New lathe day - Warco GH600

[Ben17484]

I’m calling this my first time of single point threading. I have done it a couple of times before, but a long time ago. New bolt made for holding the quick change tool post on:

Definitely not the cleanest part, but the first part on this lathe and my “first” single point threads.

All fitted.

I also tried to tighten the bolts that hold the lathe to the bench, but there’s still some movement if I push on the lathe. I don’t think two bolts is enough to hold this to a surface. They probably need at least three to give some lateral support as well.


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[WobblyHand]

If that's how you set your compound for threading that's not the correct angle. It should be 60 degrees from the spindle axis. You have it set to 30 degrees. If you set it to 60, your threads will be a lot better, with less tearing. Most of us have made the same mistake, myself included. I probably have a similar post here on HM. Try 60 degrees.

Even so, congratulations on trying single pointing. Decent job, but it will be much better with the compound angle set correctly.

 

[Ben17484]

If that's how you set your compound for threading that's not the correct angle. It should be 60 degrees from the spindle axis. You have it set to 30 degrees. If you set it to 60, your threads will be a lot better, with less tearing. Most of us have made the same mistake, myself included. I probably have a similar post here on HM. Try 60 degrees.

Even so, congratulations on trying single pointing. Decent job, but it will be much better with the compound angle set correctly.

Oooohh. Thanks for the info. I thought it had to be set to just under half of the thread angle, so 29.5 for a 60 degree thread?

I also watched a Joe Pie video a couple of days ago that said for insert tooling, plunging straight in is fine and no need to use the compound. Not sure of people’s opinion on that?


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[BGHansen]

Unfortunately for whatever reason the compound protractors on USA-made (old iron) and Import lathes are usually different. There are many threads (pun intended) here with "bad threads" from an incorrect compound angle. It's not completely operator error, it's because of the change in locating schemes. Most of the internet instructions/videos refer to old American iron which has a different compound protractor orientation scheme.

Typical import lathes have "0 degrees" for the compound parallel to the Z-axis or spindle axis. American lathes had "0 degrees" as parallel to the X/Y-axis or the cross feed. On an import lathe, the compound is set to 60 (or 60.5) degrees; 30/29.5 degrees on an American lathe.

Another way to literally look at it is to set up your lathe and look down on your setup. The compound's angle is the direction of tool travel; it should be parallel to the face of the thread face being cut. Or, chuck up a bolt and dry-run your cutting tool along the face with the compound. If the tool walks away from the face of the thread, your angle is off.

Most of us end up running a flat file on the top of the threads to do a little post-single point clean up. I'll also run a triangular file down the thread to do some clean up. And it's not unusual to post run a die too if it's a common sized thread.

And just in case you ever get into cutting gears, there's a problem in labeling there too. Involute cutters are numbered from 1 - 8 depending on teeth on the gear. The numbers go from something like 12-13 tooth gear at one end of the scale to a rack (infinite teeth) on the other end. I don't recall the correct scheme off the top of my head, but the numbering systems are flipped between US and import cutters. A "1" on a US involute cutter is an "8" on an import cutter.

Bruce


American-made Clausing lathe set to cut a 60-degree thread.

A 30-degree gauge block set on the side of the compound; edge is parallel to the X/Y-axis or cross feed.

The compound protractor is on the far side of the compound, angle is set to 29.5 degrees

Import Grizzly lathe set up for a 60-degree thread

Note that a 30-degree gauge block set to the edge of the compound is parallel to the X/Y-axis or cross feed.

The compound protractor is on the front side of the compound, angle set to 60.5 degrees

 

[Ben17484]

Unfortunately for whatever reason the compound protractors on USA-made (old iron) and Import lathes are usually different. There are many threads (pun intended) here with "bad threads" from an incorrect compound angle. It's not completely operator error, it's because of the change in locating schemes. Most of the internet instructions/videos refer to old American iron which has a different compound protractor orientation scheme.

Typical import lathes have "0 degrees" for the compound parallel to the Z-axis or spindle axis. American lathes had "0 degrees" as parallel to the X/Y-axis or the cross feed. On an import lathe, the compound is set to 60 (or 60.5) degrees; 30/29.5 degrees on an American lathe.

Another way to literally look at it is to set up your lathe and look down on your setup. The compound's angle is the direction of tool travel; it should be parallel to the face of the thread face being cut. Or, chuck up a bolt and dry-run your cutting tool along the face with the compound. If the tool walks away from the face of the thread, your angle is off.

Most of us end up running a flat file on the top of the threads to do a little post-single point clean up. I'll also run a triangular file down the thread to do some clean up. And it's not unusual to post run a die too if it's a common sized thread.

And just in case you ever get into cutting gears, there's a problem in labeling there too. Involute cutters are numbered from 1 - 8 depending on teeth on the gear. The numbers go from something like 12-13 tooth gear at one end of the scale to a rack (infinite teeth) on the other end. I don't recall the correct scheme off the top of my head, but the numbering systems are flipped between US and import cutters. A "1" on a US involute cutter is an "8" on an import cutter.

Bruce


American-made Clausing lathe set to cut a 60-degree thread.
View attachment 464858

A 30-degree gauge block set on the side of the compound; edge is parallel to the X/Y-axis or cross feed.
View attachment 464859

The compound protractor is on the far side of the compound, angle is set to 29.5 degrees
View attachment 464860

Import Grizzly lathe set up for a 60-degree thread
View attachment 464861

Note that a 30-degree gauge block set to the edge of the compound is parallel to the X/Y-axis or cross feed.
View attachment 464862

The compound protractor is on the front side of the compound, angle set to 60.5 degrees
View attachment 464863

Thank you for the detailed explanation. The next single point threading I’ll do I’ll set to 60 degrees and hopefully they’ll improve. I did do the flat file and triangular file trick to neaten then up.


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[Ben17484]

Added an aluminium angle extrusion to the chip guard at the back to hold the tool holders. I’ll try and figure something out for holding drill chuck, Chuck key etc on the back there as well.

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[Ben17484]

This angle looks a bit healthier. It is measuring on 60 degrees (just below) now.

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[Ben17484]

I wasn’t happy with the surface finish on my tool post bolt I made above, so now I’ve got the QCTP on and can more accurately centre the tools I thought I’d give it another shot. I also tightened up the gibs on the cross slide and compound (both definitely needed adjusting) and added metal plates under the bolts that hold the lathe to my workbench to hopefully make the lathe more sturdy. I came out with the below:

I’m pretty happy with that for now. This was without playing too much with feeds and speeds, so I’m sure I could improve more with some further tweaking.

I think given what I know now about the angle I had the compound at and now I’ve tightened everything up, I’ll remake the toolpost bolt. I also want to mill some flats on it to tighten it to the compound and also try my hand at cold bluing.


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[Ben17484]

I remade the bolt for this and am much happier with the result. I took onboard what you all said about the angle of the compound, I took my time and it definitely tuned out better. I've posted the pictures of the new part on my new thread (which I'm going to use as a diary of my projects whilst I'm learning): https://www.hobby-machinist.com/threads/adventures-of-a-newbie.108979/

 

[AllenV]

With the 10mm tools and standard holder I come to 1mm below centre line:

I think that should be fine? Is there any reason I’d ever need to be below centre line anyway? And if so, how far? The XL tool holders should get me 3mm below centre line.


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I have recently been collecting data on a few different tool holders. This is in the context of my 13-inch lathe with BXA QCTP. I was fitting it out with 5/8-inch tool holders with inserts. For years I was running 1/2-inch tooling with no issues. At 5/8-inch I found my regular Phase II and my Shars XL holders were a bit too tall. However, some recently acquired Precision-Matthews XL holders worked okay. I wound up removing material from the bottom of the Phase II and the Shars XL. I used a carbide insert face mill. All of them fit fine now.

The good news is that the PM holders are also the most economical. With any luck, the AXA size might also work for you.

Before you ask: I bumped up to 5/8-inch as they have room for shims under the insert.