Author Topic: Metal for Triple Clamps  (Read 5661 times)

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Offline wobblywalrus

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Metal for Triple Clamps
« on: March 16, 2009, 08:45:26 PM »
The Triumph needs new triple clamps and no one makes any with the needed offset and tube spacing.  No choice but to make some.  This requires 10 inches of 1" x 5" 6061 aluminum bar and another 10 inches of 1.5" x 5" bar.  Locating suitable metal in backwater areas like this is a real pain.  I almost gave up, but I was lucky and I found a source.  The local Fastenal shop ordered it and it will arrive in a few days.  They stock exactly what I need.  Amazing.  Their website address is fastenal.com and their "Blue Book catalog is full of things us fabricators use.  Hopefully this will help others working in out-of-the-way places.   

Offline Tzoom

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Re: Metal for Triple Clamps
« Reply #1 on: March 16, 2009, 09:04:32 PM »
I will go out on a limb here and say that you are one of the very few who has gotten good service from Fastenal.  I've been employed as a buyer for two companies in the last few years and in both cases I worked hard to get Fastenal off of our vendor's list.  My experience has been that they will get you what you want when they have it but if they don't they will take your order then after you call about the status of your order they will lie to you for a couple of weeks and tell you it will be in next week and then finally admit it's on a ship in the Pacific somewhere on its way from China.  I only do business with McMaster=Carr and Grainger.  If these people don't have it I didn't need it.  My rant for the day.  Carry on...... 
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Offline Stainless1

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Re: Metal for Triple Clamps
« Reply #2 on: March 16, 2009, 09:42:12 PM »
In Wichita we either drop by the Boeing (now Spirit) Surplus Store on a Friday, or we go to The Yard any day but Sunday.... 
Stainless
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Offline Rex Schimmer

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Re: Metal for Triple Clamps
« Reply #3 on: March 16, 2009, 10:11:43 PM »
Another great place for material of any alloy and size is Aircraft Spruce. They will not only have it is 6061 but 2024 and 7075 if you need it.
Look them up on the web.

Rex
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Offline Tzoom

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Re: Metal for Triple Clamps
« Reply #4 on: March 16, 2009, 11:18:22 PM »
In Wichita we either drop by the Boeing (now Spirit) Surplus Store on a Friday, or we go to The Yard any day but Sunday.... 

I've been to the Yard Store a few times.  You guys in Wichita got it made.  Especially if you need Al-you-minium, 
Auto racing, bull fighting, and mountain climbing are the only real sports ... all others are games --- Ernest Hemingway

Offline wobblywalrus

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Re: Metal for Triple Clamps
« Reply #5 on: March 23, 2009, 12:51:50 AM »
Thanks for the advice about McMaster-Carr and the other company, Grainger.  I wish I knew about these guys years ago.

Offline wobblywalrus

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Re: Metal for Triple Clamps
« Reply #6 on: March 23, 2009, 11:39:17 PM »
The 6061 aluminum billets arrived today.  My plan is to cut them into shape, to drill and tap all bolt holes, and to polish them.  I figured there would be some stress relief distortion during my work, so the very last step is to bring them to the machinist to get the fork tube and steering stem holes line bored.

"Anneal them", a co-worker told me.  He got vague about the reason why, the heat time, or the temperature.  Any advice about this is appreciated.  One billet is 1-inch thick and the other is 1.5 inches thick.

Offline Stainless1

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Re: Metal for Triple Clamps
« Reply #7 on: March 23, 2009, 11:53:13 PM »
What is the current temper of the 6061 plate you have... T6?  I don't think I would anneal them... They should be fine after machining
Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Offline Peter Jack

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Re: Metal for Triple Clamps
« Reply #8 on: March 24, 2009, 12:35:29 AM »
Don't heat treat them. You'll just make them soft. There aren't internal stresses in aluminum like there are in cold drawn steel. I'd assume it's T-6 and if so it'll machine up beautifully.

Pete

Offline 38Chevy454

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Re: Metal for Triple Clamps
« Reply #9 on: April 01, 2009, 04:16:17 PM »
I am a metallurgical engr, so here is a question just made for me  :cheers:

What temper is your 6061?   It should be labeled as 6061-T6xxx, where the xxx may or may not be present.  The -T6 could also be different number, but I am pretty sure you have -T6 as it is most common.

T6 is the heat treated for max strength version, so do not do anything to it or you will mess up the strength.  It *could* distort some as you machine your part out, there are some residual stresses in the material.  But the 1 inch thickness should keep distortion under control.  Being the peak strength, the chips will fall away nice and should machine well.  Polishing will help any potential stress risers, but is probably more for looks.

Use some anti-sieze in the threaded holes so you  can get it apart if you have to.

6061 is a weldable grade, but of course any welding will screw up the heat treat.
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Offline wobblywalrus

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Re: Metal for Triple Clamps
« Reply #10 on: April 06, 2009, 12:42:36 AM »
The bars are listed as "6061 Aluminum" in the Fastenal catalog.  One bar has writing on it saying "6061-T6511"

I use stainless bolts.  Normally I spray ACF-50 anti-corrosion spray on a bolt before I thread it in the hole, then I tighten it down to typical generic dry torques specs for a grade 3 bolt.  ACF-50 is similar in lubricating qualities to silicon spray.

This bothers me.  In machinist school 32 years ago they told us that oil or anti-sieze overcomes friction and it allows bolts to be overtightened and this will distort the part.  They said the torque specs listed in the manuals are for clean dry threads unless they state otherwise.

Any advice is appreciated.

Offline Stainless1

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Re: Metal for Triple Clamps
« Reply #11 on: April 06, 2009, 09:23:24 AM »
Over the years we have learned that if you want to take it apart again, a high quality anti-seize on any bolt you take to the salt is a good idea.  If you are concerned about over torquing, set the wrench under the standard dry setting....
Stainless
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Offline 38Chevy454

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Re: Metal for Triple Clamps
« Reply #12 on: April 06, 2009, 12:43:00 PM »
The bars are listed as "6061 Aluminum" in the Fastenal catalog.  One bar has writing on it saying "6061-T6511"

You have 6061 (alloy), T6 temper (peak strength), 511 (which is stress relieved by stretching the plate).  This should work good for you.  It is not stress free, but it is more stable than if it did not have the stress relief.  Basically by stretching a couple percent, you align all the residual stresses so you minimze distortion.

I would use a heavier anti-sieze than the light oil you are using.  Mostly so it is effective against corrosion.  Torquing should just stretch the bolt, not cause much distortion of the part.  Unless you actually pull threads out of the aluminum.  By design, bolts are stretched when properly loaded.  The trick is to stretch the right amount.  Hence the rod bolt micrometers used as an example of a very critical fastener.  Torque is always a very rough indicator of stretch.  But it is the easiest and fiarly repeatable method.  But lubricants, coatings, metal finish, galling, and other factors all contribute to torque vs stretch.  I do not know the proper torque setting to use vs your dry, but I think you could go with a lower grade bolt torque, such as grade 5 dry torque for a grade 8 with lube.

If you really want better results, a threaded insert in the aluminum is better than direct threads in the aluminum.  The big problem you have is that the aluminum will corrode in the threaded hole and that is what make disassembly difficult.  That is why I said use anti-sieze.  I do not recommend oil.
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Offline Rex Schimmer

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Re: Metal for Triple Clamps
« Reply #13 on: April 06, 2009, 06:34:36 PM »
If you are going to thread your aluminum use only coarse threads and I agree with all of the other posters that you MUST use antiseize especially if you are using stainless bolts. Really be careful with stainless bolts as many are nothing but 303 or 304 stainless, which is good for crossion but are very weak.

Regarding lubing bolts for torquing, the most important place is between the bolt head and the hardened washer that you are using between the bolt head and the aluminum (you are using hardened washers aren't you?) I watched an experiment where rod bolts were being torqued using a micrometer to measure the amount that the bolt stretched, which of course is the real measure of the bolt clamping force. We torqued one bolt to the specified stretch and checked the torque setting, we then repeated using a completely dry bolt and dry threads and the amount of torque required to get the correct amount of stretch was approx 15-20% higher. We then did the test again with only adding oil below the head of the bolt and the torque required was ony about 5% more, lubricating the threads only improved by about 1%. I think that the reason for this is that the area of the threads is greater than the bearing area of the bolt head therefore the pressure is less than the pressure between the bolt head and the material that it is bearing on. On a 1/2-13 bolt with 1.5 D thread engagement the area under the head is approx 1/4 of the area of the threads therefore the pressure is also approx 1/4 of the pressure below the head. So lubing under the bolt head is the most important.

Also use high grade fastners with rolled threads and use roll taps to tap your holes this ensures the very best thread fit between the bolt and the threads.

Rex
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