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balancing my cuts for a short taper?

sourdoughsmitty

Aluminum
Joined
Mar 17, 2009
Location
cashmere wa
I have been having a problem turning a certain taper. What I have is a 5deg taper that is small on the headstock end and measures .93 @small end and 1.170 @ large end by 1.5500 long it seems like no matter how I make the cuts one end is always under spec I am using the compound to cut this. The measurements are probably flexible and the guy on the tray machine would;nt even notice it but I do as I want consistancy and accuracy in my work
thanx smitty
 
You need to do a little math, in which you subtract .930 from 1.170, which equals .240; which is the amount that the part tapers in 1.550. Then you need to set up a test bar, or something similar in the chuck of your lathe. Use blue dye to make two scribe marks visible 1.550 apart on the test bar. Mount a dial indicator on the toolpost of your lathe, with the plunger centered on the axis of the test bar, and with the plunger on the center height of the lathe, and at right angles to the axis of the test bar. Feed the compound rest along the test bar and adjust the angle setting until the indicator needle moves exactly .120 when traveling between the two witness marks on the test bar. Notice that the .120 is half the difference between the two diameters, which is the angle with the centerline of the test bar. If you follow these instructions, it should result in the exact setting that you need.

Lord Byron
 
I have been having a problem turning a certain taper. What I have is a 5deg taper that is small on the headstock end and measures .93 @small end and 1.170 @ large end by 1.5500 long

Using 0.930 at the small end, 1.170 at the large and 1.550 distance between the two, I'm coming up with 4.44 degrees, not 5.

Maybe I'm doing it wrong?
 
I like to set my tapers up using 2 indicators. I figure the tpi then use a 1 inch travel indicator on my longitudinal axis. and another on my workpiece. the one on the workpiece has to be on center as well as your cutting tool. the biggest thing you have to be careful with is making sure you have all backlash out before you start cutting.
 
HI guys ,
Sorry for the slow reply ,holidays and all ,good info so far when I posted I goofed on the length it is 1.500 and when I measured the original part with protractor it was 5deg ,however this was a basic protractor not the fancier one to give deg,min,secs so I see where "FTF" gets gets his dim's I am going to try "Bruce Nelsons" and "eight balls technique . and yes I always make sure I am on center. Thanx again every one for the help it is always frustrating for me to have the solution this simple that i did not see it but that is the fun of this as I am about 50/50 hobby and vocation type machinist learned all my basics from my dad who was a machinist with his advice that rest is all experience, how true that is . I had the benefit of working the bering sea fisheries for years to be allowed the freedom to just do it as that sometimes is all we had , and an even better benefir was having an old crusty ex merchant marine chief who stoo over your shoulder as you made the part as he instructed ,thereby you knew from then on how to do that task merry axmas a hopefully ahappy new year smitty
 








 
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