Power Pro Case

dusty · Post by **dusty** » Fri Nov 05, 2010 4:39 pm

mickyd wrote:Gotta destroy 'em to QC 'em. Only do destruct tests on aerospace and militiary spec fasteners.

Got an opening for an old Environmental and Nuclear Survivability Test Engineer?

horologist · Post by **horologist** » Fri Nov 05, 2010 4:55 pm

mickyd wrote:What's Ftu / Fsu? Haven't dealt with that in my QC world.

Sorry Mike, I should have been clearer.

Ftu = Ultimate tensile stress
Fsu = Ultimate shear stress

Most of our standard steel or titanium bolts have a minimum Ftu of 160 ksi (160,000psi) and an Fsu of 95ksi.

Troy

robinson46176 · Post by **robinson46176** » Fri Nov 05, 2010 5:20 pm

With all of the engineering going on here you guys missed the obvious "strip of duct tape slapped across it" cure...

Also in my history are incidents of covering a gap with a nice piece of chrome trim.

or maybe a nice strip of walnut.
.
Actually, the return to SS is the best answer since curing it will tell them exactly what they need to do to permanently eliminate the problem in assembly. "Someone could get the chop"...

horologist · Post by **horologist** » Fri Nov 05, 2010 6:17 pm

robinson46176 wrote:With all of the engineering going on here you guys missed the obvious "strip of duct tape slapped across it" cure...
Also in my history are incidents of covering a gap with a nice piece of chrome trim. or maybe a nice strip of walnut.
.
Actually, the return to SS is the best answer since curing it will tell them exactly what they need to do to permanently eliminate the problem in assembly. "Someone could get the chop"...

What's that expression? Can't see the forest for the trees...

Although a chainsaw and a woodmizer will soon have that problem settled.

Troy

JPG · Post by **JPG** » Fri Nov 05, 2010 7:05 pm

horologist wrote:What's that expression? Can't see the forest for the trees...

Although a chainsaw and a woodmizer will soon have that problem settled.

Troy

I like that!!!!!!!

mickyd · Post by **mickyd** » Fri Nov 05, 2010 7:17 pm

horologist wrote:Sorry Mike, I should have been clearer.

Ftu = Ultimate tensile stress
Fsu = Ultimate shear stress

Most of our standard steel or titanium bolts have a minimum Ftu of 160 ksi (160,000psi) and an Fsu of 95ksi.

Troy

Troy,
In 'my' fastener world, the stress vs. strain curve (load vs. deformation) yields UTS (ultimate tensile strength) and UYS (ultimate yield strength). The alloy cap screws aren't spec'd out shear strength like a dowel or roll pin is unless your considering max rotational torque shear. UTS on an alloy socket cap screw is 180,000 psi minimum and UYS is 162,000 psi minimum.

Wonder what your Ftu / Fsu acronym stands for??

horologist · Post by **horologist** » Fri Nov 05, 2010 9:33 pm

mickyd wrote:Troy,
In 'my' fastener world, the stress vs. strain curve (load vs. deformation) yields UTS (ultimate tensile strength) and UYS (ultimate yield strength). The alloy cap screws aren't spec'd out shear strength like a dowel or roll pin is unless your considering max rotational torque shear. UTS on an alloy socket cap screw is 180,000 psi minimum and UYS is 162,000 psi minimum.

Wonder what your Ftu / Fsu acronym stands for??

Mike,
Sounds like we are on the same page, indeed you may manufacture some of the fasteners we use at work. But are these values for the cap screws found in the typical hardware store? Not that it makes a bit of difference in this case, even the lowest grade Chinese screw will have ample margin.

F is a symbol commonly used to denote stress, the subscript t is for tension and u is for ultimate and so on.

Troy

mickyd · Post by **mickyd** » Fri Nov 05, 2010 11:01 pm

horologist wrote:Mike,
Sounds like we are on the same page, indeed you may manufacture some of the fasteners we use at work. But are these values for the cap screws found in the typical hardware store? Not that it makes a bit of difference in this case, even the lowest grade Chinese screw will have ample margin.

F is a symbol commonly used to denote stress, the subscript t is for tension and u is for ultimate and so on.

Troy

Troy,

Inch alloy steel socket cap screws are required by US law to meet the same specification requirements. If they don't, they cannot legally be called a socket cap screw.

Metric alloy socket cap screws however can come in 3 different minimum spec ranges for strength. All metric cap screws are required by US law to have specific head markings in order to differentiate the three. The metric head marking '12.9' approximates the strength of the inch socket cap screws.

FYI - The US Borders and Customs Agency is responsible for overseeing all fasteners imported into the country to ensure that they comply with US mandated specifications.

Stitch · Post by **Stitch** » Sat Nov 06, 2010 8:53 am

There has certainly been a lot of discussion for a "cosmetic" problem. Has anyone asked if it is possible that the holes are in the wrong location. Were these holes drilled as part of the DIY upgrade.

mickyd · Post by **mickyd** » Sat Nov 06, 2010 10:25 am

Stitch wrote:There has certainly been a lot of discussion for a "cosmetic" problem. Has anyone asked if it is possible that the holes are in the wrong location. Were these holes drilled as part of the DIY upgrade.

jctorick already sent it back to ShopSmith but to me, it would be very doubtful that the condition could be from holes not lining up. I've had times when holes didn't line up by just a smidgen and it was a bear to get the screw started. It would take a gorilla to buckle the sheet metal that much IMHO. The PowerPro unit was new.