Step 7: Welcome to the DRO

Most modern lathes have a Digital Read-Out fitted to them. This is a lot easier than squinting at the tick-marks on a handwheel. 

The two metal lathes at TechShop San Francisco (Jet Model GW-1440 W3 if I recall) both have DROs.

So here's the idea; get a clean surface that is aligned to the lathe (by facing and turning). Now, without moving the tool from the last operation, zero the DRO. Now you know that any number you see on the DRO will be relative to the surface you just cut.

Following facing, you zero the Z axis (that's the spin axis) on the DRO. This means the cutting edge of my tool will display its position relative to the clean end of the piece.  Here's the trick; because of backlash on the carriage traverse, you have to do this in a specific way. Starting off the piece, turn the handwheel until you are cutting into the face. Now lock off the carriage using the lock-off lever. Use the cross-feed traverse to make your facing cut then, without touching anything, go to the DRO.

Hit "set zero" and then hit the button next to the Z axis.

You do the exact same thing to set the X axis on the DRO, except that you are working at right angles to the previous operation, and you don't need to lock the cross-feed.

There's another wrinkle to this, but before we do anything else to this piece we need to install the live center.

<p>Awesome project . Just got a grizzly lathe. Will have to make it for sure</p>
<p>Nice job. I love your attention to detail, and I hope to try out this project someday. Your descriptions are easy to follow and precise, so I think I will have no issues when I try to make this.</p><p>I thought the coolest part was how the aluminum insert blended in perfectly after it was faced on the lathe. That was very neat- I expected some sort of line or gap, but there was none. Very, very cool :)</p>
MOST of the time!<br><br>I did have one where my drill bit wanted to wander. It chewed up the hole a bit, and I ended up with a visible gap. Could have probably taken more of a bite with the face but I was doing a set of four at once I wanted to be as close to identical as possible.<br><br>Getting the plug sized right is a huge pain. My average is three plugs cut for every finished grenade. Only one so far was so loose I had to drill it out, at least.<br><br>
<p>Sorry, when I saw this picture on the EMAIL feed, with the cap, All I could think of right then was...... Nitro-9... (The Only can of deodorant that registers 9 on the Richter scale!) (--Doctor Who, Ace) </p>
<p>That was absolutely awesome brother. And I was thinking man this guy talks like he has previous military experience. If its safe to be presumptuous here I would say you are prior services, maybe even more specifically army. If not you are definatly talented enough to get in on the GOV work crew with this kind of attention to detail.</p>
<p>Yup. That was twenty years ago, but I was Army, twelve boom-boom to be precise, plus got to wear the red beanie and jump out of perfectly good airplanes while they was still in the air.</p>
<p>Wow. Awesome Project. I am a high school 'shop' teacher. I am always looking for machine lathe projects. Might have to make this first before I turn my students loose on it. That 45deg. knurling looks tricky. Thanks</p>
Thanks!<br><br>That knurl was scary all right, and with two tries I still haven't gotten it quite right. Might be safer to flip first and knurl towards the headstock, at that...<br>
<p>Outstanding work! </p>
<p>Nicely written and documented.</p>

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