rotor head jesus bolt

[asra]

Gents remember this is my preference & my opinion only. In a heavy machine like the GTG KRUZA well

[Russell]

Sam......your earlier post stated.........."rolled threads were stronger". Hence my reply to that, i see you have now removed that mention, re stronger, ( i took your comment as factual, in fact it was not.........i see it"s preference/opinion........that"s clearer )All serious "spec" mechanical jointing is "cut threaded"..........period. Why AN stuff is roll threaded, beats me. ( probably just a yanky thing )Did hear that the reason was ...............most aero bolting is with nyloc and similar typed nuts, and rolled threaded bolts did not "cut" into the nut and damage the locking feature..................true/false ??? ???cheers mate............keep up the good work ( hope to be driving down your way easter, see you then )

[mad max]

I Know of a gyronaught in the old days who used a grade 8 J bolt, Had a prang and the bolt snapped instead of bending and the blades shot away luckly missing him. I prefer A/C bolts because they just bend and hang on. Iv"e got sample bent bolts and bent 6061 alloy with no cracks to show my students to convince them to stick to A/C bolts. I allso like the Rosco rotor head because of the long Jesus thread.

[MilesW]

Sam......your earlier post stated.........."rolled threads were stronger". Hence my reply to that, i see you have now removed that mention, re stronger, ( i took your comment as factual, in fact it was not.........i see it"s preference/opinion........that"s clearer )All serious "spec" mechanical jointing is "cut threaded"..........period. Why AN stuff is roll threaded, beats me. ( probably just a yanky thing )Did hear that the reason was ...............most aero bolting is with nyloc and similar typed nuts, and rolled threaded bolts did not "cut" into the nut and damage the locking feature..................true/false ??? ???Not preference or opinion...........fact.Are you suggesting that only high tensile is serious "spec"and anything of lower tensile is not? More high specification critical service bolting is roll threaded than cut. High tensile material does not lend itself to rolling, simple as that. The material has to "flow" and high tensile/high strength materials just don"t do that. That flow of material is akin to forging and is what gives a rolled thread its greater strength and integrity over a cut thread. Why are AN bolts roll threaded? They can be (lower tensile/higher ductility), rolling is cheaper than screw cutting, reduced weight (reduced shank diameter) and therefore less material required (important during the war when the spec came about), and the added bonus of a stronger thread. A lot more to bolts than meets the eye!Miles

[Russell]

Interesting ................just staying on "threads" here, not metal strengths etc............moons ago i was in and around earthmoving ( rugged, high wear, huge forces, etc etc ), later became involved in the building trade.To the best of my recollections, all "specs" were rated by "grade",

[Russell]

The topic got me looking...........Rolled vs Cut Thread BoltsQuestion: What is the difference between a bolt with rolled threads and one with cut threads and does a fastener with a reduced body and rolled threads meet ASTM specifications?Answer: Threads of a mechanical fastener, regardless of whether it is a headed bolt, rod, or bent bolt, can be produced by either cutting or rolling. The differences, misconceptions, advantages, and disadvantages of each method are described below.Cut Threads Cut threading is a process by which steel is cut away, or physically removed, from a round bar of steel to form the threads. A 1″ diameter bolt, for example, is produced by cutting threads into a full 1″ diameter body of the bolt.Advantages of Cut Threading Few limitations with regard to diameter and thread length.All specifications can be manufactured with cut threads.Disadvantages of Cut ThreadingSignificantly longer labor times means higher costs.Rolled ThreadsRoll threading is a process by which steel is extruded to form the threaded portion of a fastener, instead of being removed as in cut threading. In this process, a bolt is manufactured from a reduced diameter round bar. For example, a 1″ diameter bolt is manufactured from .912″ diameter round bar. This “pitch diameter” material is approximately the midpoint between the major diameter (peaks) and minor diameter (valleys) of the threads. The bolt is “rolled” through a set of threading dies which displaces the steel and forms the threads. The end result is a fastener with a full 1″ diameter threaded portion but a reduced body diameter (.912). Roll threading is an extremely efficient process and often results in significant cost savings. Therefore, Portland Bolt will roll threads whenever possible.Roll Threading Misconceptions Roll threaded bolts do not meet ASTM specifications.Technically, any specification with the exception of A325 and A490 structural bolts can be produced with a reduced body and rolled threads.A bolt with a reduced body will be weaker than a bolt with a full sized body.The weakest area of any mechanical fastener is the minor diameter of the threads. Since the thread dimensions of a cut thread and rolled thread fastener are identical, there is absolutely no difference in strength. One could actually argue that the work hardening which occurs during the roll threading process may even make the fastener with rolled threads stronger. Additionally, cut threading interrupts the natural grain structure of the round bar whereas roll threading reforms it. One could again argue that cutting into the grain of a round bar when cut threading may produce threads which have less structural integrity than a part which has been roll threaded.Advantages of Roll Threading Significantly less labor times means lower costs.Because a roll threaded bolt has a smaller body diameter, it weighs less than its full bodied counterpart. This weight reduction reduces the cost of the steel, galvanizing, heat-treating, plating, freight, and any other costs associated with the fastener that are based on weight.Cold working makes threads more resistant to damage during handling.Rolled threads are often smoother due to the burnishing effect of the rolling operation.Disadvantages of Roll ThreadingPortland Bolt is limited to a maximum diameter of 1″ and a maximum thread length of 8″.The availability of pitch diameter round bar is limited for certain material grades.150 ksi minimum tensile strength material is too strong for Portland Bolt to roll thread.A325 and A490 structural bolts cannot be produced with a reduced body diameter.In rare wood applications where shear strength is the critical requirement, bolts with a full sized body may be required.

[asra]

Russ seems your on a witch hunt bud.The comaprison you found is not a comparison against AN hardware. The advantage verses disadvantage is logical. Why not ring the experts AVIA QUIP

[Russell]

No sam........no witch hunt, opologies if you took it that way. Many times over the yrs, the topic of "AN" hardware cropped up, and reasons opinions were varied as to the "why"..........some LAMES, said twice the price for half the strength etc etc. I understand AN bolts are graded as grade 5, which is not all that flash. The " pro"s and cons" are wide and varied re AN stuff. I for one will continue to use AN hardware at all times.My earlier post re "rolled v cut" was via a

[asra]

No sam........no witch hunt, opologies if you took it that way. Many times over the yrs, the topic of "AN" hardware cropped up, and reasons opinions were varied as to the "why"..........some LAMES, said twice the price for half the strength etc etc. I understand AN bolts are graded as grade 5, which is not all that flash. The " pro"s and cons" are wide and varied re AN stuff. I for one will continue to use AN hardware at all times.My earlier post re "rolled v cut" was via a

[MilesW]

Hi RussI have a bit of plant here, so went through a pile of CAT bolts in the shed and they were all rolled threads...This was at odds with your "facts", so I grabbed my CAT Hardware Catalogue and low and behold, what was the first bullet point for bolts? "+ Designed with smooth rolled threads for better clamp load, shear resistance and resistance to stripping".I know I"ll take CAT"s word for it.Grade 5 is not as strong as grade 8 (or higher for that matter) but it is for want of a technical term "stretchy". The yield point and ultimate tensile strength are further apart which means it gives before it fails. In really high tensile steels, the yield and tensile are very close together which means this is little to no give before failure. As Max mentioned in his post, would you prefer in a bingle all the bits to be still held together in a fashion by bent and stretched bolts, or a pile of bits flying around the flat? Also, it is sometimes better for the fastener to fail before what it is holding together does.It is not a case of one grade being better than another. AN5 bolts do a great job in the application they are intended for. Similarly, Grade 8 bolts are excellent for where they are specified. Horses for courses.....MilesMiles

[elwynne]

Hi all, I worked for Hastings Deering (Cat dealer)in Mackay for 13 years as a leading hand diesel fitter & was sent to a couple of failure analyses courses.

[Greg Mitchell]

Amen to that Elwynne! Stress risers...I think thats the key. Same as a AN bolt bending afore it breaks, rather than something that simply snaps off. Hey Russ,Talking today to an old student of yours from a few years back. Sounds like Blue is about to get a gyro soon, he asked if you still had your old trainer. I told him I thought you didn"t have a gyro right now you were waiting on the new Raftorr. Hope I got it right. He"s up Cairns way so I suggested he talk to Bones.Cheers,Mitch

[Greg Mitchell]

Why"s that Bones?Dont you have a trainer?Cheers,Mitch

[GraemeMonro]

Why"s that Bones?Dont you have a trainer?Cheers,MitchThat"s got nothing to do with it Mitch.It"s just that ringing up Bones to talk to him would be a waste of a phone call.Graeme.

[asra]

Hey Russ,Talking today to an old student of yours from a few years back. Sounds like Blue is about to get a gyro soon, he asked if you still had your old trainer. I told him I thought you didn"t have a gyro right now you were waiting on the new Raftorr. Hope I got it right. He"s up Cairns way so I suggested he talk to Bones.Cheers,MitchGee there is nowhere to hide. But yes you are correct, looking for gyro and training.Blue