QCTP too tall

[WobblyHand]

Or you can use a left hand tool. I have two left hand threading tools, a Micro100 carbide one for small internal threading and a 3/4" Kennametal threading grooving bar. I thread away from the chuck with them. Single pointed a M8x1 internal thread with the Micro 100. No visibility into the hole. Just have to have confidence that if you do the right thing, in the right order, it will come out fine. Pays to practice first though!

The Micro 100 tools are awesome. But if you bump them or crash them, even an eensy bit, they snap. Otherwise they'll last a long time. I try to get them as surplus stock, because they are relatively expensive, especially if you snap one within 5 seconds of possession! That was a sad moment.

 

[chris.epp]

Stainless bearing steel is usually 440C, if it’s annealed, you might be able to turn it with your lathe, if hardened, not a chance. Take a file and see if it cuts it or skims across the surface. If it cuts it, then you might be able to turn it.

So.... I had tried just a bit on this stainless steel. It squeaked and felt sketchy so I stopped pretty quick. Then file tested it and can't get a file to bite at all... definitely hardened! Everything else so far seems so easy now though, and not terrifying. Hahaha

This shave was not easy going...

 

[chris.epp]

The problem with cutting metric threads on a lathe with an inch lead screw is that in order to resync the half nuts once opened is the lead screw has to travel some multiple of 127 turns. When cutting inch threads with an inch lead screw, you regain sync at least once an inch. Metric thread dials are a complex mechanism compare to the inch dials. This is because metric pitches are set up as mm/thread whereas inch threads are threads per inch.

It is possible to use the half nuts when cutting metric threads on an inch lathe.To do so, you make your first pass engaging the half nuts on a designated number on the thread dial. When you reach the left hand end of the thread, disengage the half nuts and shut the lathe motor down. Reverse the lathe and when you reach your designated number on the thread dial, reengage the half nuts and continue until you have passed the right hand end of your thread. Shut the lathe motor down and make your adjustments for the next pass and start the lathe in the forward direction. Repeat this process until you have completed your thread.

I think I need to work through your second paragraph on metric threads with indicator when I'm in front of the lathe. I was thinking if you disengage the feed then power off you were out of sync and can't really get it back for Metric. I'm probably not following right and have yet to use the threading dial at all yet so will revisit that when I'm there!

 

[ltlvt]

10 mm tool holders may be your ticket to success. Import tooling is usually 10-12 and up for the larger machines.

 

[Ischgl99]

So.... I had tried just a bit on this stainless steel. It squeaked and felt sketchy so I stopped pretty quick. Then file tested it and can't get a file to bite at all... definitely hardened! Everything else so far seems so easy now though, and not terrifying. Hahaha

This shave was not easy going...

that actually cut more than I thought your lathe would, but not something you will want to use. A big heavy turning center would have no problem with that, but hobby size lathes are not cut out for that material in the hardened state.

I think I need to work through your second paragraph on metric threads with indicator when I'm in front of the lathe. I was thinking if you disengage the feed then power off you were out of sync and can't really get it back for Metric. I'm probably not following right and have yet to use the threading dial at all yet so will revisit that when I'm there!

you will lose sync if you let the thread dial go too far and you don't know where to reengage on the return. What RJ is describing is you shut the lathe off quickly after disengaging the half nuts so that you can resync in the proper place each time. It's vital to reengage on the same number AND rotation of the thread dial for this to work. If you reengage on the correct number, but are off by 1 rotation of the thread dial, you are screwed. This is a modification of keeping the half nuts engaged for lathes that cannot stop fast at the end of the thread. By using this method, you are still keeping the half nuts engaged for the return to your start position and the next threading pass. This simply gives you a way to avoid smashing into a shoulder while threading metric threads.

 

[RJSakowski]

that actually cut more than I thought your lathe would, but not something you will want to use. A big heavy turning center would have no problem with that, but hobby size lathes are not cut out for that material in the hardened state.


you will lose sync if you let the thread dial go too far and you don't know where to reengage on the return. What RJ is describing is you shut the lathe off quickly after disengaging the half nuts so that you can resync in the proper place each time. It's vital to reengage on the same number AND rotation of the thread dial for this to work. If you reengage on the correct number, but are off by 1 rotation of the thread dial, you are screwed. This is a modification of keeping the half nuts engaged for lathes that cannot stop fast at the end of the thread. By using this method, you are still keeping the half nuts engaged for the return to your start position and the next threading pass. This simply gives you a way to avoid smashing into a shoulder while threading metric threads.

Tom Lipton, OXTools, did a great video showing this method of cutting metric threads on an inch lathe.

 

[chris.epp]

Tom Lipton, OXTools, did a great video showing this method of cutting metric threads on an inch lathe.

I'll see if I can dig it up, thanks!

 

[RJSakowski]

I'll see if I can dig it up, thanks!

 

[chris.epp]

Should I be starting a new thread? Just wondering if I could get some recommendations on starting speeds feeds and depth of cut. Turning down 15.8.mm down to 12mm before profiling. Aluminum. Hss carbide cutter. On a lathe this size, for starting out beginner. Rpm, DOC and feed speed safe to start with? If it's like other tooling too slow can overheat as well?

 

[twhite]

Is this practice or the real deal? Just wondering. If practice experiment. Start with 150 RPM. First pass just do a witness cut so you can verify threads are correct. After that try .005 per side first few passes. Then taper off. The last couple of passes take .001 and do a spring pass.

You will be able to tell off the pass s too heavy.

FYI. This is just my experience. It does not matter if you plunge straight in or set compound at 29 or 30 degrees. I find I like going straight in as it is easer to get my desired depth straight away.

You will find your preferred method. Take what people suggest and incorporate what make best sense to you.


Cutting oil is my blood.