Repairing 12' fiberglass dish

[Forvak]

Hello folks,

First time dish user here and I've gotten my self into the deep end. A friend took me out for dinner in exchange for me taking this 12' dish off his hands. The central mounting pipe is 7.5 inches across!

Unfortunately he took it down without any help so it took a little beating.

Most of the dings are like the first two pictures, but the third photo has the worst of the damage. Fortunately it's basically all on the edges of the petals so I think the reflecting mesh/foil should be safe enough. Most of the mounting holes are intact so I think I probably could bolt it together as is, but I think I can/should make an attempt at fixing it up.

My thought at the moment is to give them all a good wash down, particularly cleaning the areas around the damage. Then cut 1/8 or 1/4 inch sheet metal into splints for the damaged section and epoxy them firmly over the tears. Then drill holes through the metal after everything is cured and finally paint everything with some outdoor spray paint.

Thoughts? Comments? I'd love some feedback and advice.

Thanks!

 

[N6BY]

Hello. Welcome to the site!

Thats great that you got the dish AND dinner. I had to pay $25 for my 8.5' C Band dish, but it was well worth it.

If the mounting holes are intact, I would be tempted to bolt it together right away and check to see if it is warped using the "intersecting strings" method.

Anyway, you have definitely found the right place to get advice.

I'm in Roseville, how far away are you?

 

[armadillo_115]

Repair fiberglass with fiberglass mesh and resin.Done correctly it will be as strong as new..maybe even stronger if you use more layers.

It takes a lot of grinding around the areas needing repair to get a strong bond.you don't just repair the hole in other words.That's a lot of work and expense for an old FG dish,IMHO. But do-able.

Good luck!

 

[beavs2112]

welcome to the site I think that's a General Dynamics Satcom (ex Prodelin) antenna. A 12 foot GDS antenna with polar mount is worth repairing in my opinion. I think the other guys are right. I would do it with layers of fiberglass matting and resin not metal.

 

[. Raine]

Welcome to SatGuys!

I too, would repair it with fiberglass mat and resin. Use a board lightly coated with oil as a form for the fiberglass [so it can be removed easily later] clamped to the outer edge so you can get it nice and straight. Maybe thick cardboard, if the edge curves too much for a board to fit alongside of it easily. I've used heavy tape a few times and have had it work good. Grind away any flaky weak deteriorated/dirty pieces and paint around the breaks and make sure it's real clean, it should come out stronger than new.

Wear a mask when you do it! Fiberglass dust from grinding is nasty stuff to breathe in.

 

[armadillo_115]

Wear a mask when you do it! Fiberglass dust from grinding is nasty stuff to breathe in.

For sure.Back when I was doing fiberglass repair, I was told that any fiberglass dust that reaches your lungs will never come out.It is supposedly too heavy to cough up.And it keeps cutting like...well glass.lol.

A few tips: Wear coveralls.The dust will get around your pants waistline and put a red ring all the way around your waist if you do much grinding.Long-sleeved overalls are even better because the bottom of short-sleeves can cut a ring as well.I never did find a way to prevent to dust from entering at my neckline though.
Safety glasses! Fiberglass in your eyes is rough.A face shield is even better.
Be careful blowing off the dust with an air hose...if you have to use one.
Shower when you finish,don't take a tub bath.Rinse with water as COLD as you can stand WITHOUT rubbing.Cold water closes the pores and washes much of it off.Then use warmer water to wash.Try not to rub much with the soap and PAT dry with the towel rather than scrubbing.

Not trying to scare you,just hope to make it a more enjoyable experience.What you have is not that large a job anyway and you can keep above the work area..I sometimes had to lay underneath a fiberglass boat or down low on a Corvette and grind most of the day.Would come home with 'glass in my drawers,socks,ears..you name it.lol

 

[. Raine]

For sure.Back when I was doing fiberglass repair, I was told that any fiberglass dust that reaches your lungs will never come out.It is supposedly too heavy to cough up.And it keeps cutting like...well glass.lol.

A few tips: Wear coveralls.The dust will get around your pants waistline and put a red ring all the way around your waist if you do much grinding.Long-sleeved overalls are even better because the bottom of short-sleeves can cut a ring as well.I never did find a way to prevent to dust from entering at my neckline though.
Safety glasses! Fiberglass in your eyes is rough.A face shield is even better.
Be careful blowing off the dust with an air hose...if you have to use one.
Shower when you finish,don't take a tub bath.Rinse with water as COLD as you can stand WITHOUT rubbing.Cold water closes the pores and washes much of it off.Then use warmer water to wash.Try not to rub much with the soap and PAT dry with the towel rather than scrubbing.

Not trying to scare you,just hope to make it a more enjoyable experience.What you have is not that large a job anyway and you can keep above the work area..I sometimes had to lay underneath a fiberglass boat or down low on a Corvette and grind most of the day.Would come home with 'glass in my drawers,socks,ears..you name it.lol

Coveralls and all of the above is excellent advice! I've done some fiberglass jobs where I've thought to myself, small job, gloves and mask will be fine. Yeah, no! Itching and scratching for days afterward!

 

[Forvak]

Hi folks,

Thanks for the welcome!

Yes, I can agree that using resin and fiberglass matting is the right way of doing the repair. I have a fear of making the situation worse though, such as fouling up the edges and having them not mate well. It seem that the first step in the repair after all is to turn a one inch hole into a 7 inch hole! I have never worked with fiberglass before and while it all looks possible, it does look time consuming for this many locations.

Does anyone have good resources for learning about fiberglass repair or recommendations on choosing the resin and matting for the repair?​

I have a full face respirator and will definitely use that, along with full body covering and a good set of gloves for the sanding. I don't have a grinder, but I have a feeling I'll have to borrow one for a day and do the sanding that way or I'd go crazy.

After I get the structural repairs done (one way or another) I'll need/want to paint the dish and do anything else that's "best practices" for a 20 year old dish before putting it up for another 10+. I know to avoid glossy paints, but any other advice?

What care and maintenance should I do to the dish after repairs? Matte off-white outdoor paint over the entire dish after a good wash is my current plan.​

N6BY, I'm just an hour or so away from you over on the border of Sonoma county. Ever done fiberglass repair?

Thanks!

 

[N6BY]

...
N6BY, I'm just an hour or so away from you over on the border of Sonoma county. Ever done fiberglass repair?
...

Never repaired fiberglass. But I am pretty good at aligning a motorized dish to the Clarke Belt if you ever need help with that.

 

[Forvak]

Never repaired fiberglass. But I am pretty good at aligning a motorized dish to the Clarke Belt if you ever need help with that.

Thanks! I have a bunch of work to do before then, but I'll be sure to reach out if I get stuck with my alignment. Maybe I'll catch you on HF or Amateur Satcom? AG6PO

 

[armadillo_115]

It seem that the first step in the repair after all is to turn a one inch hole into a 7 inch hole!

No that would make it VERY hard to repair.Grind the fiberglass good on the BACK side and lay the glass matting.The objective is to get a good bond for the matting.Try to keep the damaged pieces in place during the glass laying.That helps keep your edges straight and true.Any small holes can be backed with tape.You want the matting to lay flat...not dipped into the holes and cracks.Three layers or more on the back is what gives it the strength,not the 'original' edge. Make sure the matting is completely wet with no air pockets.Fiberglass resin has no strength by itself, It's the mesh/matting that gives it strength.

Once your matting hardens, (Usually 12 hours or more) Then you take some type of grinder to knock out the bad spots in the front/original fiberglass.Groove all cracks really well.Only remove the old fiberglass that has shredded fibers.A dremel type grinder bit works well.Then you can chop up a little matting with a razor blade and mix it with resin to fill up the holes.Do not fill holes with resin alone. (On a really bad project, it may be necessary to remove so much that you need to add fiberglass matting to the front side as well.) Grind/sand the front sides to shape.You can smooth small blemishes with body filler if desired.

Paint/primer will not adhere to the fiberglass unless it is roughed up some with a grinder or sander.The surface is too slick.

Note: Sometimes I use the term 'mesh'. Just read that as 'matting'. Technically there is a difference, mesh is more porous. You will be using matting.
Also,when I speak of resin...that ALWAYS includes the hardener.Don't want to confuse ya.It will never set-up without the hardener.

< I don't say much...it just takes me a long time to say it.lol >

 

[danristheman]

I would talk to an auto body man that works at a collision center to get his advice on what to do that's just my two cents. I talk to an auto body man about my 1.2 meter dish said it would be 300 bucks since it was multi layer fiberglass I don't have a workshop so no go for me.