24 replies to this topic

[charlie orzech]

Hi all,

 

I have a finderscope with blown out crosshairs--does anyone have suggestions on what to use to replace them?

 

Charlie

[TOMDEY]

Fine wire is good. Traditional true spider webs are too fine for a finder. I've used both... it's an easy project, rather impossible to screw up. Use your imagination.    Tom

[Jay_Reynolds_Freeman]

Fine wire is good. Traditional true spider webs are too fine for a finder. I've used both... it's an easy project, rather impossible to screw up. Use your imagination.    Tom

If you can find a particularly ugly, gigantic, horrendous, monstrous, man-eating spider, its web material may be large enough to be useful. If at all possible, try to stay on the spider's good side.

 

Seriously, I have used spider-web material and it can work. Fine fishing line and fine black thread are other possibilities, particularly if you can find a thread that is smooth and does not have itty-bitty threadlets sticking out every which way when you view it under eyepiece magnification. I believe that some nylon or other plastic threads are suitably smooth.

[ccwemyss]

Spiderweb is the classic. Very fine wire is often used. Another option is to get an etched reticle from Surplus Shed and glue it in. 

 

Chip W. 

[Jon Isaacs]

Charlie:

 

I use 0.004" diameter hard brass EDM wire. It's large enough to be easily seen even under very dark skies.

 

I have quite a bit of it. If you want a foot or so, send me a PM with your addresses and I will send you some. I just tape it to a greeting card so it costs nothing to be send.

 

Jon

[NiteGuy]

Here's something that I've used for many years with great success and more good comments than I can count. It's a semi-large stainless steel sewing needle. I cut/broke it about 1/16" to 1/8" short of the center-to-inside-of-the-barrel length. When you glue it in place, make sure that the tip of the needle is slightly below center (see photo). Cutting the needle to length can be difficult but, if you can bend it back and forth with pliers or put it in a vise, that might be easiest. Eyepiece shown is a Konig 32mm 2" eyepiece and the glue has held strong for 40 years now. Most eyepiece barrels will unscrew to make this an easy project.

 

Easier than crosshairs...just set your object on top of the tip of the needle's point. The needle remains easily visible, even in the darkest of skies, and doesn't hide your target like other solutions. It also won't fry and melt if you're pointed at the Sun.

 

 

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[TOMDEY]

Here's something that I've used for many years with great success and more good comments than I can count. It's a semi-large stainless steel sewing needle. I cut/broke it about 1/16" to 1/8" short of the center-to-inside-of-the-barrel length. When you glue it in place, make sure that the tip of the needle is slightly below center (see photo). Cutting the needle to length can be difficult but, if you can bend it back and forth with pliers or put it in a vise, that might be easiest. Eyepiece shown is a Konig 32mm 2" eyepiece and the glue has held strong for 40 years now. Most eyepiece barrels will unscrew to make this an easy project.

 

Easier than crosshairs...just set your object on top of the tip of the needle's point. The needle remains easily visible, even in the darkest of skies, and doesn't hide your target like other solutions. It also won't fry and melt if you're pointed at the Sun.

Gave me this déjà vu feeling and I realized reminds me of this instrument of mine. The context is entirely different, but the visual memory imprint is the nearly identical! Great minds think alike... if at all?   Tom

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[wolf man]

   Plastic sprue! What is it? Sprue is the plastic 'tree' that holds molded plastic model parts together. If you've built model airplanes, cars, etc. you know that this is the stuff you throw away after you break off the parts you want to glue together to make your finished model.

   Simply take a length of the sprue and roll it over a candle flame. Quite suddenly it will grow soft, and that's when you stretch it by pulling the ends in opposite directions. A couple or three tries and you'll be an expert. It's glueable, and the clear pieces can be illuminated by the light source of your choice. Good luck!

Edited by wolf man, 20 February 2025 - 07:40 PM.

[Kasmos]

I've used my own hair at least half a dozen times, but I tend to keep my hair on the long side so it makes using it easier.

Here's one of my post on how I do it.

 

https://www.cloudyni...0mm/?p=10017007

[Cavs56]

I’ve used the wire out of a phone charger, very fine.

[NinePlanets]

Niki is a long-haired black cat who lives across the road. He has donated cross hairs a couple of times. The stranded copper wire in headphone/earbud wires is better though. Sometimes that stuff is made of extremely fine strands.

[strdst]

I have used ear bud wire. I worked in parks for years and collected lots of wire from ? patrons who left their various items, (wine glasses, bottles, pipes, ganja, undies, I pods, still half full pony kegs, nice shades, jewelry, watches, cameras and tripods on a bench, or in a shrub bed. Pleasantly distracted by ? I imagine. Our lost and found rarely had a visitor. The wire I used was relatively thick but the thickness made the crosshairs visible in a dark sky, 

 

I barely remember science projects in like Jr. High using human hair to make a hygrometer. The hair would tighten or relax depending on the relative humidity, Is that not an issue or is the hair protected within the tube?

[ccwemyss]

I’ve had my students build them. You need a long hair attached to a short arm on the far side of a pivot point for a long pointer to see any movement. A 1” length is unlikely to sag unless it was installed when very dry and then used at a high humidity level.

 

Chip W.

[deSitter]

I use a strand of copper extracted from a typical low-current wire. This is large enough to easily see even in dark sky.

 

My method of installing can be verbally described. It assumes you can extract the field stop where the crosshairs go. There may be witness marks from the previous crosshairs.

 

I make a jig with 4 thin wood/plastic screws at the corners of a square about 3" on a side. Wind the copper strand around two diagonally opposite screws. Do enough turns to secure one end, then do the turns in the same sense on the opposing post. Say, clockwise on both screws. Use good tension to keep the wire straight and taut.

 

Repeat with the other two screws. Use the same orientation for winding. Now you have 2 taught strands precisely perpendicular.

 

Now, I work the field stop under one wire between a screw and the center - use the wire which passes under the center crossing. Then nudge the field stop toward the center so that it lifts the other wire as you approach the center. Switch to some sort of optical aid (e.g. a long eyepiece with the barrel removed) to examine the centering in the field stop and keep nudging the field stop until it is right.

 

Now the hardest part - a TINY dab of superglue over the 4 places where the wires cross the field stop. Be very careful not get glue on the edge of the field stop. I apply it with a sewing needle.

 

After it dries, cut the wires near screws. To trim off the excess, do not use scissors, as this may pull the wire free from the glue spots. Instead, use a utility knife to push into the excess in a convenient hard place on the field stop - if you were careful that can be right where the threads start - but it is easier to fold the wire over the threads and push the knife into the first whole thread until it parts the wire. Now make sure any leftover is bent up and away from the threads.

 

-drl

[jragsdale]

I have used hair before, and it works well. But variable thickness so make sure you get 2 strands that are on equal thickness. I don't know how long it would last though. 

 

A good professional alternative is to buy fine tungsten wire on eBay specifically for crosshairs. I tried .0005" once and it was VERY hard to use and almost impossible to see at night. I definitely recommend something like .0015" or thicker depending on what you prefer. Daytime/nighttime use are very different.

[T1R2]

I use fine black thread (fly tying thread) an 8/0, and a sheet of graph paper, some super glue and some fine tipped scissors. 

 

Draw a circle on the graph paper, use a center point where two lines cross + for your compass,  then add your 4 marks  N,S,E, W on the paper, put the EP field stop down on the paper and try to glue two sides ( N&S) at once by placing a couple drops of super glue at the marks on the FS, set the thread on and wait a few sec's, then trim the thread ends, repeat for E & W, its ok of they are not exactly perfect since your aligning your main optic and axis with object to be in the center when the star is in the center anyway.  

Edited by T1R2, 21 February 2025 - 04:38 AM.

[Jon Isaacs]

It assumes you can extract the field stop where the crosshairs go. There may be witness marks from the previous crosshairs.

 

 

If one is adding cross hairs to an eyepiece that is not designed for crosshairs, extracting the field stop is probably not possible and if it can be extracted, more than likely it will be difficult to reinstall.  

 

I like the 0.004" hard brass wire.  It is stiff enough to remain straight so I can work down inside the eyepiece directly on the field stop.  I cut the wire to length using nail clippers and then using tweezers, carefully place the crosshair on the field stop. Then I use a toothpick with a drop of crazyglue on the tip to glue each end in place.  Placing the second on is more tricky. But when I am done gluing, I don't have to try and install the field stop. 

 

When I was still working, I traded favors with some superb machinists.  If I still had access, I would have them drill 4 small holes, through the field stop from the outside at 90 degrees. I would then insert the wire from the outside and hopefully find the hole on the other side.. The holes would have to be slightly oversized, I am thinking 0.020" though a quick calculation says two 0.020" holes would have a maximum misalignment of about 1/2 degree, a 0.040" hole might make it easier.

 

Jon

[deSitter]

If one is adding cross hairs to an eyepiece that is not designed for crosshairs, extracting the field stop is probably not possible and if it can be extracted, more than likely it will be difficult to reinstall.  

 

I like the 0.004" hard brass wire.  It is stiff enough to remain straight so I can work down inside the eyepiece directly on the field stop.  I cut the wire to length using nail clippers and then using tweezers, carefully place the crosshair on the field stop. Then I use a toothpick with a drop of crazyglue on the tip to glue each end in place.  Placing the second on is more tricky. But when I am done gluing, I don't have to try and install the field stop. 

 

When I was still working, I traded favors with some superb machinists.  If I still had access, I would have them drill 4 small holes, through the field stop from the outside at 90 degrees. I would then insert the wire from the outside and hopefully find the hole on the other side.. The holes would have to be slightly oversized, I am thinking 0.020" though a quick calculation says two 0.020" holes would have a maximum misalignment of about 1/2 degree, a 0.040" hole might make it easier.

 

Jon

Most low-power finder eyepieces are Kellners or Ramsdens with an easily accessible field stop. I have one old classic finder with zapped crosshairs where the field stop is really frozen in the works, but other than that, it has always been very easy to remove it for work. I have converted a couple of 25mm Kellner eyepieces to crosshairs for alignment purposes - very easy.

 

-drl

[NinePlanets]

Most low-power finder eyepieces are Kellners or Ramsdens with an easily accessible field stop. I have one old classic finder with zapped crosshairs where the field stop is really frozen in the works, but other than that, it has always been very easy to remove it for work. I have converted a couple of 25mm Kellner eyepieces to crosshairs for alignment purposes - very easy.

 

-drl

True!

Often there are scribe marks on the field stop at 90 degrees where you can simply solder new crosswires where the old ones were. The wires have to be kept under tension (with a small weight) as they tend to lengthen while the solder is hot.

[Kasmos]

Back in May 2024 I repaired the crosshairs on two near identical finders

 

One had this field stop/crosshair cell but it's the first one I've worked on that didn't have scribed marks where the hairs go

 

On the other it was missing, so I made one from a piece cut off of a PVC conduit.

It was made thick enough to make the hairs come to focus when placed in the EP

 

Using may own hair (specially selected) I did my usually progressive taping to tighten them and Super-Gluing.

Then quickly a brass washer was placed on the glue to be a field stop.

 

Once installed a O-Ring was placed to take up the gap between it and the finder's visual back.

 

For a more detailed look and explaination, here's a link to the post:

https://www.cloudyni...day/?p=13477818

Edited by Kasmos, 21 February 2025 - 03:19 PM.

[grif 678]

Charlie:

 

I use 0.004" diameter hard brass EDM wire. It's large enough to be easily seen even under very dark skies.

 

I have quite a bit of it. If you want a foot or so, send me a PM with your addresses and I will send you some. I just tape it to a greeting card so it costs nothing to be send.

 

Jon

Jon sent me some a while back, and it woks great. Cut it with finder nail clippers, place it down into the cross hair grooves on the washer, and use a strong super glue, just enough to do the job, I put a dab on the end of a sharp tooth pick,  and use that to place the glue in the right place, without putting too much. Let it dry, then screw it into the tube, the screw on the eyepiece. It works great.

[RichA]

If you can find a compliant black widow spider to lay them down for you.

 

https://owlcation.co...of-World-War-II

[Jon Isaacs]

Most low-power finder eyepieces are Kellners or Ramsdens with an easily accessible field stop. I have one old classic finder with zapped crosshairs where the field stop is really frozen in the works, but other than that, it has always been very easy to remove it for work. I have converted a couple of 25mm Kellner eyepieces to crosshairs for alignment purposes - very easy.

 

-drl

 

In my experience, finders with Kellners and such are easily repaired, someone made them.  But they are poor eyepieces for finders because even older finders are quite fast.  

 

Jon

[x-ray]

I just replaced the wires on a 1900ish 3 inch Fecker finder for a 12.5 inch W&S refractor.  I had a roll of 44ga copper wire, a zillion feet.  This finder has screws to secure the wires, made it really easy.

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[Bomber Bob]

I have used ear bud wire. I worked in parks for years and collected lots of wire from ? patrons who left their various items, (wine glasses, bottles, pipes, ganja, undies, I pods, still half full pony kegs, nice shades, jewelry, watches, cameras and tripods on a bench, or in a shrub bed. Pleasantly distracted by ? I imagine. Our lost and found rarely had a visitor. The wire I used was relatively thick but the thickness made the crosshairs visible in a dark sky, 

 

I barely remember science projects in like Jr. High using human hair to make a hygrometer. The hair would tighten or relax depending on the relative humidity, Is that not an issue or is the hair protected within the tube?

Yep.  Dollar Tree wired earbuds.  You can get enough fine wire to re-do all your finders.

 

My coolest crosshairs are in the brass finder on my Dakin 4 -- hand-painted on a glass disk... tiny clear center gap for stars.