Club 80-90 Forums

Help needed please
I thought I was doing the right thing sanding down my van with an orbital sander, recently had a comment about it leaving crescent shaped marks only visible when new paint is added. Am I doing the right thing or are there better sanders out there? Feeling very confused? Help before its too late. I have been going over with wet and dry after the sander!

Northantsandy

finish off with a wet fine grade paper it should be ok, theres a vid somewhere on youtube by covkid.use a circuit breaker to be on the safe side
are you rollering ?

I am using an air powered sander. No not rollering, somebody I know is going to spray it (two pack paint). I am spending weekends at my sisters farm in Waterfall, Staffs do the prep; but its slow going even with the sander. There are so many inaccessible areas with the sander. I may buy a smaller orbital than the one I am using.

Thank you for your help.

Northants

dont let the paper clog up too much as this can make it dig in..i found brushing the paper with a wire brush can prolong its life if its getting clogged

Thanks
I have had a bit of clogging up on the paper, as you mentioned. Thanks for the tip with the wire brush. I think its going to be a slow job.

Northantsandy

it is..ive done it twice now and i think its shortened my life somewhat

i did this recently . it was one of the most boring things ive ever had to do and took me weeks. i lost my mind a fair few times . keep at it. good luck

northantsandy wrote:Help needed please
I thought I was doing the right thing sanding down my van with an orbital sander, recently had a comment about it leaving crescent shaped marks only visible when new paint is added. Am I doing the right thing or are there better sanders out there? Feeling very confused? Help before its too late. I have been going over with wet and dry after the sander!

Northantsandy

You need a d/a sander [dual action]. It uses a counter weight on the drive shft to make the pad rotate in a random orbit, thus avoiding the half moon marks. A litle expensive for an electric one, but will take many hours off the job if used carefully. And you can use various grit papers with it, like 40 grit [really coarse] right up to P2000. Generally though, P80/120/180/240/320 grit papers will be fine for preparation work.

Been there, done that and have the crescent swirl marks as proof.



I used a large DA, a small DA and a lot by hand.

A couple of coats of primer filler and most disappear.
Then rub the primer filler down by hand or again with a DA but use 600 paper.
I find that a light dust coat of a contrasting colour helps with the rubbing down.
You rub down until the contrasting colour has gone and you have a flat surface.

That's strange. Could be that the paint you were sanding wasn't original and was clogging the disk and that would give the crescent marks Mind you, its always a good idea to buy the best discs you can run to - they aint cheap, particularly 3m ones - but it helps.

Agree that its a good idea to put a guide coat over the primer to highlight any low spots, craters, etc in any filled repair areas.

Random orbit sanders always leave scratches. As you go finer they are less obvious. This happens even with Festool rotex sanders. Although they have a fine finish switch which makes it more circular and less random, reducing the scratches.

Buy a DA sander. But don`t buy snapon, they`re cr*p. I had a brand new one last year it lasted 3 months. expensive crap. I brought a sealey DA and no problems with it yet 10 months later. Use high build zinc primer to get rid of swirls after going over it with 400 grade Da discs. Use the air blow to clean dust off discs if dry. get them cheap on ebay. So go o ver her first with 240 discs then 400. As for akward bits buy a rubber velcro back block to put DA discs on. Job done. Use wetndry 1200 to remove any runs. Never used a orbital sander on bodywork in bodyshop. Never heard of anyone using one. By the way them air blowers are only about £4 on ebay. Handy for blowing dirt out of things.

Thanks for all of the advice. I am using a DA sander, I just didnt know I was until I read the replies. I will probably look for a smaller version too, the large one is hard to get into the smaller places with. I will now go out and buy some 240 paper and a rubber block for the awkward places. Thanks for the advice, it really is very much appreciated.

Northantsandy