I can finally utilize an old chuck

[Buckshot]

................Probably 80% of the work I do on my lathe is held in 5C collets. The bulk of work held in chucks is hollowpointing bullet moulds. To go from the 5C setup you have to pull out the collet closer, then knock out the spindle nose adaptor. Then remove the spindle nose protector (it has a L00 spindle nose) and stick the chuck on. Going back to the 5C is the reverse, putting the stuff back.

About a year ago I'd bought a nifty little 4" 4 jaw chuck with a 5C back so it may be used with the collet setup. It's a nice little chuck but if you're going to turn something down several thousandths, and it's not too long a 3 jaw is nice. It's nice because it's fast. It's fast because you don't have to fiddle around with 4 independant jaws.

http://www.fototime.com/399BE768073A69B/standard.jpg

On the left is the 4" four jaw I bought. On the right is the 5" 3 jaw I adapted. The 3 jaw chuck was from the old *** lathe-mill combo I had first. I say IT was a *** and not all combo machines are but this one was having no power anything and no threading ability, and mainly because everything was loose.

But as it turned out, where ever they sourced this chuck from, they knew what they were doing. It's extremely well machined and finished with it's jaws tightly fitted. The scroll is very smoothly machined, but the kicker is that places that didn't have to be are very well finished. I've wanted to use it for a long time. They don't make a L00 backplate for such a small chuck.

http://www.fototime.com/B098A4398940041/standard.jpg

As you can see in both photos, I adapted a 5C blank to use as a backplate. Enco had these on sale and it seemed like a workable solution. This chuck was bolted to a backing plate on the old combo machine's spindle and so it would be to the 5C adaptor. The adaptor was 1"x6" to start with. The chuck requires a locating spigot which is a decimal 4.464" and .217" deep. I turned the 1" thick disk to 1/2" thick then faced it out to leave the spigot 4.465+" for a shrink fit.

Before fitting them together I had to drill the 3 holes in the backing plate. A math wiz I am not. I have a handle on the basics but trying to figure the bolt circle by measuring the chords is way beyond me. I clamped the chuck upside down to a center in the rotary table and with a center in the quill brought it down to center a hole. Naturally the holes were 120* apart so I was now set. I clamped the backplate down against parallels to give the drill bit room for penetration through the plate and drilled the 3 holes.

The backplate went into the chest freezer. The next day the chuck was put into the oven at 400 degrees, with a guide in each hole. Yes, Donna was a work :-). I turned on the swamp cooler and opened the back door in the kitchen so I had 3600 cfm of airflow through it. I don't find the smell of hot oil and grease offensive, but Donna probably wouldn't enjoy it.

The hydraulic press was all set up with a plastic cuttingboard across the bed. I carried out the chuckbody with hot mitts, and still with the mitts pulled the 5C adaptor out of the freezer (which is like 4' away), set it down over the guides and still holding it ran the ram down and pressed the 2 pieces together.

After removing the guides and bolting them together it went into the lathe and had the adaptor plate turned down to match the chuck body.

It's no big full size chuck but it's size is VERY useable and has allowed me to retain the 5C setup on may occasions. It beats doing that plus humping an 8" 3 jaw chuck up onto the spindle nose.

................Buckshot

[redneckdan]

nicely done.

[Trailblazer]

Good idea!

[grumpy one]

Nice work - if I'd done that it wouldn't have fit.

You now have a considerable overhang between your 5C adaptor and your cutting plane in front of the chuck. If you do my usual trick and get a dig-in while parting, it is likely to end badly for your 5C equipment. I'm sure you've thought of that, and it is obvious from your projects that you are a much more careful machinist than I am, so it need not be a problem, but it would worry me.

Geoff

[Buckshot]

................One early triumph for me in using my lathe is that I've had no problem in parting off. As a matter of fact I part off using the power crossfeed :-). The guy I bought my lathe from is mystified. He parts off with a hacksaw! I guess I'm just living right.

The only bad thing I've had happen was to get ready to part off, but I had the lever on the apron set for longfeed. I pulled up the clutch lever then turned away to get my can of pop. When I turned back the parting blade had run down a .700" die body and wiped off the .720" head. Nothing major but it did ruin the job.

...............Buckshot

[grumpy one]

It sounds as if I'm doing something wrong, as well as you doing everything right. To part without severe chattering I have to get the spindle speed and cross-feed rate just right, and keep changing both as the effective cutting diameter changes. Maybe I should check my front headstock bearing for lift again. However the problem seems to follow me around from lathe to lathe, so it probably isn't that. What top rake and clearance angles are you using on that parting tool? Would it be convenient to post a photograph?

[Buckshot]

..............I'll try to get a photo up tomorrow before work. If not then it'll probably be Monday when I'm off shift.

................Buckshot

[Buckshot]

..............Grumpy one, sorry for being so late with this.

http://www.fototime.com/BE4B06482FE9A4A/standard.jpg

These are the 2 I use. The carbide insert one to the rear has a .087" wide cut and the HSS one is .098. I use it most as it's so close to a tenth inch it's easier to figure cuts without a bunch of wierd numbers.

http://www.fototime.com/2024DF1D694C1DC/standard.jpg

My 1 Mpx 6 year old cast iron steam driven digital camara won't do good closeups so I lined in the angles. I grind in the front relief at 28*. Behind that I grind in a short back rake at 12*. The side relief as bought is 5*.

http://www.fototime.com/D03172DC0FF3AFC/standard.jpg

And here tis peeling off some W-1. If you really get after it the chip is blue and coils up tight as a pigs tail, right on top of the blade.

..................Buckshot

[grumpy one]

My guess at the moment is the main problem is that I use a top rake angle of zero. I also use zero side clearance. Front clearance isn't important - I aim for about 5 degrees but don't care as long as it doesn't touch the workpiece.

The problem with zero top rake is that the tiniest bit of wear on the cutting edge of the tool effectively gives a large negative top rake, which is disastrous. With my extremely simple tool geometry I get good cutting for the first cut or part of a cut after I sharpen the tool - sharpening is a trivial business for this tool of course, it's just a matter of touching the front of the tool against the wheel, without even removing it from the holder, for just a second or two. I tell myself I must do it every time I use the tool, but then I don't do it and suffer bad outcomes instead.

I notice one of your toolholders (the one nearer the camera in your first pic) mounts the tool at an angle, so you'd get about five degrees of top rake if you just sharpened the tool my way. That would be way better than zero top rake, which is what I have now. The disadvantage, of course, is that you then have to set up for centre height. At present I just put my "standard" packer under the toolholder, and it comes up exactly on centre every time, regardless of how far the tool is sticking out from the toolholder.

There was a type of parting tool holder years ago that mounted the tool at about 30 degrees rather than your five degrees. It was overdoing a good thing - that was way too much top rake, and made it prone to digging in - and anyway that toolholder was a pain to mount in the toolpost.

It used to be very common for machinists to grind a dip into the top of the parting tool just behind the cutting edge, as a way to get a top rake angle despite having a zero-angle toolholder. I was taught not to do it, because you can't resharpen without grinding away three or four tenths of an inch of tool.

If you are using both a top rake angle and a side clearance, it is no wonder you are getting good results. It does sound, though, as if you'd have to invest a fair amount of time in setting up (by comparison with my quite rudimentary setup arrangement).

[Buckshot]

.............. For the carbide inserted one you never grind and it's always at center once you set it. It's built in to the holder and insert. The other nifty thing about it is the moulded chipbreaker. It naturally cuts across it's face and has a central groove that literally crumbles the chip as it comes off the workpiece.

What I'd been using before the REX HSS blade was a cemented carbide with zero toprake. It was .100" wide with a 1.25" long carbide and the blade was relieved. I'd had it in my holder for so long I'd forgotten who'd made it. It worked wonderfully on everything from hardened 4140 to cast iron. I thought it was a Micrograin 100 product. Turns out it was acid etched "Champion Tool Co" with a part number. Danged if I could find a Champion tool that had them.

I'd bought it for $5, when a local machine tool company was moving and they were blowing out a lot of old stock. MSC, McMaster-Carr and the usual suspects carry the cemented carbide cutoff blades but none are .100" and I like those.

The REX AA's came from a E-Bay auction at $2 each so I got 5 of'em and just never used them until recently. So far that one blade has plowed through a bunch of steel. I ran a batch of lube-size die bodies off a 3' stick of W-1 so that was 20 some cuts right there. I run cutting oil on it through a hypodermic needle. So far no edge build up. If I'd have known they would perform like this I'd have bought more of'em. I haven't used them on cast or hardened steel yet. I might be longing for those old Champion cemented carbides.

................Buckshot

[HotGuns]

One thing that may help the chatter is to set the tool a few thousanths below center.

If its on center and the tool has no releif, the wear will cause negative rake and it will require more force to cut as well as more rigidity to cut without chatter. It will vibrate and squall like a mashed cat.

I use the carbide inserts quite a bit. When they are dull you just pop them out and replace and you can turn your RPM's way up.

[grumpy one]

I haven't tried deliberately mounting the tool a tiny amount below center - it's a frightening thought, but that doesn't mean it won't work. I see Buckshot is having success with fixed carbide tips - as I've said before, he's a much better, gentler machinist than I am. I keep destroying them with intermittent cuts. Same outcome with replaceable carbide tips; I get a chipped edge in no time when I use them for intermittent cuts. You could say I'm ham-fisted, of course, and you wouldn't be wrong. Recently I destroyed a brand new 1/8" endmill by trying to take a cut nearly 1/8" deep with it, which it shouldn't have taken long to figure out was a bad idea. It was even sillier than that, because all I did then was put in a 1/8" slotting saw and did the job in seconds. Why didn't I just do that in the first place?

Buckshot, with those soldered-on carbide tips, I resharpen them and it seems to work OK, so long as the cutting geometry is simple and you are only touching up a slightly blunted edge. You can experiment a bit by trying it with old masonry drills that have become blunt. You should use a special soft grinding wheel of course, but what I do is use very gentle pressure on a standard wheel - being very careful not to let the heat build up. After a while you'll dull the abrasive in the wheel, and then you won't be able to grind carbide any more until you've used the wheel on steel enough to wear off the surface of it slightly.

I started out with the view that you mustn't do things like hand-sharpening milling cutters, but I quickly found that my hand-sharpened ones were at a minimum, infinitely better than blunt ones. Some types you can't sharpen on a standard bench grinder of course, but in most cases you can still use something like a Dremel tool or an electric chainsaw sharpener. You can't use these villainous-looking resharps for finishing cuts of course, but for general purpose cutting they usually do the job.

[floodgate]

grumpy:

Get yourself a set (coarse, medium, fine - and extra-fine if you can find it) of the little "EZE-LAP" diamond files. A plate of diamond about 3/4" x 3" on a color-coded plastic handle. I use the "el cheapo" carbide tipped tools from Enco, and have learned to touch them up between jobs, just trying to maintain the original angles. I've found I can even file out small chips or nicks (I'm a REAL cheapskate!) with these inexpensive little gizmos. I got mine in a "Big-5" sporting goods store at the hunting-knife and fish-hook counter. They also have a diamond-coated rod about 1/4" diameter x 4" long for sharpening hooks; I use it and the flat stones to take the burs off steel sprueplates, and to swipe a tiny vent chamfer at the top of the block joint; the round one is especially nice on Lyman plates, where they come up against the stop pin and raise a burr if closed too sharply too many times. I have managed to wear out a couple of these EZE-LAP "stones", but they've had a LOT of use! And they are pretty cheap; under $10 each as I recall.

And on intermittent cuts: DON'T use ordinary carbide tools on these! I understand they DO make a carbide mix that will stand up to shock loads pretty well; check with MSC and see what they say.

Doug

[grumpy one]

Thanks Doug,

I have had a red-handled EzyLap for about 25 years and it still works to some extent. Along the way I've used it for power-lapping tapers in the lathe, so I guess it's well past its youth. I do use it for touching up the clearance surface on the end of two and four flute end mills when they are in decent shape and I've used them lightly, and it seems to work pretty well. At this point I haven't found a good way to deal with seriously blunt end mills, of which I inherited a fair supply when my uncle passed away ten or so years ago. I sharpen the clearance surfaces on the end, which gives me good end cutting, but I haven't tried following the spiral down the outside to recut the sides of these cutters. I'm pretty sure I could do it with a chainsaw sharpener, if I took my time and tolerated a pretty wavy outcome. Touching up that outside surface with the EzyLap is no problem, but only if it's fairly sharp to start with.

So far I've tried several types of carbide, selected by the traditional criteria ("If it's cheap at the local flea market, I'll get some and give it a try") but had no success under rough or intermittent-cut conditions. Here in Australia at least, most good cutting tools are very expensive because they are only available through an "official distributor", so I prefer to improvise either with HSS or whatever carbide items are unwanted by everyone else. With items like thread-cutting tools, which I frequently damage by winding them out incompetently as I come to the end of the cut, I dislike spending $15 per cut to replace carbide tips. I can resharpen a specialised HSS thread-cutting tool in about the time I could replace a carbide tip, and it's a lot cheaper.

The most important lesson I've learned is "don't keep using a slightly blunt tool". Doing this changes the situation from needing a few strokes of the EzyLap, to a long and low-quality job with a grinding wheel. It's just never a good idea to take that extra couple of cuts before resharpening, especially with milling cutters.

Geoff