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More "forgotten wisdom" - The Zip Tie mod...

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#1 Eddgie

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Posted 02 August 2019 - 01:10 PM

I did not come up with this one, but it is a great submission by one of the forum members maybe 5 years ago.  Again, a lot of new users in that time and this one may have slipped out of the current best practice knowledge base.

 

Many inexpensive BVs have screws that retain the eyepeice.  Some have one and a compression band, but some have three holes. Often only one hole has a screw in it and it is typical that the spare screws will be in the case. Often these work against the compression band.

 

Now this setup serves a purpose. Generally there is a tiny bit of play in the eyepiece holder, and the three screws (in theory) would let you slightly sift the eyepieces to allow slight changes in accomdation.   

 

Here is the problem though.  These screws/band do not play well with undercuts.  What happens is that if the screw tip goes into the undercut, it takes several rotations of the screw to get it to clear the undercut so that the eyepiece can be removed!  If you change eyepieces a lot, this can be a real nuisance. 

Here is the "Zip Tie mod."   First, remove the compression band (and again, this is primarily for eyepiece holders that use one or three screws).  Now, find a small zip tie.  You want one that is as wide as the groove for the compression band.  It can be a little narrower but in a perfect world, it would be just very slightly less then the width of the groove.    

 

Cut the zip tie to the lenghth just sufficient to go into the slot all the way around. A small gap is OK, no gap is better. 

 

Next try to insert an eyepiece. If the zip tie sits proud of the slot, the eyepiece will not clear it.  If this occurs, you need to thin the band until it does.  The easiest way to do this is use sandpaper.   It will take several tries to get it right, but when you have it right, the zip tie should fit flush to the inner barrel so that when the eyepiece is inserted there is slight or no drag.

 

Now, when you use the small screws to hold the eyepiece in, the screws press against the back of the zip tie, driving the zip tie onto the safety undercut.  This greatly limits the amount of turning needed to get the screw/metal band to clear the undercut. 

If the unit is well collimated, you may even find that you can use the zip tie as a replacement for the screws.  In this case, the zip tie is left a little thicker and the top side is beveled slightly so that the eyepiece is simply pressed into place and is held by the friction of the zip tie.  I had my Maxbright set up this way and with light eyepieces, I did not even have to tighten anything after the eyepeice was in.  When I used the zooms, I used just one screw to put enough pressure to keep them from slipping when I zoomed. 

 

This tip may not help very many people but if may help someone today, or maybe one day in the future. 

 

A lot of these little tricks and tips get lost.  These are form many years ago, and there are a lot of new users that maybe have not seen them. 


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#2 TOMDEY

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Posted 02 August 2019 - 01:49 PM

Very good! One of these nights, one of these nights, Alice... some inventor will develop a ~Smart Focuser~ comprising an  "eyepiece recognition Ap", which will notice what eyepiece is coming its way --- and adaptively compensate exactly for that eyepiece. But, until then... Zip Ties!    Tom


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#3 junomike

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Posted 02 August 2019 - 02:14 PM

I do recall that thread although I my TV BV's don't require the  ZTM (Zip Tie Mod).



#4 Eddgie

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Posted 02 August 2019 - 04:55 PM

Yeah, this is really only good for the BVs that have the radial screw(s) with compression band.

 

 

It would not work on the Arcturus.   I see a lot of the WO and similar BVs for sale though, and for someone that buys a used one, this could be a handy tip

 

Now the older Burgess has smooth inside walls with no compression band, so this does not work for me, but I really only use zooms with this, so the diopters are locked down, and the zooms are locked into a parfocal position with one another.  The only time I use BVs is when I am doing solar system work.



#5 Ed D

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Posted 05 August 2019 - 07:33 AM

Thanks for reviving this idea.  I remember reading about it years ago and did it to my William Optics BV.  I'm still using the original pieces of Zip Tie to this day.  It really does work!

 

I use older Sirius Plossls with my BV because they have the smooth hard chromed barrels.  I believe most of the Meade series 4000 Plossls are still sold with smooth barrels.  I have owned a few and they are very good eyepieces.

 

Ed D




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