Are all scrolls created equal?

[Chipper5783]

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.

Rauce, what you say is probably true, except doing a nice job of getting through the case hardening (you’ll need to cut a male or female key in the long and cross direction) is no minor task. I have made 2 sets of the master jaws, and 3 sets of soft top jaws - it is not particularly difficult, but my advice is one is better’s off purchasing since they are not very expensive. If you can make jaw tops, or have the ability to cut a solid jaw down to make master jaws, then cutting the scroll teeth will not be difficult for you.

As a bonus, you don’t wreck the factory set of outside gripping jaws, which are pretty handy to have (I use my outside grippers pretty often, perhaps 10% of the time).

I’m a guy who has made 2 piece jaws from scratch, the scroll teeth turned out to be one of the easier steps. The link I shared earlier, from Harold Hall, describes the function - they really are not all that special that they have to be an exact shape (even a row of dowel pins would work fine).

 

[trevj]

I'll drag this up.

I bought a New, Old Stock, Burnerd Grip-Tru 100mm chuck for my Myford, at an auction. The darn auctioneers stuffed the little pouch with the matching cosmoline packed outer jaws, in to some other random lot, and they were long gone by the time the chuck came up for bids.

I found an unused set of outside jaws on ebay, after a long while of watching and waiting. I was very fortunate, in that the seller knew what they were for. So that is one option to watch. Lots of guys in the UK, parting out old tools and tooling, and postage is pretty cheap(ish), IMO.
Just searched "Burnerd Jaws" and came up with these. https://www.ebay.ca/itm/325497684113
The scroll is going to be some variation of threads per inch, likely, though if newer enough, a metric pitch. You can measure the teeth on the jaws.

After that, a quick go-round of the jaw, will give you the slot dimensions and depths.

I have, in the past, run across catalogs that listed the various dimensions of the jaws they sold. There are also a few sellers that make aftermarket soft jaws, as well as two piece jaws and bases, but I honestly could not point you at one, I ran across them while seeking out the ones I needed, quite a while back.

 

[JustaDB]

Check out this thread re: 1.5/8 chucks. I bought one of each and they work fine

https://canadianhobbymetalworkers.com/threads/1-1-2-8tpi-3-and-4-jaw-threaded-chucks.1833/

Kevin, you furnished the winning suggestion. I did order one of each, they arrived yesterday (woohoo!) & I'm still smelling of Varsol & grinning like an idiot. Freight was brutal at a buck 30 but whatever. Cleaned up, that Bison 3 jaw is a work of art.

4 jaw had one issue. I'd thread it onto the spindle & it would hang up when it got to the shoulder where the spindle threads ended. Threads looked OK. Further diagnosis revealed that the ID of the chuck was 1.497" & the spindle shoulder was 1.520 OD. Now, how the hell am I going to machine that?

This morning I devised a solution: I pulled the jaws off one of the 5" 3 jaw chucks for clearance, threaded it onto the spindle, reversed the 4 jaw & clamped it to the 3 jaw OD, centered it (first time I've used a 4 jaw, took about a 20 minutes, got it within 2-1/2 thou), bastardized a tool to machine the ID as I don't have a boring bar (had to grind the bottom for clearance), 5 minutes & a teaspoon of cast iron dust later, et voila! It's no aircraft engine, but maybe it makes me worthy enough to sweep the floor...

Thx to everyone for your suggestions, ideas & time.

 

[JustaDB]

I'll drag this up.

I bought a New, Old Stock, Burnerd Grip-Tru 100mm chuck for my Myford, at an auction. The darn auctioneers stuffed the little pouch with the matching cosmoline packed outer jaws, in to some other random lot, and they were long gone by the time the chuck came up for bids.

I found an unused set of outside jaws on ebay, after a long while of watching and waiting. I was very fortunate, in that the seller knew what they were for. So that is one option to watch. Lots of guys in the UK, parting out old tools and tooling, and postage is pretty cheap(ish), IMO.
Just searched "Burnerd Jaws" and came up with these. https://www.ebay.ca/itm/325497684113
The scroll is going to be some variation of threads per inch, likely, though if newer enough, a metric pitch. You can measure the teeth on the jaws.

After that, a quick go-round of the jaw, will give you the slot dimensions and depths.

I have, in the past, run across catalogs that listed the various dimensions of the jaws they sold. There are also a few sellers that make aftermarket soft jaws, as well as two piece jaws and bases, but I honestly could not point you at one, I ran across them while seeking out the ones I needed, quite a while back.

Thx for the link. Being new to all this, that price seems ridiculous for just 3 jaws.

 

[trevj]

Thx for the link. Being new to all this, that price seems ridiculous for just 3 jaws.

It's not. Esp. compared to what Burnerd charges, IF they can supply them.

Your alternatives are to make your own, or live without, and hope some cheaper ones come along.

Stephan Goettswinter (prolly butchered his last name again) shows making a set of jaws for a chuck on his channel on youtube. Non-trivial, if you want them to come out right

 

[trevj]

Oh yeah. If you are new with a 4 jaw, try this...

Put you indicator on a magnetic base. Set it up on the cross slide, with the face up, and the point contacting the work being centered (or the rod you are indicating off), at about center height, behind the work. (other side from operator)

Use the cross slide, to move the needle, so the tip, is moving the same way as the work is out of center (needle moves back, when the high point of the work is at the back, forward, when the high spot is forward. By hand turning the chuck, pick one direction or the other, at max travel of the needle. Loosen, or tighten, as appropriate, the adjuster that is nearest your belly. It should be opposite the indicator tip.

Use small increments, and the work will not fall out. You will find that it takes very little time, to get the runout down to very close to nothing at all, by simply adjusting the nearest adjuster, and watching which way the needle moves.

By having the needle tip move the same way as the work, it becomes a very instinctive thing to be able to see both where the inputs are required, as well as to be able to see them taking place as they happen, rather than placing the indicator above the work, and guessing at the adjustment every time. Adjustments and the indicator, are in line with each other.

As you approach a dead zero runout, or as close as you see fit, you work around the adjusters, gradually snugging each in turn, and watching the movement of the indicator, so you are tight, and zero'd, at about the same time.

Dunno why, but four jaw chucks seem to freak out the newbs, almost as much as threading and HSS Tool grinding.

About the "rod" mentioned above. I have used knitting needles, or just a bit of welding rod, with a sharp point on it, held in a tailstock chuck, and with the point in a Center Punch mark, to zero in on a wanted hole location. I have used similar, but bent to spring load themselves against the front side of a bore, when zeroing in on a previously placed bore. In both cases, the indicator tip rides on the rod. When the motion stops, while turning the chuck, you are there.
Some guys build spring loaded bars for this, but I prefer something that does not have the ability to spin, thus ruling out errors from damage, bends, etc.

 

[JustaDB]

Oh yeah. If you are new with a 4 jaw, try this...

Put you indicator on a magnetic base. Set it up on the cross slide, with the face up, and the point contacting the work being centered (or the rod you are indicating off), at about center height, behind the work. (other side from operator)

Use the cross slide, to move the needle, so the tip, is moving the same way as the work is out of center (needle moves back, when the high point of the work is at the back, forward, when the high spot is forward. By hand turning the chuck, pick one direction or the other, at max travel of the needle. Loosen, or tighten, as appropriate, the adjuster that is nearest your belly. It should be opposite the indicator tip.

Use small increments, and the work will not fall out. You will find that it takes very little time, to get the runout down to very close to nothing at all, by simply adjusting the nearest adjuster, and watching which way the needle moves.

By having the needle tip move the same way as the work, it becomes a very instinctive thing to be able to see both where the inputs are required, as well as to be able to see them taking place as they happen, rather than placing the indicator above the work, and guessing at the adjustment every time. Adjustments and the indicator, are in line with each other.

As you approach a dead zero runout, or as close as you see fit, you work around the adjusters, gradually snugging each in turn, and watching the movement of the indicator, so you are tight, and zero'd, at about the same time.

Dunno why, but four jaw chucks seem to freak out the newbs, almost as much as threading and HSS Tool grinding.

About the "rod" mentioned above. I have used knitting needles, or just a bit of welding rod, with a sharp point on it, held in a tailstock chuck, and with the point in a Center Punch mark, to zero in on a wanted hole location. I have used similar, but bent to spring load themselves against the front side of a bore, when zeroing in on a previously placed bore. In both cases, the indicator tip rides on the rod. When the motion stops, while turning the chuck, you are there.
Some guys build spring loaded bars for this, but I prefer something that does not have the ability to spin, thus ruling out errors from damage, bends, etc.

I was fine w/ it. I set the indicator up on the operator side, sitting on the cross slide, center height of the chuck & worked one direction at a time. The biggest issue I found was that you needed to keep the jaws somewhat loose in order to move freely & the 4 jaw chuck kept falling off the 3 jaw. Needed one more hand & the damn cat wasn't interested.

Haven't tried threading yet & I'm entirely comfortable grinding HSS tools. No good at it, but comfortable, nonetheless...

 

[trevj]

I was fine w/ it. I set the indicator up on the operator side, sitting on the cross slide, center height of the chuck & worked one direction at a time. The biggest issue I found was that you needed to keep the jaws somewhat loose in order to move freely & the 4 jaw chuck kept falling off the 3 jaw. Needed one more hand & the damn cat wasn't interested.

Haven't tried threading yet & I'm entirely comfortable grinding HSS tools. No good at it, but comfortable, nonetheless...

Easy way to keep the work in place, if you can, is simply hold it with the tailstock. But honestly, set up as I described, you only really need one hand to adjust, and can hold the work in place with the other if required.
For something as you did, a bullnose center (oversized cone on a live center) can be used to push the work to the 4 jaw, and the jaws each brought up to contact in turn, much reducing the run out at start.

I found that the way shown in many of the shop manuals, pretty much caused a lot of dicking about for no good reason, esp with the gage out front, or worse, on top of the work. With the gage behind the work, it is clear of the adjuster you are using, and out of way of your hand, if you need it on the work. If indicating off the interior of the bored hole, a stick of wood in a tool holder is pretty handy too. Just need enough pressure to keep the work from falling out. Press on the work anywhere that it will ride smoothly.

Good that you are comfortable, keep practicing! I heartly recomend ignoring anyone that says that you should not use a tool rest, as well as anyone that insists HSS should not be allowed to get hot while grinding!

Suggest that you practice with the 4 jaw too. Not dissing on you or what you are happy with, but you should have not a lot of trouble dialing in to 2 1/2 thou, on an OD, with just a reference, whether it's a tool in your tool post, or a scriber on a stand, and a bit of white paper, and some decent light. Chuck the paper down below the set-up, for a reflective surface, move your reference in, and rotate the chuck by hand, watching the light gap between the reference and the work. The base theory of this is that you watch the light gap get wider and narrower, and adjust it out until you can turn the chuck by hand and the light stays constant through the gap. The human eye is a mighty tool, when used well. And, worth protecting!

As a point of reference, set your caliper to 2 1/2 thou, and hold it up and look at the computer screen light through the gap. Seems like not much, but the eye can see an awful lot less of a gap, with a decent surface behind it to reflect the light.

....And that's all for this sermon.... LOL! Use it or don't, as you see fit! And fear not, the threading!