Attached are some photos of a handle for a speargun. Would it be possible to model this? What would be the best approach?
I've had a few does at this. The first step is to obviously draw and outline of the handle.
Derek wrote: Can anyone advise how to join two curves that are converted from the same sketch that has a break.
Try using Fit Spline (Tools> Spline Tools)
The handle will be used as part of the overall model of the gun. The purpose is manufacture of the barrel, not the handle.
To give some idea, I started off with a few sketches based on handle measurements. The first sketch being vertical profile in section. I'd like to be within a millimetre (0.039 or 1/25 inch) on the overall contours. The parts at the handle interface need to be say within 0.2 of a millimetre (8/1000 of an inch), but these are typically flat surfaces.
There are different techniques for modeling a finger grip on a handle. I prefer to use a boundary surface by sketching the path (direction 1) for the finger grips with profile or cross-section curves (direction 2) to control the height / elevation (see image below).
This could also be done using an indent feature, or deform (curve-to-curve) feature. However, I would use the boundary surface feature first and try the indent feature, or a combination of both second. I rarely use the deform for anything that is to be manufacturered by injection-molding.
If you need help on this project, I could use the cash as I am in-between paid projects and cannot attend SW World this year.
I do not mind answering questions, and I ask some myself on this forum from time-to-time. The purpose of these forums are for asking questions, so everyone should feel free to ask for advice.
Only when people start asking for work, which requires more than one hour maximum of my time, do I ask to be paid as a independent contractor / consultant. I have a few start-up companies not be able to pay for my services as they were trying to attact seed-money from VCs.
Concerning your question, I think Matt Lombard has an example of a finger grip on his website as well. I do not recall where it is located, or what technique he used.
Find someone who can 3D scan it for you, then create your surface model over top of this. With all the Next Engine scanners out there, it should be pretty easy to find someone who could get you .020 accuracy for cheap. I'd offer some suggestions, but you're on the wrong continent for any help I can provide.
If I were to create this I would probably do it with 1 boundary surface for the three bottom fingers, then trim away for the trigger. Then create a boundary for the index finger, and another for the top part (shown on the bottom in your image). Then I would blend both of those and build the trigger guard. All the surfaces would be boundaries, exept a few filled surfaces for some of the blends at the end.
That's just a rough guess though, looks like a day or two of work, to me.
Working from the assumption that 3D scanning is not an option.
Firstly I would take measurements in the FRONT, TOP and RIGHT view. Normally as accurately as possible. This will always give you clues as to how the original was modeled. I would spend most of my time getting the measurements right. This is very important.
Secondly I would start modeling. At this point I believe any approach is a good approach. Keep on trying different methods and you'll get closer and closer to the original model with every attempt.
This is the nature of reverse engineering.
However you'll find that moment when everything falls into place very rewarding. And the result will be a model that can be used to reproduce the part if anything goes wrong with changes or modifications to the original.
The most common mistake I see in this sort of model is that the user assumes the surfaces are somehow defined by their borders. This is a trap that usually leads to unmanageably wrinkled surfaces.
For instance, imagine what the finger indents would like like if they were extended in every direction and not cut by other intersecting surfaces. Then each groove becomes a simple sweep, perhaps with an additional guide curve. The groove surfaces then take their final shape by where they intersect the larger outer surface (and are thus trimmed).
I had a modeling challenge on my blog several months ago where the theme was handles. Check out the links. There were a lot of good submissions, some with models you can download.
Fun project, it's ambidextrous so that saves you a ton of work. Yeah, you need to sketch the profile first...even if you're gonna cheat (indents and squishy solids). This picture isn't much help, you need something with less perspective. You can try a scanner, or cut it in half and then scan it!
The ridges of the finger indents are actually fairly complex so you can't just drop a plane in there, a 3d curve driving a multiple section loft will do it. The valleys of the finger indents are normal to the "main" sketch. You can drop a a plane in there with a 2d sketch to provide an anchor point to keep everything curvature correct. The idea is to get a skeleton that you can draw the loft sections onto so you have control of tangency and curvature, things you can dimension and control. Anyways, my opinion...let me know if that's completely greek I'll make you some notes if you want.
Progress to date is posted below.
Using the boundary surface I notice it is critical to get the number of curves and straignts the same on both boundaries. Can anyone advise how to join two curves that are converted from the same sketch that has a break. This means that the two converted curves are coincident with the same line and just need to be joined. Thanks.
Feel free to coment on how best to proceed.
The final product.
Generally have to say that I'm pretty impressed with the SolidWorks surfacing capability. Not that I have tried any other surfacing packages. I've played around with it for a while and am pretty much a complete novice in this aspect of design. Given the tools, the hard bit is working out strateges for using the tools to achieve the required end. The rest is just trial and error and plenty of patience.
The software performed pretty well in general. I had one bug that caused the computer to crash a number of times. This seemed to right itself in the end and I could carry out the same sequence without failure. Not sure what the problem was. Given the way spline sketches go haywire I was surprsied there were not more crashes.
The renderings took a matter of seconds in Photoview 360. The only gripe there would be the difficulty in rotating the model.
This is a surface model. Any hints on how to convert it to a solid would be helpful.
Glad you finally made one and happy to know that it was a good learning curve for you as well
Any chance or possibilities of sharing the final part.
Try knit command under surfaces to combine all the surfaces and convert to solid.
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