Compound Slide Angle

KevinMaiorka

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So I have been machining now for 10 1/2 years with a smithy 1220 machine. I have been using the compound for almost all of these years set at a 45° angle when I do general machine work. I have my compound set at this angle due to the fact that if I increase my cut by .010 then the cutter only advances .005 into the workpiece and I only remove .010 from the diameter of the work. Makes it a lot easier for me to do the math in my head and if I only need to remove a thou then only advance it one thou and not have to try for a half thou which is nearly impossible on some compounds. My compound is graduated in .002 divisions so this also makes it a bit more accurate when cutting in my opinion.

What do y'all set your compound angle at? I see most people usually have there's set parallel with the bed ways.

Kevin

Sent from my LGLS991 using Tapatalk
 
So I have been machining now for 10 1/2 years with a smithy 1220 machine. I have been using the compound for almost all of these years set at a 45° angle when I do general machine work. I have my compound set at this angle due to the fact that if I increase my cut by .010 then the cutter only advances .005 into the workpiece and I only remove .010 from the diameter of the work. Makes it a lot easier for me to do the math in my head and if I only need to remove a thou then only advance it one thou and not have to try for a half thou which is nearly impossible on some compounds. My compound is graduated in .002 divisions so this also makes it a bit more accurate when cutting in my opinion.

What do y'all set your compound angle at? I see most people usually have there's set parallel with the bed ways.

Kevin

Sent from my LGLS991 using Tapatalk
If you have your compound set at 45 degrees to the cross slide and the bed ways, you advance the tool .707 for every 1.000 that you feed in on the compound. That means you will cut 1.414 if you have a radius reading compound dial. If you want to advance .500 for every 1.000 you feed in on the compound, you will need to set the compound at 60 degrees to the cross slide, 30 degrees to the bed ways, which will cut 1.000 on the diameter when using a radius reading dial. Simple trigonometry learned 50 years ago, still remember the numbers for those angles without a chart or electronic gizmo...
 
Isn't it wonderful what we can remember. I remember that the diagonal of a one inch square is 1.414, the same figure bob mentioned above, Somehow, half the diagonal is .707, but I can't remember what its for. Why can't I remember what I had for breakfast?
 
So I have been machining now for 10 1/2 years with a smithy 1220 machine. I have been using the compound for almost all of these years set at a 45° angle when I do general machine work. I have my compound set at this angle due to the fact that if I increase my cut by .010 then the cutter only advances .005 into the workpiece and I only remove .010 from the diameter of the work. Makes it a lot easier for me to do the math in my head and if I only need to remove a thou then only advance it one thou and not have to try for a half thou which is nearly impossible on some compounds. My compound is graduated in .002 divisions so this also makes it a bit more accurate when cutting in my opinion.

What do y'all set your compound angle at? I see most people usually have there's set parallel with the bed ways.

Kevin

Sent from my LGLS991 using Tapatalk
I have set my compound to a variety of angles. 29.5º for threading, 0º if I want some extra travel capability on the cross slide. and I set it at 90º for controlled travel in the z direction.

BTW, setting the compound at 45º advances the feed by .0071" in the x direction for every .010" If you want to advance .005", the compound angle should be set at 60º. Setting at 84.3º will advance the feed .001" for every .010" of compound travel. Note that this angle is measured relative to a plane perpendicular to the spindle. If your compound dial is set differently, subtract the stated angles from 90º.
 
If you have your compound set at 45 degrees to the cross slide and the bed ways, you advance the tool .707 for every 1.000 that you feed in on the compound. That means you will cut 1.414 if you have a radius reading compound dial. If you want to advance .500 for every 1.000 you feed in on the compound, you will need to set the compound at 60 degrees to the cross slide, 30 degrees to the bed ways, which will cut 1.000 on the diameter when using a radius reading dial. Simple trigonometry learned 50 years ago, still remember the numbers for those angles without a chart or electronic gizmo...
Bob, I do not have a radius compensating compound. My wife (high school math teacher) and I are now trying to figure out your assessment on this and understand your math. We are not having luck doing so far. Please explain further as my wife will not be able to sleep until she understands this.

Sent from my LGLS991 using Tapatalk
 
I have set my compound to a variety of angles. 29.5º for threading, 0º if I want some extra travel capability on the cross slide. and I set it at 90º for controlled travel in the z direction.

BTW, setting the compound at 45º advances the feed by .0071" in the x direction for every .010" If you want to advance .005", the compound angle should be set at 60º. Setting at 84.3º will advance the feed .001" for every .010" of compound travel. Note that this angle is measured relative to a plane perpendicular to the spindle. If your compound dial is set differently, subtract the stated angles from 90º.
Please explain further as my wife and I are going crazy now trying to understand this. She is a math teacher with many years under her belt.

Sent from my LGLS991 using Tapatalk
 
Isn't it wonderful what we can remember. I remember that the diagonal of a one inch square is 1.414, the same figure bob mentioned above, Somehow, half the diagonal is .707, but I can't remember what its for. Why can't I remember what I had for breakfast?
If the hypotenuse is 1.000 then the other two shorter sides of a 45 degree right triangle are .707. If the short sides are 1.000 then the hypotenuse is 1.414.
 
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