Scratching my head!

[Max Headroom]

So I am doing my best to cleanup and recondition my Jet Mill. I am using the manual from a Grizzly 3102 because I can't find a Jet manual and it seems that the Griz is virtually the same machine. I am not willing to take the machine completely down because I don't have much experience with this kind of machinery. (If it was a small block Chevy, I would already be finished with the rebuild) Anyway what I am doing is cleaning whatever I take apart, checking tolerances for (what I consider) excessive wear, lubricating and reassembling. I can't figure out the fine adjustment dial for the quill. I had a hard time getting the shaft and parts out and can plainly see how the manual says they go back together but the clutch worm gear and the clutch don't seem to have any play. (they don't slide at all) If I press them back in I don't see how I can lower the quill without stripping the teeth. I should mention that when I got the mill, the fine adjust clutch was jammed against the gear and I did some serious praying while getting them apart. The clutch spring seems too short and nothing seems to have any movement. I could use some advice, if anyone has any comments. I guess I should start a new post for this but it is what I did today.

 

[jwmay]

The head should be pretty similar to a Clausing 8520. May see if there are any diagrams or videos on that.

 

[vocatexas]

Keith Fenner recently had some videos of rebuilding a Bridgeport. Might check out his videos to see if there is anything there that might help. That mill looks a lot like a scaled-down Bridgeport in a lot of ways.

 

[jcp]

So I am doing my best to cleanup and recondition my Jet Mill. I am using the manual from a Grizzly 3102 because I can't find a Jet manual and it seems that the Griz is virtually the same machine. I am not willing to take the machine completely down because I don't have much experience with this kind of machinery. (If it was a small block Chevy, I would already be finished with the rebuild) Anyway what I am doing is cleaning whatever I take apart, checking tolerances for (what I consider) excessive wear, lubricating and reassembling. I can't figure out the fine adjustment dial for the quill. I had a hard time getting the shaft and parts out and can plainly see how the manual says they go back together but the clutch worm gear and the clutch don't seem to have any play. (they don't slide at all) If I press them back in I don't see how I can lower the quill without stripping the teeth. I should mention that when I got the mill, the fine adjust clutch was jammed against the gear and I did some serious praying while getting them apart. The clutch spring seems too short and nothing seems to have any movement. I could use some advice, if anyone has any comments. I guess I should start a new post for this but it is what I did today.

How about some pics of the clutch parts and the clutch end of the quill drive shaft.. The arrangement isn't anything like the Clausing or Bridgeport.

 

[brino]

@Max Headroom

There was another thread here recently with a fine down-feed issue.
It seemed a few mills looked similar, but had quite different internal designs.
Here it is: https://www.hobby-machinist.com/threads/rutland-rf-30-fine-feed-travel-issues.97411/post-914432

What is your Jet model number?
They do have more recent manuals online here: https://jettools.com/support-us/catalogs
If the one you need is not there, you could also try calling their customer support: https://jettools.com/support-us/faqs

I have also seen times where a Jet manual was not available on that Jet site, but another member here was able to provide a link to it.

Good Luck!
Brian

 

[Max Headroom]

How about some pics of the clutch parts and the clutch end of the quill drive shaft.. The arrangement isn't anything like the Clausing or Bridgeport.

I'll put up some pics today. Thanks all for the responses.

 

[WobblyHand]

wrong area. sorry.

 

[Max Headroom]

So I just took some pics of the Fine Feed mechanism. Be advised that this mill has a lot of damage/wear from someone trying to force the feed. The quill has some stripped splines(?) too. They still function but I am treating things gingerly. So, what I believe is how to reassemble is:

1. The gear on the right in the first pic goes in against the back of the shaft in pic 4 with the gear teeth facing out.
2. The clutch spring from pic one goes onto the shaft next. However, I am convinced that the spring is either broken and thus to short to provide separation for the locking gear (which goes in next), or it is the wrong spring entirely.
3. The locking gear (clutch) goes teeth in and up against the spring.
4. The threaded knob goes on last and engages the clutch when it is tightened and disengages when loosened.

My issue is that the gears seem to be a press fit and I can't see how the fine feed wheel won't strip the first gear when the Coarse feed is engaged. I have not re-lubricated anything and so don't know if that will make a difference in operation.

Still scratching my head.
Any help or comments welcome.

 

[jcp]

Looks to me as though the worm gear should be be a slip fit on the shaft. The shaft could rotate inside the worm gear when the sprag clutch is released, (the spring separating the sprag clutch) and the course feed would drive the quill. Tighten the engagement knob and the spray clutch would engage and drive the quill with the fine feed. The clutch spring is obviously not the correct one.
.

 

[Max Headroom]

Looks to me as though the worm gear should be be a slip fit on the shaft. The shaft could rotate inside the worm gear when the sprag clutch is released, (the spring separating the sprag clutch) and the course feed would drive the quill. Tighten the engagement knob and the spray clutch would engage and drive the quill with the fine feed. The clutch spring is obviously not the correct one.
.

Thanks. That's kind of what I thought might be how it worked. However, that would mean that the quill lever on the coarse side would also move when the fine adjustment was engaged and used. Is that correct? Looking closely at the spring, it looks like it migh be the correct spring that broke off short. I am looking for somewhere to get a different spring.