Looks good OSTexo - I will get there .... slowly. Moving from 2d pen and paper to 3d is a hard journey for me.

Martin

Hi Martin, the result that you have at the end there is not a solid - it's a bunch of separate surface pieces. So that's why it's not behaving like a solid, because it is indeed not one...

It looks like your original sweep in this case is done with an open curve:




It can be ok in some situations to use a surface as a cutting object, but only if it fully divides the solid - your cutting surface in this case does not fully divide the solid at the very top and bottom spots I don't think. So it would be better to form a solid as the cutting object in this case instead.

You can make a solid for the cutting object by drawing in a line segment on the ends of that open "V" curve and then select the V and the line and use Join to make a closed triangle profile curve. Then the sweep result of that will be a solid.


Also you'll probably be better off making the cylinder be slightly shorter than the cutting object rather than having the cutting object stop right where you have it currently since that makes a sort of teeny little notch at the end.

See the attached 3DM file for an example - here I've shortened the cylinder so that the cutting object runs cleanly off the end, if you wanted the same sized cylinder as before you would probably instead want to make the helix path slightly longer instead.


At some point in the future I could see making a "helix cut" type plug-in that would automate this particular type of thread type stuff, but that probably won't happen anytime too soon though.

You can probably find a lot of various premade standard parts like this in IGES or STEP format so that you wouldn't need to model it at all though - I'd recommend checking out http://grabcad.com, and also see the links here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=1826.1
http://moi3d.com/forum/index.php?webtag=MOI&msg=3505.3

- Michael

Hi Martin, also the screw threads tutorial on the Resources page that OSTexo mentions above will take you to his video tutorial here: http://vimeo.com/30765016

And also some previous discussions here on the forum:

http://moi3d.com/forum/index.php?webtag=MOI&msg=4623.1
http://moi3d.com/forum/index.php?webtag=MOI&msg=767.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=490.36

- Michael

.

Just watched the videos you did with threads and knurled finishing - Impressive stuff. You must come from an engineering background as you made that look so easy too, even working with fractions that i have to faff about with for hours. Landscaper v's Draughtsman = Embarrassed landscaper. LOL

Nicely done OSTexo

Martin

Thanks for the links Michael - Excellent stuff

Martin

Hi Michael, will have to try this cutting solid with solid some more, I normally end up having to loft or blend holes left by cutting objects. It was 3am after all - That's my excuse and i am sticking to it lol

Martin

Edit ... Eureka! - That's what i am looking for, now i feel reel dumb and need to coin Homers catch phrase DOH!

Hello,

Just a great deal of trial and error. The Wikipedia article on screw threads helped me a great deal to realize that instead of having to use a calculator for anything all that was needed was the base pitch number and everything else is ratios. I also thought it would be good to have MoI do the precise calculations for me rather than rely on pen and paper. FelixPQ was kind enough to send me some engineering handbook scans as well for reference.

Well here is my result, I got bored and decided to play with my nuts :¬)

Also this link may be of use to someone else with what was our conundrum ... http://www.roymech.co.uk/Useful_Tables/Screws/Hex_Screws.htm

Martin