Gallery, Projects and General > How do I??

MT2 die holder....attempt

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ieezitin:
I agree with everything said with the advice given... i have this to add.. you were surprised when you moved over the tailstock the given amount to give you the desired taper.. that's the power of trigonometry and a the biggest asset to understand  in machining, a humble hobbyist bench top lathe can with reputability remove .0001 (not a typo) with the compound using trig.. as already discovered sliding over the tailstock using math will create accurate tapers.

The process is the same it all boils down to solving a right angle and applying the decimal point and reading as far to the right as needed to get the precision required..im encouraged your experimenting its the best learning practice.. best of luck..

Anthony.

smthrll:
Thanks for the great tips guys.  I'm totally stoked to try this again.  I've read so many posts and watched so many videos - lots of conflicting advice and some of it is pretty tough to decide what is exactly applicable.   It's nice just to ask a direct question to a real person. 

I like the idea of  "sneaking up" with a heavier cut as well, rather than my .003".  I'll have another go at it this weekend.

Rollie

sparky961:

--- Quote from: smthrll on January 23, 2017, 09:20:34 PM ---I like the idea of  "sneaking up" with a heavier cut as well, rather than my .003".  I'll have another go at it this weekend.

--- End quote ---

You have the notion of "sneaking up" a bit reversed.

Sneaking up more accurately describes what you were probably doing the first time around.  As in, you take heavy roughing cuts until you're as close as you're comfortable with, then you take a lot of very light cuts trying to end up at the final dimension without going too far over what you want.  You probably only take 0.003" or so because you figure if you go over it won't be by that much and the part will still be ok.  Right so far?  Yup, been there.

The method I'm describing would be called (pretty sure anyway) a "trial cut".  You're essentially taking one extra pass before your finishing pass that duplicates the cutting conditions of the finish pass, except it leaves very close to the same amount of material on the part for one more final pass.  It gives you one chance to make adjustments based on a measurement after the trial cut.  As long as your final cut is removing close to the same amount of material, you should be able to directly dial in the difference and end up with the right size.

I think you probably got most of that the first time around, but if you're telling anyone else what you're doing you'll want to differentiate between "sneaking up" and a "trial cut".  Sometimes you can't avoid the former, and sometimes the latter is the only way that gives acceptable results.

Biggles:
I agree to all that has been said already except that I would keep the heat down if you’re going for an accurate job. In addition let the work cool down before you take your last few runs.  :coffee:

Pete.:
Next time you are going for a parallel cut make a trial cut then measure eaxh end with a mic. Adjust the tailstock until its cutting true then bring it down to size. Of course now you have hit the taper angle first time with your set-over you're guaranteed never to manage it again :)

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