Rotary Broaching The Night Away

you [Music] [Music] [Music] a longtime viewers of this channel know my wife all too well but I don't think I've ever told you specifically what it was about her that really closed the deal for me she has a lot of great qualities and picking just one isn't easy but if I'm being honest with myself with the benefit of wisdom that comes with old age I can now definitively tell you what it was my wife has a great can and perhaps more importantly she let me touch it you may be thinking I'm exaggerating I've managed to secure my wife's permission to show you her can okay okay fine maybe it has seen better days this one's got some hours on it but pragmatically speaking it still works just fine now that said and I hope you don't think less of me for this I've gone and got myself a new side can I know I know it's not metal that freaked me out a bit at first too but let's face the music it's 2019 all the best cans are plastic these days this is a spill proof can which is more than I can say for mine I got it on Amazon or online somewhere all the other YouTube machinists have long since upgraded to these fancy new high-tech cutting-edge cans and well I suppose I'm late to the party as usual anyway I didn't gather you all here today to discuss my penchant for nice cans I got a rotary broach although they confer similar levels of dignified accomplishment don't confuse this rotary broach with this rotary broach one of these tells everyone you've made it in life and the other one just gets you through the door at the club all right settle down don't get your poopoo head all up in a bunch I know it's not a broach it's a pin fine I've wanted one of these ever since I learned that they exist and up until recently I always figured I'd end up making one and they're not all that complicated if you wanted to make your own just takes a ton of care and patience and very likely a surface grinder to make the broaches I didn't get all the brooch sizes I would have wanted but beggars can't be choosers and I have plenty of broken half-inch end mills just waiting to be turned into brooches you may be wondering what a rotary broach even is it's a freaking milestone is what it's a tool for making not funny shapes usually round ones into funny shapes in this case a hex because the brooch is a hex but I believe you can have just about any shaped brooch you want square torques flying hearts rainbows whatever in fact check out the custom broaching I did on this bolt head for now if all goes well I can cut internal hex shapes at least the ones I have brooches for you need a brooch for each size to make this video a little more interesting I wandered around my garage a bit and found two two maybe three little projects we can use this for little things screws mostly in fact but it should be fun and anybody that doesn't like fun please raise your hand that's what I before we get to practical projects though I'm eager to try this thing out this works in either a mill or a lathe I'm gonna start off on the lathe so I'll race you there I've got a small aluminum cut off I've pre-drilled it that's a few percent over the flat 2 flat dimension on the hex and there's a really small chamfer just broke the edge provide a little bit of a lead-in for the sharp corners the excitement was building I was anxious to just plow my way into that when let's say a bit of an inconvenience cropped up the rotary broach has a 3/4 inch diameter shank and my drill chuck doesn't open up that far so unfortunately I have no way to mount this tool however this lathe has a three Morse taper in the tailstock and the rotary broach fits in there just fine [Music] [Music] you know what I got an idea I have a 3/4 inch adapter for the mill so that's 3/4 inch straight shank it's an end mill holder which in this case goes to an ISO 31 dur if it might not be better to make an adapter like this but for the lathe 3/4 inch Morse taper 3 sometimes you know you just get a hunch and you got a run with it hey Stefan Robin I know if you guys are watching check out what my lathe [Music] and this should be it got a three Morse taper in the back with the tang so I can actually remove it and a three-quarter inch bore in the front set screw just to retain the rotary broach I guess this is the moment it all went well I should be able to unlock my tail stock all right Morris tapers or self locking you get that out I can either extend the quill so I can get a key in the back I could drive this through to pop the tooling out but on lathes you can usually fully retract the tail stock to bump the tool out you oh sorry about that [Music] [Music] [Applause] those results are likely hard to see I having trouble seeing them myself pull it out of the leave and try to backlight it hey that looks pretty good you did have some chips down on the bottom what I did is I flipped this part and counterbored it just so I could get those chips to fall out let's try an allen wrench in there I think I can proceed with my projects now one thing I'm not sure about I do some homework are the speeds and feeds for a rotary broach I don't know if that broach is particularly sharp or they just cut awesome by the nature of how they do what they do but it's very light on the hand wheel I was really just trying to keep the broach moving consistently constant speed more than I was actually pushing my way through like you might expect with a non rotating broach it's make a couple of parts and we'll talk about how these things actually work how they do their cutting this is the oil fill port on my motorbike engine some time ago the OEM plug broke and I made this replacement at the time and frankly I'm now embarrassed to admit I was rotary broach 'less so I simply slotted the head and as you can see it looks terrible I'm not a hundred percent but I think this is affecting my performance mentally so let's make another one at the time and I don't remember exactly I think this took me about seven hours to make now that I have a rotary broach I should be able to cut that down to six and a half and to think they won't like ten bucks for one it I think I'm going to make the new one out of bronze mostly for the bling factor but I was digging through the scrap bin and found this short little piece it'll be tight but I think I can get that out of there I mean there's enough material there to get a new plug out of just workholding might be a little tricky thermal expansion of bronze is less than aluminum and this bolt creates a face heal so I think I should be alright not to mention none of what I just said probably matters anyway [Applause] I had to clean that groove up a little bit the dye chased some threads into what will become the o-ring seat and while I was here I just knocked the corner off the back edge now to flip this around and hold on to that threaded portion I've found a nut that matches that thread and just split it with a zip disc this happens to be a lock nut doesn't have to be a lock nut just the only one I had that matches I'm not gonna snug that up completely now I should be able to use that split nut as an intermediate clamp obviously you'd want to leave the gap between two of the jaws you [Music] I don't know why it's so difficult to film hexes I didn't want to go too deep there as this cut gets really close to the groove for the o-ring so that's the certain section of least of material and that's where the original one broke I think that should work just want to polish it up a little bit when it comes to polishing it's a bit of a fine line you want it shiny enough to catch the lady's attention not so shiny a magpie might swoop down and steal your motorcycle all right I think that's it let's go try it out I don't know about you but I think that looks pretty good Oh credit Rick these things have up their sleeve that gets them doing what they do is hard to show on camera in fact it's even hard to see when you're holding it in person unless you're already looking for it the brooch actual cutting brooch is attached to the holder at a slight angle it's about one degree I believe not very much at all this shank and Cup I guess is all straight coaxial but the bore on the inside where the bearings go that hold approach are canted at about a 1 degree angle hold on a minute at first blush this is perhaps what you see but in fact the cutting tool as I mentioned is mounted at an angle not this much of course but the ability to exaggerate is the whole point of my resorting to brutish analogies the very small angle means the cutting tool touches the work on only one cutting edge because it's crooked right combine that with its ability to rotate because of the bearings the crooked broach bit can spin and the end effect is approached that sort of wobbles not a lot but rotary broach is wobble I only just got this so I can't tell you yet if they fall down perhaps it's not as intuitive since I demonstrated on the lathe where the tool stay still and work rotates but think of this brooch as a universal joint in a mill or a drill where you're spinning it and driving it into the work perhaps the fact that it wobbles and there's only one cutting edge touching at a time is more intuitive in that situation this is a regular broach non spinny kind at least it shouldn't be anyway this happens to be four key ways but it does the same job turning not shapes into funny shapes a regular broach like this just gets pushed through the work usually using a press of some kind and strong-arming its way through I still have one analogy left for this video so might as well cash it in now imagine if you will this chisel is our regular broach like a keyway broach we just push it through it works because it's sharp it might take a ton of force but it works I mean I don't know if it's a ton depends on the size your approach probably but it takes a lot of force in comparison a rotary broach works in smaller steps maybe wobbling slowly sharing its way through I'm sure you've instinctively resorted to this wobbling motion with your dull chisels and no it takes less effort there are some other subtle features built-in that make this work well the clearance angles on the broach tool and its overall length it's no coincidence that all of these brooches are exactly the same length but getting into those nuances is probably too much info for this video as i mentioned earlier sooner or later I'll be making my own brooches I'd really like some square ones maybe we'll get into those details then for now however I think that's it I have a couple other projects I plan to keep you long for in this video but on second thought this is getting long and they're really just more of the same like the plug for that oil port remember this old boring head the hex drive on the adjustment screw is all worn out that I think is due to a combination of it being a brass screw and me making adjustments for final passes with the Gibbs tightened up it still works I just use a torque driver instead I'll be putting a new hex in it recutting that but I think you've gotten the idea well that's all for now I hope you like that thanks for watching

Channel: This Old Tony

Views: 1,478,559

Rating: 4.9153223 out of 5

Keywords: broaching, rotary broach, polygon solutions, slater tools, hex hole, drilling a hex hole, broaching a hex hole

Id: GWyHJVOxKK4

Length: 14min 58sec (898 seconds)

Published: Sun Aug 04 2019

Reddit Comments

[u/jfc62]

He later posted a supplementary video , which shows how does it work better, on a stationary piece , here https://www.youtube.com/watch?v=4-3gPWl6wfU

[u/Guysmiley777]

It makes total sense but I never realized that the slight offset angle was what made rotary broaches work. Really liked TOT's explanation.