Making a ballshape on the milling machine

hey welcome back a good friend asked me for a favor he's a chef and the chef's jacket has these off style buttons of the ball and the large discs in the back and as it seems to can only get them in plastic they're injection molded and not not very nice so he asked me if I could make him the same style of button out of metal I made a first prototype in aluminium and this seems to work there's this there's a ball milled I melt this on a milling machine using a rotary table and just seems so we're quite nice I have some some blemishes on there and it's not finished at all but the general idea works so what I want to do is walk you through the process of turning the rough shape machining the ball on the milling machine and then doing all finish work the reason I'm not doing it on the lathe I tried it with a form tool I made the form tool and tool steel and I tried to plunge the whole ball shape in one try and this diameter back here this is only five millimeters and it just snapped off on her - ear cutting force so that's not that's too much I don't have a ball turner for my form I am Khalif still not so I remember the technique of using a boring head on a rotary table to circle emotions over late to each other that Tom Lipton showed in his book thinkorswim metalworking metalworking sink or swim that's the title of the book eros showed this technique in quite a detail and I always wanted to try it but I rarely have to knead for a ball machine a ball shape so let's let's see how we do this I laid out the rough dimensions back here this is 18 millimeters the ball has 12.7 in reality it's more like twelve point six but we'll go for twelve point seven this shank here is five millimeters so that's the overall damage so we're just going to hog out the rough shape on the leaf leaf this diameter here point one normally the larger in diameter so we have something to cut into when we finish it and see where this goes [Applause] that's how we prepare the blanks for ball milling cutting cutting the slotting back here turning this to the OD that we need for the ball slightly oversize to the candle take an actual finish cut do this on both sides of the of the stock and then we're off to the mill we don't have a crazy high precision for this for this job we just won't want it to be good good enough okay there we go that's our first double ender now we can take it like this in a milling machine and mill the ball and the idea behind making it as a double ender is to make two at a time and have something to hold on I'm going to lose about six millimeters of stock between those two parts but those six millimeter stock will allow me to make two if I made only one I also needed about six to eight millimeter extra stock to hold on I cannot machine them from from the stock from the bar because the OD does not is not turned precisely and does not fit into the 5c collet I'm using on the mill so that's very good technique for parts like this [Music] there we go took about two and a half minutes to cut this ball judging by but a recording time on my camera and the result is just marvelous this is just beautiful diameter is 12.75 that's 50 micron oversize I I feel a little bit sloppy today so we're just going to leave it like that to be honest this is way good enough but the ball milling that way is it's it's beautiful the crosshatch finish it's just a thing of beauty well we'll throw these parts and the vibratory tumbler once they are done that's another one finished and I wanted to show you the the two motions that are overlaid to each other I retracted the tool 0.1 millimeter so we don't scratch it while we'll play around here as you can see I have a carbide boring bar that's facing inwards and it's cutting in this direction so I have to run the mill in Reverse I have to keep that in mind when I turn it on otherwise I destroyed a tool and as you can see it it barely Nick's this diameter here and the other side goes through the center of the ball and at the same time this is rotating like this all in your reality way faster of course art goes into collet and to about this position here it's clamped then I move my tool over to the outside position go down to my depth and I touch off on the end of the - of the part this doesn't have to be super precise just reasonably closed and I move in point one millimeter this direction and we're good to cut [Music] okay you saw me spinning the indexing head my hand cranking it and and at the same time constantly down feeding very slowly on the quill of the machine until I hit my my depth stop and then I just did a few rotations to clean up the ball shape that's the overall setup I have my Walther UTA 80 indexing head held and Weiss set to an angle of L 11 degrees plus a little bit I will show you later how I calculated the necessary angle and a 5c collet Chuck mounted on here Topsy call that Chuck is just a very convenient way to hold the work the angle the 11 degrees are needed so the cutting tool when it spins when it's on the side of the material it clears the shank of the ball form a complete 360 degrees fear but that would not hold on to anything and it would just drop off and gets playing through the air and be annoying so that's the reason why you tilt this Pamela to make room for a shank to round over the the foot of this button I need a form tool and I took a brace carbide parting tool my die grinder and the 2 millimeter diamonds Branton point and I'm just working the shape into the face of the parting tool to create a 180 degree radius tool check your progress and after we're done it just hit the top top surface of tool lightly on on a diamond lap clean it up and you have a a carbide carbide radius tool all that's left after milling the ball is to take two parts and part them off this goes pretty well in the six jaw Chuck holding power is very good first we clean up this this tiny corner here where the ball meets with the shank then we come in and partially cut it off then we change to our half rounds tool that would ground earlier with die grinder and we just eyeball it over the center of the remaining material cut the full radius until until this this section here cleans up completely and we switch back to our parting blade move back in position and part it off all that's left is to file off this does not on the back and now I'm not going to grind an angle and leading angle on my standard parting late because it's thin high speed steel blades tend to wander of course if you grind the leading edge back I'm on an angle and that's all the waste I get by making two parts it's reasonably low amount of waste [Applause] and all this goes quite fast this is one of those projects that we don't want to make a science fair project out we just want to do a good job in a reasonable amount of time [Music] [Music] okay all the parts are in the tumbler we can talk about math just for fun we have to tilt the indexing hat so the cutting tool can clear the shank of the ball if you look at this button here and the black ring the O ring around it this is the as basically the path that the tool sweeps around the ball and the ball is rotating at the same time and creates this hemispherical shape and this angle that this path here is tilted that's what we need to calculate and it's basically a triangle in here with the base length equals the diameter of the ball and the height equals half the diameter I the radius of the of the shank of this ball that gives us triangle down here 12.7 as diameter and 2.5 that's the radius of the shank because the shank is 5 millimeter in reality do some tree noggin true-true do some math 2.5 divided by 12 point 7 tangents of that equals alpha that's the angle we have to tilt of 11 point 1 3 degree and that's the angle this o-ring in this in this demonstration here is our whoops falling down is compared to the centerline of this whole part you can also just draw it up in CAD and and figure out the dimensions there but in this case it's quite easy to do the math by hand so that that's one way to do it have them about four hours in the tumbler and as you can see they they came out quite even have some scratches from just handling them it's aluminum after all softest softest can be but apart from that they are quite nice and I'm pretty sure you will be happy with them and yes this is quite a bit of work but not as much as you might expect all in all each one of them took about maybe five to six minutes to make if you add it up if I had to make only one that would be quite some time for one one would have taken about one or two hours but making so many and having everything set up it goes those robotic cuts so hope you enjoyed this thank you all for watching and see you next time you

Channel: Stefan Gotteswinter

Views: 59,976

Rating: 4.9820685 out of 5

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Id: 31iAlFyAGLM

Length: 19min 2sec (1142 seconds)

Published: Sat Mar 14 2020