In this lesson, we'll be understanding and using spring passes. After completing this lesson you'll be able to; create a 2D contour with a spring pass, and modify tangential extension distances on a contour. Lets carry on with the file from our previous example and let's finish off the inside of our larger pocket. So far we've taken a look at finishing the outside using a 2D contour, we've done an adaptive tool path to get rid of the bulk of the material inside of the pocket and then we took a look at using that adaptive tool path to finish off the floor and the lower portion of our pocket. Now, we want to take a look at using a 2D contour to finish off the bottom inside of the pocket as well as the area above the four bolt holes. We're going to do this by going to 2D and selecting 2D contour and we're going to be using tool number eight which is the flat end mill. Again, this can be found inside of your Cloud library or if you store that locally, make sure that you navigate and select tool number eight the quarter-inch flat end mill. In the geometry section, we're going to continue to use this sketch that we created, and again make sure that the arrow is on the correct side. We're not going to deal with rest machining, we're simply going to use our parameters to control the tool path. Under heights, the bottom will be from our selected contours, so we'll leave all the heights as set by default and go to our past this section. We're going to use multiple finishing passes and we're going to use the repeat finishing passes option which will turn on a spring pass. Instead of parameters, we have minimum cutting radius and finished smoothing deviation values but we're going to leave those both set to zero for now. We're going to do two finishing passes with the step-over of 0.025. We have a finished feed rate which can be adjusted if we need to. We can also dictate a finishing overlap and I'm going to put a small overlap in here of 0.05, this will allow the tool to go past the starting and ending points so that way we don't start and end at the same spot. This helps prevent us from making little divots or deviations inside of that wall. We're not going to worry about roughing passes or multiple depths we're going to do it all at a single depth and we're going to leave on all the defaults for linking parameters and leads in transitions. We'll say "Okay", and take a look at the tool path that's created. So here you can see that we have two finishing tool paths, and if we take a look at where the lead in and lead outs happen you can see that there is a small amount of overlap between those. They're actually happening at the small gap which is perfect because we don't have to worry about any surface finish imperfections in that area because it's going to get removed anyways. So now that we have this let's go ahead and select the entire setup and do a quick simulation. We're going to go past our first contour, pass our adaptive clearing, pass our rest clearing, and then down to the contour. If we take a look at this you can see for the contour that what we've done is we've gone all the way down to the underlying geometry. You can see if we rotate this around that we've cut all the way down we haven't left any stock, but let's double-check our tool path just to be sure. If we edit this and go back to passes, you'll notice that stock to leave is turned off and everything is good. I did notice while taking a look inside of there that this adaptive tool path was leaving a small amount of material on the top of these bosses and that's perfectly fine. We just need to make sure that we understand we have to completely clear off those faces and not just do a finished cut on the inside. There are two things that we can do. We can go back to our adaptive tool path that was used to remove the majority of the material and we can change the axial stock to leave to zero. This will allow it to go back and clear off that pocket, or inside of our 2D contour to finish this geometry we could simply create some step overs. So let's take a look at both of those options. We've already modified adaptive so that it will cut all the way down to that face but let's also create a 2D contour tool path that will allow us to clear it. We're going to continue to use tool number eight, the quarter-inch flat end mill. We're going to start by selecting just a single edge and then we'll go back after we're happy with all of our settings and we'll select the rest of them. Inside of here we're not worried about rest machining we're going to tell it exactly where we want to cut. But I am going to add a small extension here. So we're going to add 0.065 which will extend the contours at the start and the end. The heights will be based on our selection, so we don't have to worry about making any adjustments there and then for passes, what we can do here is we can turn on multiple finishing passes in small incremental steps. So this will allow us to move over a small amount to get the finishing cuts and if we want to we can add a roughing pass with a higher step over value. In this case, we'll make this a little bit smaller but we'll say we'll step over at 0.1. This will allow us to do one or two roughing step overs to make sure that we can clear that part and then we'll say "Okay". So now we can take a look at this tool path and let's select all of our operations and simulate. We'll start by jumping past our external contour. We'll jump past the first adaptive pocket, the second adaptive pocket, the contour and the bottom, and in this case I'm going to turn off transparency and I'll play through the next operation. So you can see we're coming in. We're going to go down to the depth. Then we're going to work our way in. We'll come back over because we're only cutting in a single direction, we'll make that second cut and then we'll come back over for the final finishing pass going all the way to that wall. So you can see that we weren't able to clear everything out with this operation and the other corners still need to be taken care of. So what we can do here, is we can close this operation, and make an edit to this tool path. So let's right-click on our contour operation and select "Edit". For our geometry, we want to add a few more chains. So we'll start by adding this chain. Then we'll come down into this corner and follow it up with this last corner. All the rest of our parameters will be kept so that way it will extend at the entry and exit of each of these and we still have the same movements. You will notice that the tool is coming up rather high so we're wasting a lot of time moving the tool into and out of each position. So let's explore some of our options inside of here by going into edit and going to are linking parameters. We're going to select keep tool down and then we're going to say "Okay" and see how that modifies our parameters. So now you can see we have an entry and an exit at the beginning and end. But overall we're moving inside of the pocket. Let's select entire setup one and simulate this one more time. Again, we'll jump past our external contour, our first pocket, our second pocket, then the contour at the bottom, then we're going to play through the contour at the top and I'll speed this up a little bit. So you can see now that it's taking care of all of the edges. This wall right here was already machined as was this wall and the other two sidewalls in the previous operation. The walls above these small pads where the holes are where machine just now by using this 2D contour to go back and making sure that we have a lead in and lead out and that we extend pass and that we repeat those finishing passes will allow us to ensure that we're leaving a nice smooth finish on the inside. Keep in mind that as we're creating these operations some things that we need to think about in terms of spring pass, is how much material we're engaging when we start to create these cuts. The key thing is going to be for us to make these cuts in small increments if we're worried at all about the deflection. The spring pass allows us to go back without changing any other perimeters and simply cut the same tool path again at the last step or the last finishing step. What this does is it takes into account the fact that the wall may flex outward as we're machining, and once the tool is passed it will flex back inward. So taking and repeating this last pass will help us maintain a nice thin wall with a consistent surface finish. There's plenty more that we can do to this part we haven't finished the other pocket yet, we have a lot of geometry that still needs to be removed. But for right now, let's make sure that we go ahead and save the file before moving on to the next step.
