutting, not digging. What did the finish look like after that cut?

2. Something that I noticed, you used the cross slide and said you were taking .002". That is a huge cut for .002". Please see my attached videos showing what I am doing at .002" which would be .004 total, and then .004 which would be .008 total.

3. When you thread the normal way by putting the cross slide back to Zero each time and only advance the compound, how much are you advancing the compound each time? In this test, even .005 at that RPM was too deep. I had to make quite a few light passes to keep the finish nice.

Hi Matt,
Thanks for posting the videos. No doubt the 1440GT produces nice threads. I could post similar 16TPI threads from the Sharps lathe I used this in Trinidad, CO while building my rifle. The issue is the 1236 has not been producing those kinds of threads. To clarify the range in line 1. quoted above (0.0005" to 0.0008") was the movement on the DTI not what I was dialing in on the cross-slide. I was taking cuts of 2-3 thousandths at a time. These are hardly heavy cuts. Bamban travelled down to my shop today. We figured it out........