Lathe fun

[Pistolero]

Yes, Keith, my machinist friend pointed me to a Shars boring bar set.
This seemed a real serious bargain. And we used one of his larger ones to take a cleanup cut on the
taper surface for my 5C collet chuck to get concentricity runout to zero, needle doesn't quiver.
The weird thing is that my three jaw shows a TIR of .0008, no typo! My friend was truly amazed,
as was I. I took the time to check it at all six positions (D1-5 style) and marked the best one. That
cuts down my use of 5C collets a good bit, unless I am recentering on a critical finished surface. For
most purposes, that is plenty close enough for my work. Still really pleased with this lathe G4003G.

Here is the boring bar set I got.

http://www.shars.com/3-8-1-2-5-8-3-4-sclcr-indexable-boring-bar-set

I have used the threading cutter, it works wonderfully. The one I used for most of the work on
the adapter is the third from the left, long diamond insert. I put in a new, very sharp edged
insert, and it cut wonderfully.

Ian- I have time, decided to start on it now. I measure a 5/8-18 thread on the Lee powder thru
expander die. If you want something different.....speak up. Will start cutting metal in a few minutes.



Bill

 

[Ian]

Ian, are you using hand taps or spiral point taps?

I guess they're all hand taps. They're straight, four-flute, typical hardware-store taps. Never heard of spiral point taps before.

 

[KeithB]

Spiral point taps push the chips down to the bottom of the hole. I use them for through tapping under power and for hand tapping through and blind holes. Regular hand taps push the chip into the flutes. Spiral point taps have a bevel on the cutting edge to push chips ahead, hand taps don't. That's why you have to reverse direction so often to break off the chips. For the record, we use spiral flute taps for power tapping blind holes. These have spiral flutes like an end mill, the chip comes up out of the top of the hole. No pulling out chips from the bottom of blind holes.

https://www.mscdirect.com/browse/?n...archAheadTerm=taps&typahddsp=Taps&hdrsrh=true

Look on the second line of illustrations, the first three taps on the left are what I am referring to.

 

[KeithB]

Bill, that's a nice set of boring bars, I have a set like that, but it's not a Shars. I also bought a 1" bar for some of the bigger work we do. If you ever run into a chatter problem one thing that helps is getting inserts with a .015 tip radius instead of the more common .031.

 

[freebullet]

Trying to soak up all I can on this here. Thanks for the tips gents!

 

[KeithB]

Too bad we don't have a machining subforum.

 

[Pistolero]

Trying to learn from Keith, thank you for the information, sir. Please, never be shy to point
out things that you see where I could improve. Not going to hurt my feelings any.

Ian -
Here are some pix of Mk. 1 version.
Will be in the mail tomorrow.


The knurling didn't go as well, need to study up on that. Serviceable, but certainly can be better.
Shorter than you wanted, but I had a time slot free so went for it before I got your reply. Always learning, even (especially?) from parts
that might not be right.

 

[Pistolero]

My machinist friend recently explained spiral point taps to me, and I bought a handful of the
standard smaller sizes. He says that they are dramatically less likely to break, cut with
far lower torque, to the point that the was thinking something was wrong the first time he use
them. Visually, the cutting (leading edge) side of the first 6 threads or so is tapered back, so
that a line faired thru the leading edge of the teeth is angled about 15 deg. No real spiral,
except that angle on the cutting edge of the first teeth. They cost a bit more but not outrageous
prices. I have not yet tried one, just hasn't come up yet.

I had seen the wild spiral taps, but that is not what we are talking about, and he said that they
were esp fragile. These things, at a glance, look just like a regular tap. Only the leading edge of
the first few threads will be different, back edge of those few threads is straight, like a normal tap.

Bill

 

[Ian]

Mmmmmm......dangit. Not going to work, I'm afraid, not nearly enough room to work the handle on the measure. It might do with a Lee powder measure riser though. Just got called to supper but I'll sketch something out later tonight with dimensions. My 55 will actually work with the Lee funnel plug I just discovered, the threaded drop tubes are a perfect slip fit inside the aluminum Lee plug.

 

[KeithB]

Sometimes its hard to get a good knurl. Knurling wheels have a certain pitch, or tooth spacing. Knurling is like putting gear teeth on the outside of a cylinder, the size/pitch of the tooth and number of teeth determine the proper diameter. Any larger or smaller diameter and you won't get a whole number of teeth around the cylinder. Sometimes changing the pre-knurl diameter just a little bit can make a world of difference. Somewhere online I found a knurling calculator that will help you select an appropriate diameter to match your knurl's pitch so you get a whole number of knurls/diamonds. If I can locate that I'll post a link.

For shallow holes and unsupported (no rigid mechanical support) tapping hand taps work OK. They are strong, self align a little better, and don't force chips down into a blind hole. but you have to reverse direction frequently to break off the chips. They are also good for cleaning up damaged threads.

For deeper blind and through holes, and especially where you have some rigid mechanical alignment, spiral point taps are the berries. Hand or powered, they work great if you don't bottom them out on chips and snap them off.

Spiral flute taps are fragile and require mechanical support. I've used them when hand tapping using my Enco hand tapping machine. But everything has to line up perfectly. These are what we use to power tap with our CNC machines. One benefit, there are no chips to winkle out of the bottom of the tapped hole. A while back we tapped around 500 plastic (food grade colored acetal rod) ball halves with 10-24 threads using spiral flute taps. We power tapped to within .025" of the hole bottom and got perfect threads that came out of the hole and broke off as the spindle reversed direction. No tearing at all, no cutting fluid used.

 

[Pistolero]

Sounds like those spiral taps good for acetal. Boy that stuff machines just BEAUTIFULLY. IMO, if it
will do what you need, it is really excellent.

Yeah, Keith, I see what you mean about getting the knurl pitch matched to a diam. Should
be calculable from counting teeth on the wheels and diameters, then getting integer numbers
of teeth around for various diameters. I will work on that and make a table in Excel. Now that
you say it, it is obvious that the teeth have to hit in the same spot around the diam, and for
some diams, it just won't work. Thanks for the tip, basically pointing out what should have
been obvious, but I never really spent any time thinking about it. This diameter was smaller
than the other, piece had some damage and I just machined it smaller to clean up, OD is not
a critical dimension....except for the knurl.

Actually, it would make a fine adaptor, but the biggest I have in stock is 5/8", IIRC. Threads are 5/8, so no shoulder
for the o-ring.

Ian, send me a sketch and I will build it. Maybe tomorrow if you get it to me in time.

Bill

 

[Pistolero]

Keith, what is that in your pic? my guess is cutaway heavy duty water separator for engine fuel... Aircraft or diesel truck?

Bill

 

[JSH]

Bill, I have a couple of B&M powder measures if you need anything for a pattern or what not.

Sad to say but I have just not had the time to get the Sheldon project moving as quick as I would like. That thing called a job sure gets in the way a lot of times.

I did get over to metal by the foot and got some 12L14 for some projects.
All is not bad though. I have been amassing pieces and parts and odds and ends to complete some projects.
It has been long enough ago that I would really like to take some night classes just to help the "light" come back on. KCCC did not look like the offered an evening class. Am going to look at JOCO.
Of coarse with Warren close you can get hands on, and chances are learn more in an hour than one could in several evening classes. Richard on my end is also a wealth of knowledge, but a 45 minute drive one way.

I am going to look at a mini lathe with a mill attachment. With the long wait and slim availability of some rear sights for revolvers, I am sure tempted to try and make what I want.

Heck I bought a Blackhawk just to get the dang Bowen sight. Tied up some funds but I got the sight for dang near free. Then bought another project, 7.5 Blackhawk in 357 max that has had some custom work done by Mr Harton. Bisley grip frame, free spin cylinder, front and rear sight, action job grips and a fair bit of other.
The week before when we shook hands on the Sheldon, I had spoke to a gent about another FA, then never heard back from him. The night Richard and I stopped by guess who called, so I ended up with another FA only this one is a 44. No regrets though. It is almost boring to shoot.

Have been looking around for a small bench top type mill. For what I will be milling at home, I may just go with a new mill drill from grizzly.
Jeff

 

[Brad]

Too bad we don't have a machining subforum.

I can easily fix that. Good idea Kieth, and very relevant to cast bullets shooters

 

[smokeywolf]

As Keith has pointed out, spiral point taps are kind of the "go-to" for small batch tapping. In 30-odd years of machining I don't think I've used a plug tap (aka hand tap) more than a dozen times. I have a few in my tool boxes, but they don't do much of anything better than a spiral point, helical/spiral flute, or an express (thread forming) tap.
Spiral flute or express tap is usually my choice for just about any plastic.

Because I made a lot of parts and assemblies used in and around caustic chemicals I machined a lot of stainless, titanium and hastaloy.
Used to see guys with limited experience trying to tap those tougher metals with the idea of producing a 75% thread; a recipe for a broken tap.
In plastics or thin cross-sections of metal I usually drill to produce a 100% thread.
In aluminum I'll choose a drill that results in a 65 to75% thread.
In stainless, titanium and other of "space age metals" I choose a tap drill size that will yield a 55 to 65% thread.

 

[Ian]

Bill, upon further review that WILL work out. I had in mind to extend the threaded end of the plug with a smaller-diameter, smooth portion so it would hold the PTE spud securely at the bottom of its bore rather than let it slide up and down per the way Lee intended, but in fact doing that will make at least some of the PTE die bodies too short to function. Also, I studied the measure some more and the clamp fixture will nestle between the other die parts quite well, and if it's ever a real issue I have other measures.

Since the depth adjustment of the PTE die is usually accomplished by adjusting the die body in the tool head, the orientation of the measure will have to be established and held by the thumbscrew on the measure's base after swiveling the measure on the adapter, so the detent hole is probably always going to be in the wrong place and essentially irrelevant. A groove could be cut for it all the way around the adapter, but there's no upward pressure on the measure at all and nothing more than slight pressure on the thumb screw will keep the measure from twisting around as the tool head rotates.

The threads on the 55's drop tubes are extremely fine, foiling my thread gauges entirely. It's between 28 and 32 TPI and is between .8 and .9 mm per thread as well, in any event far too fine to repeatedly thread in and out of aluminum. I didn't check diameter but it's about 5/8".

If you need to practice knurling I'm your huckleberry.... Unfortunately I'm leaving for Co. early Saturday morning so anything you send will probably arrive after I leave.

 

[Ian]

Here's a mock up showing approximately how the adapter you already made would situate the measure using my 35 Remington tool head and a Lee rifle charging die (one of the long ones). Note one of the two original drop tubes and lock ring sitting atop the rear left column bolt next to the Lee seating die in the tool head.

 

[Pistolero]

Thread on drop tube??? I never saw a drop tube, mine came without it. Thru hole in
the adaptor is 5/16" like the Lee funnel I was copying. Can increase that if you want, too.
Looks like plenty of clearance, that is good.

My measure is smooth inside the bottom casting hole with the set screw, .563 diam. The
threads on the Lee are 5/8 -18. Not sure what you are talking about. Please explain again.

OK, the piece will be waiting when you return.

If you want a retention groove, that is easy to add. If you don't care, fine. You choose.

Bill

 

[Brad]

My drop tube has very fine threads which thread into an adapter for 7/8-14 presses. I think the threads on the drop tube are for older Lyman presses with different threads.
My measure is a mid 80s version, Orange in color.

 

[Ian]

Thread on drop tube??? I never saw a drop tube, mine came without it. Thru hole in the adaptor is 5/16" like the Lee funnel I was copying. Can increase that if you want, too.
Looks like plenty of clearance, that is good.

Those are the pieces you're missing which started this whole project, I'm calling them drop tubes for lack of a better term, but I checked your OP and you call it a funnel/adapter, sorry for adding confusion. In my photo, it's the blued steel piece with the lock ring around it, perched atop the press pillar bolt and the bright yellow die box behind it in the background. There are two, one is for small calibers and the other is for large, the difference being the size of the hole in the coned bottom end. They fit in the bottom of the measure (mine's .563" ID as well) and thread into something, I have no idea what, maybe a press charging die like Brad mentioned. You can also just barely see the set screw detent similar to the one you made in your adapters in the side of the drop tube, or rather you can see the burrs from its edges, close to the "G" of "357 MAG" written on the ancient RCBS die box behind it.

Should be good to go with that part, no detent hole or groove required for my purposes. It will be nice to finally be able to use this fine old measure for something really useful other than a conversation piece!