Used to using C4D for design or creating parts for 3D printing, today I am asked to create a part with a screw thread to the standard. The problem is that I know absolutely nothing about screws.
My screw thread must be type 3/4 or 20/27, after having done tests, this corresponds to the screw thread of the tap or mixer fittings, other info, it would be a thread for piping called "GAS". After a lot of research I found a lot of information on standards and ratings, but where it sticks is that once you have to put it into practice in SW, well that's what. In the company that allows me to use one of its SW-equipped offices, there is not one who knows more than I do.
Creating a screw with thread is quite simple by following a tutorial, where I get stuck is at the data level (Fig.1). If I take the numbers of a 20/27, I have: Pitch in mm: 1.814Number of steps in 25.4 mm: 14 h in mm: 1.162 Outside Diameter 26.441
Diameter on sidewalls D2 = d2 : 25.279 Core Diameter: 24.117 Deviation over d in : -0.284 Deviation on d2 Class A: -0.142 Deviation on d2 Class B: -0.284 Deviation on D1 mm: 0.541 H = 0.960491.P h = 0.640327.P r = 0.137329; p
To be sure, I tried to reproduce the part that I used as a test with its 11 fillets. (Fig.2)
It doesn't really look like a screw thread like in the Fig.3 picture. If I understood everything correctly and calculated well, in my 20 mm (SW gives me 19.95 mm) I have 11 threads with a pitch of 1.814, r corresponds to the radius of Fig.3, the angle is good, it's not complicated to understand and it should be 55°. On the other hand, instead of the 0.866 and the 1.732 I have absolutely no idea what to put ? Should I put, as I think H/2, i.e. 0.960491/2 = 0.4802455 instead of 0.864 and 1.814 instead of 1.732?
Anyway, I'm wondering right now if I shouldn't have done an extruded bosage rather than a removal of material because if I look at the result, my screw thread looks more like a square than a triangle. If anyone could help me reproduce my piece, a big thank you for your help.
Why don't you use the data directly rather than calculating it.
Pitch: 25.4/14
r=0.137329*p
your angle = 27°30' x2 (you don't have that on your sketch, you have 59°)
And you draw your cylinder on the outside side and not the average diameter. Then your propeller. You put your net sketch on your propeller and you get what you want.
At first glance, the odds of 0.866 and 1.732 do not seem to be the most judicious. What matters is the odds of 4.513 which must be equal to D1/2 (24.117/2). Then, I will put an outer radius which must be at least that of the cylinder (if it protrudes there is no problem). Unless you want to integrate the radius at the top of the net, then this dimension must be equal to D2/2.
That said, I would be wary of the tightness of a 3D printed thread of this type. Personally, I think I'll leave at least an extra thickness to go over the die and have something cleaner.
gt22 : Yes the odds are not the corresponding ones, but at the time of the post I didn't have access to the PC equipped with SW.
.PL : Thank you for this list of very interesting sites, which I put aside, but all done, personally, I don't find it top notch, but it's true that it can frankly help in some cases.
opiep27 : Oh frankly, it really looks more like my screw thread. By the way, .PL passed me a link with this figure, on the other hand, well I tried to do it again and then... how can I put it? It's not C4D... !! If you have a lead that will explain this method, well it would be welcome, because for the moment I have only found "simple" steps like the one I did.< And since I am surrounded by broken arms in the field...!
Gérald : I agree, I've already noticed it, and I've had to fold more than one calculator. For this time, I'm discovering it in paine SW, so I took what I had on hand on an English tutorial and strangely in millimeters.
Chamade : Uh, yes ok...! Not only am I discovering SW, but also all kinds of screw threads, constraints etc., etc. I didn't even imagine that there were so many. Why keep it simple as usual, but I'm going to look into the question you raise.
Thank you opiep27 and Gerald it's great, it really corresponds to what I'm looking for. I just have to try to do it again.
Chamade : Compared to 3D printing, indeed it will be necessary to provide a greater thickness, the problem is that for the moment, I don't know if it will be in FDM or Stereolithography with a Form Labs +1 type machine.
Number of steps in 25.4 mm: 14
