I thought glued on tranfer cover was was amazingly stupid and now this- garbage saw imo- I stick with rebuilding older quality saws- almost like china parts- like they care to improve- NOT as long as long as the money keeps flowing in
Tom, I see it more as a removal concern than a install concern, give them a few years to corrode in the atmosphere where I live and they may be prone to snap off on removal, heck even steel screws are known to break off on removal around here. For my own use aluminum screws will never be used for assembly, they can all go in the scrap metal bucket.Couldn’t agree more, it’s utter insanity they’re using them. They’ll snap and cause more problem, guaranteed
You can't predict whether a screw of a given material will break in tension or strip the internal threads of a mating piece of different material by simply comparing the strengths of the two materials. The threads are primarily in shear (not tension) and the shear area increases with greater thread engagement. In other words, you can reach the tensile yield of a high strength screw in a soft female thread by increasing the thread engagement length.*I honestly don't see the issue with using aluminum screws, if you look at the tensile strengths of materials, a grade 8 bolt (standard metric) has about 900MPa yield strength, 7075 AL has about 500MPa yield strength and 6061 AL has about 260MPa yield. Compared to even the best cast magnesium alloys that only provide about 160-200 MPa yield. So as long as they are properly installed they will not yield until after the magnesium threads have been pulled out (assuming pure tension). You can still obviously break the aluminum bolts from removing and installing multiple times due to fatigue, but they shouldn't fail without cause.
You can't predict whether a screw of a given material will break in tension or strip the internal threads of a mating piece of different material by simply comparing the strengths of the two materials. The threads are primarily in shear (not tension) and the shear area increases with greater thread engagement. In other words, you can reach the tensile yield of a high strength screw in a soft female thread by increasing the thread engagement length.*
The snug then turn another 90 degrees tightening instructions makes me believe the aluminum cap screws are torque to yield fasteners (AKA TTY; stretch bolts; turn-of-the-nut) in order to control the clamping pressure and sealing between the case halves, and a steel screw that matches the "stretchiness" of an aluminum fastener would be unreasonably small.
*The rule-of-thumb for UNC threads is that approx 3 threads is enough to break the screw if the screw and internal thread are of similar materials.
You can't predict whether a screw of a given material will break in tension or strip the internal threads of a mating piece of different material by simply comparing the strengths of the two materials. The threads are primarily in shear (not tension) and the shear area increases with greater thread engagement. In other words, you can reach the tensile yield of a high strength screw in a soft female thread by increasing the thread engagement length.*
The snug then turn another 90 degrees tightening instructions makes me believe the aluminum cap screws are torque to yield fasteners (AKA TTY; stretch bolts; turn-of-the-nut) in order to control the clamping pressure and sealing between the case halves, and a steel screw that matches the "stretchiness" of an aluminum fastener would be unreasonably small.
*The rule-of-thumb for UNC threads is that approx 3 threads is enough to break the screw if the screw and internal thread are of similar materials.
Understanding the reasons behind the introduction of such fasteners (TTY) for a certain type of application like aluminum cylinder heads, I guess such screws don't necessarily have to be made of aluminum.Torque to yield screws. Been using the in automotive head bolts for years. Designed not to loosen. Not weight reduction. A more perfect tension for tightening.
Just normal stuff if you spent time in the auto industry.
Torque to yield screws. Been using the in automotive head bolts for years. Designed not to loosen. Not weight reduction. A more perfect tension for tightening.
Just normal stuff if you spent time in the auto industry.
Since I started at GM in the 80s, those "Good old days" were well on the way out. But then again, I was the Olds diesel guy. Explains a lot, doesn't it.
I had a 69 Goat with 400 BB and M21 gearbox...you could hit the gas at 70mph in 3rd gear and spin the wheels...good times. Passed anything but a gas station.I had a friend with a ratty Olds 88, he put a 455 and muncie out of a GTO in it. That car surprised a lot of the later "smog" hot rods
Friend of mine had a 76 TA with a 455 and 4 sp.I had a 69 Goat with 400 BB and M21 gearbox...you could hit the gas at 70mph in 3rd gear and spin the wheels...good times. Passed anything but a gas station.
Friend of mine had a 76 TA with a 455 and 4 sp.
55 in 1st, 85 in 2nd, 115 in 3rd, and then the tires would hook up in 4th. Could shift back into 2nd and do it all again lol. Good times.
RIP Ox
Yep, that’s called torque-to-yield. Totally overkill for case bolts if they just used decent hardware like they have for the last 80 years. I still think this is going to cause a lot of snapped bolts stuck in cases, and it’ll be a nightmare for customers with all the extra labor.Good logic, I liked it, and about the tightening, 3Nm plus 90º. Is that right?
Yep, that’s called torque-to-yield. Totally overkill for case bolts if they just used decent hardware like they have for the last 80 years. I still think this is going to cause a lot of snapped bolts stuck in cases, and it’ll be a nightmare for customers with all the extra labor.
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