You're certainly correct, angle torque relies on friction torque to a degree, whether it's by feel or with a torque wrench. The elongation gauges use a totally different method though-they actually measure the elongation of the fastener. Obviously there are some limitations to this approach.It works well on con rods though! Still, you have to used the specified fastener, and you need the proper spec. You're also right that the example given is a good example of pilot error...
Micrometer Click Type -vs- Dial Type
- Thread starter Merkava_4
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Originally Posted By: Merkava_4
Originally Posted By: doitmyself
When I was researching which torque wrenches to buy a few years ago, I actually struck up a conversation with a person in charge of tools at a Lockhead airplane plant. He described to me which ones they used.
If a torque wrench can be used to assemble jet airplanes......?
Which kind does Lockheed use; clicker or dial?
I was specifically inquiring about the durability of Snap On Tech Wrenches, which he replied:
"I checked with my fellow engineer in the Precision Gage Lab department here at Lockheed who is in charge of overseeing torque wrench calibrations. He tells me that we haven't had a single failure of a Techwrench yet and they haven't had any issues with them. They come down for their periodic calibrations and pass with flying colors. They've been in service in an industrial environment for several years now - even the battery life seems to be exceptional."
Then he added "For what it's worth the single most accurate style of torque wrench (and most durable) is the old style beam type wrench - especially the Sturtevant-Richmont brand with a ground flat beam. It would meet your needs of being slim enough to get into tight spots and gives you a good way to watch the torque increase on the fastener. We have some of those in this plant that are over fifty years old and still in use."
Keep in mind that I don't know this person, so the info is worth what I paid for it.... Merk, you need to add beam style into your decision!
Originally Posted By: doitmyself
When I was researching which torque wrenches to buy a few years ago, I actually struck up a conversation with a person in charge of tools at a Lockhead airplane plant. He described to me which ones they used.
If a torque wrench can be used to assemble jet airplanes......?
Which kind does Lockheed use; clicker or dial?
I was specifically inquiring about the durability of Snap On Tech Wrenches, which he replied:
"I checked with my fellow engineer in the Precision Gage Lab department here at Lockheed who is in charge of overseeing torque wrench calibrations. He tells me that we haven't had a single failure of a Techwrench yet and they haven't had any issues with them. They come down for their periodic calibrations and pass with flying colors. They've been in service in an industrial environment for several years now - even the battery life seems to be exceptional."
Then he added "For what it's worth the single most accurate style of torque wrench (and most durable) is the old style beam type wrench - especially the Sturtevant-Richmont brand with a ground flat beam. It would meet your needs of being slim enough to get into tight spots and gives you a good way to watch the torque increase on the fastener. We have some of those in this plant that are over fifty years old and still in use."
Keep in mind that I don't know this person, so the info is worth what I paid for it.... Merk, you need to add beam style into your decision!
I don't think torque wrenches are useless. I use them myself, and I've written a number of technical manuals specifying torque specifications....but I also understand the limitations.
Sure, they use friction torque in aerospace, but that's a function of the headroom built into the joint, not the method of measurement. For applications which require precision, other methods are used.
Sure, they use friction torque in aerospace, but that's a function of the headroom built into the joint, not the method of measurement. For applications which require precision, other methods are used.
JOD,
In my internet "education", I have read that engineers are suppose to design fasteners to accommodate the variables that are encountered in real life. Lug bolts come to my mind, which receive all kinds of abuse.
Do you think this idea is laughable? Or, is this what you mean by "head room"?
In my internet "education", I have read that engineers are suppose to design fasteners to accommodate the variables that are encountered in real life. Lug bolts come to my mind, which receive all kinds of abuse.
Do you think this idea is laughable? Or, is this what you mean by "head room"?
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No, that's exactly how it is! The margin is built into the joint, because fasteners get reused, threads get dirty and there are a ton of variables to deal with.
I can do the maths on a set of wheel lug nuts when I'm at a computer, but I can guarantee that there is a very large margin built into the overall joint. For laughs I did this on a Honda drain plug earlier today. I'll post that later if anyone is interested but I hate typing on my Swype keyboard on Bitog. My browser doesn't seem compatible with the site!
I can do the maths on a set of wheel lug nuts when I'm at a computer, but I can guarantee that there is a very large margin built into the overall joint. For laughs I did this on a Honda drain plug earlier today. I'll post that later if anyone is interested but I hate typing on my Swype keyboard on Bitog. My browser doesn't seem compatible with the site!
Originally Posted By: doitmyself
I was specifically inquiring about the durability of Snap On Tech Wrenches, which he replied:
"I checked with my fellow engineer in the Precision Gage Lab department here at Lockheed who is in charge of overseeing torque wrench calibrations. He tells me that we haven't had a single failure of a Techwrench yet and they haven't had any issues with them. They come down for their periodic calibrations and pass with flying colors. They've been in service in an industrial environment for several years now - even the battery life seems to be exceptional."
Then he added "For what it's worth the single most accurate style of torque wrench (and most durable) is the old style beam type wrench - especially the Sturtevant-Richmont brand with a ground flat beam. It would meet your needs of being slim enough to get into tight spots and gives you a good way to watch the torque increase on the fastener. We have some of those in this plant that are over fifty years old and still in use."
Keep in mind that I don't know this person, so the info is worth what I paid for it.... Merk, you need to add beam style into your decision!
That's some good insider information. On that Techwrench, you gotta keep looking
at it as you're pulling on the fastener don't you? It's like using a dial type isn't it?
I was specifically inquiring about the durability of Snap On Tech Wrenches, which he replied:
"I checked with my fellow engineer in the Precision Gage Lab department here at Lockheed who is in charge of overseeing torque wrench calibrations. He tells me that we haven't had a single failure of a Techwrench yet and they haven't had any issues with them. They come down for their periodic calibrations and pass with flying colors. They've been in service in an industrial environment for several years now - even the battery life seems to be exceptional."
Then he added "For what it's worth the single most accurate style of torque wrench (and most durable) is the old style beam type wrench - especially the Sturtevant-Richmont brand with a ground flat beam. It would meet your needs of being slim enough to get into tight spots and gives you a good way to watch the torque increase on the fastener. We have some of those in this plant that are over fifty years old and still in use."
Keep in mind that I don't know this person, so the info is worth what I paid for it.... Merk, you need to add beam style into your decision!
That's some good insider information. On that Techwrench, you gotta keep looking
at it as you're pulling on the fastener don't you? It's like using a dial type isn't it?
Originally Posted By: Merkava_4
That's some good insider information. On that Techwrench, you gotta keep looking at it as you're pulling on the fastener don't you? It's like using a dial type isn't it?
IF you want to see the torque values as they progress, then yes, you need to see the screen. However, it also beeps AND VIBRATES when it reaches the set torque value (just a percent before torque value to compensate for people over-pulling).
The female mechanics always come back with a smile on their face after borrowing this vibrating wrench.
That's some good insider information. On that Techwrench, you gotta keep looking at it as you're pulling on the fastener don't you? It's like using a dial type isn't it?
IF you want to see the torque values as they progress, then yes, you need to see the screen. However, it also beeps AND VIBRATES when it reaches the set torque value (just a percent before torque value to compensate for people over-pulling).
The female mechanics always come back with a smile on their face after borrowing this vibrating wrench.
Originally Posted By: Vikas
Quote:
I'll post that later if anyone is interested but I hate typing on my Swype keyboard on Bitog. My browser doesn't seem compatible with the site!
Please do!!
I posted the results of the calculations here. I figure it's kinda more relevant and I don't want to hijack Merkava's thread more than I have.
Meanwhile, since the OP likes tools, I think he should rock this one here: http://www.checkline.com/product.php?id=125935&lang=en
Made in the USA! Go big or go home, as they say.
Quote:
I'll post that later if anyone is interested but I hate typing on my Swype keyboard on Bitog. My browser doesn't seem compatible with the site!
Please do!!
I posted the results of the calculations here. I figure it's kinda more relevant and I don't want to hijack Merkava's thread more than I have.
Meanwhile, since the OP likes tools, I think he should rock this one here: http://www.checkline.com/product.php?id=125935&lang=en
Made in the USA! Go big or go home, as they say.
Originally Posted By: SIXSPEED
Originally Posted By: cchase
Originally Posted By: SIXSPEED
Originally Posted By: cchase
I prefer the click type for convenience but I can't help but think they are less accurate, or easier to use less accurately anyway, than a good dial wrench.
Depends on the manufacturer. PI dials are spec'ed at 2% accuracy vs. 3% for their micrometer types, whereas CDI's are spec'ed at 4% same as their micrometer types.
Is that % of full scale?
Accuracy is percentage of set torque or indicated torque (dial).
Interesting to know. It's not common for accuracies quoted to be % of reading, most temperature and pressure indicators for example are specified as accurate to some % of full scale. For example, an indicator with a range of 0 to 1000 psi and 1% accuracy reading 10 psi, actual may be anywhere between 0 and 20 psi.
Originally Posted By: cchase
Originally Posted By: SIXSPEED
Originally Posted By: cchase
I prefer the click type for convenience but I can't help but think they are less accurate, or easier to use less accurately anyway, than a good dial wrench.
Depends on the manufacturer. PI dials are spec'ed at 2% accuracy vs. 3% for their micrometer types, whereas CDI's are spec'ed at 4% same as their micrometer types.
Is that % of full scale?
Accuracy is percentage of set torque or indicated torque (dial).
Interesting to know. It's not common for accuracies quoted to be % of reading, most temperature and pressure indicators for example are specified as accurate to some % of full scale. For example, an indicator with a range of 0 to 1000 psi and 1% accuracy reading 10 psi, actual may be anywhere between 0 and 20 psi.
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