Where's Confused?

[WOLF_RIVER_MIKE]

Where's Confused... he must have known about Lisa Marie's marraige to Dude and just decided to lay low for awhile. No kidding. A couple of months ago he had a comment on every subject. Confused was a student right? I remember telling him to study Rotax's Engine and to better that. You don't suppose he's sobered up and is going back to school? Naaaa.....

 

[John in MA]

Maybe he's...confused?

 

[dbabcock]

I wouldn't think Confused is going to school in the summer unless he's on the get-rich-quick program. Maybe he's working his family land this summer.

Get with the program, Confused! Get your a$$ back here, son.

 

[HUSKYMAN]

He's not posting because when school is out he cant sit in computer 101 and post to arboristsite while the prof is lecturing , or sit in the library on the net as all the college girls walk by

 

[confused]

To everyone, I’m still alive.

A brief synapse of the first summer internship and how it might be relevant to all here. I worked for Bosch diesel systems doing torque testing on components for diesel injectors and pumps. I learned a lot about torque and what it really is, torque is friction between threads. Torque really isn’t a real good way of measuring how much load is between the two parts. So we would put strain gauges either in the parts or build up something that can be used to test the load in pounds that is put into the part as a torque is achieved. I used hyper accurate automated torque wrenches to torque parts and then used an oscilloscope to measure the amount of load felt. Here is what might be relevant.

1) any oil (crisco works really well, seriously) put on threads before assembly will increase the amount of force (sometimes by as much as 200% but mostly around 125-150%) that the bolt/screw will put on the joint for the same torque. i.e. always oil threads before use because you’ll have more force holding the things together.

2) locktite (we tested 271,272,and a couple others I cant remember) is not a lubricant. locktite will actually lower the load if used on threads by appr. 10-30%. I thought as all of you probably thought its wet and therefore it will lubricate the threads. nope not true. Locktite contains a friction agent that is why it’s called locktite. So if your thinking about using locktite on a screw check with the manual to see if they have a corrected torque for a certain locktite or if you believe me just add about 15% to your torque and be done with it. O and oiling the bolt and then putting locktite on it too doesn’t do a ???? thing so don’t bother.

So school starts the 26th and ill be around more so that I can keep up with ya all. Hope you all had a restful and productive summer, but I'm back now so get ready.

 

[CMBetz]

Confused,

Were you over at the 52nd St facility?

CB

 

[confused]

44th street in Kentwood MI but thats not that important

 

[CMBetz]

I didn't know they have a spot on 44th St. I drive by the one on 52nd almost every AM, though. Just idle curiosity, I guess.

What else did you encounter over the last couple of months that would help us out?

 

[WOLF_RIVER_MIKE]

Welcome back confused. Go ahead, post away.

 

[geofore]

bosch

confused, were those bosch threads or metric(german) or american metric???? I have a collection of bosch pumps i tinker with and found out you can't put them back together in the same order you took them apart. Each cylinder and piston are matched and not interchangable. They can do tricks though. I have some that have been in service over 35 years with no down time for repairs, run them at low pressure at idle( 900-1500 rpm). Only have one ten cylinder off a piece of mining equipment. I guess the real question was were they american bosch or german bosch? Did you heat treat the locktite?

 

[confused]

everything bosch does now is metric that i know of. as far as heat treating locktite i dont understand what you mean.

 

[geofore]

locktite

The different types of locktite require they be heated to tempeture for a given time to set and lock properly.

 

[confused]

geofore,

we were doing torque testing with the locktite on the screw. IF the part has to be baked afterwards to set it is inconsequential to what we were doing. The only thing we cared about is how it effects the measured torque during intial installation of the screw

 

[TheTreeSpyder]

Wow, really neat tech stuff!
Thanx for the inside view man!

A 1/2" circumfrence 'screw' (simple machine) that must be screwed in 30 turns(30 x 1/2" =15 inches of travel) to go into mount 1" will have 15/1 mechanical advantage increase on input force; but minus loss to friction, lubricant reduces that friction greatly allowing more of mechanical advantage to be realised.

Just like better bearings on axle, pivot, greasing slide; they don't increase torque, they allow what is there to be closer to maximum potential.

Locktite comes in bottle with a lot of airspace, because it is an aerobic adhesive ie. it cures in places without oxygen. Should be used fresh, has shelf life even unopened. So between tight threads, without air it cures, not on outside ever totally i think. Heat could effect this effecting curing by burning up oxygen around adhesive and forcing curing with heat curing chemical too; it would effect faster curing in between threads where it is made to cure. Not really, really sure heat would make necessarily a stronger joint, nor weaker. Heat is used for breaking free stronger variety (red and specialty products), purple and blue are coded 'bluz' for cold breaking identification.

i think locktite isn't necessarily for lubricating, but for sealing out stuff, vibration, disallowing movement through adhesion.

So confused, now i am confused, are you saying that you can't get same amount of tightening tourque in a locktite joint by using longer wrench, hit rated tourque and have the best of both worlds? Or using finer threads for compressing more travel into same area, if you need locktite, to hit rated tourque/ tension???

 

[confused]

Tree Spyder,

For the testing we used a automated torque gun. The torque gun was accurate to + .1 Nm / ftlbs (appr. $5,000 wrench just to give you an idea) The nature of our testing was we would take a screw and tighten down to a specific torque say 2.7 Nm 10 times with no lube, lube, locktite, and then measure the clamp load the screw applies to the joint with a stain gauge. So the same torque was applied each time its not a question of torque. The thing i was trying to tell everyone is that with the same torque you dont always achieve the same loads. with lube you will have more load, than without. But interesting enough with locktite you have less than without. A dry screw will have a higher clamp load than with using locktite.

i hope this clears things up.

 

[WRW]

Confused,
Welcome back.
No, you have not cleared things up. I thought torque was a rotational force. I also thought friction was a drag that sufficient force could overcome. I thought that clamp load was affectable by the level of torque applied to the screw...need more clamp load, apply more torque...need equivalent clamp load, apply the same torque to all screws (bolts).
Further, I can only guess as to why one would want to increase clamp load without increasing torque, but won't go into that, cause I'm sure that the company you are testing for has their reasons.
As for the loctite, some manufacturers specify it's use as well as the torque values and I have to wonder if they also have done the tests you have described.

 

[confused]

WRW,

You are right torque is simply a rotational force. We were testing the implications of different lubes and locktite on a screw and how that effects clamp load. We torqued the screws all to the same torque what we found is that locktite on the same screw and the same torque will lower the clamp load. It does this by increasing the friction in the joint. If the friction in the joint goes up the torque to overcome this friction goes up. So what you see if you use locktite on a screw is that you will get say 10 ftlbs but your clamp load is lower because the locktite creates more friction than wouldve been there if the screw was dry.

 

[WRW]

Confused,
That loctite thing does seem contrary to what you would think. You can't argue with the test results, though.
Were you going to try to contact the threadlock manufacturer to see what they thought?

 

[treeclimber165]

Thinking about it, that makes perfect sense, Confused.
LocTite is DESIGNED to prevent bolts/screws from backing out, so it stands to reason that they would put some sort of friction additive in it.
When we tighten bolts, we measure one thing (torque) in order to estimate something else (clamp load, or grip). Since the local hardware store cannot sell us a $20 tool to measure clamp load, we use a torque wrench to measure how much force we put on the fastener. This usually correlates to a certain amount of clamp load, but clamp load is affected by all sorts of factors. Dirt, lubrication, other additional friction, how many times the bolts have already been torqued (stretched), even the temp of the fasteners!

Thanks for the info, sounds like fascinating work!

 

[confused]

WRW,

I was only to do the test and report the results as far as i know the engineers that requested the test did contact Locktite to discuss what might be done.

Tree Climber,

Yeap, torque is just the energy required to overcome the friction on the threads. So it is imparitive to clean the threads and use some sort of lubricant to achieve the higher clamp loads.