CNC Lathe Servo Spindle Upgrade

@JimDawson

LOL I've got to pile on.

I'm away from home and have limited tools available. I have some round parts with 5/16 hex center hole. I wanted to use a cordless tool as a lathe to spin the part so I could deburr and cleanup an OD thread. Great, all I need is a 5/16 hex insert bit or power bit. I would have sworn I had one (or more) in my kit. No such luck. ACE Hardware doesn't stock it. Even struck out at a used tool shop. I went to two brick and mortar stores (in a highly populated area of Los Angeles, CA) wasting my time and probably $10 on fuel.

On Amazon, an industrial supplier in Houston, TX had exactly what I wanted (Bondhus 3" long power bit, USA made) for $3.09 total delivered. It was sent FedEx, in a 8" x 8" x 7" cardboard box and arrived in 2 or 3 days. They must have lost $$ on this one. McMaster has a 2" long option for $11.53+tax+S&H.
 
First parts! :dancing banana: No more secondary operations on this part. Just the time savings on this part will pay for the C axis upgrade in a couple of months. A typical run of these is 400 parts, done about once a month.

Here is a part right out of the lathe, no deburring or other finishing. This particular part is #18 since I got the setup done, we get 26 parts out of a 48'' bar, 3/4'' 303 SS. 17/32'' center hole, 1/2'' slot, cross drilled 0.265'', 1/2-20 threaded end, takes exactly 5 minutes to run one part.

Order of operation:

Drill center hole and chamfer the edge with the drill bit.
Enable C axis mode
Rotate spindle to -90 deg
Mill the slot, 5 passes
Rotate the spindle to -180 deg
Cross drill the first hole
Rotate the spindle to 0 deg
Cross drill the other hole
Disengage the C axis
Face and profile the large diameter
Make a pass with the 17/32 bit again to clean the burrs from drilling
Groove each end of the threaded area for tool clearance
Profile the threaded area and rear chamfer
Thread, 6 passes
Part off
Bar Pull the next piece into position
rinse/repeat

Next step is into the vibratory deburr for finishing.

1630815350439.png
 
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And for the next installment:

Another part that is similar to the one above, but has a couple of features that required the full C axis interpolation capability which up to this morning we didn't have. This required some additional programming (and debugging) in order to get full coordinated motion between the Z and C axis. And of course we were in a time crunch as normal. :eek: The good news that I work better under pressure, a bit more motivated anyway. I'm old enough it takes a lot to get me very motivated. :grin:

We have been making a similar part for some time, but were doing it a different way. First we were cutting the slot and lead in chamfer on the mill in a second operation as below.
1631332734958.png

Then we installed the live tools in the lathe and were able to slot and chamfer in the lathe. Ran this way for a couple of years. Cutting the slot was pretty fast, about 30 seconds or so. But the chamfer was taking forever, well about 1.5 minutes anyway, just because we couldn't take a very big bite at a pass. We could make this part by locking the spindle and doing the slot and chamfer with the live tooling. Run time a bit over 6 minutes. :cautious:

1631332975358.png

And the current part hot off the press lathe, the last part out of today's run. I said time crunch above, as these were coming off the lathe, the first 8 pieces were being packaged and shipped. o_O Absolutely positively had to ship today. Not bad considering we couldn't even make them until late this afternoon. The bad news is that I didn't get my nap this afternoon. :mad:

The radii at the top of the slot are profiled by the spindle rotating in a coordinated motion with the Z axis. So as the tool is feeding in, the spindle rotates the proper amount to create the radius. The radii and the slot are all cut in one pass, in one nice smooth motion, in about 30 seconds. A huge time savings, total part time is now 04:45, vs. the 6+ minutes the part used to take. And with some optimization I can maybe shave a few more seconds off of the time. We run at least 400 of these a month, so saving over a minute per part will save a day of run time over a batch. Won't take long to pay for the spindle upgrade at that rate.

And as a bonus I worked some magic on the part-off to eliminate a second operation to chamfer the hole on the bottom. Now just requires a quick deburr with a hand drill and chamfer tool. This part is now ready to install & ship right off the machine without further processing.
1631333786770.png

I'm going to try to get a video of this part being machined. I need to get some 3/4 aluminum or brass round stock so I can run it without coolant. I'll kill the tools without coolant in the stainless.
 
Very nice. I missed that those were SS. Yes video would be awesome!
Robert
 
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