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True Grit


robtheplod

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Hi All

 

I'm about start on my long journey of Narrowboat maintenance so familiarity with 'grit' rating is needed so I get the right one for the right job. What grit rating do you all use for the following jobs?

 

Remove large areas of rust - finish not important

Remove light rust patches

Key between paint layers?

 

anything else I've forgotten or not mentioned?

 

thanks all!!!

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Rust on flat areas, 40 or 60 grit, anything pitted or in angles, corners, wire brushes and grinders.

Key between layers, depends on which coats and how you've put them on. Anything from 120 to 400 (rolled primers to undercoat and initial top coats). Following that, different level scotch cloths for subsequent top coats, if you are brave, last coat straight on without keying ( favoured by Colin Dundas(ex spiderworks))

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1 minute ago, matty40s said:

Rust on flat areas, 40 or 60 grit, anything pitted or in angles, corners, wire brushes and grinders.

Key between layers, depends on which coats and how you've put them on. Anything from 120 to 400 (rolled primers to undercoat and initial top coats). Following that, different level scotch cloths for subsequent top coats, if you are brave, last coat straight on without keying ( favoured by Colin Dundas(ex spiderworks))

fantastic thanks so much!

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Forget abrasives to begin with and use a knotted wire cup brush on an angle grinder. It will give a similar finish to shot blasting. 

 Don't buy anything above about 60mm as they are generally very badly balanced and unsuitable for smaller machines. 

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2 hours ago, robtheplod said:

Hi All

 

I'm about start on my long journey of Narrowboat maintenance so familiarity with 'grit' rating is needed so I get the right one for the right job. What grit rating do you all use for the following jobs?

 

Remove large areas of rust - finish not important

Remove light rust patches

Key between paint layers?

 

anything else I've forgotten or not mentioned?

 

thanks all!!!

I find the best way by far is to get someone to do it for me!! Orrible mucky job.

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3 hours ago, BWM said:

Forget abrasives to begin with and use a knotted wire cup brush on an angle grinder. It will give a similar finish to shot blasting. 

 Don't buy anything above about 60mm as they are generally very badly balanced and unsuitable for smaller machines. 

 

I use flat wire wheels on a mini angle grinder with a diameter of 125mm and generally find they're fine. They're no more unbalanced than smaller diameter cups, just that if they do become unbalanced through brittle loss you feel it. I used them professionally got a couple of years and they're better for larger areas.

3 hours ago, stegra said:

And wear goggles. When those little wires fly out they can pierce skin, as I found out. 

Yes, very important and leather gloves and ear defenders. Those bristles can sting when they hit you in the face but no harm unless they hit you in the eye!

 

Watch the angle grinder cable too. Keep it away from the work. It's very easy to get it caught in the wheel of you're not careful.

 

Flap wheel (linishing) discs do a good job too but I wouldn't use them below the waterline because as well as the rust they take off good steel.

Edited by blackrose
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6 hours ago, robtheplod said:

Hi All

 

I'm about start on my long journey of Narrowboat maintenance so familiarity with 'grit' rating is needed so I get the right one for the right job. What grit rating do you all use for the following jobs?

 

Remove large areas of rust - finish not important

Remove light rust patches

Key between paint layers?

 

anything else I've forgotten or not mentioned?

 

thanks all!!!

I watched this guys videos, every second of every one :) :

 

http://www.johnbarnard.biz/tips-tricks-videos/

 

as a consequence, I use Mirka Abranet 125mm sanding discs ranging from about 80 grit to 320 grit, and Mirka Mirlon sanding pads, green (320 grit), red (360 grit), and grey, (1500 grit).

 

I have a Bosch 125mm orbital sander, with a Mirka 5mm interface pad.

 

 

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11 hours ago, blackrose said:

 

I use flat wire wheels on a mini angle grinder with a diameter of 125mm and generally find they're fine. They're no more unbalanced than smaller diameter cups, just that if they do become unbalanced through brittle loss you feel it. I used them professionally got a couple of years and they're better for larger areas.

Yes, very important and leather gloves and ear defenders. Those bristles can sting when they hit you in the face but no harm unless they hit you in the eye!

 

Watch the angle grinder cable too. Keep it away from the work. It's very easy to get it caught in the wheel of you're not careful.

 

Flap wheel (linishing) discs do a good job too but I wouldn't use them below the waterline because as well as the rust they take off good steel.

My recommendation is specific to the item mentioned, i don't use the flat type as more effort is needed for an inferior result. 

 As for flap wheels, they have a tendency to 'bite' into the steel leaving half moon shaped depressions that require more work and filler than the original rust.

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1 hour ago, robtheplod said:

Thanks for all the really helpful replies, much appreciated!!!

If you post some pictures of the rusty bits, people can be more specific about what is needed.

 

I am getting the sense that some responses are talking about taking the whole lot back to the bare metal, which may be appropriate. John Barnard uses a scabbler in his videos.

 

However, if it is not as bad as perceived, sanding with a rough grit, 40 or 80, or whatever, in and around the area, followed by Vactan, (or similar), 2 coats of primer, undercoat, and topcoat, is a fairly comprehensive solution. (If you are happy with Vactan as a primer, you could do away with the primer).

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7 hours ago, Richard10002 said:

If you post some pictures of the rusty bits, people can be more specific about what is needed.

 

I am getting the sense that some responses are talking about taking the whole lot back to the bare metal, which may be appropriate. John Barnard uses a scabbler in his videos.

 

However, if it is not as bad as perceived, sanding with a rough grit, 40 or 80, or whatever, in and around the area, followed by Vactan, (or similar), 2 coats of primer, undercoat, and topcoat, is a fairly comprehensive solution. (If you are happy with Vactan as a primer, you could do away with the primer).

thanks, I shall do this next time on the boat.... :)

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On 14/10/2019 at 11:20, BWM said:

My recommendation is specific to the item mentioned, i don't use the flat type as more effort is needed for an inferior result. 

 As for flap wheels, they have a tendency to 'bite' into the steel leaving half moon shaped depressions that require more work and filler than the original rust.

 

My recommendation was also specific to the item mentioned (by the OP - removing large areas of rust), and in that case I have to disagree that a flat wire wheel requires more effort for an inferior result. Quite the opposite in my experience.

 

The OP also mentioned that the finish wasn't important which is why I suggested flap wheel discs. I've used them on deck areas where I wasn't worried about the finish and didn't apply any filler.

 

 

Edited by blackrose
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I used flap discs in an angle grinder to strip the roof of Belfast back to bare metal. Slow and messy, but gave a good smooth finish for repainting without any gouging or grinding marks that showed through the first coat of primer. 

I think this is the type I used:

https://www.toolstation.com/flap-disc/p67922.

 

Suppplemented by the use of both cup and disc wire brushes to get into areas of pitting and awkward corners.

 

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