New Loupe

[Patrick Chase]

I'll admit that I have NEVER SEEN or heard of a 60X

I think that somebody (possibly the offshore manufacturer of said "cheap" loupe, to quote Ken) is confusing diopter with "power" here, and that it's more like a 20X loupe.

When people talk about optical "power" they typically specify it relative to the ~10" near point for a human with fully corrected vision and normal accommodation, so power = 10/focal_length. For example loupes with 1"/25 mm focal length (40 diopter) are typically rated as "10X".

If the FL is 12 mm as Ken stated then it's a 20X (~80 diopter) loupe.

As some in this thread have implicitly pointed out, the actual degree of assistance depends on the individual. Back when I was more nearsighted my near point was ~6" (though I could still accommodate to infinity), so the aforementioned "10X" loupe would have been about 6X for me. If you're farsighted then you'll get more than the stated benefit.

EDIT: I should have pointed out that I made a simplification here, that's valid at high magnifications as for loupes but not so for lower-magnification optics like bench magnifiers. It's actually power = 1 + 10/focal_length. The "+1" is to account for the contribution from your eye's optical power, again assuming normal vision and near-point. Ken's loupe is still ~20X though :-).

[george wilson]

I use a 10X triplex fold out small magnifier. The triplex is the best for lack of any distortion.

[Patrick Chase]

I use a 10X triplex fold out small magnifier. The triplex is the best for lack of any distortion.

Aspheric triplets are the way to go if you can afford it. I mostly use an old Rodenstock 6X loupe, carried over from my days 4x5 and 35 mm slide film photography. IMO optical quality matters a lot more than power, though unfortunately quality optics still aren't cheap.

[george wilson]

My gold (or is it Titanium oxide plated?) loupe was cheap. It was a gift! I keep it at the Hardinge lathe . I hope it's titanium nitride. A beautiful gold color,but harder than carbide. You see it being used on the name plates on some cars,as well as milling cutters. Wonderful stuff. If it is titanium,it will never wear off.

It was given by the mother of a young teenager who was nearly blind. She was an albino,and her eyes were pink.(I use the past tense because I lost track of the family eventually). Well,she WAS legally blind. She had to get her friend to copy her homework off the black board for her. Then,struggle to try to make out the words in books. I told her that she could not go around relying on her friend to do that every school day. What if she (her friend) was sick? A doctor had made a half hearted attempt to help her with an expensive looking 1 1/2X "monocular",which wasn't working. I got her a 7X monocular for deer hunting and it worked just fine. She was able to fend for herself at school and read the black board.

I had a very powerful set of 4 lenses from an old microfilm projector. They were over 3" in diameter. We re stacked them to find the best combination until she could read a book the best. Then,I bored out an aluminum tube and permanently mounted the lenses in that order. Then,she could read books just fine.

She was a very intelligent young person,and was then able to take care of herself in those 2 valuable departments. She also seemed able to see pretty well through a pair of 4X drugstore reading glasses that I frequently used to do very small work. However,since she might be using such glasses more often than the other two items,I did not want to cause damage somehow. So,I left it to her mother to discuss with the doctor as to if she should be allowed to go wearing such glasses.

As it was,though,I definitely did her more good than she had been getting from the doctor. I don't think he realized that she needed more powerful help than the 1 1/2X monocular. And,it would do no harm for her to occasionally look through it,or the reading magnifier I made for her.

[lowell holmes]

Are you guys admiring the chisel or working wood?

[george wilson]

We are discussing LOUPES,Lowell. You are in the wrong thread! As for the chisel,not something I'd make for myself,but as a tool maker,it is interesting to me. It would make a GREAT prop for an elfish woodworker in a "Lord of the Rings" movie,too!!! Not that I am into those movies. The American public is way too interested in superstition and MAGIC,especially. And WHO KNOWS what else(No kidding). I have met a few nut balls that actually believed they were witches. Good folk to stay away from!

In any case,it doesn't hurt woodworkers to learn a bit about metals OR loupes.

What a grouchy post,I must say!!

[bridger berdel]

I'm the one who encouraged them to carry it. I teach sharpening at that woodcraft store and i keep one in my kit for the students to really see what is going on with their edges.

It's a pretty decent cheap loupe. I initially considered stocking them myself to sell to the students but that didn't seem like the right approach. Having the store carry them makes them more available and avoids a possible ethical conflict.

[Patrick Chase]

It's a pretty decent cheap loupe. I initially considered stocking them myself to sell to the students but that didn't seem like the right approach. Having the store carry them makes them more available and avoids a possible ethical conflict.

It also avoids them demanding refunds from you when they catch on that the contents aren't exactly as advertised (though as George implicitly pointed out, the very idea of a "60X" loupe should set anybody's detector off. That's what caused me to go back and look at the focal length again).

[lowell holmes]

What a grouchy post,I must say!!

I didn't mean for it to be grouchy.

I just didn't expect to see that much written about a loupe. Obviously looking at magnified edges is something I haven't done.

I know a chisel or plane iron is sharp if it will leave a smooth surface on end grain. I used to see if it would shave arm hair, but not any more.

I keep diamond hones out on my bench and use them when an edge needs sharpening. I free hand sharpen most of the time.

[george wilson]

I don't use a loupe for seeing edges either. Just for small parts I am making on the lathe mostly.

[Jim Koepke]

I just didn't expect to see that much written about a loupe. Obviously looking at magnified edges is something I haven't done.

It is seldom one of my honed edges is examined with magnification. Usually it is only if something is leaving a line when paring end grain. Then it is to see how much more work has to be done to remove a nick or pit.

More often a loop is used to see a makers mark that has been obscured.

jtk

[bridger berdel]

If that is actually +/- 20x then 60x wouldn't be particularly useful for sharpening in the form of a loupe, or anything else handheld. the low power side of that loupe is about right, IMO.

for higher magnification the currently available digital microscopes (webcam with a mag lens) do a very nice job of inspecting the individual grit scratches for about $20 plus your computer. an example:

https://66.media.tumblr.com/9442e069...rm32o6_250.jpg

https://67.media.tumblr.com/68cee1fa...m32o4_1280.jpg

https://66.media.tumblr.com/5980b07e...m32o9_1280.jpg

https://66.media.tumblr.com/50aca163...m32o3_1280.jpg

https://66.media.tumblr.com/0250f99d...m32o4_1280.jpg

more to the point though, Randy over at woodcraft pays some hefty rent for the commercial space, franchise, utilities and licenses and such, none of which I am responsible for. any transactions taking place there should be supporting the store. I'd much rather see woodcraft stay in business than take home a couple of bucks a month profit myself.

[ken hatch]

I'm the one who encouraged them to carry it. I teach sharpening at that woodcraft store and i keep one in my kit for the students to really see what is going on with their edges.

It's a pretty decent cheap loupe. I initially considered stocking them myself to sell to the students but that didn't seem like the right approach. Having the store carry them makes them more available and avoids a possible ethical conflict.

Bridger,

Thanks for asking Randy to carry the loupe, it is one of the most useful i've found. I agree the low power side is near perfect for edge inspection. BTW, it is good you are showing your clients how to see sharp.

What I do not understand is "testing" for sharpness, a demo of sharpness makes sense if you are trying to show someone the iron is sharp but to test all you are doing is making a sharp iron dull. If a iron looks sharp and feels sharp, it is sharp. What am I missing, what advantage does "testing" on hair or EWP bring to the table?

ken

[Jim Koepke]

What am I missing, what advantage does "testing" on hair or EWP bring to the table?

When one of my blades is being sharpened, it is an easy check to shave a little arm hair. Of course if there is a lot of work and sharpening going on my arms may get a little bare.

There are different degrees of sharpness that can remove hair. It begins with only a little hair removal and possibly being able to feel the hairs catching in the nicks or pits along the edge. It extends from barely removing a few hairs all the way to having the hair practically popping off in front of the edge.

Beyond that there is a "hanging hair" test where a free hanging hair is used in the test. There are various degrees in this test. Something about this could likely be found on a razor forum.

Testing on end grain will show a line on the cut if there is a nick, pit or other spot needing more honing.

Of course many of my tools do not get tested after sharpening. Shovels and garden tools usually just have a visual inspection. An axe, hatchet or froe usually just does its work to prove their edges.

Drill bits are almost always tested for equal cut from both sides before being stowed. Most often with drill bits they are noticed to be deficient and sharpened before being put to use.

jtk

[ken hatch]

When one of my blades is being sharpened, it is an easy check to shave a little arm hair. Of course if there is a lot of work and sharpening going on my arms may get a little bare.

There are different degrees of sharpness that can remove hair. It begins with only a little hair removal and possibly being able to feel the hairs catching in the nicks or pits along the edge. It extends from barely removing a few hairs all the way to having the hair practically popping off in front of the edge.

Beyond that there is a "hanging hair" test where a free hanging hair is used in the test. There are various degrees in this test. Something about this could likely be found on a razor forum.

Testing on end grain will show a line on the cut if there is a nick, pit or other spot needing more honing.

Of course many of my tools do not get tested after sharpening. Shovels and garden tools usually just have a visual inspection. An axe, hatchet or froe usually just does its work to prove their edges.

Drill bits are almost always tested for equal cut from both sides before being stowed. Most often with drill bits they are noticed to be deficient and sharpened before being put to use.

jtk

Thanks Jim,

AS with most things wood YMMV and there are many ways to get there and I expect "how" is usually how you learned.

ken