Need Help Sand Blasting ?

[Keith Poe]

Hello guys i started grinding yesterday sucks but not one itch yippie.


I used a small air pump for an aquarium to pump air conditioned air in to my dive mask to reduce the fogging worked pretty good but i need a little more flow.


I was only able to stand about an hour and fifteen minutes to hot.


I have a small shop vacuum I'm going to use to cool my suit by putting the inlet inside in the AC and the the out put side 35' hose in the leg of my suit it's 1-1/4" and then a flexible 1/2" hose up the inside of the suit to my dive mask to reduce fogging.


I thing the sand parer is 36 grit and does not cut as fast as i would like i think there is a roughfer grit what should i use ? to cut the meat away get it down fast ?



I have a concrete diamond tip grinder tip of stick to the heavy grit grinder ?


After i get it down to the hull i would like to clean it up every where between all the grinding and am thinking about renting a ingersoll rand air compressor and sand blaster to hammer it and get it done with a lot of wrapping the motors.


I did this with silica sand on the 24' skip jack on the gel coat and it worked out great so fast i fell in love.


I think standard sand would work good inside the hull ?


Here's a picture of the skip jack i sand blasted the out side gel coat before spraying imron air craft paint on.

[Buju]

Damn Keith...
I can honestly say I've never heard of anyone dreading, or over-thinking their grinding to the level that you are presently at.
It's just grinding... Here's my grinding line up- seriously.


The itch goes away quickly.
By the time your done covering yourself up like a radiation leak technician, then rigging up cool air feeds and whatnot to compensate for the added heat from covering, and to remove condensation in your tempered mask... you could be a lot further along in the progress. And watch those extra hoses / air lines around the grinder wheel....
K.I.S.S... get it done
$0.02

36 grit is the most aggresive grit readily available... 36 takes off a lot of substrate at a pretty rapid pace.

[CaptPatrick]

ROFLMAO!

Bingo, Mark!

Now Keith, add one tool to your arsenal and most of what you have pictured above can go back up on the shelf... Just put this behind you and grind comfortably in shorts, and if necessary, a T-shirt.



As to sandblasting, don't use anything other than crushed walnut shell or baking soda. Sand and other hard media will fracture the surface and fibers of your fiberglass. Not a good thing.

24 grit in 4 1/2" discs is available. 36 grit is as far as it goes for 7" disc. If the 36 grit isn't getting the job done then you are probably:
a. Not using enough pressure or b. Trying to sand with a clogged disc. or c. a+b

Bottom paint is notorious for clogging a disc. Pressure blasting with either crushed walnut or soda will remove the bottom paint with no harm to the gelcoat or fiberglass. Compressed air is good for blowing out the plugged paper as long as you do it frequently. Once you have the paper really tightly plugged, even compressed air isn't very useful.

Enjoy your grinding, it's a right of passage...



Br,

Patrick

[Keith Poe]

Last 31-B i grinded inside i had a barrel full of fibers when i was done after doing it all day and i was itching for a week sleeping did not come easy so if there is any way i can prevent that with the suit and AC and shop vac i already have I'm doing it.

I picked up some 16 grit today going to murder it.

School me here how is using the grinder with sand any different than using air sand seems like they would both fracture it ?

Moderating the pressure would seem important just enough to do the job, i did not notice any fracturing of the gel coat or ply glass decks on the 24'.


Thank for any help.




Here is a picture of the first 31-B i grinded for this remodel.

[Harry Babb]

The proper attire for grinding fiberglass is featured in the pic below.......

If you are approached by a fashion expert and informed that the Tyvek suit makes your ass look fat an acceptable answer is "Bite My Ass".

The trick is DON'T THINK ABOUT GRINDING......think about riding the high seas




Now.....look closely at the pic......do you see leaves on the PEE CAN trees in the backgound......nope you don't......that means that its winter in the sunny south......which makes Grinding Attire much more pleasant.......it was blistering cold the day this pic was made.....I think it was in the high 50's.....LOL

Mr Higgins introduced me to blasting with walnut shells and corn cobs........... using this technique I completely removed all of the bottom paint from the bottom of DeNada in about 3 hours.

hb

[Buju]

School me here how is using the grinder with sand any different than using air sand seems like they would both fracture it ?

I'd think the difference is in that:

when blasting- the particulate abrasive is being shot at the substrate at a high velocity, causing impact abrasion

when grinding- the particulate abrasive is being held against the substrate at varying rates of downward force- but the abrasion is occuring uniformly, from left to right in a circular (grinder) or random circular (DA or RO) motion, with no impact.

[CaptPatrick]

School me here how is using the grinder with sand any different than using air sand seems like they would both fracture it ?

Sanding with a grinder is a rotational force, under hand pressure, that runs parallel with the surface being reduced. Blasting is a point blank bombardment of material under high pressure against a surface at, or around, a 90º angle. BIG difference in applied forces...

Mark was quicker on the draw with an answer, and the two pretty much say the same.

Br,

Patrick

[CamB25]

Are you guys really using 4 1/2" angle grinders with 36 grit flappers to remove gelcoat and prep glass? My Dewalt grinder is so agressive it will destroy the boat in a heartbeat, leaving nothing but craters that have to be filled and faired. I put it back in the workbench...too risky. I am using a cheap 7" harbor freight grinder with 80 grit disks for big areas, and my Festool RO125 with 40 and 80 grit papers for tighter spots. Slower, but leaves a nice finish. Some results:


As for the itch, I must be immune. I wear a set of coveralls, a hat, and respirator. No itch, but there is no way to conquer the heat, Keith. Sweat lodge, man...gotta learn to enjoy it!!

If I had to grind an entire B31, I would seriously investigate blasting. Even if you limited yourself to soda and walnut shells, it would give you a head start. Good Luck!

[Buju]

Keith, what is the extent of the grinding you're doing?
You're not taking off all the exterior gel/paint are you?
Just doing interior removal & prep for glasswork at this stage right?

Cam, she's really coming along. Looking forward to see her, post splash.

[Keith Poe]

Yes just the inside grinding all the areas sticking up from sawzalling everything out.

I'm using the 7" grinder and a 4" grinder 36 grit and will try the 16 grit using my 235 pounds against it.


Think i will try low pressure with blasting and increase it till it starts to remove the built up crap hazed over the glass every where with the hose on an angle so i do not have to try and sand every little nook and cranny by grinder removing so much material just clan it up for glassing in all the new stringers and removing all the glue and crap on the sides that are going to be exposed above the deck.



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[Keith Poe]

The proper attire for grinding fiberglass is featured in the pic below.......

If you are approached by a fashion expert and informed that the Tyvek suit makes your ass look fat an acceptable answer is "Bite My Ass".

The trick is DON'T THINK ABOUT GRINDING......think about riding the high seas




Now.....look closely at the pic......do you see leaves on the PEE CAN trees in the backgound......nope you don't......that means that its winter in the sunny south......which makes Grinding Attire much more pleasant.......it was blistering cold the day this pic was made.....I think it was in the high 50's.....LOL

Mr Higgins introduced me to blasting with walnut shells and corn cobs........... using this technique I completely removed all of the bottom paint from the bottom of DeNada in about 3 hours.

hb

I hear you Harry and wish i could avoid grinding in summer but i can't wish i could.



Last time i grinded a 31-B it was about 90-F outside the hull and there was two of us going at it with large grinders all day none stop.


Think i had glass embed deep in every place possible.


Oh don't tell my wife butt your butt doesent look to big

[Carl]

Shouldn't be pushing on the grinder...use light pressure and let the abrasive do the work.
Pushing just clogs the wheel which requires more push and faster clogging.
Once wheel is clogged, change it...you do go thru a bunch till you get past the sticky clogging stuff but you get done quicker.

Blasting...aside from abrasive media that needs to be dealt with later...Dry Ice Blasting is gaining momentum around here...especially on restorations.

[CaptPatrick]

Carl,

Dry ice blasting is the cat's ass, aside from the very specialized equipment needed... Talk about no fuss, no muss, no mess!

[CaptPatrick]

Another interesting technique is proprietary & called "Dustless Blasting" (website)

Dustless Blasting video

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[Kevin]

I just called Big Green Men Dry Ice blasting in S. Florida. They gave me a quote of around 2300 for my boat. Seems like it would be money well spent. My days of grinding bottom paint are over.

[Carl]

Carl,

Dry ice blasting is the cat's ass, aside from the very specialized equipment needed... Talk about no fuss, no muss, no mess!

Yes and no...

Yes you don't have the media to clean up...but you still have the crap you blasted off to deal with, at least in some cases.

[Stephan]

I've had good luck with an infrared system too. http://www.silentpaintremover.com/spr/index.htm

Watch for flash if you are working on light color, glossy surfaces but no need to get all dressed up and the clean up is just broom and shop-vac. Using a third-arm to hold the box while you scrape the adjacent are makes the job go reasonably quickly. Like the other methods it will do damage if you try hard enough..

[Raybo Marine NY]

3M does sell air cooled suits such as the versaflo, but its tough to beat the large fan behind you like Pat pictured.
That inferred scraper is pretty cool- will look into that

[Keith Poe]

I have a 3' fan and 5' fan that i can use but won't they fan glass all around me inside the hull in circles ?

[Carl]

Exhaust...have it pull out the dust.