Need help with epoxy putty on ready-made cast aluminum product

[Tele_sg]

Hi guys I'm new here, found this forum by google.

I've bought this telescope mount recently and have seen fellow astronomy enthusiasts successfully reduce the vibration settle down duration by bolting on steel plates or jamming in a wooden block.
http://www.cloudynights.com/ubbthre...ge/0/view/collapsed/sb/5/o/all/fpart/all/vc/1

What I intend to do is to fill up the open gap in the cast aluminum entirely with knead-able epoxy putty to make it more robust.
I have calculated that the void would take about 105 cubic CM volume and the epoxy required would weigh 210 grams.

My preliminary test result from last night with the putty as follow
2minute 30 seconds , the putty start to mix well and gum together , a little heat is felt
3minute 30 seconds , the putty is near the end of working time
4minute+ , the putty start to get hard
1 hour 30minutes, the putty is really hard , I crushed the putty sphere with pliers and it only made surface bite marks.
Tried to mix another thumbnail size blob of epoxy to test it's grip on the putty sphere with original smooth surface, the result is inseparable by pulling with fingers for such small surface area, I'm quite satisfied.

Here's the questions...

The aluminum mount is powder-coated in white, do I need to sand it off with sandpaper before I epoxy it ? The epoxy does not carry any weight load so I hope this step can be avoided.

Do I need to install 2mm diameter reinforcement steel wire for the epoxy to cross the 48mm wide opening in the middle ? My concern is rust in the long term cracking the epoxy.

There is a remaining magnet which the superglue have not fail, how can I weaken the superglue ? with an ice cube ?

Thanks !

 

[Tony Wells]

I believe I would not use a kneadable epoxy in favor of a more fluid type, such as J-B Weld, and position the mount in such a way that the bottom of the cavity would be sealed and flat. Then mix as much as needed and pour it in. It does not set as quickly, and will settle smoothly. Devcon also makes a similar product. I am sure there are others as well.

 

[Tele_sg]

I believe I would not use a kneadable epoxy in favor of a more fluid type, such as J-B Weld, and position the mount in such a way that the bottom of the cavity would be sealed and flat. Then mix as much as needed and pour it in. It does not set as quickly, and will settle smoothly. Devcon also makes a similar product. I am sure there are others as well.

Thanks for replying.

I shipped the kneadable epoxy (10x 50grams) together with the mount from China,
there were other liquid slow curing epoxies to choose but there are shipping regulations against liquid on a plane so I went with the kneadable.

I also have some clear epoxy in small tube form bought from value store but it cracked when I tried to repair my scissors last year.
JB weld and Devcon are not available in my country region and similar products under different brand ain't cheap.
Since the kneadable epoxy is already bought , I just hope to put it to good use before the expiry sets in 2-3years.

 

[tertiaryjim]

I would just hang a rock below the tripod CG by a light rope.
It adds stability and dampens vibration.
In areas where rocks are few they carry a bag and fill it with dirt or sand.
Many photographers and star gazers do this and they don't have to carry the extra weight in the tripod.

 

[LJP]

I have used kneadeable before, it will work for you. Just make sure that you "wrap" the epoxy around something. In other words, if you enclose the part, then the epoxy will not fall away, becuase it has a "mechanical" bond, not just a "chemical" bond. Hope this makes sense.

 

[Tele_sg]

I tried to fill the obscured bottom void first to familiarize myself with the putty first as I expected it to turn out ugly with putty lines and fingerprints.
Waited 1hour 30minutes for it to hardern before I fill the adjacent area.

Will continue to fill the bigger 3x4 inch area tomorrow.

 

[Splat]

For vibration dampening how about trying something like expanding foam, like Great Stuff ? It won't give you the weight you want but you may be able to get that another way. I've used it for dampening on tubing for electronic drums and it worked beautifully.

 

[Tele_sg]

Did the mount arm today.
My fingers feels so wrecked after kneading the 9 ounces of epoxy and washing them off in repeated hourly cycles.
70% done


fixing the steel wire


almost covered


completed 1 side and flipped over

 

[GarageGuy]

Did the mount arm today.
My fingers feels so wrecked after kneading the 9 ounces of epoxy and washing them off in repeated hourly cycles.

Wear nitrile gloves. I like the thicker heavyweight ones. HF sells them for ~$7 a box. The epoxy is not affected, and your hands stay clean.

GG