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Hf 7 X 10 Dial Graduations

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meikj

Swarf
Registered Member
Joined
Mar 15, 2014
Messages
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#1
Newbie question:

I was doing some setup on the mini lathe with a DTI, and trying to figure out what the wheel graduations actually represent. They are marked as .025mm and .001", but that doesn't seem to be correct!

How do you calculate exact measurements with this dial?
 

Ulma Doctor

Infinitely Curious
Active Member
Joined
Feb 2, 2013
Messages
4,300
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3,496
#2
mount a dial indicator on your apron and measure the direct movement.
if you want to know actual depth of cut multiply the measured movement X2 = the actual depth of cut.
you'll play for a long time to try to cut to depth off the dial graduations that seem to have no real correlation to rational measurement.:mad:
as an approximation .04" is usually a graduation, but don't hold me to it- test it and see for yourself.
 

meikj

Swarf
Registered Member
Joined
Mar 15, 2014
Messages
4
Likes
3
#3
mount a dial indicator on your apron and measure the direct movement.
if you want to know actual depth of cut multiply the measured movement X2 = the actual depth of cut.
you'll play for a long time to try to cut to depth off the dial graduations that seem to have no real correlation to rational measurement.:mad:
as an approximation .04" is usually a graduation, but don't hold me to it- test it and see for yourself.
Thanks. I also have the HF X2 mill, and I replaced the original feed screws with the 20TPI version from LMS. That makes it very simple to change positions by counting hand wheel rotations. I was hoping to be able to do something similar on the lathe, i.e. counting turns or dialing in a few thous by reading the indicators.
 

meikj

Swarf
Registered Member
Joined
Mar 15, 2014
Messages
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3
#4
Valuable lesson learned - don't trust an old Harbor Freight dial indicator! I noticed some "anomalies" in my measurements, and it turned out that the old HF dial indicator that I was using was less than accurate across some of it's range. I suppose it's time to invest in something a little better :)

So, the lead screws on the lathe are moving as expected, but the dial indicator I was using was not.
 
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