Dogbone Milling - A Great Way to Hold a Small Part

hey guys go fine welcome back and I recently accepted a job here at the shop and if the jobs that you take or the jobs that you do or anything like mine they always look bigger in the drawing that was look bigger in the model and when you start to put the numbers to the material and you find out that sometimes for its kind of small or flimsy or whatever so I just accepted a job recently that looks exactly like this piece behind it and it's black Darin let me put some dimensions on this thing to show you how small this it this is own ninety-fourth it here this is oh 78 here so that's 2 millimeters in the middle these are three millimeter diameter holes the whole thing is just about an inch long so it's not very big and it's ten millimeters wide here so it's not a very large part it's incredibly flexible and I have to make a hundred of these so it's not a difficult part the majority of the part is accessible from one side except for this Center cut out is a mirror feature so you've got to flip it over and that's that adds a little bit of difficulty to it you could strap it down you could mill it but boy when you got to start flipping it over and jerking around time is money right so I'm gonna do what is called or what I call a Dumbo approach on this part now a dollar bone approach in my world in my mind is when you support a part that you're working on with grip stock but symmetrical grip stock about the ends of the part so now the part is going to look like this and you can see why I call it a dog bomb because it's exactly what it looks like when you get to the end of the day well that's pretty ugly huh anyway you can see how the park fits in it's real easy to clamp on these pieces when you clamp on the top with toe clamps or whether you hold it in a vise flip it over this part can be done 50/50 with the material on the ends and in the final operation you can squeeze it in the center and lock the ends off and you have a finished part which is exactly the way I plan to do this job but making a hundred of these you can't handle a hundred pieces so what's the next best thing make it in a strip make a really long piece and make a bunch of these all at one time and come back in with a cutter come between them and then you have what looks like a railroad track when you're done and the next phase on that cut them all off hang them from pins 20 30 at a time squeeze them in a little fixture and cut the ends off this is a great way to proceed on a difficult part dog-bone symmetrical grip stock in plastic aluminum whatever the time that this process will save you is pretty incredible and it's a good way to do round stock in the middle voice with a bunch of v blocks - you can do strange things - round material that you would never be able to hold conventionally so dawn blue material let's take a walk out to the CNC mill I'll show you the setup I'll show you the fixture and we'll look at some parts this is how the materials been prepped now when you have plastic or any type of material and you start chopping out long sections out of one side you can bet that the material is going to react it's gonna bow it's gonna crown it's just not going to be pretty so whatever kind of fixture you designed for your job make sure you take that into consideration this piece was actually flip-flopped only twice and I know that the first side was trapped so well that I could trust the features in relationship to the raw material now when I cut the second side it had a tendency to not give me what I thought I was going to see because of the bowing of the material but the fixture itself pulls this down nicely and the even removal of material from both sides helps to stabilize the material and return it to being flat this is a plus or minus five job but this particular Center relief configuration is currently right around plus or minus one plus or minus one and a half and this is black Delrin so it's it's pretty tough to do if you were to do it any other way let's take a look at the fixture and take a look at the final procedure here I think you're gonna like it here's the fixture we're going to use the prepared blanks slide right in here like a drawer there's a tooling hole in here that you indicate so that you know where this fixture is a relationship to the program the next time you set the job up and we have relief cuts in the end so I can get a micrometer under the part and measure my features as I am seeing it let's pop a part in here press the Go button watch it happen art is loaded you can see a pretty good cross-section of how the fixture works and why I refer to this as a dog bill [Applause] I'm gonna pop 42 holes in this real quick and then put the slices in mr. favish [Applause] [Applause] these are incremental boobs which means I do not have every one of these holes to find in the program the machine is just called the move X the distance between centers and loop the code that shows the hole so this is a very short program to do this there's an awful lot of information contained here but if you use incremental moves in conjunction with your absolute positioning you get the job done real quick the instrumental shift needed to go in before the actual drill cycle so we go beyond the part come back to the hole and we're doing the down side at this moment just finish out come back to the slicing operation [Music] [Applause] [Applause] [Music] [Applause] is also an incremental moon code itself is just loose this process finishes both sides of two parts actually one size of two parts with each pass moet shift everything is climb cut because it just doesn't leave any birds with a nice sharks cutter rather play it out and we're going to come back when all the spots are in I'll give you a real-time reading from the monitor Islam okay the machine just finished up a load off see we got [Applause] I'm happy with that [Applause] real time five minutes 55 seconds 21 pieces 42 holes and 21 slots six minutes not bad yeah here's a quick look at the before and after you'll notice the registration mark on the parts that's a real good idea if you have a fixture and you have to take the piece out of the picture make sure it goes back in the fixture the exact same way so you can see all the work that was done on both pieces this is a three-eighths - flute carbide end mill about 4000 rpm 40 inches a minute and it give me a nice finish so we'll run this back piece across the saw front and rear put two pins and all of these squeeze them together and finish the length done very pleased with the results of that fixture [Applause] okay it is time to separate the parts from the carrier from the nest from the dog bone I have an aluminum ripstop fence set up on my bandsaw because the dog bone material will have a tendency as the parts release the parts are going to want to spring down because they're a different height I also have a riser to support the actual part squamos close enough to the dog bone so it supports the part more than a dog bone but it allows me to Bank up against this and we're going to cut these off here pretty quick okay there you go guys all's we need to do is Mount this in the next fixture on pair of pins use the pins as the locator feature since the part is rough and asymmetrical at this point lengthwise anyhow it's very symmetrical this way and we'll just finish the ends off let's take a look at how that's done okay guys this is the fixture for the final operation it is a simple aluminum block these bosses here are sized to the exact distance between the pins so that it's basically self centering all I need to do is trim this and establish a centerline in the machine and the whole idea here is we're going to come down with an end mill sweep the outside jump the fixture sweep the outside on the opposite side and we are done now this is a no brainer little fixture it should work very well doing fifteen pieces at a time eat your cake very simple let's put this in the mill set it up and watch your pass [Applause] here's the final setup fifteen pieces Spanish between two aluminum plates centered by the bosses on the fixture let's push the Go button and see how long this takes [Applause] [Applause] 27 seconds gotta say not bad finish on the edge is beautiful [Applause] both sides of 15 pieces 27 seconds too bad I don't have a thousand of these to make hey guys that's it job's finished alright guys well I think that you can see the benefit of creating the part with that particular dog-bone technique it has served me well over the years and it should serve you well as well but be sure that once you take your piece to that part worth you're going to lock the ends off that you're done holding that part and addressing all the features that you're needed because that is also a one-way part it will not be going back into fixture that you built initially and you don't want to waste time building a bunch of different fixtures because you're made a mistake so plan ahead anyway that's all I got I hope you liked what you saw try it it works very well to oppose any advance innovation in Austin Texas I'm out you

Channel: Joe Pieczynski

Views: 121,367

Rating: 4.9390273 out of 5

Keywords: Joe Pie, Joe Pieczynski, Advanced innovations, Advanced Innovations llc, Dogbone Milling, Dogbone technique, machine shop, home shop, home machining, machining, shop tricks, shop hacks, shop techniques, machining tutorials, how to machine, manual milling, small part machining, multi part machining, grip stock, cnc milling, milling videos, milling, production fixtures, one way parts, 1 way parts, milling fixtures, fixture design

Id: r4vaeRLFfD8

Length: 16min 1sec (961 seconds)

Published: Mon Nov 20 2017

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[u/sotik9]

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