How do you ensure your sanding or filing is flat

[nheather]

Something that I have always struggled with is filing/sanding a squared-off surface and keeping it flat - applies equally to metal, plastic and wood.

 

I appreciate if the subject is suitable you can get good results by putting a piece of wet and dry down on a flat surface and sanding with the object but even that isn't foolproof.

 

But that is suitable for all cases.   Say I have a piece of plastic that has a flat end, nicely squared off on all sides.  It is a little too long, not enough to get the razor saw out.  Now no matter how careful I try to be, how slowly I do the task I end up filing/sanding in a slope or rounding off the edges.

 

Any tips?

 

Cheers,

 

Nigel

[colin]

Try sanding in a fiqure of eight motion, as this helps even out the pressure that you are putting on the part

[PhoenixII]

Hi Nigel,

only thing I can suggest is to mark the part, if that's feasible? and sand to the line, at least then you have something visible to work to. Otherwise you'll have to reduce the time spent sanding and check your work more frequently. If you think of what your sanding as gold, it makes the last suggestion easier!

Best of luck,

Paul

 

 

[rayprit]

In situations where I need a relatively flat surface, I use a black marker pen/Sharpie…......run the pen over the area your going to flatten and do a couple of passes...………...checking where the black remains untouched shows you how accurate your passes are and you can adjust accordingly

[nheather]

Thanks for the suggestions, all sensible but picture the task I’m facing at the moment.

 

I have two aluminimum surfaces that mate together.  The surfaces are small, say a 5mm x 2mm. I need to remove a total of 0.3mm.  The two faces are visible and need to mate together neatly - no chance of filler or paint to cover up.

 

So it would seem that the surface is too small to do figure of eights.

 

And the amount that I removing is too little to mark.

 

There is another area which is an open recess that I need to take down the same amount - it has to go right up to the shoulder but mustn’t touch the shoulder.

 

Cheers,

 

Nigel

[Fatcawthorne]

I use my Dremel with the angle grinder/metal cutter type attachment and Grind from the end at 90 degrees until I reach my mark (not cut accross the piece).

[JamesP]

Stick sand paper to a block of would that you know it square. Lay plastic piece on another flat block that has a square edge to which you align the edge you wish to sand. On a flat surface place the sanding block against this edge and gentle move back and forth while pushing the plastic with slight pressure  against the the sanding block.

 

Sorry just reread you post and you want to sand the flat surface not the edges. Stick the piece down to a flat surface and sand using a flat sanding block as above.

Edited January 12, 2019 by JamesP

[nheather]

Have to put some pictures up - but need to chhose a photo hosting and sign up.

 

Chees,

 

Nigel