[roc-chat] Re: Using Aluminum Hardware: Lighter but strong enough?
- From: Richard Dierking <richard.dierking@xxxxxxxxx>
- To: roc-chat@xxxxxxxxxxxxx
- Date: Mon, 20 Aug 2012 09:05:21 -0700
Thank you - An excellent tip about the chamfer. It was very difficult to
start the thread on the first rods. I'm using a cutting oil that says it's
for aluminum.
Richard
On Mon, Aug 20, 2012 at 8:24 AM, Jim - TFJ <jim@xxxxxxxxxxxxxxx> wrote:
> **
> Try setting them on a screw.
> That should put them pretty close to where you want them in the need.
>
> ah, 3/16 right?
> That's the nominal OD for 10-24.
>
> Also, be sure to chamfer the end of the rod before trying to thread.
> That helps a lot!
>
>
> ------------------------------
> *From:* roc-chat-bounce@xxxxxxxxxxxxx [mailto:
> roc-chat-bounce@xxxxxxxxxxxxx] *On Behalf Of *Richard Dierking
> *Sent:* Sunday, August 19, 2012 11:22 PM
> *To:* roc-chat@xxxxxxxxxxxxx
> *Subject:* [roc-chat] Re: Using Aluminum Hardware: Lighter but strong
> enough?
>
> Sorry, yes, adjustable *die*. Always get those mixed up. It's a 13/16"
> diameter rod die with three adjustment screws for the diameter. Really
> looking forward to receiving it tomorrow and doing some testing.
>
> Again, sorry for referring to the wrong tool.
>
> Richard
>
> On Sun, Aug 19, 2012 at 9:58 PM, jim <jim@xxxxxxxxxxxxxxx> wrote:
>
>> ******
>>
>> Adjustable tap? or do you mean an adjustable threading die (taps make
>> internal threads, dies make external ones.)****
>>
>> ****
>>
>> Unless there’s something I haven’t understood yet, I haven’t bought a
>> threading die yet that didn’t need to be opened up wider to****
>>
>> make the correct pitch diameter on a stud.****
>>
>> ****
>>
>> ****
>>
>> Jim G****
>>
>> ****
>> ------------------------------
>>
>> *From:* roc-chat-bounce@xxxxxxxxxxxxx [mailto:
>> roc-chat-bounce@xxxxxxxxxxxxx] *On Behalf Of *Kurt Gugisberg
>> *Sent:* Saturday, August 18, 2012 3:07 PM
>> *To:* **roc-chat@xxxxxxxxxxxxx**
>> *Subject:* [roc-chat] Re: Using Aluminum Hardware: Lighter but strong
>> enough?****
>>
>> ****
>>
>> Hey Richard. Great work on the testing. It confirms my thoughts on fin
>> attachment. I am interested in seeing how nylon nuts hold up under high
>> shock loads. After pulling steel eye bolts straight and seeing fender
>> washers pulled through 1/2 plywood bulkheads, I have my doubts about
>> aluminum and nylon holding up.
>>
>> Also, what is an *adjustable* 10/24 tap?
>>
>> Kurt****
>>
>> -----Original Message-----
>> From: Richard Dierking
>> **Sent: Aug 18, 2012 10:20 AM
>> To: **roc-chat@xxxxxxxxxxxxx**
>> Subject: [roc-chat] Using Aluminum Hardware: Lighter but strong enough? *
>> ***
>>
>> Since I've had the opportunity to go through some of my old projects
>> lately (cleaning out the garage), I've been taking some rocket airframes
>> apart including some destructive testing. It's interesting to see what
>> holds and where weakness occurs. For example, for through the wall fins,
>> the surface fillet doesn't seem to do much. The most important thing is
>> that the fin slot is tight. So the lesson here is to create tight slots
>> and don't expect for epoxy to fill the gap and hold strong. ****
>>
>> ****
>>
>> For attaching the fin, creating many small slots (1/8" deep) in the root
>> edge for attachment to the motor mount works well and doesn't require much
>> epoxy. ****Bryan**** showed me how to do this. If the surface is
>> roughed-up with 80 grit sand paper a fillet doesn't seem to be required.
>> The failure I'm seeing is the motor mount tube material. The surface of
>> paper tubes peels and phenolic fractures and peels. And, as expected,
>> fiberglassing the root to the motor mount tube works best, and it doesn't
>> require much resin. In fact, the lay-up can be pretty dry and it seems to
>> do fine. The extra amount of resin I commonly use for a good finish is not
>> necessary. I guess drilling small holes in the motor mount tube where the
>> fins are attached might help hold the epoxy bond between the fin and the
>> tube. I haven't tried this yet.****
>>
>> ****
>>
>> *Another thing I've been experimenting with is the altimeter bay. This
>> is the important part of this message, and sorry it took so long to get
>> around to it.* Recently, I've done a few deployment tests using 3/16"
>> aluminum rods that are tapped to 10-24 tread and nylon hardware (nuts
>> and wing nuts) to hold the bay together. Also, I reduced the size of the U
>> bolts significantly. I replaced the 1/4"-20 U bolts (1" wide) with U bolts
>> from Home Depot that are in packs for cable clamps (5/8" wide). Even
>> though the cable clamps say they are 1/4" size, the nuts are actually 6 mm
>> metric. Just to give an idea of the weight savings; Replacing the steel
>> hardware and reducing the size of the U-bolts on a 4" diameter altimeter
>> bay reduced the weight from 495 grams to 325 grams (34% less). Also,
>> instead of using metal fender washers, I've been fiberglassing both sides
>> of the bulkheads, and switched from 1/4" thick plywood to 1/8" thick. So,
>> no more fender washers. I'm wondering if I could make aluminum U-bolts
>> without causing too much stress on the aluminum rod during the bend? ***
>> *
>>
>> ****
>>
>> The deployment tests have gone so well, that I just ordered some 3/16"
>> high-strength aluminum (alloy 7075) rod, aluminum nuts, and other
>> light-weight hardware from McMaster-Carr. I also ordered an adjustable
>> 10-24 tap. I would appreciate any advice on threading this new aluminum
>> rod.****
>>
>> ****
>>
>> So, do you think this will hold? Are there problems with using aluminum
>> hardware I need to consider. ****
>>
>> ****
>>
>> If you're interested in using light-weight materials and techniques for
>> your project, I would like to discuss at the September launch. I'm
>> planning on launching a two-stage rocket with the 'new' hardware.****
>>
>> ****
>>
>> Richard****
>> **
>> -- ROC-Chat mailing list roc-chat@xxxxxxxxxxxxx
>> //www.freelists.org/list/roc-chat
>
>
>
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