No, there's no need to 'redraw' the model. Start by double-clicking the first sketch in your timeline (the leftmost one). This will put the sketch into edit mode. Add a dimension to the circle. This dimension will drive the circle's diameter. If you want to change the diameter of the circle just double-click the dimension, enter a new value and hit 'enter'. You will see that the size of the circle gets bigger or smaller depending on what you typed in. Click 'Finish Sketch'. Notice that the model immediately reflects the changes you've just made. Repeat this for the remainder of your sketches. However this on its own will not stop your model 'blowing up' if you change your dimensions beyond certain values. I've not looked at your model in that much detail but I'd say the reason it's falling apart is down to the 'Delete Face' features.
Probably the easiest way of addressing this would be to delete these features and add them back in once you've got your model sized correctly. 'Delete Faces' is not ideal as it can cause these sorts of issues but I have to admit that I do use it on occasion. You could model it in a slightly different way to avoid using the 'Delete Faces' feature which would be better in the long run.
If this answers your question please mark the thread as solved as it can help others find solutions in the future.
Marcus Wakefield
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I've created a Windows application (and now Mac as well) for creating custom thread files for Fusion. You can find out about it here. Hope you find it useful.
If you need to know how to offset threads for 3D printing then I've created a guide here which you might find useful.
If you would like to send me a tip for any help I've provided or for any of my software applications you've found useful, you can do this via my Ko-Fi page here.
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