How Much Play Should There Be?

Jmanb13

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I'm cleaning my old LeBlond piece by piece. I just finished putting the apron back together and It seems that I have lots of leeway on how far I drive in the bushing on the bevel gear. If I drive it in all the way flush the 2 gears in the picture below do not even touch. If I drive the bushing out a little it takes up some play, but I don't know how far out I should drive it and I did not measure it before I took it apart. Any ideas?

The picture below shows how I currently have it and how much play is in the gears.

apron.jpg
 
It kinda depends on what is happening at the other end of the shaft. There should be some way to make adjustments that are intentional and will hold where you set them. The fit is also determined by the protrusions of both gears, not just one of them.
 
The other end of the shaft of the big gear is just a bushing to support the other end.

The feed rod runs through the little gear. It just floats back and forth, there is no adjustments on it that I have seen. The only adjustments I seem to be able to make is pushing the brass bushing of the big gear out and in. There is a set screw that locks the bushing in place whenever you have it at the position you want it. At the point it is at right now, the bushing is as far out as I could possibly move it without the apron case covering the oil hole in the top of the bushing inside of the apron.

Here is a slightly wider angle shot to see what is being worked with here.
Apron2.jpg

Here is the exploded view from the manual. The diagram showing where the small gear goes is incorrect however, it goes in the bottom hole not the top.
Exploded.jpg
 
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If you're talking about part 15, isn't there a divot where part 12 locks it in? (there appears to be, or that may be the oil hole. I can't say I have been that deep into the apron on a LeBlond. That is, if 12 is the set screw. If there is no divot, they expect you to set the clearance in the geartrain and make a divot so that it is locked into place. In the future, if there is adjustment needed, simply rotate the bushing and put a new divot in place.
 
When I rebuilt the Boye Emmes powerfeed this past summer there was no integral adjustment. This looks like a similar situation. Maybe...
I played with shim stock behind the small bevel gear until it would spin freely but fully engage all the teeth.
Seemed to work very well.
Not sure if this helps. Tony may be right.

Daryl
MN
 
Proper setting of bevel gears is typically done using Prussian Blue on the gear teeth and shimming to obtain the correct contact pattern. To explain the correct contact pattern and how to correct improper contact patterns is way too involved to explain here and is best demonstrated with visual examples. There are many resources, especially on the internet that will explain the process. Google is your friend :). There is also a lot of information in Machinery's Handbook about proper backlash settings. But, as with many things in MH, you'll feel like you're studying for a Mechanical Engineering degree before you get your answer.

Ted
 
Yep, that's what I used. Well I actually used a sharpe.
Watch for an even print.

Daryl
MN
 
I'm cleaning my old LeBlond piece by piece. I just finished putting the apron back together and It seems that I have lots of leeway on how far I drive in the bushing on the bevel gear. If I drive it in all the way flush the 2 gears in the picture below do not even touch. If I drive the bushing out a little it takes up some play, but I don't know how far out I should drive it and I did not measure it before I took it apart. Any ideas?

The picture below shows how I currently have it and how much play is in the gears.

View attachment 141952
When you have a worn pinion as you have here, there's not much you can do to take up all of the play. What you do is line up the the bigger OD's of each gear or the big end with each other and call it good. At this point in life, it's not going to hurt any thing to move the pinion past this point a little to take up the slop and secure. You may even have to shim up behind the bull gear a little to help. Ken
 
If you're talking about part 15, isn't there a divot where part 12 locks it in? (there appears to be, or that may be the oil hole. I can't say I have been that deep into the apron on a LeBlond. That is, if 12 is the set screw. If there is no divot, they expect you to set the clearance in the geartrain and make a divot so that it is locked into place. In the future, if there is adjustment needed, simply rotate the bushing and put a new divot in place.

There was a divot in the bushing, but there is also a oil feed hole in the top and an oil drain hole in the bottom. However, when I removed it I did not notice the set screw so I buggered up the divot quit a bit when I removed the bushing. The bushing is made from brass and is quite soft. I actually plan to make another one whenever I get the lathe up and running.

The way I think it works is that the oil drips into the bushing from above, gets spun around inside the bushing where it finds its way into a groove and then drains out the bottom. I guess this means that the bushing needs to stay oriented in the same general direction.

Before I took this apart it had crud on it so thick that there was no play, the crud on this section of the lathe was the WORST it is anywhere on the thing. At least 1/4" thick or more.

When you have a worn pinion as you have here, there's not much you can do to take up all of the play. What you do is line up the the bigger OD's of each gear or the big end with each other and call it good. At this point in life, it's not going to hurt any thing to move the pinion past this point a little to take up the slop and secure. You may even have to shim up behind the bull gear a little to help. Ken

If the bull gear is the bigger one, I don't think there is much option for shimming it. The bearing (#15 in picture) fits exactly between the gear (#13) and the gear teeth on the shaft (#17) with maybe only 1/32" between them.

When I rebuilt the Boye Emmes powerfeed this past summer there was no integral adjustment. This looks like a similar situation. Maybe...
I played with shim stock behind the small bevel gear until it would spin freely but fully engage all the teeth.
Seemed to work very well.
Not sure if this helps. Tony may be right.

Daryl
MN

This might be something I have to do, I will have to look more into it and see if possible.

Proper setting of bevel gears is typically done using Prussian Blue on the gear teeth and shimming to obtain the correct contact pattern. To explain the correct contact pattern and how to correct improper contact patterns is way too involved to explain here and is best demonstrated with visual examples. There are many resources, especially on the internet that will explain the process. Google is your friend :). There is also a lot of information in Machinery's Handbook about proper backlash settings. But, as with many things in MH, you'll feel like you're studying for a Mechanical Engineering degree before you get your answer.

Ted

Thanks! i'll look into it and see if I can check on alignment.


Overall I think there is lots of slack in this setup regardless of where I put the bushing, and unless the teeth on both gears have SIGNIFICANT wear (like 1/8") then I think it came from the factory with quite a bit of slop, because even with me moving the big gear out as far as I can before it blocks the oil holes, it is still quite a bit of space between gears.
 
It sure looks like a shim could fit between the end face of the bushing and the bull gear, if that would help the gear mesh. It is helpful to be able to shim both gears when fitting bevel gears.
 
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