Having trouble unscrewing chuck from lathe

[Ironwood]

I am in the process of pulling apart my lathe, so I can clean it up to paint it.
Its a Forbes lathe made in 1975.
169427
Getting the chuck and faceplate off is giving me some problems at present.
The previous owner damaged the backgears while he had it ( maybe trying to do the same thing )
I have tried to unscrew it by locking the spindle by engaging the backgears, putting the chuck key in and tapping with a hammer, all I did was break another tooth off the backgear.:-
I tried with a large pair of stillsons on the outside end of the spindle to stop it turning, tried tapping the chuckkey, also tried large shifter on one of the chuck jaws.
No good its too tight.

Does anyone have any other ideas how to unscrew it, without doing any more damage ?

I have thought about unbolting the chuck from the faceplate, and heating the faceplate.
I'll be replacing the seals on the spindle anyway, and not too much heat should transfer into the spindle if it goes to plan.
But I'll leave that as a last resort for now.

If someone has some ideas, I'm all ears :).

[aametalmaster]

Maybe unbolt the chuck from the backplate so you can spray some good spray lube into the end of the spindle/backplate. You sure don't want to break off anymore teeth. Then make some kind of holder to lock the spindle and try to turn it off. Good luck and keep us posted...Bob

[Bryan]

Hi. I have a similar lathe. I hold a block of wood on the rear way under a jaw and bump the reverse button (don't let it latch on). You can apply more force by starting with the jaw further from the block and/or using a higher speed. It's the momentum of the chuck that does the trick rather than the motor. You have to be careful that the block is square or it can spit out.

[Ironwood]

Thanks for the idea Bryan.

Trouble is my lathe doesnt have reverse. The switch starts the lathe in forward direction in both positions.

The motor was replaced at some stage, the previous owner said when the electrician wired it up, he said it would only run one way .

[Stustoys]

Ironwood,
You could try a can of freezing spray on the inside of the spindle.


Bryan,
The momentum of the chuck would be working against you wouldnt it?

Stuart

[Dave J]

One you could try is to take out all but one jaw, place a piece of board on the ways. Then cut a block of wood (4x2) to sit on the board and come to centre height. Place the block over towards the back level with the outside of the chuck then turn the chuck so the jaw so it is at the lowest point facing the ways and with the lathe in low gear turn on the lathe in reverse.
This sudden stop should crack the thread undone, just be prepared to catch the chuck.

Dave

[Dave J]

Everyone posted while I was typing.

Dave

[Bryan]

I just meant that you don't drive the chuck into the block under power. I suppose it's actually the momentum of the spindle etc that does the unscrewing. If you want to be pedantic. :rolleyes:

[Ironwood]

Ironwood,
You could try a can of freezing spray on the inside of the spindle.



Stuart

Hi Stuart, never heard of that stuff before, is it like a can of liquid nitrogen spray ?

[Dave J]

If it's as stuck as he said and broke another tooth off the back gear trying, I would say it has been on for years and is going to need a bit of speed and a sudden stop to get it off.
I had a chuck like this on my old Hercus when I got it.

Dave

[Ironwood]

I just meant that you don't drive the chuck into the block under power. I suppose it's actually the momentum of the spindle etc that does the unscrewing. If you want to be pedantic. :rolleyes:

It would be the inertia of the spindle and other masses that would try to keep turning once the chuck suddenly stopped.

I would be trying that as we speak if only my lathe had reverse :( as it would probably get it loose.

[Dave J]

Is the motor reversible? Can you swap the wires over to get it to run in reverse?

Dave

[Ironwood]

If it's as stuck as he said and broke another tooth off the back gear trying, I would say it has been on for years and is going to need a bit of speed and a sudden stop to get it off.
I had a chuck like this on my old Hercus when I got it.

Dave

Hi Dave, I think it has been on there for the life of the lathe, as he didnt have a 4 jaw chuck, or anything else to go onto the spindle, which makes me think its only ever been used with this 3 jaw chuck fitted.

One more tooth off the backgear is no great loss, as its missing 3 others from a previous misshap. Which makes it useless for doing any turning with it engaged anyhow. But I dont want to damage it any more.

[Ironwood]

Is the motor reversible? Can you swap the wires over to get it to run in reverse?

Dave


Not sure on that, will have to check it out.

[Bryan]

How about removing the motor belt and turning the countershaft backwards by hand? To allow more of a turn (extra momentum) you could remove all the jaws but one, like Dave said. A helper would um, help. :)

[pipeclay]

It appears that the Backplate is well and truly attached to your spindle,either through work tightening or the possability of rusting either through coolant or water.

Does there appear to be a thin shim between the Backing plate and the Spindle register (this could possably be a piece of paper or gasket material) if there is but I doubt it you could heat or burn that shim out this would then give a little clearance between the Backplate and register.(The Hercus 260 are prone to freeze there chucks on there spindle if left in the one configuration for extended periods,the shim allows for a none metalic/metalic mounting).

Seeing that the Backgears are allready damaged and further efforts to remove by locking backgear have resulted in further damage,one of the easiest ways to now remove the Backplate would be first to remove the Chuck as you have suggeted and then machine off the troublesome back plate.

I believe the Backgear is available from American suppliers if not from Local.

The cost of material for a new backplate would be around $25/$35.

[Stustoys]

Ironwood,
I'm not sure what gas they use and the name of the one I have used escapes me ATM but it has a penetrating lubricant in it unlike the ones plumbers use to freeze pipes. Got it from a bearing supply place.

Bryan,
Got you now, not trying to be pedantic.

Stuart

[Gavin Newman]

Ironwood,
I'm not sure what gas they use and the name of the one I have used escapes me ATM but it has a penetrating lubricant in it unlike the ones plumbers use to freeze pipes. Got it from a bearing supply place.
Stuart

Loctite make a product called "Freeze and Release" that might help.

[Stustoys]

Loctite make a product called "Freeze and Release" that might help.
Thats the one, I knew it was a well known brand. Great stuff
Stuart

[Bryan]

BTW, in case you're not aware, that lathe (with minor variations) is still sold new by Grizzly: G9249 12" x 37" Belt Drive Gap Bed Lathe (http://www.grizzly.com/products/12-x-37-Belt-Drive-Gap-Bed-Lathe/G9249)
Notice the links to manual and parts listing. The parts prices are reasonable but not all parts are in stock. I've had a set of back gears on back order for months. And their $200 minimum for international orders means I can't buy the bits they do have in stock. :~

[Ironwood]

Well a big thanks to all concerned :2tsup:.

I got it to unscrew.
I went with Bryan's advise, and removed the motor belt and guards, to give a better grip on the pulley, put the other belt on the highest ratio.
Took 2 jaws out of the chuck, clamped a 4x4" piece of hardwood across the bed.
Then about a dozen hard whacks by turning the large pulley by hand, it finally came loose.

There was no rust or corrosion, in fact the threads were well lubed.
I'm glad its off, I can get back to stripping it down now.

Thanks again to everyone.:2tsup:

[eskimo]

Everyone posted while I was typing.

Dave

u got ten thumbs?

[Cliff Rogers]

Well a big thanks to all concerned :2tsup:.

I got it to unscrew.
I went with Bryan's advise, and removed the motor belt and guards, to give a better grip on the pulley, put the other belt on the highest ratio.
Took 2 jaws out of the chuck, clamped a 4x4" piece of hardwood across the bed.
Then about a dozen hard whacks by turning the large pulley by hand, it finally came loose.

There was no rust or corrosion, in fact the threads were well lubed.
I'm glad its off, I can get back to stripping it down now.

Thanks again to everyone.:2tsup:
That is the best way to get a frozen chuck off, I have done similar with my woodwork lathe. :2tsup:

[Ironwood]

BTW, in case you're not aware, that lathe (with minor variations) is still sold new by Grizzly: G9249 12" x 37" Belt Drive Gap Bed Lathe (http://www.grizzly.com/products/12-x-37-Belt-Drive-Gap-Bed-Lathe/G9249)
Notice the links to manual and parts listing. The parts prices are reasonable but not all parts are in stock. I've had a set of back gears on back order for months. And their $200 minimum for international orders means I can't buy the bits they do have in stock. :~

I had a look at the backgear on their website a while back. It has a different tooth count than the one on my lathe, so I didnt pursue it any further.

I would be interested to know if yours fits when it arrives.

[pipeclay]

The different tooth count wont be a great concern as long as the Diameters of the replacement are the same as what you have.
Some manufacturers of the Older belt type back geared lathes changed there tooth counts on the same models.
Only allteration would be slight to final RPM.

[Bryan]

Glad you got your chuck off (and that my idea worked). That's interesting about the tooth counts. Mine came with the whole back gear assembly missing so I don't know what mine were. If Pipeclay is right it's probably worth a punt on the Grizzly items. I'll let you know if they ever materialise - though that may not help you. Meanwhile a VFD will improve matters. Might be a good option for you as well.

[Ironwood]

Meanwhile a VFD will improve matters. Might be a good option for you as well.


Yeah, I've been tossing up the idea of a VFD.
I didnt really want to spend too much cash on this lathe, but it would solve a couple of problems.:rolleyes:

With the different tooth count with the same diameter, wouldnt that change the pitch ?
I'll wait and see if yours turns up, and see how it goes, before I order one too :)

[pipeclay]

The pitch of what?

[Ironwood]

The pitch of what?

The spacing of the teeth, if there's more teeth to fit into the same diameter wheel, wont they need to be closer together ?

[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

[pipeclay]

Depending on the amount of teeth extra there will be,what is yours at the moment?
You can get away with 1 possably 2 extra.
The ones that I see regularly are Spur gears with an extra tooth.

[pipeclay]

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.

[neksmerj]

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

[pipeclay]

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.

[Pete F]

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

[old_fella]

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.

[Pete F]

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

[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.

[Ironwood]

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.

[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.

[Ironwood]

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.

[pipeclay]

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

[Bryan]

Thanks Ironwood. Small Parts have the pins.
These have flat heads: Pinshammerdriveflathead - Small Mechanical Parts And Components (http://www.smallparts.com.au/store/partslist/pinshammerdriveflathead/fasteners/wide/1/)
And these have domed heads: Pinshammerdriveroundhead - Small Mechanical Parts And Components (http://www.smallparts.com.au/store/partslist/pinshammerdriveroundhead/fasteners/wide/1/)

[Ironwood]

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 (http://www.smallparts.com.au/store/partslist/pinshammerdriveflathead/fasteners/wide/1/)
And these have domed heads: Pinshammerdriveroundhead - Small Mechanical Parts And Components (http://www.smallparts.com.au/store/partslist/pinshammerdriveroundhead/fasteners/wide/1/)



Thanks guys I will chase them up.:2tsup:


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 )

[Ironwood]

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.

[Bryan]

Thanks for the info Ironwood. Those tooth counts sound familiar. Will check mine tomorrow.

I would call your lathe a normal Lantaine. They are/were Taiwanese and got rebadged with at least a dozen other names. Mine is a bit different. I believe it's a Chinese copy of yours. It's not even dignified with a name. (I have several names for it but this is a family forum.)

I know my change gears are 16DP, 20PA. Yours may or may not be the same. I have no way of knowing what the Grizzly ones are. One way to check yours is to look at the Hercus gear catalogue: Spur Gears - F W Hercus Pty. Ltd (http://www.hercus.com.au/spur-gears/) On the last page is a set of actual size tooth profiles. Print it out and lay one of your change gears on it. If you find a match you can get spur gears from a number of suppliers - if they have the tooth counts you want. I've dealt successfully with both Hercus and Ronson Gears: Stock Gears and Racks - Gear Racks, Spur Gears, Mitre Gears, Bevel Gears | Ronson Gears Australia (http://www.ronsongears.com.au/stock-gears.php)

Hope that helps.

[pipeclay]

If the Backgear and or spindle gears are the same dimensions as given they appear to be Module gears.
Seems strange if the Headstock is Module that the Change gears would be DP.

[Bryan]

Ironwood, my spindle gears tally with yours: 44 & 74, same diameters. I notice Grizzly give the smaller spindle gear as a 39T. No count given for the bull gear. I can't see a way to find out if their back gears would mesh with our spindles.

Pipeclay is right - it would be odd to have metric and imperial gears on one machine. Though I've found some odd things on mine so anything's possible. Anyway you should try to verify your change gears independently of mine.

[pipeclay]

Is the Centre distance between your Backgears and Spindle something around 96.456 mm.

[Ironwood]

Is the Centre distance between your Backgears and Spindle something around 96.456 mm.

I measure the centre distance on mine at 102.05mm.
The backgear shaft has an eccentric offset of approx. 6mm.

[pipeclay]

Is that with the Backgear in or out.

[Ironwood]

Is that with the Backgear in or out.

My headstock is completely disassembled at the moment.

That is what I measure the distance to be, from the centre's of the bores in the headstock housing.

The way I am seeing it, the 6mm offset on the backgear shaft, gives a possible 12 mm of movement of the backgear.

[franco]

Pipeclay,

Brian's back gears at 12.26 DP don't sound like standard DP gears, so, as you say, they are probably metric. If metric, they work out consistently to 2.07 mod, which is also an unusual number, though fairly close to 2 mod. However they are very close to 6.5 mm circular pitch. What do you reckon is the likelihood of using metric circular pitch gears on a relatively modern lathe which uses DP change gears? The equivalent circular pitch in inches is 0.256 from Brian's figures, so maybe it is a possibility also, though it is not as close to a conventionally used number as is the metric equivalent. It seems strange to mix Mod and DP or circular pitch gears on the same machine though

Just trying to make some sense of the figures.

Frank.

[pipeclay]

That being the case you maybe able to replace the spindle gears and backgears with the grizzly spare parts,there centre distance equates to approximately 97.486,1mm bigger than what you have now.
I suppose at the worst you could allways convert to a spur gear headstock drive.

[pipeclay]

Frank I would take a punt and say they are 2 mod in the Headstock.
After seeing what machine manufacturers do in regards to the gearing they use in the machine tools the gears could be anything.
Hercus is a fine example,they make the machine so they can make the gears or other items to suit there needs.
Even on there Metric machines there Cross slide Screws are not as far as I have found a true Metric size,there dials may be metric and have the correct amount of markings but a complete rotation dosent come out to a full number or even a half.
There change gears and Back gears,bull gears are a similar story.
If you calculate for a certain DP tooth count the OD can and is the same for gears with different tooth counts.
Even there small change gear 16 tooth is not a standard size.
There is no problem with anyone doing this,and there are reasons why with the 16 they would but cant really understand why the change the normal practice on the bigger gears.
At least the keep there 16,18 and 20 DP gears together.

[rusty steel]

Hello Ironwood,
If You can't buy the gear with the correct tooth count,you could possibly get someone to build up the gear with hard bronze and then with a couple of files and a lot of patience you could file the teeth (assuming you don't have a mill) . With a little inginenuity you could perhaps hold the gear in the chuck and turn your lathe into a shaper by mounting a tool of the correct profile in the toolpost and cut the teeth by winding the saddle towards the chuck.
Russell

[Sterob]

What about a large strap wrench around the chuck or cutting a timber lever to wedge in the chuck jaws?
I would not use any jarring forces as you may do more damage.
Sterob

[pipeclay]

What about a large strap wrench around the chuck or cutting a timber lever to wedge in the chuck jaws?
I would not use any jarring forces as you may do more damage.
Sterob
If this is in regards to the stuck chuck its off.

[pipeclay]

Russell its a Helical gear.

[rusty steel]

Oops, That makes it a little more difficult .Russell:doh:

[Ironwood]

That being the case you maybe able to replace the spindle gears and backgears with the grizzly spare parts,there centre distance equates to approximately 97.486,1mm bigger than what you have now.
I suppose at the worst you could allways convert to a spur gear headstock drive.


I have been wondering if it would be easier ( and possibly much better ) to just go the variable speed route.

If you had variable speed, would there be any need for a backgear ?

[pipeclay]

Cant help you with the vfd thing ,ecept only to say if you were doing a heavy or large job would you have the torque.
Also if you were drilling large holes it could also be a problem as well as hand taping large threads in the lathe,you wouldnt have the gearing to provide resistance.
Having never used one for more than 1/2 an hr I cant comment.

[Ironwood]

I just read Bryans new thread on his new setup. Will be interesting to see how it goes.