Threading question

[Caleb85]

There is something wrong with my threading and I just can put me finger on it. I was useing a carbide tool but switched to a HHS and I just don't like the way they look! One thing I can't figure out is on my grizzly lathe to me the compound is sitting " sideways " ? So to put it at 29.5 according to the scale on it is not right! I'm only threading about 1" to 2" ahead of the chuck and I'm useing my tailstock . Anything else? Maybe I'm just being too picky?

 

[Ggmac]

The scale isn't correct on those , use a protractor to set to 29.5 . Remark your lathe . If you use the lathe 29.5 you end up cutting a buttress thread .
Yup , I just set it and realized it real quick .

 

[Ggmac]

I should say it wasn't correct on mine and a friends 12-36" . Hope that's the case , easy remedy. I use an inexpensive digital from Lowes and place against the barrel if unturned or side of the chuck .

 

[Caleb85]

Mine is the 12-36 as well.

 

[jkohler]

On your grizzly I bet if you set it to 60deg you'll have what your looking for. For threading they really don't need to be set right on 29.5 just close and you'll be just fine. I've threaded straight in plenty and that works fine also.

 

[carlsbad]

Can't see your photo enough detail but I bet the tips you're got about the scale are right. Your compound should be lined up with the face of the thread. Chuck up a threaded bolt with large threads and see if your compound is following the thread surface. --Jerry

 

[hogpatrol]

I grind my toolbit with clearance on the trailing edge and set the compound at 29 & 1/2. Tool then cuts on one side only. Straight in or a tool bit that cuts on both sides is gouging material, not cutting it.

 

[Danny1788]

I had the same problem with my older import lathe until I finally figured out that my compound was marked ''0" at 90 degrees. I just used a protractor and set up at 29.5 and used a carbide scribe to etch a mark on my compound so I can return to 29.5 quickly.

 

[jkohler]

With your compound set @ 29.5deg your tool will still cut on the right side more than you may think. I new when I posted cutting straight in that some would bock at that.

 

[bigngreen]

I grind my toolbit with clearance on the trailing edge and set the compound at 29 & 1/2. Tool then cuts on one side only. Straight in or a tool bit that cuts on both sides is gouging material, not cutting it.

Your tool needs to cut on the trailing side as well or your tearing the face of the thread that is making contact when tightened, you cut on the back side the amount your dialing in.

 

[hogpatrol]

Your tool needs to cut on the trailing side as well or your tearing the face of the thread that is making contact when tightened, you cut on the back side the amount your dialing in.

It is cutting on the trailing side, only the amount the cross slide is moved in on each cut.
Of course, one man's method is always better than another's.

 

[TRA]

It really doesn't matter what the angle the compound is set at. All you accomplish with the compound set at 29.5 degrees is a number of sharp steps in he back side of the thread. Every time you tighten and remove that thread it shaves metal. That 29.5 compound angle is and has been obsolete for a very long time.

 

[hogpatrol]

 

[jdh47]

Setting the compound over to 29.5* is the text book way everyone is taught. In truth you can cut good threads by plunging in .005 or less per pass with the cross slide. It is easier and less time consuming.

You will run into trouble boring threads in a smallish hole that way [ tapered threads] if you do not take very small cuts and repeat often because of tool deflection. That can happen no matter which method you choose.

Joe

 

[carlsbad]

You will, however, have problems at 33 deg or even worse at 60 degrees if you misinterpret the scale on your lathe. The main reason for 29.5 degrees is to make sure you aren't at 30.5 degrees. As joe implied above, you're much better plunging with your cross slide than setting at 31 deg. --Jerry

 

[Danny1788]

Your tool needs to cut on the trailing side as well or your tearing the face of the thread that is making contact when tightened, you cut on the back side the amount your dialing in.

The videos that this guy has on youtube are pretty good stuff, he is very clear and he shows you exactly what he is talking about not like other junk youtube videos. Rihan has posted a few videos of this guy before and I started watching a bunch of them.

 

[Puzzaz01]

Very informative!

 

[Erik Cortina]

Get yourself a "fish gauge" and verify that everything is in proper alignment, especially the cutting edge of your tool.

Your compound should read around 60.5 degrees if you want to set compound at 29.5 (90-29.5 = 60.5)