Havin Trouble Cutting Threads Correctly

[Ray73]

After figuring out how to set up the change gears on my 8x14 HF/LatheMaster lathe I want to learn to cut threads and have been practicing but my threads aren't a nice v shape like they should be. I am using a 60 degree HSS tool that I ground and have tried it with a store bought carbide 60 degree tool as well. My threads always "point to the right of the chuck" is the only way I know how to explain it. I am going by the videos and articles that I have read. I have my compound set to 30 degrees like I see done in the videos and have lined up my tool with a fish tail gauge. I am using the compound slide to advance in a couple thousandths after each pass and I always engage the half nuts on the same number. I'm cutting 20 tp i and that seems to come out correct but they just aren't shaped right. Could it be that my compound is different and needs to be set to something other than 30? I did try 29 once but it didn't really make any difference. I have attached a pic and maybe someone will see this and be able to tell right off what I am doing wrong. Maybe someone even has this same lathe and can give some tips on threading with this particular lathe. Thanks in advance!

 

[T Bredehoft]

Perhaps you should set your compound to 60º? The compound needs to be 30º off square with the work, not 30º off parallel with it.

 

[pdentrem]

Some lathes are marked opposite like Tom has suggested. 60 instead of 30. I posted apicture awhile back showing a easy way to set the top slide using a drawing triangle.
Pierre

 

[Handy4563]

Looks like to me the thread cutting bit is not 90 degrees to the shaft you are threading. I have cut lots of threads on my lathe, but if the cuter is off the threads will look off to one side.


Sent from my Venue8 3840 using Tapatalk

 

[RJSakowski]

Your problem is with how you align the threading tool. After you set your compound to the desired angle, you need to adjust the alignment of the threading tool. The tool must be set so the angle of each face to the spindle axis (work) is the same. This is normally done with a fishtail gauge, also called a 60 deg. center gauge or threading gauge, (a little gauge with 60 deg. Vee cut into the end). The threading tool is adjusted so it matches the vee when the other end of the gauge is contacting the work.

Bob

 

[RJSakowski]

Here is a Starrett center gauge.

Bob

 

[Doubleeboy]

You might also simplify your life a bit and set tool square with work using fishtail gauge like others mentioned and then use crossfeed to control depth of cut. On threads as fine as you are cutting the cross feed method works fine. Lot easier to cut threads when you take the compound out of the equation.

michael

 

[Ray73]

Your problem is with how you align the threading tool. After you set your compound to the desired angle, you need to adjust the alignment of the threading tool. The tool must be set so the angle of each face to the spindle axis (work) is the same. This is normally done with a fishtail gauge, also called a 60 deg. center gauge or threading gauge, (a little gauge with 60 deg. Vee cut into the end). The threading tool is adjusted so it matches the vee when the other end of the gauge is contacting the work.

Bob

Thanks for the reply. As I mentioned in my post I have lined up the tool using the fish tail gauge. maybe it is the angle of the compound. I will try a different angle.

 

[Ray73]

You might also simplify your life a bit and set tool square with work using fishtail gauge like others mentioned and then use crossfeed to control depth of cut. On threads as fine as you are cutting the cross feed method works fine. Lot easier to cut threads when you take the compound out of the equation.

michael

Perhaps you should set your compound to 60º? The compound needs to be 30º off square with the work, not 30º off parallel with it.

My compound only goes up to 40. I'll have to take a look at the angle and see which way I need to go with it.

 

[Ray73]

Your problem is with how you align the threading tool. After you set your compound to the desired angle, you need to adjust the alignment of the threading tool. The tool must be set so the angle of each face to the spindle axis (work) is the same. This is normally done with a fishtail gauge, also called a 60 deg. center gauge or threading gauge, (a little gauge with 60 deg. Vee cut into the end). The threading tool is adjusted so it matches the vee when the other end of the gauge is contacting the work.

Bob

Yes, I mentioned in my post that I used a fish tail gauge to align the tool. I think I'm doing that the correct way. I did it in the way that I see in most of the videos I have watched. It must be in the angle of the compound. mine was set to 30 but others have mentioned it may need to be 60 on my lathe. My lathe stops at 40 though so I guess its just a matter of measuring without the numbered plate.