Simplifying an assembly

GHamsz

As an exercise, I’m creating a functional V8 engine, but when I revolve the crankshaft with the attached rods and pistons in the engine block, positional updates are very slow. I realize that as the complexity increases, redraws will slow down, but I’m wondering if there are some things I can do in my design to improve the redraw rate.

The approach I used to build the crankshaft was to create separate features for parts of it, then transform those features to the correct location with mate connectors. As a result, there are a large number of mate connectors for a part that will never change once it’s assembled (see the pic below). What I’m going to try is to make the crankshaft a union of all the assembled features that make it up, hopefully eliminating all the mates, and possibly lessen the computational requirements when I rotate the crank rods and pistons.

Is there anything else I should be doing?

tim_hess427

If you are trying to create a single-part crankshaft, I think you may be better off positioning your parts in a part studio rather than an assembly. Then you can easily use a Boolean operation to combine all of the parts into a single body. 

GHamsz

I made the crankshaft in a part studio, and used mates and transform mates to assemble it in the part studio. When I bring that part into an assembly, all the mates come with it. 

I did create a union of the constituent features, and was able to use it in the assembly which came across without all the mates. Unfortunately, rotating the crankshaft in the assembly is very smooth until I add the 5’th rod and piston, when it seems to hit a wall and gets very jerky. It’s almost as if it’s hit a memory limitation, and has to start swapping parts in and out of cache. That’s a WAG, but it’s a reasonable educated guess.

Prachi

Are you hiding the mates in the assembly? short cut 'k'
Had to use  lot in something I worked on a while ago (parts on a peg board essentially, but not nice round holes) and found with all the mates displayed the assembly got very slow.

john_mcclary

You shouldn't be hitting a processing limit on such a small assembly. It may be your tablet is not powerful enough.

But like any assembly, the fewer mates the better.
Also  when rotating you may need to drag and wait for a few seconds until you can rotate. Once you give it time to process your request then you can continue to rotate freely. Every time you let go of the mouse button it finalizes the position and you have to start over.

What I usually do is click-hold and wiggle, once you get smooth control then you can quickly turn it.
Notice the delay before it lets me spin. This assembly has hundreds of mates, you should be able to have much more complexity than just that crankshaft

GHamsz

Here’s a link to a YouTube video where I’m rotating the crankshaft with the rods, pistons and cylinders in place and mated.

https://youtu.be/CvCjk3BpNvo

GHamsz

My theory was if the mates were in the assembly, they’d have to be evaluated which would slow things down. To get around that, I created a union of the components that make up 5he crankshaft, and loaded that into the assembly. It came in with no mates, but in the end made no difference.

im using an iPad Pro, so it should have plenty of power.

Here’s where I’m at now, and I’ll include a link to the document below the pic.

https://cad.onshape.com/documents/cbf688cb549886dc44fb530c/w/40df3a829302d04a0e520f6a/e/421e83004c63015865903134