Noisy lathe spindle! Heeeeeelp Please!

[LX Kid]

I just bought a 1993, 17-20XMTC with CNC attached. My lathe spindle "snaps" or maybe "knocks" when running. I thought it might be a bad bearing so I disassembled, cleaned and inspected both bearings but they look to have normal wear. Called Shoptask and JT suggested it might be the gear broke in the key-way area next to the front bearing. Removed and inspected the gear and it looks fine. Only other moving parts, is the intermediate shaft with the hi/lo gears just below the spindle. The hi/lo selector lever, lower gear set, is in the "neutral" position so it's not moving and would not be able to make the noise. The lube is a "heavy" axle lube and not a light 10W machine oil as manual says. Jt says they use transmission fluid for serviceing. Has anyone ever had the same symptoms with theirs or have any ideas for me to check? Thanks

[smallblock]

I just bought a 1993, 17-20XMTC with CNC attached. My lathe spindle "snaps" or maybe "knocks" when running. I thought it might be a bad bearing so I disassembled, cleaned and inspected both bearings but they look to have normal wear. Called Shoptask and JT suggested it might be the gear broke in the key-way area next to the front bearing. Removed and inspected the gear and it looks fine. Only other moving parts, is the intermediate shaft with the hi/lo gears just below the spindle. The hi/lo selector lever, lower gear set, is in the "neutral" position so it's not moving and would not be able to make the noise. The lube is a "heavy" axle lube and not a light 10W machine oil as manual says. Jt says they use transmission fluid for serviceing. Has anyone ever had the same symptoms with theirs or have any ideas for me to check? Thanks

Does the noise go away or change when you engage the Hi-Lo shifter? On the shift lever there is a roller that moves the lower shaft back and forth- this could be worn and knocking as it turns-
Also check the end play on the upper gear. This gear is adjustable so it can be lined up with the gear on the spindle. Once aligned, the shaft is fixed by that allen bolt and cone shaped bushing in the front. At the rear is a big allen bolt that sets the thrust bushing in place so the gear can't move back and forth. If that bushing is not set, the gear can go back and forth and cause a knocking sound.

[LX Kid]

Thanks once again for your suggestion. I tried adjusting the allen head screw, when it was running, and seemed to make no difference. I've got new bearings on order and thought I would try and remove the shaft and gears to inspect them. There are internal parts inside the shaft "but" I cant get the shaft out! I removed the allen head screw and the large slotted screw and used a drift pushing it backwards. Movement stops after about an inch and I didn't want to force anything. Have you removed this shaft before? Thanks

[LX Kid]

Finally removed the intermediate shaft and gears with the help of JT at Shoptask. There was no problem found with them so I cleaned and reinstalled. Removed the bird cages of the bearings to see if there was any scaring on the inner races and found none. This is really getting ridiculous! Ordered the new bearings and I guess they will be here in a few days. Guess I'll remove the heavy axle lube and replace with the thinner Velocite lube in the gearbox.

[wormwood]

I have an 08' Patriot, but your lathe gear housing looks similar, you might consider first the selector levers. If I remember right the throw on them from FNR & LH are assembled by dimpling the shaft & attaching a control arm & set screws, if they fully engage the selection your choose the gearing will slip out of it's meshing.

Also I vaguely remember the spacing of the gears being a pain to reassemble in the lathe spindle housing....

Oh yeah! those intermediates shafts in the lathe housing have bronze/oilite bushings on the ends which are pressed into the casting during assembly. They were extremely thin on mine & I could see the shafts moving if you gave resistance to the output shaft while turning the input.

Hope that helps...

Wormwood

[LX Kid]

Thanks WormWood. The selector lever was one of my first thoughts, as there is play in it. But while running, it can be centered by hand to ensure it was not bouncing into the gears. On my older lathe there are no bronze bushings. The one black steel bushing, in the pic, is on the pulley side. The intermediate shaft is adjusted properly and is not the problem. My gears rotate on the shaft, while the shaft is tight in the housing, and has no slop. If you think of something else "just yank my chain!" LoL Thanks again for your inputs.

[instructor37]

Thanks WormWood. The selector lever was one of my first thoughts, as there is play in it. But while running, it can be centered by hand to ensure it was not bouncing into the gears. On my older lathe there are no bronze bushings. The one black steel bushing, in the pic, is on the pulley side. The intermediate shaft is adjusted properly and is not the problem. My gears rotate on the shaft, while the shaft is tight in the housing, and has no slop. If you think of something else "just yank my chain!" LoL Thanks again for your inputs.

Are you sure the noise is coming from the gearbox? There is a key that holds the main pulley on the spindle- if this is worn and loose, the pulley could be making the noise- also check the bushing behind the pulley that rides in the seal for looseness- further back, it could even be in the idler pulley or the motor pulley or even the motor mount. There is also an output shaft that drives all the threading gears- check all the gear train for chipped teeth etc.
The best way to find the noise is to start disconnecting stuff until the noise goes away.

[LX Kid]

Are you sure the noise is coming from the gearbox? There is a key that holds the main pulley on the spindle- if this is worn and loose, the pulley could be making the noise- also check the bushing behind the pulley that rides in the seal for looseness- further back, it could even be in the idler pulley or the motor pulley or even the motor mount. There is also an output shaft that drives all the threading gears- check all the gear train for chipped teeth etc.
The best way to find the noise is to start disconnecting stuff until the noise goes away.

Before teardown I spun the spindle pulley and it was barely audible due to low speed of my hand spin. Pulley is a nice tight fit with no slop and spindle nuts tight. Because of the heavy axle lube, does anyone think it could be any part of the problem? Shoptask calls for 10W or automatic transmission fluid.

HERE'S THE TWO DIFFERENT GEARBOX LUBES I HAVE AND INTEND ON USEING ONE OF THE TWO. #6 OR #22 ??????? THE THIRD ONE IS WAY LUBE.

[LX Kid]

Here is a discussion I had, on another web forum, and "may" be an answer to my knocking problem.

The beveled cone, on the chuck side, is tightened securely to keep the shaft secure. The black bushing is "squeezed" against the shaft, at the opposite end, by the large slotted screw on the pulley side. This is where "end" play is adjusted. Now that you mention it, "when I was taking the intermediate shaft out I did notice there was too much end play and could have been "the" problem by rocking/knocking against the column casting. (Maybe .015-.025) There are no specs for this adjustment so I tightened it untill gear got tight and backed off a hair for free movement. I took a large screw driver and preyed up and down on the gear assembly and got no play. If that was it your can come on down to Florida and I'll take you out fishing!! Ron

[LX Kid]

Problem found!!! A big thanks to JT at Shoptask for his help! The problem was the gear on the spindle. When ever it was pressed onto the spindle, the key was too tall causing the gear to deform on a couple of the gears' teeth. After filing the key, making it a lower profile, and filing the deformed teeth it now runs nice and quiet.

[Nmbmxer]

The hi/lo selector lever, lower gear set, is in the "neutral" position so it's not moving and would not be able to make the noise.

I would not recommend running the machine with the hi/lo in neutral, the spindle bearings are splash lubricated and only the lower gear set is in the oil bath. If it isn't spinning, your spindle bearings are not being oiled and they will not last long.

[LX Kid]

I would not recommend running the machine with the hi/lo in neutral, the spindle bearings are splash lubricated and only the lower gear set is in the oil bath. If it isn't spinning, your spindle bearings are not being oiled and they will not last long.

The spindle bearings are grease packed and not too much splash lube has any effect on the spindle bearings. The manufacturer recommends removing the spindle bearings every six months, depending on usage, and repacking them. I didn't replace the spindle lube either. Being it's pretty hot in Florida I just left the axle lube in the gear box.