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How to avoid rounding over edges?

Posted: Fri Nov 13, 2009 11:54 pm
by mredmond
I haven't posted much but have been reading and learning a ton from all of you for a while. I find myself having a recurring issue and hope to get some
advice. I'm a big fan of modern, architectural designs and enjoy the interesting things that happen when you juxtapose smooth curves with hard lines and sharp planes...many of you pros do this expertly. I can't seem to keep an edge or hard line on any freehand stummels. Are there any techniques that I can use to avoid rounding over everything? This happens most when hand sanding. I'm using Kurt's awesome disc sanding setup and it works great, but I do 220 and up by hand. Should I try to do each grit on the disc sander or should I just keep working at becoming less hamfisted?

Thanks!

- Micah

Re: How to avoid rounding over edges?

Posted: Sat Nov 14, 2009 12:01 am
by Sasquatch
In general, rounding over occurs when a soft media-based abrasive is used on a sharp edge. Our hands are like a big spongey backing for sandpaper, so as we draw a piece over an edge, if there is any pressure, the paper gets pressed "around the corner". There are a number of ways to avoid this. If you can stiffen up your paper (I use a fairly stiff foam-backed pad product) by using a sanding block of rubber, or wrapping it on a tongue depressor or something, it will help. The other advice I would offer is to press very very gently.

If you have foam backed sand paper, you can roll it into a log, and this helps keep it from knocking the edges off too.

This all assumes fairly flat surface on the pipe. If you are working a convex area, yes, get less hamfisted. :D

Re: How to avoid rounding over edges?

Posted: Sun Nov 15, 2009 12:58 am
by mredmond
I have avoided sanding blocks because most seem too big for this application. I'll try to fashion something smaller and try some different types of abrasive pads. I've had difficulty finding discs and pads that do what I want. I finally found hook and loop backed pads at my local Woodcraft to use with Kurt's setup on my lathe and got excited...to find that this particular mesh type disc rips to shreds when any pressure is applied. I've read about the foam backed abralon pads, I just prefer to see stuff like that before purchasing...can't have it all I guess. Thanks for the advice.

- Micah

Re: How to avoid rounding over edges?

Posted: Sun Nov 15, 2009 6:09 am
by pierredekat
Years ago, my wife had one of these wooden incense burners laying around.

Image

So, one day I was looking around for a suitable sanding block, and I grabbed that thing, wrapped a piece of sandpaper around it, and I've been using it as my primary sanding block ever since.

I also made a smaller version out of a piece of scrap hardwood for fine-tuning the curves on bent pipes.

I tend to use these things on the shanks/stems because it's so easy to see when those lines are off.

And there, I will only switch off to finger/hand sanding in the final grits.

But I will often do courser sanding on the bowl by hand, without a block, because it's easier to sand those contours with softer hand pressure.

I guess the key is just practice. After awhile, your fingertips start to know exactly how much pressure, at what angle, etc., to use.

Re: How to avoid rounding over edges?

Posted: Mon Nov 16, 2009 3:37 pm
by Nick
It just takes practice really. I hold most all my paper by hand, or occasionally use a nail file or emmory board. Still, most of that won't work for the concave edges. Practice practice practice.

Re: How to avoid rounding over edges?

Posted: Tue Nov 24, 2009 1:25 pm
by daniel
Or...
you might want to try it oldschoolio with these:
http://www.dick.biz:80/dick/product/703500/detail.jsf