Need help with polishing motor / angle grinder

[Elby]

I've been trying to do a large scale polishing job and need a little help. By the way, I'm a total newb at this. I'm attempting to polish the surface of one of those OLD OLD C-band satellite dishes. It's probably 10 feet across. I was lucky enough to come across one made of stainless steel (probably 304??).

I started with some 8" wheels on a 7.5" Central Machinery angle grinder from Harbor Freight. I didn't want to drop a load on a grinder if it wasn't gonna work. First grinder quit working within 10-30 seconds. Not good. I got it replaced and the grinder seemed to work fine, but kept popping the breaker when I put a load on it. After a lot of very aggravating trouble shooting, I fixed that problem with a shorter, heavier gauge extension cord, and a rewired, dedicated 30 amp outlet. Success!!!, I was just starting to get a good shine on in a small area, when the angle grinder burnt out both brushes and quit working. I replaced the brushes and gave the grinder to a friend. Kinda tells you something when a new grinder comes with replacement brushes, huh?

Anyway.

What now I need a motor that can handle the heavy polishing load without melting down in my hands. Would a name brand, (dewalt or milwaukee) grinder hold up to the strain, or would I be wasting more money? Should I be looking at some other type of motor? I could really use some guidance here!

[woodjames]

HF is like that, either the tools work anywhere from 5 minutes to a week, or you can run over them and drop them all the time, and a year later they still handle whatever you throw at them. I gave up on them, as the majority of my experience was the further.

If you've got a decent shine started, you can go with a dewalt vs buffer. I've got one for paint work, and discovered that the same auto compound can be used on metal with terrific results. I only use 3M brand paint buffing compounds, you'd have to experiment with other brands. However they don't cut real well, mainly for a final finish. The dewalt will cost you, but you can't beat the quality. Most auto shops swear by them. Once and a while you'll see them on ebay used. I used cotton pads with a velcro backing. But I've ran it for quite a while with no heat buildup.

-Jimmy.

Originally Posted by Elby

I've been trying to do a large scale polishing job and need a little help. By the way, I'm a total newb at this. I'm attempting to polish the surface of one of those OLD OLD C-band satellite dishes. It's probably 10 feet across. I was lucky enough to come across one made of stainless steel (probably 304??).

I started with some 8" wheels on a 7.5" Central Machinery angle grinder from Harbor Freight. I didn't want to drop a load on a grinder if it wasn't gonna work. First grinder quit working within 10-30 seconds. Not good. I got it replaced and the grinder seemed to work fine, but kept popping the breaker when I put a load on it. After a lot of very aggravating trouble shooting, I fixed that problem with a shorter, heavier gauge extension cord, and a rewired, dedicated 30 amp outlet. Success!!!, I was just starting to get a good shine on in a small area, when the angle grinder burnt out both brushes and quit working. I replaced the brushes and gave the grinder to a friend. Kinda tells you something when a new grinder comes with replacement brushes, huh?

Anyway.

What now I need a motor that can handle the heavy polishing load without melting down in my hands. Would a name brand, (dewalt or milwaukee) grinder hold up to the strain, or would I be wasting more money? Should I be looking at some other type of motor? I could really use some guidance here!

[samtgallagher]

i was hesitant to order one of those motors and the shaft cause of the cost... but i've used it heavily for going on 2 years now and have never had the first burp from it.

not sure if that would be feasible for your application, but it's worked great for me. (since i cannot run a compressor system to power tools here)

[Elby]

The shiny spot I have isn't really that good, and it's only a little bigger than my hand. I have some real work ahead of me still.

What about using a dewalt single speed grinder? The 7" is rated for 8000 rpm. The variable speed would be nice, but that's alot of extra cash if it's not absolutely necessary. Especially as I only intend to do this the one time. I just started getting a polish out of it when I began applying pressure to the cut. I'm kinda worried that ANY motor I put to that kind of an extended load is gonna live short and fast, and I've got a large area to cover, which means spending a long time at heavy load on the motor before I'm done.

Forgot to mention earlier, I tried several compounds/wheels, but ended up with a sisal wheel and black compound.

[woodjames]

Spot? Ohh, sorry misunderstood. I thought that you have a shine started on the entire piece. Hmm... considering your intentions, I'd look into renting one. Should be able to get a good quality large angle grinder, and outfit it with a buffing wheel. You may want to look into 400 grit greasless to start also, it'll cut much faster, and cleans up good with emery.

-Jimmy.

Originally Posted by Elby

The shiny spot I have isn't really that good, and it's only a little bigger than my hand. I have some real work ahead of me still.

What about using a dewalt single speed grinder? The 7" is rated for 8000 rpm. The variable speed would be nice, but that's alot of extra cash if it's not absolutely necessary. Especially as I only intend to do this the one time. I just started getting a polish out of it when I began applying pressure to the cut. I'm kinda worried that ANY motor I put to that kind of an extended load is gonna live short and fast, and I've got a large area to cover, which means spending a long time at heavy load on the motor before I'm done.

Forgot to mention earlier, I tried several compounds/wheels, but ended up with a sisal wheel and black compound.

[Elby]

That sir, is gold plated genius. Seriously.

I can rent one for the weekend and I think you can get no-fault renter's insurance for a couple extra bucks. That way if it does go out, it's taken care of without hassle or drama.

Thank you very much!

[baz]

Originally Posted by Elby

The shiny spot I have isn't really that good, and it's only a little bigger than my hand. I have some real work ahead of me still.

What about using a dewalt single speed grinder? The 7" is rated for 8000 rpm. The variable speed would be nice, but that's alot of extra cash if it's not absolutely necessary. Especially as I only intend to do this the one time. I just started getting a polish out of it when I began applying pressure to the cut. I'm kinda worried that ANY motor I put to that kind of an extended load is gonna live short and fast, and I've got a large area to cover, which means spending a long time at heavy load on the motor before I'm done.

Forgot to mention earlier, I tried several compounds/wheels, but ended up with a sisal wheel and black compound.

in my opinion 8000 rpm is way too much , get a better quality tool with variable speed it s better and safer.
what size wheel are you using ?
10 feet across is quite a large project for a newbie , but i guess by the time you get that job completed you ll be an experienced buffer

[Elby]

Originally Posted by baz

but i guess by the time you get that job completed you ll be an experienced buffer

And tired too...

I'm using 8" wheels. I justed checked with the local tool rental place. They have a 7" grinder (I didn't ask about the brand) for 15.00 per day with a 5% extra insurance policy for minor damages.

If I rent after 3:00 on Saturday, I can keep it all weekend. Looks like I have a plan!

[Elby]

All right! I'm starting to see some success!

I rented a 7" miluakee angle grinder and it performed flawlessly, but......
I didn't have time to get the reccommended greasless polish. The black compound w/ sisal wheel showed some decent polish but was leaving the surface with an orange-peel look. It took a little time an pressure, so I didn't get far with it, but progress is progress. I'm presently assuming I need something more aggressive to work out the orange peel. I have just placed an order for some 400 grit greasless + a new sisal wheel + some of the Glu-tite. (also some black and green regular).

Is there anything I need to know before I get rolling with this? No one I know is familiar with the greasless, also how and how much of the glu-tite to use?

Thanks.

[woodjames]

You can use the greasless without the glu-tite, but it's messy and you will lose a lot of it in the air, on the ground, on any cars in the area, and on you, and pretty much anything within a 5' radius. Don't stand in a direct line behind it when you apply it to the moving wheel - you'll really get covered. You'll go through more wheels too when using it.

I haven't used the glu-tite, so can't make any recommendations there as far as how much to use, be sure to post what you find, as I'd like to find a better way to work with greasless.

The orange peel could be a number of things. The black compound won't quite cut the stainless enough to completely level things out, it may be in the metal to begin with, and with a higher level of gloss comes an exponential level of highlighting defects. The greasless will cut across the tops of the high spots at first, so it'll level things much better for you. Overall try pushing harder, should help a lot. You're going to look like Lou Ferrigno when you're done! That and stiffer wheels will help, but are much harder to get into recesses without distorting everything.

-Jimmy.

Originally Posted by Elby

All right! I'm starting to see some success!

I rented a 7" miluakee angle grinder and it performed flawlessly, but......
I didn't have time to get the reccommended greasless polish. The black compound w/ sisal wheel showed some decent polish but was leaving the surface with an orange-peel look. It took a little time an pressure, so I didn't get far with it, but progress is progress. I'm presently assuming I need something more aggressive to work out the orange peel. I have just placed an order for some 400 grit greasless + a new sisal wheel + some of the Glu-tite. (also some black and green regular).

Is there anything I need to know before I get rolling with this? No one I know is familiar with the greasless, also how and how much of the glu-tite to use?

Thanks.