Need a little help with lathe chuck questions

[tominboise]

My new to me Powr Kraft lathe came with a 6" 3 jaw chuck installed, and a 6" 4 jaw in the box. The 3 jaw is way heavier than the 4 jaw. The 3 jaw is labeled as "Precision Chuck" and the 4 jaw was made by "Union Manufacturing Company". The 3 jaw is also mounted to an adaptor that goes from the 1-1/2 - 8 Spindle to a flat face mount. The 3 jaw has three 8mm screws on about a 72mm bolt circle diameter. The 4 jaw is direct mount to the spindle.

3 jaw chuck:





4 jaw. Seems like it would be used for small work as it is very light compared to the 3 jaw:



I think I need a heavier duty 4 jaw, and am wondering is this mounting to the flat plate is a standard for any particular manufacturer. I can't seem to find any info on the "Precision Chuck", concerning who made it or if they make a 4 jaw. It seems to be of high quality.

 

[matthewsx]

3 jaw is heavier because it has a scroll, also the backing plate adds weight. Union is a good maker, nice to have a direct mount as it saves space between centers. I would just use it, let us know if it gives you any problems.

John

 

[G-ManBart]

For starters, I think the 4-jaw is more than enough chuck for that lathe. As mentioned, 4-jaws tend to be lighter because they've simply got less parts. I wouldn't hesitate to use that chuck at all. I haven't weighed them, but I know the 8" 3J on my 16" victor weighs more than the 10" 4-jaw I have for it. I have a 10" 3J for it as well, and that's way heavier than the 10" 4J.

As far as the 3-jaw, you've got a couple of things going on. It's hard to tell exactly from the pictures, but looks a touch big for that machine. I'm probably a bit biased, but at one point I wound up with an extra 6" 3J adjustable structure chuck and got an adapter to use it on my 14" Logan. I though the machine ran a bit smoother, with the 6" 3J on it than the 8" 3-jaw, and 10" 4-jaw.

I will say, whoever fit the backing plate for the 3J didn't really do what I'd call a proper job. For starters, having the adapter plate be larger than the OD of chuck simply adds unnecessary weight....and it looks goofy to my eye. They also seem to have left the adapter at full thickness and there's a long way from the face of the plate to where the spindle nose sits. Reducing the thickness of the plate will reduce the amount the chuck sticks out from the spindle and will help prevent chatter. The farther the chuck sticks out, the more likely you are to get chatter when doing things like parting where the's a lot of pressure on the cutter. You could face off something like 1/4" to 1/2", still have enough meat for the bolt heads and plenty of clearance to the front of the spindle. Next up, they didn't turn a hub for the back of the chuck where it has the recessed section. Adding a hub will help keep the chuck centered and you won't get chips in there like you do now (picture of the back of the chuck shows where those chips wind up.

I would turn it down to the OD of the chuck, then face off the extra meat and add a hub for the chuck to fit over. That will get the chuck closer to the headstock, save weight and simply work better.

 

[tominboise]

For starters, I think the 4-jaw is more than enough chuck for that lathe. As mentioned, 4-jaws tend to be lighter because they've simply got less parts. I wouldn't hesitate to use that chuck at all. I haven't weighed them, but I know the 8" 3J on my 16" victor weighs more than the 10" 4-jaw I have for it. I have a 10" 3J for it as well, and that's way heavier than the 10" 4J.

As far as the 3-jaw, you've got a couple of things going on. It's hard to tell exactly from the pictures, but looks a touch big for that machine. I'm probably a bit biased, but at one point I wound up with an extra 6" 3J adjustable structure chuck and got an adapter to use it on my 14" Logan. I though the machine ran a bit smoother, with the 6" 3J on it than the 8" 3-jaw, and 10" 4-jaw.

I will say, whoever fit the backing plate for the 3J didn't really do what I'd call a proper job. For starters, having the adapter plate be larger than the OD of chuck simply adds unnecessary weight....and it looks goofy to my eye. They also seem to have left the adapter at full thickness and there's a long way from the face of the plate to where the spindle nose sits. Reducing the thickness of the plate will reduce the amount the chuck sticks out from the spindle and will help prevent chatter. The farther the chuck sticks out, the more likely you are to get chatter when doing things like parting where the's a lot of pressure on the cutter. You could face off something like 1/4" to 1/2", still have enough meat for the bolt heads and plenty of clearance to the front of the spindle. Next up, they didn't turn a hub for the back of the chuck where it has the recessed section. Adding a hub will help keep the chuck centered and you won't get chips in there like you do now (picture of the back of the chuck shows where those chips wind up.

I would turn it down to the OD of the chuck, then face off the extra meat and add a hub for the chuck to fit over. That will get the chuck closer to the headstock, save weight and simply work better.

I will look into reworking the backing plate as you suggest. Right now I am trying to get the chuck off the spindle, so I can install the 4 jaw and see how it works, etc. Of course, it is fighting me, so I am working out how to lock the spindle enough to get the chuck off. Without using the gear train if I can help it.

 

[G-ManBart]

I will look into reworking the backing plate as you suggest. Right now I am trying to get the chuck off the spindle, so I can install the 4 jaw and see how it works, etc. Of course, it is fighting me, so I am working out how to lock the spindle enough to get the chuck off. Without using the gear train if I can help it.

I've been there...spent two weeks trying to get the chuck off one of my lathes. The chuck hadn't come off in decades and every trick in the book failed me. I removed the chuck from the backing plate as you have. I finally gave up on all of the methods I read about and bought a 3D printed spindle lock off eBay and had the chuck off in two minutes. Worth every penny to avoid stripping the bull gear. I'm not sure which exact model lathe you have, but I'd be willing to bet that one of the 2-3 guys selling them on eBay offers one that will work. Something like this:

Atlas Craftsman 10" & 12" Lathe Spindle Lock Wedge Stop Block --- Orange | eBay

Atlas / Craftsman 10" & 12" Spindle Lock Wedge Block. Quality 3D printed Wedge Block used to remove stuck or tight chucks from these old lathes. Note: does not include lathe or any other shown parts, and is for one plastic spindle wedge as shown.

www.ebay.com

 

[tominboise]

I've been there...spent two weeks trying to get the chuck off one of my lathes. The chuck hadn't come off in decades and every trick in the book failed me. I removed the chuck from the backing plate as you have. I finally gave up on all of the methods I read about and bought a 3D printed spindle lock off eBay and had the chuck off in two minutes. Worth every penny to avoid stripping the bull gear. I'm not sure which exact model lathe you have, but I'd be willing to bet that one of the 2-3 guys selling them on eBay offers one that will work. Something like this:

Atlas Craftsman 10" & 12" Lathe Spindle Lock Wedge Stop Block --- Orange | eBay

Atlas / Craftsman 10" & 12" Spindle Lock Wedge Block. Quality 3D printed Wedge Block used to remove stuck or tight chucks from these old lathes. Note: does not include lathe or any other shown parts, and is for one plastic spindle wedge as shown.

www.ebay.com

Great link - thank you. I am trying to find one that will fit my machine. I see them for Logan but not sure which one will work on my Wards version.

 

[Firstram]

I've been there...spent two weeks trying to get the chuck off one of my lathes. The chuck hadn't come off in decades and every trick in the book failed me. I removed the chuck from the backing plate as you have. I finally gave up on all of the methods I read about and bought a 3D printed spindle lock off eBay and had the chuck off in two minutes. Worth every penny to avoid stripping the bull gear. I'm not sure which exact model lathe you have, but I'd be willing to bet that one of the 2-3 guys selling them on eBay offers one that will work. Something like this:

Atlas Craftsman 10" & 12" Lathe Spindle Lock Wedge Stop Block --- Orange | eBay

Atlas / Craftsman 10" & 12" Spindle Lock Wedge Block. Quality 3D printed Wedge Block used to remove stuck or tight chucks from these old lathes. Note: does not include lathe or any other shown parts, and is for one plastic spindle wedge as shown.

www.ebay.com

That’s incredibly cheap too! The cost of The filament + the printer + the power and free shipping for $8!

 

[tominboise]

That’s incredibly cheap too! The cost of The filament + the printer + the power and free shipping for $8!

Imagine how cheap it would have been if Logan had machined a couple flats on the spindle, for a wrench.

 

[G-ManBart]

Great link - thank you. I am trying to find one that will fit my machine. I see them for Logan but not sure which one will work on my Wards version.

Looking at the current Logan Actuator page it seems like your lathe would be in the 200 series. I'd suggest jointing the Logan Group page which is owned by Scott Logan. You could also call Logan Actuator and talk to Scott to make sure which Logan model number corresponds with your machine.

This is the main page for Logan Actuator:

Logan Actuator Co. - Lathe Department

This is the section on the different models.

Logan Lathe Model Number Table

This is the Group page where a lot of the owners share info:

Lathe-List groups.io Group

*********************** Logan Lathe Users Group *********************** For discussion and announcements related to Logan Lathes. Hosted by Scott Logan, Logan Actuator Co. ( http://lathe.com ) Question about Back Gear Adjustment? See https://groups.io/g/Lathe-List/message/146 See our online...

groups.io

If yours turns out to be in the 200 series, this should work:

SPL Logan Lathe 200/800 series Spindle Lock Wedge Block To Remove Tight Chucks | eBay

The Spindle Lock must be slid in from the gear face. With slight pressure, the lock will slip in place. The spindle is then rotated allowing the block to wedge in place. The chuck is removed by placing a wrench on a jaw and turning it off, or your preferred way.

www.ebay.com

 

[Aaron_W]

Great link - thank you. I am trying to find one that will fit my machine. I see them for Logan but not sure which one will work on my Wards version.

If you find your Wards model number on the site below and then and click the model number it will take you to a page for the corresponding Logan model documentation.

Logan Models chart


Scott Logan runs a couple of Logan groups, one on Facebook, and one on I/O groups, that replaced the old Yahoo group.

Scott is the current generation of the Logan family and is full of useful information on these lathes, it is very worthwhile joining for a Logan / Wards / Powermatic owner.