jim2527

Any advantages or disadvantages t o either?

Will be used with right angle pneumatic die grinder for fiberglass repair.

Hook Loop




Roloc

DUB

I do not feel there is any major difference in regards to the disc saying put on the tool...and the reason I am saying this is becasue I RARELY have my air tools running at max RPM.

I am a FIRM believer that the faster the tool spins and it having sandpaper on it...it wears it out much faster that slowing down the tool. I have NO IMPERICAL evidence of this..but if I could get the guys I trained in the past to comment...they would tell you that it makes a difference becasue I made them slow down the tool and they saw how much longer they had the Roloc on the tool. Kinda reminds me like how Tom Cruise drove the race car in 'Days of Thunder' HIS WAY and darn near shredded them...but when he drove it like Robert Duvall told him the tires still looked good. For whatever the heck that might be worth to you or whoever reads it.

NOW...due to the Roloc has a threaded pin in the center of the disc ...this aligns it so the disc is centered and not off center depending on what you are planning on grinding on. IF you are grinding on something that is very precise...it might work better...becasue the hook loop might take you a few attempts to get that disc centered.

Check out this thread due to I have a 'COOL TOOL ALERT' in it and you might find that these home made tools really do help out.

Look at POST #42 and POST #53...and there may be more

http://www.corvetteforum.com/forums/...rag-car-3.html

DUB

jim2527

DUB thanks. I'm doing very similar repairs to those in the Lingenfelter thread.

Do you have a brand preference for roloc discs?

DUB

No...they all work about the same. I use 3M and also another brand that is not in the mainstream and they hold up just as well.

By you modifying a holder for the disc ( if you choose to do so)...they can be used several times. Simply by using a small diameter disc holder and cutting the disc with tin snips. I know I posted a photo of the small one...but I have two others that are different diameters..and this allows me to get every bit of teh disc used up before it is done.

DUB

porchdog

i buy my abrasive disc from mcmaster/carr . they last much longer. anything made for machine shop / industrial use will last longer than autobody supplies.

DUB

I never considered that....and it does make sense.

DUB

jim2527

Thanks for the recommendations....

How about grit recommendations floor work?

VPA between layers (evercoat recommends 40-80):
VPA final layer:
Feathering floor boards prior to 1st layer of fiberglass resin:
Sanding after each fiberglass resin layer to scuff up:
Final fiberglass resin layer:

Thanks-
Jim

jim2527

https://www.mcmaster.com/#sanding-discs/=18yf1ls

DUB

Jim,

I have 24 grit Roloc discs and also 36 grit and I go up from there for many other uses.

As for sanding the cured VPA when needing to apply more...you are correct...I use 36 grit and also 80 grit. It depends what stage of repair I am at at a that time. And as long as the VPA is scratched up and making sure you DO get the surface sanded for another coat. You should be okay. And getting the dust off of it is basically common sense before you go and apply more VPA

The final layer of VPA will depend on what you plan on priming with. I stop my blocking at 80 grit then run 180 over the panel to bring that scratch down a bit more and make it a bit smoother due to I either apply gelcoat or a polyester primer. And that is becasue gelcoat and polyester primer can really fill in deep scratches. I could apply it over 36 grit scratches and fill them in with what i sue. But...for me....stopping at 180 is good enough. Some primers may want you to take it to 220 or 320 grit...so...like I wrote above...I depends on what you plan on priming with.


Prepping your floorboards for the first layers of mat and resin can be done with 36 grit or even 24 grit. The key thing (in my opinion) is that I do not max out the die grinder and Roloc disc. I let the grit of the Roloc do the work and it does not have to be spinning like the tool is going to come apart.

AS I have mentioned in other threads that I can get a serious scratch out of 36 grit that is more than effective for maximum adhesion due to how I am allowing the Roloc disc to NOT spin like crazy and the amount of pressure I use. So...having to have discs rougher than 24 grit is NOT needed for fiberglass work.

Sanding after each fiberglass resin layer to scuff up:

I do not know what you meant in what you wrote. I know that i do not generally just apply ONE layer of mat and resin and then let it cure and scuff it and apply another and so on. In certain circumstances I will when I am filling in very large openings.

SO...when I scuff the resin for the next application...I stick with the 24 or 36 grit. AS long as I achieve the scratch I am looking for...is all that matters to me....and I can achieve it in both grits. I just do not want the surface to have a polished feel to it when I am done. I want it scratched up. And YES...this can happen and you might actually experience it also...because you will swear the disc is good and rough...and it grinds...but compared to a FRESH disc ...it is worn out and does not cut as aggressively into the surface....which is why watching your tool speed can help you out.

Sanding the final layer of mat and resin can be with 24 or 36 grit. And (in my opinion) when I laminate up an area and it is going to be painted. I always apply VPA over the ENTIRE laminated area...so I do not see any of my lamination. I do not have to cover it super thick with the VPA...about the thickness of a wood or paper matchstick works for me....but it is not like I am sitting there measuring it also. And the reason I cover ALL of my laminations with a coat of VPA is due to no matter how good I am at hand laminating. I am human and I can get micro air bubbles in the resin if I do not vacuum bag the lamination. AND those micro-bubbles in the resin will show up like crazy when you go to apply the first sprayable product on it.

DUB

porchdog

the disc for hard metals and stainless last for ever on sheet metal . one big factor is speed. on paint or glass you can heat up and melt paint causing it to gum up . i actually use around 30-45 lbs on my da or disc grinder .