Atlas gear tolerences?

[littlejack]

Here I am again.
Question regarding gear teeth clearance.
While checking out my 'new to me" Atlas 10" QC 54 last night, I noticed what looked to me to be too much clearance where the gears mesh
up. The gears are not lubricated properly, and I have that question up for opinions on another thread.
Anyway, how do you tell if the gears have the right amount of clearance, or too much? Some of the gears have adjustment for them, and
some do not. Looking at the Tumbler Assembly, when it is positioned from lo to hi or visa-versa, the gear that is supposed top be engaged
has ( what looks to be) too much teeth clearance. I you move/slide the "index plate" up or down to get tighter tolerances on that gear,
the other gear will have too much clearance when position is moved to use the opposite setting, i.e. hi or lo. I hope that description was
understandable. The gears look to have very little wear, so I do not believe it is a "worn teeth" issue.
The gear noise when running is almost deafening. Hopefully, the lubrication issue will take care of some of that noise.
Are these machines normally that noisy from the gears?
All suggestions appreciated.

Regards
Jack

 

[Terrywerm]

Welcome aboard, Jack. The tooth clearance you are seeing is probably not out of the ordinary, especially since these gears run at relatively slow speeds and at low torque. There is little pressure on them. Lube will help to quiet them down, but spur gears like these are noisy by nature, especially if there is excessive tooth clearance. If they were running in a high-torque environment, or were transmitting large amounts of power, then you would want to see about .003" clearance between the teeth.

It is difficult to determine if you have excessive clearance or not based on what you wrote, but actual measurements or photos would be helpful.

 

[Bill C.]

Welcome aboard, Jack. The tooth clearance you are seeing is probably not out of the ordinary, especially since these gears run at relatively slow speeds and at low torque. There is little pressure on them. Lube will help to quiet them down, but spur gears like these are noisy by nature, especially if there is excessive tooth clearance. If they were running in a high-torque environment, or were transmitting large amounts of power, then you would want to see about .003" clearance between the teeth.

It is difficult to determine if you have excessive clearance or not based on what you wrote, but actual measurements or photos would be helpful.

When I was in highschool school class we had to change gears in order to change feed rates. We would bring the idle gear(s) together with enough clearance to be able to barely rock the gear train when moved by hand. It took practice to get that feel. Those were well used lathes that were baby by the students.

 

[pdentrem]

I believe that in the Atlas manual, they suggest 1 or 2 strips of paper as the clearance between the two gears.
For quieter operation use grease, for easier clean up oil is used. I have used both over the years. In either case, the gear train is not whisper quiet with used gears, in my experience.

I have an old spray can of Open Gear grease, and yes it sticks like snot to a door screen! Mine is by Mobil Oil.
Pierre

 

[Dranreb]

Hi jack, yep, noisy gears are horrible, even more so when someone new comes into your shop...

A piece of paper in between the gears as you tighten the holding nuts is supposed to be about right, but in practice it's just trial and error.

The noise will vary depending on wear and sometimes it's fine in forward but noisier in reverse, or visa versa....

They may get quieter over time as the gears you use most often get worn in together, so it may help to mark which side you put toward the headstock, it helps to go over each gear before you use it and check for nicks and embedded swarf, stuffing a wad of paper towel in the end of your spindle is a good trick as it can stop chips getting out and onto the gears. If you have enough of them try swapping gears on different center bushes. This all sounds a bit fussy but it soon becomes habit and only takes a glance to check as you fit each gear.

As you know by now changing and adjusting a gear it's a bit of a juggling act, trying to tighten the nut just enough to grab, then lift or lower the banjo while moving the gear along the slot till it feels right, what happens then is when the nut is fully tightened it all goes wrong...:rofl:

I now use way oil on mine as it just takes a squirt in one or two gears for it to cling all around the cluster,

Bernard

 

[littlejack]

Back again:
I went out and done some lubricating on the gears. I used chain saw bar oil, as that is what I had available. For the record, it looks like the
"bar oil" works very well. It is stringy, and sticks to the gears. I think I will be using it for a while, and see how things work out.
Now for the gear noise, things got a little quieter, but not a whole lot. I think I may have found one of the problems.
As I stated earlier, a couple of the gears looked like there was too much space between the teeth when meshing with another gear.
The two smaller gears on the tumbler assembly are the worst. When the tumbler assembly is indexed to either the upper or lower indexing
holes, the gear teeth have too much gap to mesh properly with the spindle gear. I did move the plunger out of the indexing hole, and move
the tumbler up and down so the gears meshed properly. It looks to me that the indexing holes in the index plate, were drilled/punched too
close together. I am going to make another index plate with the two outer holes further apart. This will be trial and error until I get what
looks like the proper mesh in the gears, when engaged in either index hole.
All of the other gears have tighter tolerances than the two on the tumbler assembly. When the machine is running, I can take hold of the
tumbler knob, and literally feel the gears making the noise.
Any thoughts?
Jack

 

[wa5cab]

Jack,

One other thing to check is the running clearance (fit) of the tumbler gears on the pins and bushings that they run on. Nothing lasts forever. Wear here will increase the running clearance between the tumbler gears and the two gears that they mesh with.

Robert D.

 

[pollardd]

I didn't worry to much about the options and thought chain saw cutter bar oil will probably do the trick on the change gears. I'm glad that I'm not alone with this choice.
David

 

[littlejack]

Me again:
Thank you all for your replies. I appreciate the effort to solve another members problem.
I went and bought a piece of aluminum to fabricate another index plate. I got it made and installed. It worked perfectly.
The new positions of the index holes, allowed for a much better fit of the gear teeth in question.
With that being said, there was still way too much gear noise. It sounded something like this: gggggutt,gggggutt,gggggutt,gggggutt.
Anyway, with some very close inspection on my part, I found that the lower gears on the quadrant assembly were meshing way too tight
with the gear on the compound assembly. I started there and adjusted up the tolerances, then worked my way up through the
other adjustable gears. Apparently, who ever set the gear tolerance prior to me getting the lathe, got'um a lllliiitle too tight.
Turning the machine on, was music to my ears. No growling or gggggutt,gggggutt,gggggutt,gggggutt.
Oh, I did check the fit of the gears on their respective studs on the tumbler assembly. There is a small amount of wiggle room, but not
much. Not enough to set up a growl or chatter. I'm a lernin.
Regards
Jack

 

[Dranreb]

Glad you got it sorted, and I really liked your sound effects, that must be a first on this forum...:LOL: