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Open Pour Swim Bait Tips

Open Pour Swim Bait Tips 1
Okay guys, I had a Patreon member send me a link to this lure that he wanted to make and he was having a lot of trouble figuring out how to actually design this. This is an open pour swimbait, this one is about 21 centimeters long which is a little over 8 inches. We're not making one that long today, we're going to make it a bit smaller at about 4 and a half inches just to keep things mellow. You can make it as big as you want, of course, so let's just into Fusion 360 and get it done.
swim bait lure in Fusion 360

The XY Plane

Now I'm already starting this tutorial with the drawings in place and using the drawings I invented. I'm using the loft technique which I already have a video linked HERE if you're kind of confused on what's going on here. Where it becomes different with an open pour mild is you gave to think about not the lure body in its whole form, at least vertically, you gave to think about where you're going to make that open pour cut. What I try to do is keep in mind the XY plane here when you're looking at your drawing. From the front view. it'll be this red line and for the side view it'll be this green line. Anything above this line doesn't matter, it can be crazy tentacles or whatever it's not going to be part of your mold. You're really thinking about building the lure from this line down. Now, this line is not a hard and fast rule when we make our mold, we can make it higher or lower but you want to have a general idea on how high the top of the mold is going to be when you start. I find it's easier just to use this XY plane right here.
Open Pour Swim Bait Tips 2

Nose Slant

So a couple of areas that he was having difficulty with in particular was the nose slant and the tail section, particularly the tail. I tackle the nose slant by making my nose shape, again I just did a circle and I'm only doing half of these bodies as we go back to do our loft shape here in a minute, where I projected the top of my mold to be. In this case on the nose drawing, if we go back in and take a look at it, I used a parameter here called nose drop and it's 12 millimeters. So, I want the center of the nose to be 12 millimeters below the top of my mold and that's going to give me what's called an undercut. Open pour undercuts are totally fine because we're actually going to have a two-part mold that we're going to be able to pull apart. Again, you can adjust this however you want with these parameters in here.

If we take a look at our second sketch you'll notice I do a whole body all the way up above the top of the mold. I find that works the best because you get the right slope to the lure. I could have come in here and drawn a line straight across this section and just flattened it out but what that does is that commits you then to going and making a lot of additional changes if you want to move the top of your mold up higher or down lower. If you draw this way, then my mold is more independent of my lower body in that I don't have to change my lower body design, I just have to change my mold up and down in order to change the height of the lure.

swim bait lure height

Lure Height Parameter

So one of the parameters I have in there that I'll point out is this lure height parameter. So this is how high the lure is going to be and, in this case, it's not the overall design of the lure and it's not the final product. I want to get out of the mold and I'm just playing around with numbers but I'm roughly around 19.3 millimeter. So, I want to make sure that amount is below the top of my mold so I drew a line and then I did a dimension from this dot to the center point and made it 19.3 but my line goes all the way through.
Then for my tail sketch, it has this kind of oval connection in the tail and then our tail directly. So when we go do our loft, we're actually going to loft to the center section and then we're going to create the tail and create a loft between that. I'll show you how we do that in a second. Of course, I did my rail and again, there's a full tutorial on lofting linked HERE and you'll see how that works. So here is my lofted body and after you turn off the sketches and the rails you have your basic shape. Again, everything above this green line doesn't exist.

split swim bait lure body

Splitting the Body Pro Tip

So if it helps you visualize better to not have to imagine what this is going to look like, what you can do is come in here and split the body. We can use our splitting tool on our XY plane hereĀ  and turn on our origin then select the XY plane. That's going to split it off at the top, click on OK. Then, we can come over here and hide this and see what it currently looks like. You can decide if you like that or not and just play around with it. Again, most of the stuff is going to be impacted by this back and the front and I just didn't want to spend a ton of time in here making this highly complex model, I've done enough tutorials on that but the open pour stuff is slightly different.

lure tail

Bait Tail Considerations

Then we come to the tail. We extrude it out first and then we move it into position. The important thing about this position, again, is so much more about making sure that some of it is over the top of our XY plane or this green line. We added an angle and if you want to add you can, if not, you don't have to but you probably at least want to move it back a touch. Then we add our fillets. I added a fillet to the tail and what this does is I'm going to loft and I'm only going to loft to this face. That keeps the spread down inside of this flat face and what that looks like on the lure itself is you can see it spreads out and down and all over the place.
If you don't want it to do that, what you can do is you can put more of an abrupt connection by simply moving it closer. If I were to move this close to where it's all there and then just join this together, then I'd have a very abrupt connection there. In this case, I want more of a flared connection on the end so I'm lofting between the back of the lure body here and there. You can play with this if you want, you can get a tangent curve on here to get a little more abrupt connection. What it does is it keeps the profile from the first profile you selected longer before it flares out which I kind of like better. Then click OK.
adding fillet on lure tail

Adding Fillets

Then we're going to come in and we're going to add our fillets to this lure. We're going to leave this tail alone for now and keep it like it was. Then, we'll come through and we add our fillets on this back edge here. I wanted to see if we could do two, but it wasn't working. I've made a few changes and it's looking pretty good. This is where open cornrow has its advantages because, again, what happens above that line doesn't matter because it's not going to come into your design. You can make this even bigger and in that fillet command I also did the nose because you want to have a fillet on the nose there.

bait lure mold

Making the Mold

The next step is simply drawing our mold box which is just a rectangle. Again, I use the center point here on the origin to keep my plane line. At this point, this is where you can adjust where you want the lure to ultimately lie in the mold. I can come in here and I could change this top line, move it around and adjust it. This is where I have control over what my lure ultimately looks like. What this shape is right now doesn't really matter, it only matters what is on the inside of the mold. Now we're going to extrude one side of this mold, we only need one side right now. I use my standard 15 millimeters that I use for injection molds. Obviously, if you have a thicker bait you can make it thicker but you really don't want to make it much thinner than this because if you have too thin of resin on the outside, you could potentially introduce some warping so I just make it 15 to be safe. Also make sure that it's a new body and then we can cut it out.
Now if we come up here and we turn off our bait, you get a pretty good idea what the lure is going to look like when I pour it in. We've got the top profile, we have the bottom and I don't know if this looks very good but the focus is on the mold not the lure design. Then we simply mirror this over and we have two sides of our open pour mold. I go around and add chamfers and we're going to put holes through this and do all kinds of stuff. I have videos on all of this already which you can find HERE.
The important thing to remember where the top of your mold is, anything above that point doesn't really matter so I like to design kind of the whole sided bait instead of making it flat on the top. That gives me some flexibility later on and then I only have to do one side then mirror the mold. I learned that from Yauck Outdoors and you can find his channel HERE.
Take care- Tight lines