O-ring tool - for Ian

[KeithB]

Ian is justifiably proud of his new lathe, so I sent him a couple of Lyman type nose punch blanks to practice drilling and turning. The blanks have the stem turned to the proper OD and there is an O-ring groove already in place - the O-ring is used to keep the punch in place w/o using a setscrew. The O-rings can be difficult to put on, so I made a simple little tool to help out. Here are pictures and basic dimensions.

Diameter at large end .325" (made from 3/8" rod turned down)
Diameter at pointed end .175
OAL is about 1-5/8" (not critical)
Hole in end .265" (17/64" drill)
Hole in end is about .200 deep

I turned it between centers, shaped the shoulder profile by step cutting (you can still see some of the grooves from the tool point) and then filing with a half round file. I cut most of the point on the end (leave enough stock to not cut through, and NEVER cut anything off on a lathe that is held by the tailstock center!) then took the piece out and finished cutting off the end with the tailstock center using an abrasive wheel. Chucked it back up and finished shaping the point with a file. Sanded everything to make it smooth. Flipped part 180 in lathe, cut off end to length, squared up face, and center drilled followed by 17/64" drill.
To use just put the O-ring over the small end, set the nose punch down on a solid surface, put the hole in the end of the tool over the end of the nose punch stem, and push/roll the O-ring down the tool and onto the stem. A little light machine oil is recommended.

 

[Brad]

Neat little tool. Seeing stuff like this makes me wonder how many good ideas just need to be put into steel.

 

[KeithB]

Having the tools to support your ideas is nice. When I read about the fun that other folks have learning how to run machine tools and making things it makes my day. When I was a kid I had ideas for things that didn't exist (and still do...) but no way to make those things real. The biggest change in my life came when I took a mechanical drawing class in high school (actually a half day of classes for a year and a half) and found a way to express my ideas in 2D. Then I got a job as a machinist and got to make 3D things, just not my own. A layoff, back to college, an engineering degree, and now I have all the basic intellectual and physical tools I need to make darned near anything I want. Only took 63 years(!), hope to live long enough to use some of what I've learned to help other people and share the fun of their successes.

 

[Brad]

Those of us just beginning to learn appreciate the help and guidance we get from those with experience.
Sometimes we learn a better way to make a cut. Sometimes we realize that the impossible is actually easy.
What we get most of all is a knowledge that failures are all learning experiences. As long as no blood is shed it is all good.

 

[Ian]

Thank you, Keith! As a professional mechanic I've been finding ways to do difficult things for a long time....until now without a lathe. My solution to the O-ring thing last night was pull one of the cap adapters from a Permatex RTV tube out of the AC o-ring drawer in my tool box, roll an o-ring onto it, and transfer it to the punch that way. I keep extras of those on hand just for the purpose, the stepped Nylon "nozzles" are useful for all manner of things.

Got my outboard spider fleshed out last night and drilled through up to 5/8", need to go to 7/8" and bore it from there to thread minor size. This little Grizzly machine has impressed me to no end with the power it has, the ability to maintain spindle speed settings through fluctuating loads, and the over-all rigidity of the unit. Three hours of interrupted facing and turning cuts on that sheared slug was a workout for me, the carbide tool, and the lathe, but it all worked out great. I did learn a thing or two about carbide, it likes a deep cut and a rigid setup so it can bite in and not tend to ride over elliptical parts. I was cutting ~1.8" OD at 400 rpm and feeding by hand, no problems.

 

[Ian]

Those of us just beginning to learn appreciate the help and guidance we get from those with experience.
Sometimes we learn a better way to make a cut. Sometimes we realize that the impossible is actually easy.
What we get most of all is a knowledge that failures are all learning experiences. As long as no blood is shed it is all good.

+1000.

Little tips like keep your facing tool exactly on center under load (because guess what, it won't through the little stem in the center if you don't!) and don't cut off a part supported by the tailstock center (instant pinch of the cut-off tool and breakage) are gold for a newbie.

 

[KeithB]

Well, if any other MEMBER here wants some blank Lyman punches to practice on I will send five of them one time for the price of postage. Until I run out that is, I have about 50 or so left. Just contact me.

 

[Ian]

I may make one of those anyway, just for practice. L1A1Rocker gave me some little bits of rod that would be perfect and it would give me a chance to learn how to run a taper like that

 

[Brad]

Learning is a good thing. Start getting that small and workpiece deflection becomes a major reality. I find really sharp HSS tools and shallow cuts help reduce the flex.

 

[Ian]

Deflection must be why Keith profiled it between centers and then parted off the button end last.

 

[KeithB]

yep that's the reason.

 

[freebullet]

But, have you machined any baby toys yet...?

 

[Gary]

Thank you, Keith! As a professional mechanic I've been finding ways to do difficult things for a long time....until now without a lathe. My solution to the O-ring thing last night was pull one of the cap adapters from a Permatex RTV tube out of the AC o-ring drawer in my tool box, roll an o-ring onto it, and transfer it to the punch that way. I keep extras of those on hand just for the purpose, the stepped Nylon "nozzles" are useful for all manner of things.

Got my outboard spider fleshed out last night and drilled through up to 5/8", need to go to 7/8" and bore it from there to thread minor size. This little Grizzly machine has impressed me to no end with the power it has, the ability to maintain spindle speed settings through fluctuating loads, and the over-all rigidity of the unit. Three hours of interrupted facing and turning cuts on that sheared slug was a workout for me, the carbide tool, and the lathe, but it all worked out great. I did learn a thing or two about carbide, it likes a deep cut and a rigid setup so it can bite in and not tend to ride over elliptical parts. I was cutting ~1.8" OD at 400 rpm and feeding by hand, no problems.

I'm sure you've stated what Grizzly Lathe you have, but I can't find the post. Could you refresh my memory as to which model number you have?

 

[Ian]

G0765, 7x14 with the new, beefy tailstock and upgraded motor.

 

[Brad]

Watch that swarf Ian. Sometimes I think that what I am actually doing is making a hunk of steel into a coil of concertina wire.

 

[smokeywolf]

Watch that swarf Ian. Sometimes I think that what I am actually doing is making a hunk of steel into a coil of concertina wire.

Those unbroken coiled or spring-looking chips we used to call horse-killers.

Ian, do you know how to grind a "chip-breaker" into your toolbit?

 

[Ian]

I watched a utoob video about it so I must be an expert on chip breakers now, right? NOT. The concept I get, but the fact that each tool bit has to have the little chip deflector distance and angle tailored to the particular material and feed rate/speed/phase of moon kinda made my eyes glass over. The only long swarf I'm getting is from drilling, and when pushing a 5/8" bit with this little lathe when it gets going good I just keep pumping in oil and staying out of the way of the razor wire rather than pull back and break it off every few inches. I'm still working about 30 steps ahead of my skill level and fussing through it with some success, I can see years and years of practice getting better at the things that are tripping me up right now. Spent all evening boring, back cutting, and threading my spider to M27x1.5--ish (more like match what the Chinese hacked out for spindle threads rather than try to do it to the black book specifications) and learned that even when I thought I knew enough I didn't. I did get all the operations completed on the one end so it could be taken out of the chuck, and it fits the spindle threads just right, but the process was not unlike the making of politics and sausage.

So much to learn, so much fun!

 

[smokeywolf]

Only chip breaker when drilling is interrupting feed. I'll do that in most materials, but not stainless. Stainless work-hardens right at the point of the drill. Too hard to get the drill started again unless you have flood coolant or a mister aimed into the hole.

Geometry of the chip-breaker on a toolbit can be a bit more generic than the literature suggests. They're just trying to offer what might be idealic.

 

[Brad]

Aluminum with a sharp HSS bit has led me to have swarf up to 5 feet long. I learned to stop the feed to break the swarf every so often. I don't like handling all those long pieces to put in the trash.

I haven't cut metric threads yet. Luckily I haven't had the need. My spider was some weird thing like 1 5/8 -16. It threads in fine and that is all I care. Someday I should drill for the cross bolts and finish it.

 

[KeithB]

On a conventional lathe made with inch based drive/lead screws cutting inch based threads isn't really all that hard, it's a "by-the-book" sort of thing where you repeat the same basic process over and over until your thread is cut to size. Cutting metric threads on an inch based lathe isn't really harder, but does require following a slightly different process.

On inch based threading when you get to the end of the cut you disengage the carriage from the leadscrew, withdraw the tool to clear the part, then run the carriage back to the starting position, feed the tool back in, catch the right number on the threading dial, and take another cut. It is not necessary to shut off the spindle, and as long as you engage the lead screw on the right number you will follow the same helical path down the piece.

When cutting metric threads on an inch based lathe you cannot disengage the carriage from the leadscrew. If you do you will find it very difficult to re-engage the lead screw into the same helical path. You must keep the leadscrew engaged, stopping the spindle at the end of the cut, then you withdraw the tool, run the spindle in reverse to feed the tool back to the starting end of the cut, feed in the tool, and restart the spindle in the proper direction.

In order to cut metric threads on an inch lathe there has to be a 127 tooth gear somewhere in the gear train. This creates a factor of 25.4 to 1, which is the equivalencies of mm to inches. A gear has to have a whole number of teeth, the smallest integer multiple is (5)25.4 mm = (5) 1 inch, a gear ratio of 127 to 5. Now obviously you need more than 5 teeth on a gear, but once you have that 127 tooth gear in the geartrain the rest of the gear train can be set up to cut true metric threads of a variety of pitches.

I don't want to get all mathy here this morning but if anyone does want to go through the numbers I'd be glad to try to explain it. It's really just a series of multiplications of ratios/fractions representing gear tooth count. Suffice to say, on a conventional inch based lathe cutting metric threads requires using a different process. If you disengage the leadscew you have a 1 in 127 chance of reengaging it in the right position.

Caveat and plea of ignorance: I have zero experience with small benchtop lathes, everything I've said is based on lathes with 9" or larger swings and conventional gearing.