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Are all scrolls created equal?

J

JustaDB

Ultra Member
So, onto the first of many questions I alluded to in my intro.

I have a Burnerd Model 30A 5" 3 jaw chuck w/ internal jaws only. In a search for external jaws, I contacted Burnerd in Kalamazoo, MI yesterday & was informed that they haven't carried parts for this chuck since '08. :(

I see, in passing, external jaw kits available on [spit] Amazon. Does the aftermarket have external jaws that will fit my chuck? If so, will any set fit or do they have to be made for my particular chuck? If the aftermarket does, are they worth spending the money on or are they...crap?

TIA.
 
What kind mounting arrangement do you require? What lathe is it for?

I'm thinking you're better off buying a new/used chuck that comes complete with both jaw sets.

All of my chuck jaws are serialized and numbered to their chucks which suggests a certain amount of factor fitment.
 
Hi, Craig.

SB9, 1-1/2" x 8.

As to new/used, let's just say budgetary constraints are a concern. The coof lockdowns killed my business & I haven't worked in 3 years.

The internal jaws I have are matching serialized, but there is no corresponding number on the body of the chuck anywhere.

DB
 
I don’t think there’s any standardization on the scroll pitch/dimensions or slot dimensions between manufacturers but I could be wrong.

Similarly I have a nice cushman 5” 3-jaw that came to me with OD jaws only.

I saw somewhere that this place has a lot of parts for older chucks, but I haven’t contacted them.

WORLDWIDE CHUCK SERVICES: LATHE CHUCK SALES & REPAIR - EXPERTS AT WORKHOLDING!!

WCS is one of the nation's leading sources for lathe chuck sales and lathe chuck repair service. We offer both new and rebuilt lathe chucks, power and manual designs, in both standard and custom configurations. We sell and service all brands including Kitagawa, SMW Autoblok, Buck, Cushman...
www.worldwidechuck.com www.worldwidechuck.com
 
JustaDB said:
Hi, Craig.

SB9, 1-1/2" x 8.

As to new/used, let's just say budgetary constraints are a concern. The coof lockdowns killed my business & I haven't worked in 3 years.

The internal jaws I have are matching serialized, but there is no corresponding number on the body of the chuck anywhere.

DB
Click to expand...

At least with a 1.5-8 spindle you can prolly find lots of options.

If I were you (and I'm not) I would try to find a whole chuck. Perhaps a better one than you have. Maybe even with a spindle thread lock (highly desirable).

The trouble with buying separate jaws is that it's highly unlikely they will match given the scroll offset for each which gets you into grinding them for concentricity. Bigger job than most want to do assuming they know how.

Also, you might or might not get the right ones. Even if you know what you want, you have to trust the seller to get it right. Big risk. See @Rauce comments above.
 
Rauce said:
Similarly I have a nice cushman 5” 3-jaw that came to me with OD jaws only.

I saw somewhere that this place has a lot of parts for older chucks, but I haven’t contacted them.

WORLDWIDE CHUCK SERVICES: LATHE CHUCK SALES & REPAIR - EXPERTS AT WORKHOLDING!!

WCS is one of the nation's leading sources for lathe chuck sales and lathe chuck repair service. We offer both new and rebuilt lathe chucks, power and manual designs, in both standard and custom configurations. We sell and service all brands including Kitagawa, SMW Autoblok, Buck, Cushman...
www.worldwidechuck.com www.worldwidechuck.com
Click to expand...
[snort] That's funny. The second chuck that came w/ my lathe is a Cushman 5" 3 jaw with only ID jaws. I spent two hours yesterday disassembling, cleaning & reassembling it. Was very stiff. Nothing wrong w/ the guts, it's all in the jaws. I need to pull them again & do more filing work on the slides.

Thx for the link, I'll have a look.
 
In the 80s Pratt Bernard had a service where you could send in your chuck and they'd fit a new set of jaws to it. Very expensive, but about 40% of buying a new chuck. They discontinued it because they were actually losing money on it. Fitting jaws to a chuck is not an easy or quick job.
 
Hi Justa, how determined are you? What resources do you have access to? I made two sets for a 12” 3J. Harold Hall has a good write up for cutting the back side scroll, using manual machines - the side grooves, and other details are pretty intuitive. I did those back side scroll teeth on a CNC mill - but a manual machine can do just as good a job. For a manual machine Harold suggests making a jig/guide. On the CNC it is 2 critical lines of code (a spiral tool path in the XY plane for two different radius - G12/13 helical interpolation, plus some positioning instruction, that is repeated a bunch of times - I used G73 translation). The resulting accuracy is up to you as the machinist, the last step is to cut the ID - like you would for soft jaws (which are generally extremely accurate). I also did a final measure and grind for the elevation.

The back side teeth are not really difficult (in fact, once you know how, it is quite easily done - like most things in life). After going through Harold’s write up (about 15 times), it really made sense. Once I got into it, I made 2 sets and made them as 2 piece jaws (separate issue).

I have used them quite a bit, they work great.

The CNC is nice, obviously there is quite a bit of repetition, and you can do a good job without making a jig/guide like Harold.

I left mine soft, but you could get them nitrided if you so chose.

Soft Jaws for the 3 Jaw Chuck

Method for Making Soft Jaws for the Three jaw chuck
homews.co.uk homews.co.uk

Should you make a set? If you value your time at more than about 5 cents an hour, then go buy yourself a 5” Bison! If you want a challenging project - start making chips.
 
Hi, Chipper.

Pretty green at this sort of thing & no mill. Not sure it's something I want to tackle at this point. Kalamazoo tried to find the prints for the jaws but noted they'd probably been destroyed. I'll have a look at the Harold Hall article, but it'll be a dream at this point.

Thx.
 
Last edited:
Dabbler said:
In the 80s Pratt Bernard had a service where you could send in your chuck and they'd fit a new set of jaws to it. Very expensive, but about 40% of buying a new chuck. They discontinued it because they were actually losing money on it. Fitting jaws to a chuck is not an easy or quick job.
Click to expand...
The guy I spoke to at Burnerd said that the 30A was a good chuck & equivalent to their current precision line. To replace it would run around $900 USD. Not the kind of scratch I currently have lying around.
 
On my 11” SM lathe, I have what is probably the original 6” Pratt (PB) with only the regular jaws (SN the same as the chuck body). I was able to find a set of the outside grippers (not sure what to call them), from another 6” PB - they fit great, I have not checked the run out (the current #1 shop project). So the serial numbers are not going to all match up, better than nothing.
 
I hate to say this, but I don't think you are gunna find what you want. Jaws for your chuck are gunna be big bucks. But it's unnecessary. Keep your chuck as is for small work, and get an entire less precise chuck for bigger work. If I were you I'd prefer two chucks over one anyway. But beyond that, generally speaking the need for precision goes down with size anyway (big stuff isn't usually as precise as small stuff). And besides, for real precision, you need a 4-jaw anyway. So keep your current chuck as is for small stuff and get another chuck for big stuff. Anyway, after thinking more than I prolly should about your situation these are my thoughts:

1. Given that your chuck is a precision chuck, is there any chance at all that you have two part jaws? If so, it's a lot easier to make or buy just the outer reversible part.

2. Here is an inexpensive 3-jaw chuck with reversible 2-part jaws for $200. You cannot buy jaws for that. LOTS of other options on Amazon.

VEVOR K11-200 Lathe Chuck 8 Inch 3 Jaw,Self Centering Chuck Hardened Steel Jaws https://a.co/d/cVg9Q5n

3. Watch Kijiji marketplace for a 3 jaw with a backplate. Such a chuck is easily modified to fit your lathe by changing the backplate to fit your spindle.
 
Chipper5783 said:
Hi Justa, how determined are you? What resources do you have access to? I made two sets for a 12” 3J. Harold Hall has a good write up for cutting the back side scroll, using manual machines - the side grooves, and other details are pretty intuitive. I did those back side scroll teeth on a CNC mill - but a manual machine can do just as good a job. For a manual machine Harold suggests making a jig/guide. On the CNC it is 2 critical lines of code (a spiral tool path in the XY plane for two different radius - G12/13 helical interpolation, plus some positioning instruction, that is repeated a bunch of times - I used G73 translation). The resulting accuracy is up to you as the machinist, the last step is to cut the ID - like you would for soft jaws (which are generally extremely accurate). I also did a final measure and grind for the elevation.

The back side teeth are not really difficult (in fact, once you know how, it is quite easily done - like most things in life). After going through Harold’s write up (about 15 times), it really made sense. Once I got into it, I made 2 sets and made them as 2 piece jaws (separate issue).

I have used them quite a bit, they work great.

The CNC is nice, obviously there is quite a bit of repetition, and you can do a good job without making a jig/guide like Harold.

I left mine soft, but you could get them nitrided if you so chose.

Soft Jaws for the 3 Jaw Chuck

Method for Making Soft Jaws for the Three jaw chuck
homews.co.uk homews.co.uk

Should you make a set? If you value your time at more than about 5 cents an hour, then go buy yourself a 5” Bison! If you want a challenging project - start making chips.
Click to expand...
One option that I have considered for my cushman chuck is to machine down the jaws I have to become master jaws for separable top jaws. Saves having to machine scroll teeth but still a fair amount of work.
 
Susquatch said:
I hate to say this, but I don't think you are gunna find what you want. Jaws for your chuck are gunna be big bucks. But it's unnecessary. Keep your chuck as is for small work, and get an entire less precise chuck for bigger work. If I were you I'd prefer two chucks over one anyway. But beyond that, generally speaking the need for precision goes down with size anyway (big stuff isn't usually as precise as small stuff). And besides, for real precision, you need a 4-jaw anyway. So keep your current chuck as is for small stuff and get another chuck for big stuff. Anyway, after thinking more than I prolly should about your situation these are my thoughts:

1. Given that your chuck is a precision chuck, is there any chance at all that you have two part jaws? If so, it's a lot easier to make or buy just the outer reversible part.

2. Here is an inexpensive 3-jaw chuck with reversible 2-part jaws for $200. You cannot buy jaws for that. LOTS of other options on Amazon.

VEVOR K11-200 Lathe Chuck 8 Inch 3 Jaw,Self Centering Chuck Hardened Steel Jaws https://a.co/d/cVg9Q5n

3. Watch Kijiji marketplace for a 3 jaw with a backplate. Such a chuck is easily modified to fit your lathe by changing the backplate to fit your spindle.
Click to expand...
1. No joy.
2. Thx for the link.
3. Been watching Kijiji since I picked up the lathe. Only 5"-8" chucks I've seen in AB, BC, SK were accessories sold w/ a lathe. I'm not on social media so FB is out.
 
Rauce said:
One option that I have considered for my cushman chuck is to machine down the jaws I have to become master jaws for separable top jaws. Saves having to machine scroll teeth but still a fair amount of work.
Click to expand...
Yes but you also have to drill & tap them for the bolt-on jaws, that wont be so easy as they are hardened. And most have that funky (precision) indexing pattern to properly engage the new top jaw. Then presuming new jaws mounted you still need to true them to spindle axis. Yes a bit of work

1674675225307.webp
 
PeterT said:
Yes but you also have to drill & tap them for the bolt-on jaws, that wont be so easy as they are hardened. And most have that funky (precision) indexing pattern to properly engage the new top jaw. Then presuming new jaws mounted you still need to true them to spindle axis. Yes a bit of work

View attachment 29944
Click to expand...

I haven’t tested this so maybe it’s not universal but from what I’ve read chuck jaws are typically case hardened so once once you get through the top layer it’s not too difficult to drill and tap.
 
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