Manually Milling an Ellipse.....Say What ??
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- Опубліковано 12 січ 2024
- This video details the setup and math required to manually machine an elliptical shape. Its an easy CNC part, but doing it on a Bridgeport is a whole nuther animal. Take a Look !!
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To address all the comments. By definition, An ellipse is always an oval, but an oval isn't always an ellipse. the constantly changing arc definition of a "True" ellipse is the difference. However, the difference between the final geometric shapes is almost impossible to distinguish. A shorter, rounder example would closer represent a 'True" ellipse to the naked eye.
So your title should really be "Manually Milling an Oval.....Say What ??" The way I remember it is that an ellipse has two center points, and the sum of the two radii to the outer edge is constant. Think of a piece of string anchored to two nails, and a pen used to pull it tight and draw the circumference. An oval (ovoid) is anything that vaguely resembles an egg.
Was going to comment this as well :). I drew this up in CAD with the ellipse of the same length and width. The biggest profile deviation was 0,0085" on the large radius and 0,0034" on the small radius. Does not sound like much, but to me at least it is easy to tell which curve is the ellipse and which is the approximation. When not presented with the real thing to compare to though, its harder to tell.
I wonder if it would be possible to make a jig for cutting a true ellipse? I've seen devices with two perpendicular slots in them, and an arm with a pin in each slot used to draw an ellipse, maybe it could be adapted to cut one?
@@endotherm"Approximating an ellipse on a manual mill.....Say What ??" I think would be the better one. Oval is such a broad term.
@@2testtest2 Hobby machinist here... That is a question I've been pondering for years!
My short answer is No. You can't make an ellipsis on a lathe nor a milling machine.
My long answer is 'anything is possible, but, such a jig would have to have _a lot_ of moving parts... Levers, joints, possibly gears. and all would have to be sturdy enough to hold either the work piece or the cutting tool without much deflection.
Making one that has some adjustability would be even more complex.
"Addressing the comments" but not correcting the title Joe confirms that this was an intentional click bait attempt, which is sad. (Also, there is no such thing as a 'true eclipse ', at least till some tries to fake one for the sake of some YT clicks ...)
That is an approximate ellipse. There is a way to make an exact ellipse, but it lacks a lot of rigidity, and requires more material. Basically, you use a long boring bar in an eccentric boring head, cutting on the inside. You tip the head to the appropriate angle (for the one you made it is a rather steep angle from 90 degrees to the table). Then you raise the table to cut away half (or a bit more) of the feature. Drop the table back down. Then rotate the part 180 degrees and repeat the other half of the feature. Finally, you cut the desired thickness off.
The boring bar and material (or stand-off) need to be long enough so that you can get to complete at least half of the small end at the depth of the finished part. The more elliptical the part, the longer these things need to be.
This is why I love this channel! I am a tool and die maker and only watch manual machining videos. This skill is not taught in schools, the teacher would just say use the CNC. To me manual machining things like this takes so much more skill than programming on a computer.
Excellent demonstration of the importance of understanding how to use precision tools and fixtures to achieve the desired geometry of the finished part. Doing this on a CNC machine does not require a mastery of the underlying skills. Highly informative. Thank you!
Great tutorial Joe. Thanks! And yes, no fast forwarding here, only rewinding.
one thing i kind of like about the mathy videos is that it shows theory put into practice. that's the part our educational system seems to neglect.
Yep. It’s amazing how a little practical application can make the light bulb go off in people’s head.
It looks sort of like an ellipse but a ellipse is based on a hyperbolic curve which continuously varies. Parametric eq: x = h + a cos(t), y = k + b sin(t), where (h, k) is the center and a,b are the axis lengths. Nice looking approximation though.
Watched the video to see how to make an ellipse. Was disappointed that it wasn't a true ellipse. Came to the comments to see who else would have noticed that it's not a true ellipse. Was not disappointed.
Oval would be more appropriate
@COBARHORSE1 It's an oval shape. An ellipse has a continually-varying curvature between a minimum at both minor axis ends and a maximum at both major axis ends. The oval just has two curvatures with abrupt changes at four tangent points.
A device to provide the required cutting guidance is not difficult to design. Given the geometrical definition of an ellipse as the curved line of intersection between a conical surface and a plane secant to it, such device should surely include a slanted-axis conical piece whose axis intersects that of the milling tool, and a thin vertical-axis roller rolling on and around the cone to guide the rotating table eccentricity as the latter rotates. Not too difficult a mechanism. By adjusting the cone's height (or where the roller rolls), the ellipse's size can be selected; by adjusting the cone's inclination, the ellipse's eccentricity. You can even get a parabolic or hyperbolic shape at certain angles, a circular shape at null angle.
Not hyperbolic, (x squared/a squared) + y squared/ b squared) = 1
What a good man you are Joe for taking the time to show in great detail how it’s done and for believing that we might benefit from a greater knowledge than our own. If we “get it” then good for us, if we don’t, well then good for you for trying. I’m always amazed at how knowing something can help with it down the road or even with other seemingly unconnected tasks.
And yet, what he made is not an elliptic but an oval shape. There is a great geometric difference between both shapes even though they both have similar aspects.
Nice technique Joe.
In the toolroom where I served my time back in the sixties, we had a lathe that was modified to turn ellipses. You could also turn conical shapes that started round and transformed to an ellipse. One of its jobs was to make tooling for elliptical loudspeakers.
Just so you know ,Joe; I don't care how much math you put in your videos, I don't ever fast forward them. I totally enjoy watching you make numbers make sense. Liars can figure, but figures never lie...amazing video!
Well, this piece lied to you! The piece he made is oval, not elliptic. A great geometric difference. The video title is a lie.
@wafikiri7676 I don't really care if it's an oval, an ellipse or a horses -ss, my comment referred to my enjoying his videos and the mathematics he uses to find dimensions, edges, etc...keyboard cowboy.
Oh, by the way, I DID Google an ellipse vs an oval.
All ellipses are ovals but not all ovals are ellipses...
I thought when starting I am never going to get this. Now I am heading out to the workshop to play. Brilliant explanation Joe.👏👏🇬🇧
Excellent video, amused by the arguments about "true" ellipsis, the difference between a true and what we called a 4 centre ellipse is minimal and not at all detrimental. The standard openings for most pressure vessels are elliptical for access and stress considerations. The 4 centre method allowed an easy and quick way of cutting the plate with oxy acetylene equipment. Ray.
Not having a CNC, I love watching you do stuff like this. Very informative video Joe.
Not wanting to tear down a guy for missing a relatively minor detail considering this is just a demonstration of technique, I’ll just say thanks for sharing. You are wealth of knowledge.
Now the internet know-it-alls can resume.
I have a very high end CAD system here. Pro-E Wildfire. The current release is called Creo. It has an ellipse tool for drawing true ellipses. I overlaid a true ellipse on this part to see how different it was from a "TRUE" ellipse. As stated in another comment here, the profile deviation...at the most extreme spot...was .008" for about 20 degrees. depending on how the print was dimensioned and toleranced, this shape, as machined, would pass inspection. Let the haters hate. Freedom of speech and all. Thanks for a positive comment.
Joe,
Your rotary table vids are some some of your best work. If the new machinists learn to think in center lines and centers of rotation they'll be ahead of the game. It always pays to seriously ponder why the math works and if you mess up, slow down and walk back through whatever mistake you made. That's where the real learning happens. A print of a part is great but says nothing about the setup. Making a sketch of your setup is a giant help. The 15 dollar scientific calculator is the most important tool in the shop....along with paper and pencils. Great video.
Thanks. I think the most common error on a rotab will be not adding the cutter radius to the part dimension, or the occasional turning of the crank in the wrong direction. Otherwise, there is a lot of thinking to do.
Thanks Joe! I think! I just watched this before going to bed. It's 11:30+/- . I think I might have nightmares about this.
Don't know if you have watched any of Brandon's work on his Inheritance Machining channel but he made an attachment for his rotary table that would enable an easy setup of all sorts of complicated shaped projects on the mill. Quite a work of art in its own way.
Trust you're enjoying the weather we've sent you from Canada. Its been blowing the heck out of my home for the last 24 hours, little snow, actually had a thunderstorm last night, but tonight its colder at -3°C and expecting it to get much colder tomorrow.
All the best for your New Year 2024 from Canada's banana belt.🤞🇨🇦🍌🥋🇺🇦🕊️🇺🇲💥🏁👍
A true ellipse could be single point cut by a rotating tool angled relative to the z axis of the part. For example, tilting the head (quite a lot) of the mill, using a boring head and feeding by moving the knee up. Calculations, fixturing and clearances left as an exercise...
Post a video demonstrating your expertise. We'd all benefit by it.
Exactly, I was certain that Joe would show it on a lathe. That's the method I know of.
Thank you Joe, you are a wonderful teacher. My ah-ha moment was realising that the mill table movement sets the radius and the vice movement on the table sets the centre of the radius. That's all there is to it, the key is to not overthink anything else.
I've said before, Joe, you are the king of the rotary table! AND, I learned how to find the tangent points of the two radiuses. Brilliant! Also, although a visually complex set-up, I love the simplicity of function. Thanks for sharing your knowledge and wisdom.
Dear Joe Pie, this has enlightened me to so many
ways of accurately placing parts......Thank You so Much...
Paul
A great video of Joe using joe blocks to locate the center offsets on the rotary table. But not a true ellipse. An ellipse is described as the constant sum of the distance from the 2 foci. Not 4 tangent radii. Very interesting.
The combination of linear and rotary motion is extremely complex - but this video gives a really good insight into the sorts of complex geometries you can achieve with some thought, and more importantly the maths and the process. Much appreciated as always. Good use of the rotary table this way is a method I struggle with a bit, so having these tutorials on hand helps enormously - much appreciated as always.
I procrastinated watching this one out of fear but ended up learning in spite of myself. Joe I commend you on your sincerity when you invite questions because you actually answer them with wisdom and patience, unlike many UA-camrs who say "leave a question" then ignore pages of pleadings. You are a treasure on this platform.
Thanks. I see every comment that comes in and try to answer questions the best I can.
Of course, since this is not a true ellipse, you could make it closer by adding 4 more foci, in other words, 4 more center points. This would then require moving shims on both the X and Y axes. This would add much more time too. Operations like this are why I bought a Troyke cross slide rotary table decades ago. But then I bought CNC mills which obviated the need for the Troyke. Anyway, please keep doing these types of videos, they really help folks learn machining techniques. And are also fun to watch.
Eric
Dear Joe, Watching Alec Steele and making the same hammer myself. A happy coincidence ! A great video as usual. I appreciate your
time and great presentation ability as well as your obvious skill and knowledge. God bless from England.
I'm really benefiting from all of the work holding and order of operation methods that you have shown. I appreciate the time you spent doing so.
Another brilliant video thanks Joe.
Glad you enjoyed it
Wow. Once again some clever Fixturing and the math behind it. Loved it.
This was killer.
Thanks as always for sharing your knowledge.😊
Thanks so much. There are a ton of things to take away from this. As usual your taking momenents to highlight cutter rotation, climb, conventional, and resulting burrs/ finish, is priceless.
Your explanation of the math to come up with the end angles is a valuible reminder of the power of triangle and the ability to solve for them.
Im loving the idea of using gage blocks for precision displacements of the screwless vise on the rotary table. . It really simplifys so much.
I am struggling with holding the screwless vise in a lot of operations . Rotary table and elsewhere. I ground slots in to the sides of one, for little hold down clips . It works well enough, but does not work well with the gage block displacement idea. I always run out tee slots or room on the table.
Any screwless visee holding ideas would be great..
Also, to every all of the folks leading off with, or only commenting on the approximation of elipise fact... Fair enough. .... But i think they miss the point. Fine go watch a cnc/ gcode video ... Or show us your "tramel of Archimedes" rotary table build.
Actually that would be kinda cool.
Thanks again for the great, manual maching, skills oriented, tools in your tool box type of videos.
Nice! I appreciate your application of math. I’m a professional engineer but a novice machinist. Love your tutorials. Equates the country boy side of me to the nerd side.
@Joe Pie Excellent descriptions as usual. You do such a good job dividing complex cutting geometry into manageable and understandable steps. The hidden gem for me in this one was seeing how dramatically a plunge cut slot can be pulled toward or away from the center of rotation. Thank you.
Boy I sure could have used this video a month ago as I had to make a similar part using this same technique. You did an amazing job explaining the shifts to achieve the desired radii. I have personally applied your techniques in the real world that I wouldn’t have been able to do without your guidance. Thank you for taking the time to teach this lost art. Many new machinists will never have the ability or patience to learn any of this.
Just awesome machinig. I'm always flashed by the precission and fine parts coming from your machines. I'm far away off, but I learn on each video you post. Thanks for that :-)
Youre welcome.
Wonderful as always !!
It really makes me want to come up with an XY feature on my Rotary Table (6" Phase II) that lets me avoid having to use the Parallels. The issue with using Parallels is that you've got to have Custom Sized ones (or else make them before you start).
But the concepts you presented, you presented so well that even this 70+ year-old retired Electrical Engineer can understand them. Thanks, Joe.
You are a true Fount of Wisdom, sir.
Much appreciated !!
Hi Joe, what a challenging setup! I'll have to watch a couple more times, but then breakout the rotary table and give it a go! Honestly love the setups, and those marvelous miniatures! Thank you!
I absolutely enjoyed the "boring math" in the first part of the video. And you clearly show how to "transform theory into practical chip-making". Can you ask for more?
Yes, as already mentioned: this is not a true ellipse.
Again, thank you for taking the time to make these videos, and explaining how to do these things on a manual mill! Excellent work and I look forward to more!
Glad you like them! Stay tuned.
As an untrained amateur machinist I really enjoy your mentoring via these instructional videos. One of them has given me the insight to solve one of the oldest unsolvable problems. Will let you know if it works as well as I expect it to.
I totally understood the 2 big radius, the small one took me awhile, thank you, I always learn watching you.
Joe thank you for spending time with us. You come across as warm bright pleasant and stunningly knowledgeable.
But is that an eclipse? I see ,4 sections of acircle... I mean nicely done if that's what is called for
It's not a true ellipse but it's a good approximation of one.
Right. It's not actually an ellipse, but it is fairly similar in shape.
@@spehropefhany VERY similar.
An eclipse is when something gets between .... nevermind, surely auto correct!
@@spehropefhany One honest way to write the title would have been "pseudo-ellipse"
This reminds me of a very fast Chevy Nova I saw at the dragstrip which had "Old School sets the rules" painted on the back window.
Just plain WOW! Thanks for the look.
yup, i once used pretty much the same setup for an elliptical cam on a little vertical axis wind turbine to adjust wing pitch.
Thanks for that video! Now back to shoveling snow....
Trigonometry and Geometry are needed to accomplish this... plus a sizable brain. Nice work!
I know it's not saying much, but that is pretty cool! Love it!
Please follow up. these rotary table videos are so informative Joe.
It's very satisfying.
Thx for sharing
I loved the video. I'm retired, only spent 10 years as a Conventional Machinist. I LOVE that ya have to think and apply yourself instead of the programming. Math involved is very much like programming, but different enough. Either way, if you get 1 number off, the part is screwed up. I love it a miss doing Conventional machining.
Got to get yourself a mill & lathe! Keeps the mind active trying to figure out where I went wrong!
Really cool! Waiting fr the next one. Thanks!
I enjoy tour videos a lot and learn so much from you. Thanks for what you do.
Great video, and fun to watch, always enjoyseeing the old drafting and trig skills put to work!
It is pretty funny when you're tinkering about & long forgotten math lessons come back from four decades of neglect!
Hi Joe, true ellipse or not, isn't the issue for a hobbyist, wannabee machinist like me. The video is enjoyable and instructional in that it demonstrates the mechanics and process of cutting an elliptical shape on a manual mill, utilising a rotary table. For a beginner like myself it is a fantastic video by demonstrating the things I may be able to achieve on my mill. ("Scrambles the brain a little") on first viewing but persevere and watch a few times and the lesson is brilliant as is usual for al your videos. Joe, I work on the premise that there isn't a dumb question, ("if you don't know then ask?). During your video you said that getting cutter marks at the tangent blend points may be an issue and that filing to addŕess such issues was ok. My question is Joe, after setting up, doing the math, ensuring the planets are aligned and plunge cut roughing out fhe initial shape, is there any merit in my thought that finish by climb cutting the smaller radii first and then finally sweep the larger radii, would that help reduce the possibility of marring on the finished product?? Or am I barking up the wrong tree.? Thanks Joe
Regards allan manning
Hi Allan. Your logic is good, but the start and stop point will still play a strong role in the marking potential. Done conventionally as shown, I would think under rotating the end radii would assure no dig marks. It may result in a linear tangent line, but that would easily blend with a file. You could also alter some of the radii sizes to over cut like you are thinking.
Excellent demonstration, always a pleasure 😊.
Nice approximation of an ellipse. I guess you have to use CNC to make a true ellipse.
Yeah, more an oval than a mathematical ellipse but terrific machining.
Not necessarily but it would be tricky
it is an approximation similar to en.wikipedia.org/wiki/Ellipse#Approximation_by_osculating_circles . The approximation by osculating circles gets the radii at the vertexes and co-vertexes right, but leaves the transition between the different radii to eyeballing and use of french curves in a drawing. Joe Pie's approximation results in a smooth transition (i.e. the tangents of the different radii line up where the radii meet), but the radii are off.
No. just use the string method. It's super easy. Or alternatively machine an elliptical trammel into the bottom of the part and hook the arm up to a fixed position on the vice or whatever.
Nice stuff, Joe! Thanks 😊
I love these tutorial videos. Thanks Joe.
Great video. I love it when you explain the math for manual milling. I don't have access to CAD so the math behind it is very interesting to me.
👍 love seeing how the old school did it.
Beautiful work, Joe. I always appreciate the tips on setup and fixtures.
Perfect video for an upcoming project. Thanks Joe 😊
So glad I found your channel Joe. This video helped me understand rotary tables so much better!
I have quite a few rotary table videos. Each has value.
Wow 👍. Great stuff Joe. Many thanks for sharing
As always wonderful presentation, cant wait to make one!
0:58 HUUUUGE understatement 😂
That was a great learning experience. So easy to see once you showed us. Thanks, that's so bankable.
Glad you enjoyed it!
Really enjoyed that Joe thankyou and it did make sense. The shims offset for your axis shift but the table relative to cutter offsets for your cutter radi plus allowance. Fantastic.
Glad you enjoyed it
Pretty cool setup! Looking forward to the finished part.
At 7.08, line ‘A-B’ is the radius of the circle, not a chord. A chord is a line that has both endpoints on the circumference of the circle. The 2nd line drawn perpendicular to the radius IS a chord. If the chord runs through the center of the circle, it is then the diameter of the circle.
Interesting as always. Thanks for the video keep on keeping on.
Thanks for stopping by Harold.
I have that bald spot, and I have NOT tried this yet. I am in trouble!!!
Very interesting, but it does leave me hoping I never need an elipse
Seriously Joe, well presented, and very informative---thanks
Brilliantly explained Joe. Thank you. I will be using that technique to produce my model elliptical parts this way.
Thanks Joe, I always get something out of your rotab tutorials.
Glad to hear it!
Excellent video as always, very informative!
very enlightening. Thanks
Keep sharing the trig,
Its the mark of a knowledgable machinist. Its why i subscribed in the first place
Thank you, I will
As always Joe you deconstruct the complex into more digestible chunks and like the part on the table a finishing pass with a well chosen word the complex falls into place. Even for a failed math student your use of one, none or double pads made understanding unavoidable! Awesome. Thank you.
Joe, another great lesson, Thank you.
Joe, I have learned more from watching you than I ever did in school!
Thanks for the explanation, really helpfull.
I feel you did an excellent job of explaining the operation. The CAD visual, folled bu the drawing, really locks it in the process. You also provide many, many addition tips on procedures! THANKS!
Glad you enjoyed it!
Excellent. Too many lessons learnt. Thanks.
Very good video Mr Joe pie..thanks for your time
that is a very cool and interesting way to do this. thanks for the demo
Thanks for taking your time to explain this, quite a few concepts here to think through. J
Learned something new today. Thank you Joe.
Thank you for this approach, much easier setup than what I have tried in the past. Doing the math as you did was very helpful and appreciated! Nice Start to 2024 Joe !
Wow you make it so simple. Thanks
Very well presented, if I were to go to the mill right now I believe I could make this part. Thanks
Excellent. Once you absorb the setup logic, I'm sure you'll be able to make a bunch of variations.
Interesting setup!
Impressive, well done!
As always very beneficial and enjoyable.... thank you joe❤
A master class in rotary table technique. Everything I know about using a rotary table I learned from Joe. However, the end result is not a true ellipse--it's a spherical lenticular (spherical lens-like shape) with radiused apices. Nevertheless, it's a pretty good approximation of an ellipse.
I had to go back to my 50 year old drafting text. I started with given the major and minor axis, what gives a good approximation for the radius of the two intersecting arcs. It was a somewhat complicated manual drafting technique (made more accurate with AutoCAD). I still tend to use AutoCAD like a drafting board.🫢
try this then
An ellipse is a closed-plane curve that results from the intersection of a plane cutting through a cone. In other words, it's an oval. This is a word you'll probably see in geometry class, though it's a shape you can find all over the place. An ellipse is a closed curve that never made it around to a circle.
What does an ellipse look like?
An ellipse has an oval shape as a deformed circle. While the circle is characterized by having a center and a circumference, an ellipse also has two foci (plural for focus).
Ellipses vary in shape from very broad and flat to almost circular, depending on how far away the foci are from each other. If the two foci are on the same spot, the ellipse is a circle.
All ellipses are ovals, but not all ovals are ellipses. Ellipses are standard definite geometrical figures, having symmetry on 2 perpendicular axes. Ovals are not standard definite geometrical figures. The best definition is "shaped like an egg"
always impressed....this will be my phd project in my machining progression. great work JP
Another great video. Very informative. I probably would have to watch it another ten times before I could attemt it. I'm looking forward to seeing the next videos you mentioned. Thanks for sharing with us. Dan
An interesting lesson in applied geometry. While not a "true ellipse" it's probably close enough for many applications.
Thanks Joe
Great explanation of manually making an elliptical. I was glad I had a CNC to get off easy making protective caps for old claw foot dresser legs (3 sets of 4 each with felt inserts to protect hardwood floors).