Sand instead of grind?

[bashr52]

Instead of going nuts with a grinder on my boat to get ready to re-install the stringers, can I just sand it down to good glass? I have a big air belt sander and some 40 grit paper The stuff looks like rocks stuck on there. I could make quick work of prepping it all I would still need to grind/hand prep the smaller areas, but I'm hoping to use the big guns to take care of the majority of it.

 

[Yacht Dr.]

Re: Sand instead of grind?

Hello Bash..

The fastest most efficient way to grind is Allways the best

If it works good for you then go for it.

By the way.. when you say "big" belt sander.. just how big ?

Reason I ask is there was an old man in San Diego that made his own and Ive never seen another like it. I would pay 1000 bucks for it now.

YD.

 

[oops!]

Re: Sand instead of grind?

lol....we all want out of grinding...

while the belt sander will work on long straight sections of the stringer beds you will still need to get into the angles. as the width of the body of the tool will prevent this.

the grinder, with a rubber (not plastic) backing pad (somtimes called a flapper) and 24 grit discs. will allways make short work of the job and get into most tight spots.

i have 2 grinders a 4 inch and a 7 inch.

....during ruff and scuff, all you are doing is removing the wax and comtaminants off the very top skin of the factory fiberglass. prepping for the new glass to get a good bond.

it does not take long with the proper discs.
allso it is easy to get carried away and go too far.....
remember....rough and scuff....not grind.

please read the sticky for safety equipment at the top of this forum.

cheers
oops

 

[bashr52]

Re: Sand instead of grind?

Thanks, I'll have to pick up some of the sanding discs and a puck. Will that work well for removing the rest of the plywood that is stuck on it spots? I've scraped as much off as possible, but there is still a bit on there.

 

[Friscoboater]

Re: Sand instead of grind?

I tried using a belt sander and I went through about 50 dollars in belts and figured out that the grinder was best. Make sure you use 36 grit. Anything else will just polish the glass.

 

[clockwatcher]

Re: Sand instead of grind?

Thanks, I'll have to pick up some of the sanding discs and a puck. Will that work well for removing the rest of the plywood that is stuck on it spots? I've scraped as much off as possible, but there is still a bit on there.

It'll probably smoke and burn, but it'll come out. I used one of those vibrating cutting tools to cut the glass down close and in tight spots.

 

[redfury]

Re: Sand instead of grind?

Getting to the point where the glass is good is the goal, how you get there is up to you. Various ways have been tried and trued. Standard grinding wheel on a grinder, flap discs on a grinder, backing pad with stiff low grit sand paper. 4 to 7 inches, and a belt sander will work on those open expanses as long as you are using quality belts and a low enough grit. Nothing more than 40 or you are wasting your time if you are trying to level old glass remnants. The nice thing about the belt is that you could hook up the shop vac to collect some of the dust you are going to create, which is always a plus.

Everything is dependent on the quality of the tool and the quality of the abrasive as to how long it's going to hold up.

I used the diamond grit steel discs on my grinder to cut the excess tabbing of glass out of my boat, but I did zip through in a couple of places.

It's all about the care you take and the pre-planning you do to make sure it all goes smoothly.

 

[bashr52]

Re: Sand instead of grind?

Thanks guys. I went to Lowes yesterday and they only had 26 grit in my grinder size. That made quick work of prep and removal of all the stuck on stuff! I got the new transom cut and fitted, and the first coat of reisin on it. I screwed up though, and I guess I did not have enough hardener. I just made up a small test batch (about 1/2 an inch deep in the bottom of a small coffee can), and added about 10 drops of hardner to it. I guess it wasnt enough, or i brushed it on too thick, as of 11 last night it was still tacky. Do I have to strip it back off and start over?

 

[tdrudd87]

Re: Sand instead of grind?

What exactly did you do, brush a layer of resin onto the ply? If you are using a unwaxed resin (from UScomposites or a local 'glass shop, not cheapo lowes/auto parts place resin), then it will always cure with a tacky surface, and is ready for another layer.

If it is actually mushy, then you probably undercatalyzed. Get some paint cups so you know how much resin you are mixing, and add the proper ratio of MEKP.

If you are using general purpose waxed resin, the you MUST sand and reprep between layers. I have put my project off for weeks rather than use that stuff in the past.

HTH,
Terry