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Fusion 360 and thread sizing

PaulL

PaulL

Technologist at Large
Premium Member
Ok, I took the time to learn enough Fusion 360 to draw up a shaft extender I need to turn for a water pump at the cabin.
I got a nice cross-section drawn, spun it, and then pointed to the male and female threads and set them to M16x1.5. Then I set up a drawing to go with the design and pulled measurements. It's telling me the inner diameter of my female therad is 14.53mm, which matches the recommended tap drill size of 14.5mm. The male thread is odd, though, telling me it's 15.85mm outer dimension. I'm not finding that in any charts I'm looking at.

I'll wind up making some test threads on the way there, but I'm curious to know how trustworthy Fusion's thread sizing is.

Thoughts?
 
sounds about right. don’t forget the 16mm dimension is a nominal size of the o.d. of the blank bar. The thread is a truncated cone, so outer is less than nominal. Both the dimension are within spec depending on what tolerance class you’re working to.

External Metric Thread Table Chart and Fastener Sizes M1.6 - M18

Standard metric external thread size M1.6 to M18 per. ANSI/ASME B1.13M-1995
www.engineersedge.com
 
Last edited:
whydontu said:
sounds about right. don’t forget the 16mm dimension is a nominal size if the o.d. of the blank bar. The thread is a truncated cone, so outer is less than nominal. Both the dimension are within spec depending on what tolerance class you’re working to.

External Metric Thread Table Chart and Fastener Sizes M1.6 - M18

Standard metric external thread size M1.6 to M18 per. ANSI/ASME B1.13M-1995
www.engineersedge.com
Click to expand...
Ah, a chart with min/max tolerances! Thank you!
 
In case anyone wants to know how it turned (haha) out:

extender1.jpeg
extender2.jpeg
extender3.jpeg


Somehow I neglected to take a picture after threading the "nut" and adding the UHMD gasket washer to the recess you can see in the third picture.
Overall it went well - I only have one spoiled part instead of the 3 I budgeted for. Most hair-raising was the internal theading - I realized my only go/no-go was the shaft on the motor which I could not hold up to my chuck. I'm glad I had indexed the turning with the fron of the chuck jaws. I was able to mark orientation, pull the part, and get it back on without disturbing the threading setup; being metric in an imperial lathe this was important - I don't think I could have chased my way back into the groove if I had disengaged anything in the transmission.
So the good news is that the impeller rides on there well, and it should move water. If only my test-run attempt hadn't discovered that the spark plug snap ring terminal is only now intermittently connected. It's in rough shape - this little pump has spent 10 years of service mostly outside without adequate cover. So next job is to replace that ignition cable.
 
PaulL said:
Ah, a chart with min/max tolerances! Thank you!
Click to expand...

The price of a Machinery's Handbook is high, but the price you pay for doing without can often be much higher.

There are also many fastener websites that publish thread sizes. However, I do so much single point threading that really appreciate an app on my phone. For the Android platform I use and love the free "Tap and Drill Chart Calculator". It lists all the standard and quite a few not so standard thread sizes in both Imperial and Metric along with the classes of threads for different materials and tap types. If you select a desired thread, it will also give you a selection of drill sizes and tell you what the resulting thread fit percentage will be using that drill. It's awesome when you don't have the perfect drill for a given thread.

Here is the entry screen. The screen shot doesn't show it, but you can scroll down for more sizes

Screenshot_20220509-155727_Tap And Drill Chart Calculator.jpg



Here is the detailed screen that pops up after you select a thread.


Screenshot_20220509-155840_Tap And Drill Chart Calculator.jpg
 
Susquatch said:
The price of a Machinery's Handbook is high, but the price you pay for doing without can often be much higher.

There are also many fastener websites that publish thread sizes. However, I do so much single point threading that really appreciate an app on my phone. For the Android platform I use and love the free "Tap and Drill Chart Calculator". It lists all the standard and quite a few not so standard thread sizes in both Imperial and Metric along with the classes of threads for different materials and tap types. If you select a desired thread, it will also give you a selection of drill sizes and tell you what the resulting thread fit percentage will be using that drill. It's awesome when you don't have the perfect drill for a given thread.

Here is the entry screen. The screen shot doesn't show it, but you can scroll down for more sizes

View attachment 23782


Here is the detailed screen that pops up after you select a thread.


View attachment 23783
Click to expand...
iEngineer in tha Apple microcosm is pretty good. I spend a lot of time working out shear loads on bearing housings, this one has shear and torque values.
 
Given how much time I spend in my calculator converting imperial to metric you'd think I'd have clued into an app for the threading jobs.
I got so much out the machinist's black book that I neglected to get the next-level upgrade. Time to find a Machinery's.
 
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