# Broke my Grizzly G0765 7x14 lathe - HELP!



## ARhodes01075 (Jul 19, 2020)

As the title says, I broke my G0765 7x14 lathe yesterday.  I was using a parting tool and it suddenly jammed and STOPPED the lathe.  There was some loud clacking somewhere in the internals and I hit the emergency off.  It was running at the "slow" speed gear selection on the back of the machine.  The lathe WILL work when the gear selector is set to the high speed setting, but not the low speed.  At the high speed setting it seems fine.  So it looks as if I didn't break bearings or the gearbox frame.  There appear to be stripped teeth inside the gearbox. when I turn the spindle by hand in the low speed gear, but not in the high speed gear

I searched the web but could not find a guide on how to strip down the gearing to access the gearbox.  The exploded diagram is not detailed enough about what inserts into what, and what gears mesh with what other gears.

I think that the problem is with the combo gear (#24 in the "Main" parts diagram) but I can't tell what it meshes with.  I assume that the combo gear and/or the gear it meshes with are damaged, so I should probably replace both.  They are not terribly expensive from grizzly (hopefully they have them in stock!)

Does anybody have experience with this repair?  Can you point me in a direction to a repair operations manual?  What parts am I likely to need?


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## Choiliefan (Jul 19, 2020)

Can you post a link to the parts manual?


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## RJSakowski (Jul 19, 2020)

Looking at your parts list, it looks lke you have to remove the side cover, #44 to access the gears.  Most likely, both gears #14 and #24 will be damaged.  The spindle will have to be pulled to change #14,  You should be able to remove the shaft that #24 rides on  to change that gear. Most likely, you will have to remove the shift fork as well.


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## RJSakowski (Jul 19, 2020)

Choiliefan said:


> Can you post a link to the parts manual?





			https://cdn0.grizzly.com/manuals/g0765_m.pdf


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## markba633csi (Jul 19, 2020)

Ouch!  Looks like you have quite a bit of disassembly ahead of you
Too bad the design didn't include some kind of slip clutch to protect against that type of damage
-Mark


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## ARhodes01075 (Jul 19, 2020)

RJSakowski said:


> Looking at your parts list, it looks lke you have to remove the side cover, #44 to access the gears.  Most likely, both gears #14 and #24 will be damaged.  The spindle will have to be pulled to change #14,  You should be able to remove the shaft that #24 rides on  to change that gear. Most likely, you will have to remove the shift fork as well.



My lathe is post-2015, so, I am using the parts list for the "Model G0765 (Mfd. Since 5/125)"

On this parts list, the "headstock cover" is part # 42.  it looks as if I will need to remove all or most of the gears driving the leadscrew. Then the pivot arm (#61) and handle mount (#36).  And then the gear mount (#48).

Do I need any special tools like gear pullers or similar?  How do I get the shifter fork (#30) off?  Does the spindle with all the parts mounted simply slide out of the headstock casting toward the bed?  Are the bearings pressed-on?  

Once I get the headstock side cover off,  does the spindle and the H/L shaft (#26) come out easily?

These are probably all simple and straight forward operations, but it would be wonderful to have step-by-step instructions.  Where are the Haynes Manual people when you need them!!??

-Tony


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## ARhodes01075 (Jul 19, 2020)

markba633csi said:


> Ouch!  Looks like you have quite a bit of disassembly ahead of you
> Too bad the design didn't include some kind of slip clutch to protect against that type of damage
> -Mark


Yeah, I will have to disassemble the whole darn thing!  A slip clutch would have been great. Or maybe a weaker drive belt, or a weak key on the motor holding the drive pulley.  All these parts are much more accessible, I think.  But replacing the drive belt probably requires nearly all the disassembly required to get at the combo gears.


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## markba633csi (Jul 19, 2020)

I'm sure you will need access to a press. The spindle bearings are probably pressed on, although hopefully not too tightly.
Some of the questions you have will probably yield answers as you begin to pull it apart.  Fortunately Grizzly is pretty good about getting spare parts, though you may have to wait a bit for them
Parting off on a small lathe can be difficult/disastrous- I can do small aluminum parts on my 6" Atlas- but never steel.  I've stalled it before so I keep the belt on the loose side


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## markba633csi (Jul 19, 2020)

Pulling the spindle may require you to come up with some type of threaded rod, nut, and washer arrangement, a common technique on small lathes like Atlas


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## Firstram (Jul 19, 2020)

You'll have to pull the head stock and the spindle to change those gears. LMS sells steel replacements, use the steel one on the spindle and buy 2 plastic ones for the jack shaft. When it happens again you won't have to pull the spindle to change the plastic gear, and you'll a spare on hand! I can change mine in 30 min or so.

I have read not to use both steel gears due to the noise and the fact a crash will break the next weakest thing$$$


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## RJSakowski (Jul 19, 2020)

Be thankful it was only lathe gears.  A year ago, I took out the low range gears on my tractor.  It involved splitting the tractor. disassembling the entire transmission and rear end, including removal of the pto, hydraulics, rear wheels, and fuel tank.  All that in 100+ temperatures and 90+ RH.


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## RJSakowski (Jul 19, 2020)

And without a shop manual.


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## tjb (Jul 19, 2020)

RJSakowski said:


> And without a shop manual.


What's that?


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## RJSakowski (Jul 19, 2020)

tjb said:


> What's that?


Actually, one of the service techs sent me a maintenance manual for a similar tractor. It's close enough that many of the components are similar if not the same.  Unfortunately, I didn't get it until after the job was done.

Whether it's tractors or lathes, most of the time there is a logical sequence to disassembly.  Occasionally. though, you have to get inside the designers head to see what he was thinking.  The ones that are really fun are those that were never meant to be serviced.  Locking tabs, glued joints, and hidden fasteners and the like.


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## Aaron_W (Jul 19, 2020)

This Old Tony has a couple of mini-lathe videos which include replacing spindle bearings and gears. He is doing it as an upgrade, but should show you how things come apart and go together.


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## ARhodes01075 (Jul 20, 2020)

Aaron_W said:


> This Old Tony has a couple of mini-lathe videos which include replacing spindle bearings and gears. He is doing it as an upgrade, but should show you how things come apart and go together.



I will check the videos.  Thanks!


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## ARhodes01075 (Jul 20, 2020)

Firstram said:


> You'll have to pull the head stock and the spindle to change those gears. LMS sells steel replacements, use the steel one on the spindle and buy 2 plastic ones for the jack shaft. When it happens again you won't have to pull the spindle to change the plastic gear, and you'll a spare on hand! I can change mine in 30 min or so.
> 
> I have read not to use both steel gears due to the noise and the fact a crash will break the next weakest thing$$$



THIRTY MINUTES!  That seems incredibly fast.  What parts do NOT need to be removed to get it apart?  I think the gearbox itself needs to be removed to access the gears from underneath?  Is this correct?  It seems as if the speed selector can only be accessed and removed from the bottom??

I will try to come up with a ~4" diameter pipe and threaded rods going to the flange on the spindle.  I don't know how hard I can pull with 3x simple M6 x 80mm threaded rod. 

-Tony


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## Firstram (Jul 20, 2020)

Sorry for the giant photo!




On a stock Mini I think you need to remove the speed control and lead screw, I don't remember. Be aware of the wiring! I have relocated that to the back and can pull the head stock with it attached. My wiring is long enough to lay the assembly (head stock/motor controller) on the table behind the lathe.

Remove banjo, feed direction tumbler, double nuts and gear (from spindle), aluminum belt cover, belt and sprocket. I don't know if you can access the 3 socket head bolts holding the head stock to bed without removing the motor. (I can, I have a jack shaft  where the motor would be) They need to come out to pull the head stock.
Lift the head stock off. Remove the clips holding the counter shaft and slide it out of the head stock. Keep up with the key stock that drives the gear!

From this point I would be able to reassemble using a new plastic gear on the counter shaft.

Do not pull on the spindle flange with 3 bolts. Use 1/2" threaded rod thru the spindle with a washer on the small end. Grind, file or sand the washer so the OD is just smaller than the spindle. Use a 8" pc of PVC pipe that just fits over the chuck end (3"?). A 2x4 with 1/2" hole will cap the assembly. Tighten nut and pull spindle out. Clean/lube everything up and reassemble using a steel gear on the spindle!

The first time will take a while! Tear into it methodically, keep the parts organized and it will all fall into place. Just ask for help if you need it! I've had lots of practice with mine in the last 10 years and it's actually worn out now. I haven't done it because there are other mods I want to do and don't want to tear it down twice.


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## RJSakowski (Jul 20, 2020)

Firstram said:


> Sorry for the giant photo!
> View attachment 330909


After you insert the photo, if you click on the photo, you can resize it by clicking on one of the blue squares and dragging.


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## ARhodes01075 (Jul 20, 2020)

> On a stock Mini...
> ...
> ...
> The first time will take a while! Tear into it methodically, keep the parts organized and it will all fall into place. Just ask for help if you need it! I've had lots of practice with mine in the last 10 years and it's actually worn out now. I haven't done it because there are other mods I want to do and don't want to tear it down twice.


Thanks for the pointers.  I have some acme threaded rod on hand.  It is part of a spring compressor set.  I think it is 1/2" diameter.  I don't recall how long the rods are.  12" to 14" as I recall.  But that may be enough to get the spindle released.  I probably have some 1/2" steel plate that I could use instead of a 2x4.  I will look for some 3 or 4 inch PVC pipe.

Good suggestion about a steel combo gear on the spindle!  Will that cause more wear on the plastic gear on the layshaft than a plastic-on-plastic mesh?

Does the spindle need to be pressed back on or will the nuts on the spindle pull it up properly?

I feel almost up to this procedure once I get the parts for the puller


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## Firstram (Jul 20, 2020)

Use the same threaded rod with a smaller diameter sleeve to pull the spindle back into place. I have broken more than one gear, usually from grabbing a high rake tool while cutting Delrin.  This one pops out of high gear while under a load. 

The new steel gears have sharp edges and need to be de-burred before installation. I used needle files and fine sandpaper to ease the corners. The faces of the teeth were very smooth so I don't think they add to the wear. Not having to pull the spindle offsets any slight accelerated wear IMHO.


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## Aaron_W (Jul 20, 2020)

ARhodes01075 said:


> Thanks for the pointers.  I have some acme threaded rod on hand.  It is part of a spring compressor set.  I think it is 1/2" diameter.  I don't recall how long the rods are.  12" to 14" as I recall.  But that may be enough to get the spindle released.  I probably have some 1/2" steel plate that I could use instead of a 2x4.  I will look for some 3 or 4 inch PVC pipe.
> 
> Good suggestion about a steel combo gear on the spindle!  Will that cause more wear on the plastic gear on the layshaft than a plastic-on-plastic mesh?
> 
> ...



It may seem like a lot but you will have a lot more confidence once you've done it. I had to disassemble my lathe to get it into the basement which included pulling most of the gears out of the head stock and I was not sure I would ever get Humpty Dumpty back together again.   
Now it is not my favorite thing to do, but I no longer fear taking the machines apart, after the lathe I did the same with 2 mills, and that seemed like it was no big deal at all.

Take pictures and where possible reassemble the parts as you they come out or at least organize them in the order they go back in. Makes life much easier particularly if you get pulled away from the task. Wire can be useful to keep assemblies together.


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## ARhodes01075 (Jul 22, 2020)

OK, I have new combo-gears coming from Grizzly.  I will have some 1/2" acme-thread rod (2 feet long) coming from Mcmaster, as well as the proper nuts.  I was able to use the broken lathe on the "high" speed setting to turn a fitting for the left side of the spindle to pull against with the threaded rod.  I have some 1/2" thick 707x aluminum plate for the right side of the puller.  I am figuring out what to use as a spacer to go under the plate and against the headstock gearbox.  Likely some 3.5" ID steel or aluminum pipe about 12" length.  

So... assuming I can successfully pull the spindle to get the broken gears out, what type of grease is going to be compatible with whatever plastic these gears are made from?


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## Firstram (Jul 22, 2020)

No lube needed!


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## ARhodes01075 (Jul 24, 2020)

Firstram said:


> No lube needed!



Well, actually it seems that lube IS needed in the hi/lo gearbox.  I finally got a reply from Grizzly about this.  They recommend NGLI#2 multipurpose lube. and nothing but that. 

Maybe no lube on the crossfeed speed selector gears?  I used while lithuim grease on those gears.  That grease is supposed to be fine with plastics.


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## Firstram (Jul 25, 2020)

Thanks, did not know that!


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## stupoty (Jul 25, 2020)

RJSakowski said:


> Be thankful it was only lathe gears.  A year ago, I took out the low range gears on my tractor.  It involved splitting the tractor. disassembling the entire transmission and rear end, including removal of the pto, hydraulics, rear wheels, and fuel tank.  All that in 100+ temperatures and 90+ RH.



Well are you saying this was you just before the gearbox gave out ?


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## RJSakowski (Jul 25, 2020)

stupoty said:


> Well are you saying this was you just before the gearbox gave out ?
> Like


Not by a long shot.  It's a good thing he has a roll cage on that machine because he's going to need it at some point.  I chewed some gears dropping from high to low range while doing some yard work.



Many years ago, I transplanted a 364 c.i. V8 into a 1962 3/4 ton Chevy pickup, replacing a 235 c.i straight six.  The 3/4 trucks back then were geard down for working and the truck had a 4.411 rear end and a four speed transmission.  You could climb trees in first gear and start out in third gear.  Fourth gear would red line the engine at 55mph.

I was passing a slow moving gravel truck on an incline and dropped down into third gear and threw a rod before I had passed the truck.


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## tjb (Jul 25, 2020)

RJSakowski said:


> Not by a long shot.  It's a good thing he has a roll cage on that machine because he's going to need it at some point.  I chewed some gears dropping from high to low range while doing some yard work.
> View attachment 331414
> 
> 
> ...


My '54 (avatar) has a 4.3 built V6 in it, and that's plenty fast.  My '65 C10 truck has a built 350 V8 in it.  I don't drive either one of them like I did back when I was a teenager.  My first was a '55 Chevy with a 265 Power Pack in it.  I changed it over to a Carter AFB carburetor and dropped .411 positraction rear-end in it, and a 3-speed on the floor that came out of a '56 (I think) Corvette.  Not much beat me off the line, but my top end wasn't too good.  I did manage, however, to spring the speedometer at 110 MPH.  We were crazy.

Regards


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## ARhodes01075 (Aug 1, 2020)

I have the lathe FIXED!  I had on hand a 4" OD piece of pipe and some 1/2" Acme thread rod to pull the spindle.  But I tried using a light weight rubber mallet to gently but firmly tap it out.  It came out easily.

The teeth on both gears for the low speed drive were broken.  Mostly on the 12 tooth gear: 5 teeth were sheared off.

I got it back together again. and it works fine.

Afterward I got to thinking:  I could 3D print these combo gears pretty easily.  My CAD program has a tool to make gear profiles.  Just plug in the  specs of pitch diameter, number of teeth and pressure angle and voila, a gear is made.

They look great and are very printable.  But I need a bit more info to be sure.  I will create a new thread on this subject.




ARhodes01075 said:


> As the title says, I broke my G0765 7x14 lathe yesterday.


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