"Tiny" Independent 4 Jaw

I think I am looking around for a "small" independent 4 jaw.

Some time back I saw Steffen Gottswinter (spelling) make a video where he used offset drilled bushings to grind off center tool shanks. This is handy for making things like boring bars threading tools, and inside grooving tools. You can even make a single form single flute thread mill this way in a pinch. Basically an inside threading tool.

I certainly could do this and its pretty easy. I just need to decide what sizes I want to make first, and how far they should be offset. For any particular tool I think they would strongest if the offset is only enough to make that particular tool. I have made tool and drill bushings before. Solid and split both. I have run my solid bushings at upto 34,000 rpm (some of them, and I've got a split bushing for a drill that I use at 5,000 all the time. I'm confident in my ability to make them. The thing is for this purpose I might have to make dozens of them eventually.

This morning I was watching Steve Summers video on setting up a 4 jaw to use on his tool and cutter grinder to grind offset clearance diameters like Steffen's bushings, but you just dial it in on the 4 jaw. When your offset is ground switch it to a collet to grind in the tool's cutting surfaces/edges.

Steve used a much larger chuck than I would have chosen. I don't think I could fit that on my little single lip tool and cutter grinder (d-bit grinder). I think a little 2 inch or maybe 3 inch that would open to hold upto a piece of half inch carbide or HSS would be perfect for me. They make scroll chucks that small. I have a couple (I use them like centers on rotating arbors), but they are scroll chucks. I have not seen an independent jaw that small.

Quality doesn't even have to be all that great. It's just for grinding a clearance offset to allow for maximum remaining material for strength. The important griding all comes after its swapped back to a collet.

Reply to
Bob La Londe
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Like these 3 inch?

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Out of stock just now...

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Reply to
Leon Fisk

I swear I checked Little Machine Shop. LOL.

Reply to
Bob La Londe

I've since found a number of these down to 50MM (12mm capacity). I guess me first look was just not very good. 12mm is smaller than my target capacity, but I can adapt. Maybe two of them. One as shipped (more or less) and one with jaw ground to accept upto 5/8.

Reply to
Bob La Londe
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A lot of times knowing something is available and how it is described makes all the difference. Then you can get down to the nitty-gritty of searching for features and price๐Ÿ‘๐Ÿ™‚

Reply to
Leon Fisk

I think I am looking around for a "small" independent 4 jaw.

Some time back I saw Steffen Gottswinter (spelling) make a video where he used offset drilled bushings to grind off center tool shanks. This is handy for making things like boring bars threading tools, and inside grooving tools. You can even make a single form single flute thread mill this way in a pinch. Basically an inside threading tool.

I certainly could do this and its pretty easy. I just need to decide what sizes I want to make first, and how far they should be offset. For any particular tool I think they would strongest if the offset is only enough to make that particular tool. I have made tool and drill bushings before. Solid and split both. I have run my solid bushings at upto 34,000 rpm (some of them, and I've got a split bushing for a drill that I use at 5,000 all the time. I'm confident in my ability to make them. The thing is for this purpose I might have to make dozens of them eventually.

This morning I was watching Steve Summers video on setting up a 4 jaw to use on his tool and cutter grinder to grind offset clearance diameters like Steffen's bushings, but you just dial it in on the 4 jaw. When your offset is ground switch it to a collet to grind in the tool's cutting surfaces/edges.

Steve used a much larger chuck than I would have chosen. I don't think I could fit that on my little single lip tool and cutter grinder (d-bit grinder). I think a little 2 inch or maybe 3 inch that would open to hold upto a piece of half inch carbide or HSS would be perfect for me. They make scroll chucks that small. I have a couple (I use them like centers on rotating arbors), but they are scroll chucks. I have not seen an independent jaw that small.

Quality doesn't even have to be all that great. It's just for grinding a clearance offset to allow for maximum remaining material for strength. The important griding all comes after its swapped back to a collet. Bob La Londe Proffessional Hack, Hobbyist, Wannabe, Shade Tree, Button Pushing, Not a real machinist

------------------------------------ This 3" Sherline is good for turning eccentrics or milling with a spin index. The work can be centered or offset more easily on a lathe and then transferred for milling or grinding.

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I have 3-, 4- and 6-jaws on 5C mounts and use all of them.

--jsw

Reply to
Jim Wilkins

Here's one on ebay for 67 bucks ... seller has a good feedback rating too . Even comes with an MT2 stub arbor .

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Reply to
Snag

Reply to
Gerry

I couldn't tell you . I saw a 4 jaw that met Bob's specifications ... Though for that price I would buy one if I had a need for a chuck that small . And with the MT3-MT2 adapter I have it would fit my Logan . Hell , I might buy one just because I might need it one of these days ! Though I'd be more inclined to get a 3 jaw scroll chuck with adjust-true capabilities . My 70+ year old 3 jaw 5" varies a bit but it's usually around .002-.004 runout .

Reply to
Snag

I haven't found anything my 50mm 3-jaw with an M12-1mm mount, on a Morse #2 arbor, can do that another chuck I mentioned can't do as well or better. Unless it has drawbar threads a Morse arbor is only secure if it's in compression, as with a drill bit, it won't take cutting forces in other directions.

For me 5C is the most versatile mount for a small chuck since it fits the lathe, square and hex collet blocks, a spin index and import copies of the Kalamazoo 5C indexer. I have two of the latter, one with the sides milled parallel to the axis to go in the milling vise, the other upright on an angle plate.

To hold a Morse arbor or collet I'd have to insert it into a 1" OD adapter sleeve, and that into a 5C collet. I could but haven't needed to. I bought the 1" adapter to make a slide + rotate grinding fixture and discovered that the OD had expanded slightly around the ejection slots after grinding.

The dead centers on my surface grinder's tool grinding table aren't swappable, for shapes they won't hold I have to use a fixture on the mag chuck. Grinding is messy and 5C collets are easier than chucks to clean afterwards.

Reply to
Jim Wilkins

...My 70+ year old 3 jaw 5" varies a bit but it's usually around .002-.004 runout . Snag

--------------------

5" has turned out to be a good chuck size on my 10" South Bend because it clears the carriage and allows cutting on the headstock side of the work.

As for the largest useful chuck, my 6-1/4" Bison 4-jaw can hold up to ~8" OD with the jaws reversed, and not quite hitting the ways.

Reply to
Jim Wilkins

My 4 jaw is a Logan 444 6" , It also clears the saddle unless the work piece is larger than 7" diameter .

Reply to
Snag

Thanks everybody. This is for grinding a clearance on HSS and carbide blank (mostly chowdered endmills converted to other tools). I will likely use the cheapest one I find and put a straight shank on it. No point in spending real money on anything that's going to be plasted with silicone carbide and diamond grinding grit.

Reply to
Bob La Londe

Eventually I will likely want some chucks with 5C shanks for use on the little turret lathe. It has a native 5C spindle, so it only makes sense. I am building a new CNC router (Wood Ripper 2 (Wood Ripper 1 Must Die)), and decided I'm going to repair/modify the Hurco mill before I get to that lathe though.

Reply to
Bob La Londe

Thanks everybody. This is for grinding a clearance on HSS and carbide blank (mostly chowdered endmills converted to other tools). I will likely use the cheapest one I find and put a straight shank on it. No point in spending real money on anything that's going to be plasted with silicone carbide and diamond grinding grit.

Bob La Londe CNC Molds N Stuff

--------------------------

The 4-jaw that's cheapest and easiest to clean is a thick walled tube with two rings of four setscrews that close together like a 4-jaw.

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Dog-point the screws or else they may flare and need to be cut off to change them.

Reply to
Jim Wilkins

and the easiest to make... and the smallest profile.

Nice! Simple! Elegant!

Reply to
Bob La Londe

and the easiest to make... and the smallest profile.

Nice! Simple! Elegant! Bob La Londe CNC Molds N Stuff

------------------------

Here is a different application:

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I made one like the LMS product, without the spindle mounting threads, just a slip fit. The screws bearing on thin whippy rod stock keep it in place.

For the smaller ID of the collet closer tube a cheap Multi-craft 1/2" drill chuck with the nose turned down to fit into the tube works well. At the low speed of my leather-belt lathe 1/2" and larger rod doesn't whip or need restraint. I pressed pins into the key holes for handles and turned down the nose up to them, and removed the mounting end of the chuck body to give 1/2" clearance straight through.

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Reply to
Jim Wilkins

After some thought I decided I probably will not go with a spider inspired chuck for this. While sloppy is "okay" I would be concerned about how straight it would hold the recycled end mill or tool blank under grinding pressure. A spider is normally used to stabilize a long work piece and center the wippy end of a long work piece that is held securely at the business end in some other type of chuck or collet.

Still thinking about it. I have been known to free hand hold a tool up against the wheel on the D-bit grinder when necessary.

Reply to
Bob La Londe

After some thought I decided I probably will not go with a spider inspired chuck for this. While sloppy is "okay" I would be concerned about how straight it would hold the recycled end mill or tool blank under grinding pressure. A spider is normally used to stabilize a long work piece and center the wippy end of a long work piece that is held securely at the business end in some other type of chuck or collet.

Still thinking about it. I have been known to free hand hold a tool up against the wheel on the D-bit grinder when necessary.

Bob La Londe Proffessional Hack, Hobbyist, Wannabe, Shade Tree, Button Pushing, Not a real machinist

------------------ The plus is quick and simple, the negative is difficult to adjust and high maintenance, as the rotating high pressure line contact with the tool will expand the ends of the screws. I thought it might be useful to experiment with, grind angled tapers, or to hold the hot shank while free hand grinding it, though a spare thread-mount drill chuck on a bolt works for that.

How would a 4-jaw mount on your tool grinder?

-BIG- snow storm here after a very mild winter.

Reply to
Jim Wilkins

With a straight shank into the native 5C collet. I specifically looked for and bought one with a 5C tool holder so I would not wind up limited to a proprietary or hard to identify collet set.

Cover your emergency fire wood and check your vittles. No need to be out in that.

Reply to
Bob La Londe

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