## Monday, November 30, 2015

### Weird Request

I need an adapter for 1/2"-13 male to M10x1.5 female.  Any suggestions what industry needs this?  I really don't want to make these myself.

All sorts of adapters out there, mostly for pipe threads.  I guess I will start with 3/4" aluminum rod, drill and tap 1/2"-13 in one end, and turn the other end to .3937, then use a die in the lathe to make a male M10x1.5 stud.

Is aluminum adequately strong for this part?  I was doing the math in my head while trying to fall asleep,  Shear strength for materials is usually 60% of tensile strength,  or for 601T6 aluminum: 165 Mpa.  How much can a 10mm piece of aluminum handle? 165 Mpa/(10mm^2)=1.655 x 10^6 pascals. A pascal is one newton of force over one square meter.  The newton is one kilogram under 1 m/sec^2 of acceleration: so converting one newton under our gravity to mass is 1/9.8.  A 1.655x10^6 pascals force is what 168887 kilograms would exert.  Yes, I don't think I need steel for this.  Even better, this is same order of magnitude of what I computed in my head.  I am not completely useless yet.

Maybe easier: start with a block of aluminum.  Drill and tap a M10x1.5 hole in the top.  Drill and tap a 1/2"-13  hole in the bottom.  Drop a M10.1.5 bolt from bottom with lock washer to hold it in the hole facing up; Now screw the 1/2"-13 stem up from the bottom, which holds the M10 bolt in place.  No need to cutM10 threads on a stem, amd need to turn a rod down to size for the die.  Just drill one very long hole for the M10, enlarge it from bottom for tapping 1/2:-13, and tap top of hole for M10.  Two drill operations and two taps, and one bolt.

UPDATE: Clever not clever enough.  The socket head on the M10x1.5 bolt is too large to drop into the hole for the 1/2"-13 caster stem.  Another possibility is to buy some M10x1.5 studs for that end.

Will said...

Your calculations may not be valid. I've seen engineers make a similar process mistake. Start by calculating/measuring how much force the part(s) can exert on the junction of this assembly. Only then do you look for appropriate materials.

BTW, 6061T6 is one of the softer aluminum alloys. Probably the cheapest, though.

Consider browsing through www.practicalmachinist.com for info on metals and machining. Very helpful people on that forum.

Will said...

Consider using socket head cap bolts, or studs. I'm thinking there won't be enough clearance for a regular hex head bolt inside that double bore hole. I may not be clear on what it is you're trying to do, though. Requires sketches! :)

Anonymous said...

Sounds like a divided-thread coupling nut (10X1.5 one end, 1/2-13 on the other) may be what you want. If Loctite Primer and Loctite Stud Lock are used to secure the male threads in the female threads you can eliminate the need for a lock washer - it will become, in effect, a single assembly.

Is it feasible to butt weld two male threaded fasteners together? A 1/2-13 stud welded to a 10X1.5 stud and screwed into a 10X1.5 coupling nut would give you the assembly.

Unknown said...

I'm aware of adapters between each of those and 5/8-18, for automotive hub-puller type devices -- but not between those sizes directly.

Clayton Cramer said...

Will: socket head bolt yes.

Clayton Cramer said...

Will: My revised plan uses a steel M10x1.5 bolt (which is what iOptron uses) and a 1/2"-13 thread stem. The only remaining weak point is the aluminum block (2" x 1" x1") in which both sit.