What to sand/grind with?
 

What do you guys use to do the very fine work, like when grinding the pride for perfect sheetmetal and you need to get right THERE. I've been trying to use 2" rowlock, 80grit, on a 90deg die grinder. I use just the edge with good resukts but is get soft quick an dthen I use scissors to to trim the edge back to the rubber backing to firm it up. But I still touch the adjacent metal. I've tried and use the edge of a cutoff disc but it can leave little unwanted divots.
What do you guys use?

Try a hand held belt sander there is a picture of the one I made in my album.
Mike

5" grinder adapted to 6inch D.A. sander backing pad.
 

I'm not exactly sure what kind of contour you are looking to abrade, but ...
I've used a 5" pistol-type air sander/grinder for many years to do fine finish work on steel for plating, and on aluminum and copper for polishing. I modified this tool with a little machined adapter I made so that I could use the "eezee" 6inch soft adhesive D.A. backing pads, and 180/240/320/400 paper.
This has saved me a lot of time and effort over many years.
https://www.tinmantech.com/products/...nder-combo.php
:):)

Another option- I've used this type of diamond abrasive pads for wet polishing granite in studio http://www.shopnsavemart.com/granite...-discs-diamond for years. Not necessarily this brand, but these diamond pads with a water-feed variable speed air or electric grinder are the standard equipment for hand polishing. You can buy $$ or cheap ones now from a variety of suppliers.

When I got a stack of dirty, used no-name diamond pads with a spare side grinder, I tried them dry on metal including cast iron, steel, aluminum and brass. They work great and can take things up to a mirror polish as desired, with two caveats:

1. keep speed on your grinder relatively slow or the Velcro cannot hold them & the pad. They get off-center and then go flying. Not cool.

2. Using them dry can build heat, especially when servicing heavy items like dollies, and the adhesive holding the Velcro on the rubber backer will fail as it gets hot.

I've never bought a lot of traditional sanding discs, but these last quite a while, especially if you don't chunk the edge of the pad by catching it on sharp edges of the workpiece. The bond is soft enough so they keep a good bite and aren't prone to gouge. I use Roloc abrasive discs as well for both stone & metal, but usually only when the diamond pads won't fit.

I'll throw in a couple pix to better illustrate:


Steel body, damaged:
Attachment 48513
Standard straightening methods of pushing out, slapping flat, hot shrinks, and planishing were used ...
Attachment 48514
and then going over with metal finishing - air sander and body file.


Attachment 48515
Cutting across the crown is not advised - unless you are looking to cut down a lump of weld, and want to hit the proud area only.

Attachment 48516
Using the disc to cut along or with the highlight of the crown (longwise) allows you to sand as though you are using a body file.


This old technique goes back to the 1920's in American body shops, and is/was a very standard way to use a 9inch body grinder and a 50 grit disc to check your surfaces fast, rather than pushing a body file to do it.
For this method to work well, you must understand clearly how the disc surface is contacting the metal surface. Seeing both images together helps contrast the two geometries of disc contact.
Attachment 48517
Disc diameter makes no difference in the result, it's just that the availability of finer abrasives in the 6in diameter is far better.
Attachment 48518
I've done a lot of high-end chrome-prep and polish work using this sander and this method.
:):)

Great responses, Mike, I couldn't find your tool but enjoyed your album; lets say I want to deal only with the proud without removing any existing metal. Should I be using more body file and less air tool? What body file?

I guess the answer is really “it depends in what yo are doing”

I do have kent’s Pistol grip/da setup and I like that a lot.

Generally if I start with something aggressive to knock the weld down. 3” roloc on a right angle die grinder with 36 grit. I just remove the weld, and not quite all of it. Don’y Touch the surrounding area. Then I jump up to 50 to remove the last bit of the weld and blend into the surrounding area. Then 80 and 120 on Kent’s setup, sometimes I finish up with a scotchbrite.

This is a rear frame clip I did recently using this approach. Not perfect but a huge Improvement over what is there currently

A sharp single cut mill file works well on flat and outside contoured areas. Easier to control than a rotating disc.

OJ. The belt sander is the first picture. I use the roller tip to just grind down the tops of the welds. Start with a rough grit and work down to fine grits. I place the roller tip transversely to the weld seam to keep the ground area narrow. Now blending in the surface is another matter.

Mike

Can't see your pictures Mike. :confused:

Cheers Charlie