What's new
What's new
By:
Advanced search…

correcting a taper

C

CNCbeginer

Plastic
Joined
Aug 7, 2015
Looking for some help on a problem Im having

I am trying to program a taper to compensate for a taper over 1.165 inch
Where my problem lies is that I am putting a groove in the middle of it

any ideas?

This is my finish pass that I am trying to straighten out. I'm about .00025 and I would like to be straight as this will be have about a .0005 clearance bushing.


G00Z1.300
G00X0.24125
G01X0.28125Z1.260 (X0.28125)
G01X0.28156Z0.740
G01X0.27756Z0.720
G01Z0.635
G01X0.28156Z0.615
G01X0.28196Z0.090 (X0.28196)
G01X0.271Z0.080
G01Z-0.020
G00X0.350
G00Z2.5
 
CNCbeginer said:
Looking for some help on a problem Im having

I am trying to program a taper to compensate for a taper over 1.165 inch
Where my problem lies is that I am putting a groove in the middle of it

any ideas?

This is my finish pass that I am trying to straighten out. I'm about .00025 and I would like to be straight as this will be have about a .0005 clearance bushing.


G00Z1.300
G00X0.24125
G01X0.28125Z1.260 (X0.28125)
G01X0.28156Z0.740
G01X0.27756Z0.720
G01Z0.635
G01X0.28156Z0.615
G01X0.28196Z0.090 (X0.28196)
G01X0.271Z0.080
G01Z-0.020
G00X0.350
G00Z2.5
Click to expand...

Hello CNCbeginer,
If you're going to turn it straight by fudging the program, just do more of what you're already doing. However, based on the X0.28125 and X0.28196 coordinates, you have a taper of a little over 0.007" per foot, likely being caused by the Spindle (head-stock) being misaligned with the Z axis. At that rate, I would be fixing the cause of the problem rather than chase a fudge fix.

Regards,

Bill
 
angelw said:
...... However, based on the X0.28125 and X0.28196 coordinates, you have a taper of a little over 0.007" per foot, likely being caused by the Spindle (head-stock) being misaligned with the Z axis. At that rate, I would be fixing the cause of the problem rather than chase a fudge fix.
Click to expand...

+1 on this^

If you have that much taper due to headstock alignment you also are not cutting a flat face.
 
CNCbeginer said:
Looking for some help on a problem Im having

I am trying to program a taper to compensate for a taper over 1.165 inch
Where my problem lies is that I am putting a groove in the middle of it

any ideas?

This is my finish pass that I am trying to straighten out. I'm about .00025 and I would like to be straight as this will be have about a .0005 clearance bushing.


G00Z1.300
G00X0.24125
G01X0.28125Z1.260 (X0.28125)
G01X0.28156Z0.740
G01X0.27756Z0.720
G01Z0.635
G01X0.28156Z0.615
G01X0.28196Z0.090 (X0.28196)
G01X0.271Z0.080
G01Z-0.020
G00X0.350
G00Z2.5
Click to expand...


Well, if your spindle was straight, you would still need to map this part anyhow, it's just that you would start smaller and get bigger near the chuck - doo to tool pressure.

You have a long skinny part. This is a challange for many folks, let alone a newbie.

You have learned yourself how to "map" a long skinny part, as these don't just go continually - for whatever reason? IDK.

You are right on track, so just keep on keepin' on.

Next time, buy a swiss lathe for this part. ;)


Personally, I am impressed that you are able to get it to run at all. You will have the best luck with "sharp" tools with no dwell. Like a ground insert for alum maybe (steel inserts have a "honed" edge), or maybe a HSS "tool bit" that is ground sharp, but has no flat surface. And then feed slowly.




-----------------------

Think Snow Eh!
Ox
 
even changing insets will change it on this skinny a part. ideally you'd run this in a swiss type... but we use what we have.
I have had to tweak taper slightly in properly aligned machined- long stuff even in larger diameters one gets a little chuck flex, a little part bend, and a little action from Murphy's law of machining- you won't cut the tip small until the finish pass- and then it is ALWAYS out of tolerance low on one end only.
 
Ox said:
Well, if your spindle was straight, you would still need to map this part anyhow, it's just that you would start smaller and get bigger near the chuck - doo to tool pressure.

You have a long skinny part. This is a challange for many folks, let alone a newbie.

You have learned yourself how to "map" a long skinny part, as these don't just go continually - for whatever reason? IDK.

You are right on track, so just keep on keepin' on.

Next time, buy a swiss lathe for this part. ;)


Personally, I am impressed that you are able to get it to run at all. You will have the best luck with "sharp" tools with no dwell. Like a ground insert for alum maybe (steel inserts have a "honed" edge), or maybe a HSS "tool bit" that is ground sharp, but has no flat surface. And then feed slowly.




-----------------------

Think Snow Eh!
Ox
Click to expand...

Hello Ox,
You know, the small diameter didn't even register with me, notwithstanding that I even type their values in my previous Post. I looked at the length and thought, "you only get taper on a length that short with the Spindle out of alignment".

The amount of Taper due to tool pressure, as you would know, varies, getting less as the tool gets closer to the chuck. Not that it's applicable for the OP's part with a groove part way along, but I've had good success cutting a very large Concave arc, with the circumference passing through the Start and End point of the Taper. You have to stuff around getting the best arc radius to use, so its not that useful for short runs.

Regards,

Bill
 
Thank you for all the great ideas
I did end up getting it to turn straight. You may call it fudging but remember I am new at cnc.
But I learn fast. Thanks again. 😎
 
Fudging is exactly what you need to doo in cases like this.

BTW - you can usually up the RPM/feed as you go down the map too.


-----------------------------

As long as you're not packing it!
Ox
 
You must log in or register to reply here.








 

ABOUT PRACTICAL MACHINIST

With more than 10.6 million unique visitors over the last year, Practical Machinist is the most visited site for metalworking professionals. Practical Machinist is the easiest way to learn new techniques, get answers quickly and discuss common challenges with your peers. Register for the world’s largest manufacturing technology forum for free today to stay in the know.

Learn more about us.

STAY CONNECTED

Facebook Instagram YouTube LinkedIn Pinterest Twitter Tiktok

Register Become a forum member. Register today.

Sign Up Sign up for our e-newsletter.

© 2024 Copyright Practicalmachinist.com. All Rights reserved.

Back
Top