depth perception

[Odie]

Here it is, past 2:30am, and I'm just coming in from the shop!

I was thinking about carving out bowl interiors, and while doing this on the lathe, you've got the worst possible vantage point for seeing how the interior is shaping up. It gets worse, as the bowl is spinning. For me, at least, it gets very difficult to get a smooth contoured surface, free of subtle differences that are unacceptable for a bowl's interior. This is the main reason I have never been able to eliminate power sanding on the interiors of my bowls. Over time, I have gotten better, but not good enough.

Some of you older turners might remember the "depth perception test" while taking high school driver ed training. This was an elongated box and you look through one end and try to align two toy cars at the other end, so the bumpers were even with one another. I can remember being ok with this test, but not the best.

Just wondering if there are any comments about depth perception.....and, how this may affect others' turnings.

-----odie-----

 

[hockenbery]

I’ve not considered depth perception. Could be a factor. But turnings are close and my safety glasses are focused at the turning range.

I’ve often wondered about the possible effects of eye dominance.
I have a strong left eye dominance (too much baseball??). Both eyes open I put my thumb over an object close my right eye the thumb is still over the object close left eye the thumb is totally off the object to the left.

When I turn spheres between centers with two exceptions the right side is better. Not by much - I use a little ring to test for roundness the right side the ring usually lays completely flat the left side there is usually a slight imperfection I need to fix with a shear scrape

First time I did the left better was in a demo. I was astounded for a second. Told the audience they had witnessed history- they probably thought I had lost my mind.

I am right handed which could be a difference
All the practice turning bowls would argue for the left side being better
So could it be left eye dominance ?

 

[Odie]

I’ve often wondered about the possible effects of eye dominance.

That could be a contributing factor as well.....and, as well, I hadn't considered eye dominance.

The facts are that it's much easier to assess the exterior shape of a bowl, because you have a clear shot at seeing the profile......while the interior is like looking straight down at subtle differences in "hills and valleys".

Whatever our physical limitations are that prevents us from seeing where adjustments need to be made.....they make getting the perfect shape of an interior very difficult.

-----odie-----

 

[hockenbery]

The facts are that it's much easier to assess the exterior shape of a bowl, because you have a clear shot at seeing the profile......while the interior is like looking straight down at subtle differences in "hills and valleys".

I check the inside of a bowl with my hand and fingers.
Easier for me to feel the curve and any undulations in the surface than it is to see them
Used to mark the bumps with chalk so I could see them. Now I just remember the spot and feel for it with the tool.

 

[Paul M. Kaplowitz]

I can stand in front or to the right of the piece I'm turning. The bowl in my bio picture at the left is 36" in Dia. When I'm doing bowls the bed is detached from my VB 36.

 

[Odie]

I check the inside of a bowl with my hand and fingers.

Well, of course Al.....

Me too......

You do this while the bowl is spinning?

 

[hughie]

An interesting thought. I like many use hand and fingers and over time my depth perception has improved greatly. Especially when carving embellishments, its abit like the dry wall plasterer but perhaps not as good yet

 

[hockenbery]

You do this while the bowl is spinning?

Sometimes

 

[Odie]

Sometimes

I have done it in the past, and always felt a little uneasy about putting my hands and fingers into the interior of a bowl while the tool rest is in place, and bowl spinning. These days, I resist the temptation, and stop the lathe to check.

-----odie-----

 

[Dave Landers]

I wear reader safety glasses at the lathe. A couple years ago, I got a prescription pair. They're just reader lenses, but each lens matched to the strength needed for that eye. I noticed a difference immediately - all due to now having (better) depth perception at the lathe. Was most noticeable with small spindles. I don't know if it's helped with bowl interiors, but can't have hurt.

 

[Odie]

I noticed a difference immediately - all due to now having (better) depth perception at the lathe.

Now, there is something new to consider.....I wonder how they would apply to my tri-focals. Aren't mine similar in concept to reading glasses?......or something different?

Very interesting.

I think one's depth perception is a matter of individual ability......and, since those days of high school driver's ed, I've known my depth perception isn't as acute as a few others.

-----odie-----

 

[hughie]

Now, there is something new to consider.....I wonder how they would apply to my tri-focals. Aren't mine similar in concept to reading glasses?......or something different?

Very interesting.

I think one's depth perception is a matter of individual ability......and, since those days of high school driver's ed, I've known my depth perception isn't as acute as a few others.

-----odie-----

I have multifocal lenses and they are fine, for me its simply eye training to recognise small variations in the form or curve and in the case of embellishments depth of what ever I am doing. I find its 'a comes with practice' deal. But if anybody is having difficulties with this sort of thing they probably need to get together an experienced turner for some hands/eyes on . As we all have our methods/techniques that work for us, but often these are best passed on in person, as its all about judgement and that's very subjective.
Incidentally I went down the reading glass path and have a pair at a set focal length, the benefit was marginal for me.