Thread: Having trouble unscrewing chuck from lathe

Originally Posted by neksmerj

Pipeclay,

I'm with Ironwood. I have to disagree with your statement.

"The different tooth count wont be a great concern as long as the Diameters of the replacement are the same as what you have."

If the back gear diameters remain the same, but have a different no. of teeth, then the tooth pitch will have changed, and the replacement back gear won't mesh with the other gears.

Ken

Everyone with a Hercus 260 buying replacement Bull Gears,Backgears should be carefull then.

Pipeclay.

Please don't be pedantic. Ironwood's question seems fair to me. In my opinion, 2 into 3 doesn't go.

Do you have an engineering answer, instead of another question?

Ken

Ken I could probably come to some type of conclusion,wether it be an engineering conclusion or guess I cant say.
As I said with the Hercus there are different Tooth counts between the Gears,the OD of the Gears does not change.

Just for future reference in case somebody does a search in future. If knocking a chuck off as described doesn't work, a pretty much sure fire way is to chuck a large bolt in the chuck with enough sticking out from the chuck to put an impact driver on it.

Pete

If the OD of the gear doesnt change and the tooth count changes the pitch is different or a different module gear there are formulas to work out gear dimension and it is always going to be a different diameter for different amounts of teeth unless you get a different module gear you might get one that comes close.

Yes that's right. If a gear has the same diameter but a different number of teeth, the DP must, by definition, be different.

With back gears it's quite possible the diameter could change with the tooth count because the distance between shafts can so easily be changed.

Originally Posted by Bryan

With back gears it's quite possible the diameter could change with the tooth count because the distance between shafts can so easily be changed.

Thats possible alright, as long as both the large and small end diameters changed an equal amount.
When I get home later, I will post the tooth count of my original backgear, compared with the Grizzly replacement one.

Perhaps the Hercus's with their spur gears can tolerate a bit of variation in the teeth, not sure if the helical gears on these ones would be as tolerant .
I worked for 26 years as a Diesel Fitter, done plenty of work with gears etc. But never had much call to work out any geartooth geometry as such.

Thanks Ironwood, that would be useful to me. Diameters as well please? 'While you're down there', could I have the same info on your spindle gears? That would indicate if my back gear setup differs from the typical Lantaine one. I know other aspects do, eg change gears and feed worm. Thanks.

Originally Posted by Bryan

Thanks Ironwood, that would be useful to me. Diameters as well please? 'While you're down there', could I have the same info on your spindle gears? That would indicate if my back gear setup differs from the typical Lantaine one. I know other aspects do, eg change gears and feed worm. Thanks.

Bryan, I just came back up to the house from the shed. I didnt think to measure the gears on the spindle, but will do that tomorrow.

The backgear is as follows - 22T ( 49.7mm ) and 52T ( 111.8mm )
The grizzly one on their website is 24T and 58T.

I have finished stripping the lathe apart now, will begin to clean the parts and prepare fore painting, I think I will go with a light grey.
An old Scottish guy that comes into my shop everyday says to paint it with 2-pack Epoxy, he has refurbished quite a bit of gear and seems to know what he is on about, so I will go with that. He gave me some 2-pack primer to start off with.

Are the blind rivits that hold the nameplates on, readily available ? I have seen poprivets used to put them back on, but the proper sort would look better.

They are U drive pins,not sure how hard they would be to get each.

Thanks Ironwood. Small Parts have the pins.
These have flat heads: Pinshammerdriveflathead - Small Mechanical Parts And Components
And these have domed heads: Pinshammerdriveroundhead - Small Mechanical Parts And Components

Originally Posted by pipeclay

They are U drive pins,not sure how hard they would be to get each.

Originally Posted by Bryan

Thanks Ironwood. Small Parts have the pins.
These have flat heads: Pinshammerdriveflathead - Small Mechanical Parts And Components
And these have domed heads: Pinshammerdriveroundhead - Small Mechanical Parts And Components

Thanks guys I will chase them up.


Bryan, here are the other gear specs,

Bullgear - 74T - 157.4mm Dia. shaft Dia=51.9mm.
Small gear - 44T - 95.3mm Dia. shaft Dia.=50.9mm.

I measured the spindle where the gears sit for the shaft diameters, rather than the bore size (easier with the measuring gear I have at hand )

Originally Posted by Bryan

That would indicate if my back gear setup differs from the typical Lantaine one. I know other aspects do, eg change gears and feed worm. Thanks.

Bryan, are the change gears available from Grizzly not suitable for our lathes, or am I reading your post wrong ?

I dont have any metric change gears, and was hoping to find some at some stage.