Logan 820 direct drive?

tmenyc

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I'm teaching myself how to use the 820, my first lathe and foray into machining, all to significantly up my skills in fountain pen restoration. So I'm learning as I go, and it's a wonderful puzzle, I must say.
In the absence of Logan 820 For Dummies, I've done pretty well with the South Bend book and the 820 operators manual, and almost continuous reading of this forum, much DM help from Mikey, and watching tubalcain and other recommended YouTube videos.

At this point, I have this question I can't answer: I think I've been running on back gear rather than direct drive. I think I've been using the back gear knob as a spindle release. But I can't seem to find how to engage direct drive. I'm looking for the "lock pin located in the side of the bull gear." (Logan manual) Is the lock pin what is shown in the closeup shot? And from mid-distance. It swivels but does not pull out. Is it possible that the flat belt falls off the 4 position of the countershaft because I'm in back gear? It works fine in 1 and 3.

Many thanks in advance. I promise other questions are brewing.

Tim
20190115_175835.jpg20190115_175839.jpg20190115_180118.jpg
 
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To engage, or disengage back gear there are two steps that need to be accomplished.

1. To operate in direct drive, the pin on the bull gear is "in", or engaged with the the pulleys. In this position the pulleys, bull gear and
chuck all turn as a unit, together. To the left of the "Logan" ID plate there is a knob. In direct drive that knob must be in, as shown below.

IMG_0304.jpg

2. To operate in back gear, the pin on the bull gear must be out, which disengages the bull gear from the pulleys. The knob on the
headstock also must be out and latched as shown below. The latch is a small metal piece in a slot in the bottom of the rod, which
cannot be seen from above. If you have difficulty pulling the rod out to the engage position it's usually because the gears aren't
meshing. Just rotate the pulley a bit and try again until they do. If the rod pulls out all the way but doesn't latch, it's probably
because the latch is broken or missing. Parts are available from Logan. While in back gear, power flows from the headstock
pulley through the gear to it's left to a gear on the countershaft, which rotates another gear that engages the bull gear and rotates
the chuck.

IMG_0302.jpg

I'm not familiar with the lever style pin on your bull gear. This is what mine looks like. It doesn't matter,
as long as it engages or disengages the bull gear from the pulleys properly.


IMG_0303.jpg

The important thing to remember is that when changing in or out of back gear, BOTH steps must be accomplished.

As for your belt slipping, you might need to adjust the countershaft alignment a bit. It looks as though you have the adjustable
countershaft supports:

IMG_0305.jpg

Notice that they have a screw and locknut arrangement. By adjusting these a bit so that the shaft is angled in or out some, you should
be able to keep the belt on the pulleys properly. It's a trial and error sort of process.

EDIT: One more thing I didn't mention above. As I said, when returning the lathe to direct drive from back gear, the rod on the headstock must
be pushed back in. To release the rod, the latch on the bottom of the rod must be pressed upwards with your finger. It then can
be pushed in easily. Just pushing the rod in won't do it.
 
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Thanks, appreciated. The knob and latch work fine. The issue is the bull gear pin. I didn't know what to do with it; wonder if it's stuck in. I'll work at it tonight. Also the countershaft supports. Will let you know!

Tim
 
Your locking pin looks homemade. If the bull gear turns with the cone pulley you're in direct drive, and that pin needs to be pulled out to shift into back gear. If the pin has the gear and pulley locked together then putting it in back gear will lock everything up solid. Someone will probably flame me for saying this, but I find it useful for loosening the chuck (as long as the chuck isn't stuck and you don't crank on it hard enough to break a tooth off the bull gear, which people have done). Of course you subsequently have to remember to take it out of back gear, or the belt will squeal/the motor will stall (ask me how I know ;).

You need a long straightedge to check the the side-to-side alignment and squareness of the countershaft pulley. As has already been pointed out, that model countershaft bracket has pairs of finicky adjusting bolts on each side. I set mine so that the bearings were generally centered in the yoke and tweaked until the belt was square to the pulleys. Don't torque down on them too hard or you can distort the bearing and cause the shaft to bind. There is a set screw in the small end of the countershaft pulley that you loosen for the side-to-side adjustment if the shaft isn't buggered up too badly. I had to disassemble mine and file the divots out of the shaft.

The countershaft bracket should pivot freely front to back when the lid is open. Mine was pretty stiff when I got it because the drive box holes for the one-piece bracket shaft weren't aligned, so I made two short pivot pins retained with E-clips. Logan later went to two pivot pins when they got rid of the fiddly adjusting bolts on the countershaft bearings.

Best of luck.
 
Briney, thanks, this is really specific and helpful. If I didn't have this day job on the other end of Manhattan from my shop I'd go check this out right now. Tonight!
Tim
 
So, does your bull gear pin do anything? Can you pull it out and push it back in? Does it rotate? Or does it just not move?
 
Since I didn't know which direction it was meant to go, I didn't push or pull hard, but it has not yet come out. The little pin is hinged, now I know to provide a grip, but I wasn't sure if there was more action to it than that. So I haven't given the pin a good tug yet. I suspect the same thing is happening with the clutch on the apron, but one thing at a time...
Tim
 
Ok, back gear and direct gear work fine. The pin is actually a switch that is turned. Took me a bit to get it looser. Forward is "in", per the Logan Manual; back is "out. I can't actually tell the RPM difference until I receive the old-fashioned revolutions gauge next week.
Now, on to the belt adjustment! Sadly, there are plans afoot for tonight, so it may have to wait for tomorrow.

Thanks for the help!
Tim
 
Your locking pin looks homemade.

Logan used two different style pins over the years. The earlier design (like Tim shows in the first picture) is part number LA-676 and was used on serial numbers 37063 and below. It is called "handle" in the parts manual. The mechanism is a bit more complicated. The newer simple style that Nogoingback shows was used on later models. It is part number LA-345 and is called "bull gear plunger".
 
Rich,
That's reassuring. Did I get the explanation of how it works correctly?

Tim
 
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