There must have been an extra big gravel of sand on my sand paper, because my palm sander left a tiny spring-shaped line all across the front of my project. Worse, I couldn't see it until I put on some finish. Crap!
S.
Did you wipe the surface of all dust when changing grits?
And run your hand over everything before you finished? I often find small irregularities by feel rather than by sight.
I?ve been a machinist for 40 years now, and it never ceases to amaze me at what a finger tip or nail can feel.
As already mentioned, that could have been a grain from a previous paper. If I know I'm going to stain, I always blow off in between grits and wipe with a clean rag, wetted down with methyl hydrate. That will show any snake tracks or other scratches.
cleaning the work piece with compressed air from time to time at the very tail end of the prepping will usually show up any such scratches, that are often invisible due to being filled with fine compressed sawdust.
-P.
Lots of good information. Thanks guys.
S.
Isn't that the truth. Snake tracks are elusive though. Not as easily felt as straight grooves. Making the dust moist with methyl hydrate, then wiping the dust into the grooves, will show them nice and bright as the methyl dries... it dries a bit slower in the grooves. It also raises the grain a wee bit and give a preview of what kind of figure is awaiting a proper finish.
samson wrote in news: snipped-for-privacy@news.supernews.com:
Not on this subject, but I was sanding the other day with my ROS, and noticed that the vibration of the sander was making my wedding ring spin around!
Put the ROS in the right place and your wife will spin around
You couldn't see it because we like to flood our shops with overhead lighting but a raking light is what you need to expose all the little flaws. Usually I don't worry about it until I hit 150 grit, then either I pick up the piece to get the surface between me and the light source or I move a light if it's not feasible to lift the work. Mark all the problem areas with a pencil and back up on the grits. Repeat until everything looks consistent at 150 grit. Then move on finer if not staining.
There was an episode of Dirty Jobs where they make surfboards. In the room where they carve the foam of the board they had two lighting systems. The general overheard lights and rows of pot lights set on two walls just above the surface the boards. With the overhead lights on you couldn't see any detail on the foam. Switch to the raking lights and voila, everything is clear as day. Kind of like when you repaint a wall in an old house. As long as you point the lights straight at the wall it looks half decent. The second you move the light parallel to the wall you recoil in horror at all the bad patch jobs and holes.
-Kevin
That's a worryingly dangerous amount of vibration.
Have you ever heard of something called "whitefinger", it's caused by subjecting your hands/arms to too much vibration.
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