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Old 12-03-2006, 06:13 PM
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irnsrgn irnsrgn is offline
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Default Making Long cuts on a lathe

One of the hardest things to do is to make a long cut on a lathe and not have it tapered. A lot of people don't realize you have to zero your tail stock in some fashion. This can be a real pain, as you take a small cut, mic the ends of the cut and attempt to compensate by adjusting the tailstock, another small cut to check the alignment, it gets time consuming and frustrating.

This is a small line up tool, I borrowed from an oldtime RR machinist that makes things simple, and it will work in any lathe.

1. Drill the center hole in the stock to be turned.

2. Set the stock up in your lathe and adjust the tailstock to the proper position.

3. Remove the stock, put the line up tool in the lathe and check or reset the tailstock with a dial indicator and you are ready to go, checking the results is a good idea after the first cut.

a. To make this tool, you will need a piece of scrap round stock, a full length 1/4 inch or so brazing rod and a spring that will slide over the rod.

b. Machine the stub to any size desired, drill a deep center hole in the end, bore and tap a 1/4 threaded hole in the end.

c. Leaving the stock in the chuck, under size a section next to the chuck so that you leave a shoulder.

d. Part the end off and chamfer the edges.

e. Thread the very end of the bronze rod and screw it into the end piece leaving enough room so the tailstock point doesn't bottom out.

f. Make a stop collar with a set screw to tension the spring.

Application pictures below.

I hope this helps some of you.
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  #2  
Old 12-03-2006, 09:37 PM
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Very Nice

It looks like that would be just as useful if you needed to set the lathe to turn a shallow taper. Neat tool.
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Old 12-05-2006, 06:39 PM
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OK I'll ask the stupid questions. I have always just made test cuts and offset from there, so I am more than willing to learn a new method.

I am not quite sure how to use this? As far as I can figure you indicate at the shoulder on the chuck, zero the indicator, then run the carriage down to the 2nd shoulder and indicate there? Offset until you get to zero. That sound about right?
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Old 12-05-2006, 09:28 PM
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you got it.
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Old 12-07-2006, 10:55 PM
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very nice indeed. i'm going to make one of those. THANX
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Old 09-18-2007, 12:39 PM
stock z/28 stock z/28 is offline
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Hello,

That is a neat tool.

The one question I would have is that if you are using the taper on the center to engage the chamfer on the test piece aren't you depending a lot on the accuracy of the chamfer?

I have seen similar issues when using tapered cones to align tooling off of various bores. The cone aligns to chamfer is not concentric with the bore the set up is off.

I have made precision plugs that fit the actual bores now instead of using the cones.

This may not be same scenario, Im just wondering.
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Old 09-18-2007, 01:40 PM
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Nice. I'll file that away. I've worked my way down to a Logan 9X24 so I don't have the long cut problem right now..

It has served me well and I even resurfaced the slip rings on my Bob Cat 225G. Had to use a bed extension for the tailstock but it got-r-done...
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  #8  
Old 09-18-2007, 02:30 PM
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Quote:
Originally Posted by irnsrgn View Post
One of the hardest things to do is to make a long cut on a lathe and not have it tapered. A lot of people don't realize you have to zero your tail stock in some fashion. This can be a real pain, as you take a small cut, mic the ends of the cut and attempt to compensate by adjusting the tailstock, another small cut to check the alignment, it gets time consuming and frustrating.

This is a small line up tool, I borrowed from an oldtime RR machinist that makes things simple, and it will work in any lathe.

1. Drill the center hole in the stock to be turned.

2. Set the stock up in your lathe and adjust the tailstock to the proper position.

3. Remove the stock, put the line up tool in the lathe and check or reset the tailstock with a dial indicator and you are ready to go, checking the results is a good idea after the first cut.

a. To make this tool, you will need a piece of scrap round stock, a full length 1/4 inch or so brazing rod and a spring that will slide over the rod.

b. Machine the stub to any size desired, drill a deep center hole in the end, bore and tap a 1/4 threaded hole in the end.

c. Leaving the stock in the chuck, under size a section next to the chuck so that you leave a shoulder.

d. Part the end off and chamfer the edges.

e. Thread the very end of the bronze rod and screw it into the end piece leaving enough room so the tailstock point doesn't bottom out.

f. Make a stop collar with a set screw to tension the spring.

Application pictures below.

I hope this helps some of you.
I see how it works and it looks like a real quick way to get the tailstock aligned with the chuck.The one question I have is does it assume that the bed is pefectly level or would it also correct a minnor twist in the bed?
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Old 09-19-2007, 08:55 AM
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nothing will correct for twist in a lathe bed except having it repaired.
If you are concened about your center set this up and indicate the chuck end until it is running true then go to the tailstock and take readings every 90 degrees adjust the tailstock for minimum average readings.
any remaining error indicates the acuracy of the center used and will set the best available accuracy for the lathe set up under test.
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Old 09-19-2007, 10:18 AM
standles standles is offline
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Ok I am going to go ahead and prove my ignorance by making an alternate suggestion.

Could one chuck a laser pointer/designator in the headstock and align the tailstock to the dot?

See I told you asking a question with no machinist background would expose me


Steven
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