Centering microscope

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Centering microscope

This topic has 15 replies, 10 voices, and was last updated 14 October 2018 at 22:34 by Clive Hartland.

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11 October 2018 at 17:33 #375505
Gray62
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@gray62
Having sourced a Beck teaching head, I am now constructing the centering microscope as described in MEW 272.

I need a graticule but the ones from Hemingway are a bit pricey. Having looked on ebay, and a few other places, I can't find one that is small enough, most are over 20mm in diameter. Does anyone know of a source for these ?
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11 October 2018 at 17:33 #19107
Gray62
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@gray62
looking for a graticule
11 October 2018 at 17:51 #375509
Emgee
Participant
@emgee
Mitutoyo but they won't be cheap.

Emgee
11 October 2018 at 18:20 #375513
Martin Connelly
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@martinconnelly55370
iGauging may have somthing that suits.

Martin C
11 October 2018 at 18:21 #375514
Michael Gilligan
Participant
@michaelgilligan61133
I haven't yet read the article, but:
1. Top quality reticles |*| are [almost] never cheap
2. A quick search on ebay, for 'eyepiece reticle' sorted by 'lowest price + postage' found several that should be useable about £8 each.
Out of interest: What exactly is Hemingway selling, and at what price ?

MichaelG.

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|*| https://www.pyseroptics.com/graticules/microscope-eyepiece-reticles/

Edited By Michael Gilligan on 11/10/2018 18:23:54
11 October 2018 at 20:09 #375526
Gray62
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@gray62
Posted by Michael Gilligan on 11/10/2018 18:21:08:

Out of interest: What exactly is Hemingway selling, and at what price ?

MichaelG.

.

The Hemingway graticule is a crosshair with concentric circles, approx 17mm dia and £34 + p&p which in the grander scheme of things is not horrendous but, it represents a significant outlay when compared with what the rest of the parts cost me.
11 October 2018 at 21:53 #375548
Neil Wyatt
Moderator
@neilwyatt
Might be worth getting one of the combined eyepiece/reticles as they only cost about a pound more. Not sure if they are adjustable though.

Neil
11 October 2018 at 22:06 #375553
Michael Gilligan
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@michaelgilligan61133
Posted by NLP on 11/10/2018 20:09:24:

The Hemingway graticule is a crosshair with concentric circles, approx 17mm dia and £34 + p&p

.

If you need one with circles, then this one seems reasonable: **LINK**

https://www.ebay.co.uk/itm/Microscope-Eyepiece-Micrometer-Reticle-Concentric-Circles-Calibration-1X-2X-4X/323270458650

If you can manage without circles … I found one at £3.20

https://www.ebay.co.uk/itm/Microscope-Objective-Stage-Micrometer-Calibration-Slide-10mm-100-0-1mm-C7/262480477627

[ it's not very well described, and comes from a seller with zero feedback, but it may be a bargain ]

MichaelG.

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P.S. Neil makes an excellent point … but I very much doubt they are adjustable for centration.

Edited By Michael Gilligan on 11/10/2018 22:11:21
12 October 2018 at 06:48 #375573
Gray62
Participant
@gray62
Michael,

thanks for those links, Think the first one will fit the bill as it's only 16mm diameter which will be perfect for this application.

cheers

Gray
13 October 2018 at 22:32 #375837
John Reese
Participant
@johnreese12848
You could go "old school" and use spider silk for the crosshairs. I believe silk from the Black Widow spider was the preferred material.
13 October 2018 at 22:53 #375839
Clive Hartland
Participant
@clivehartland94829
I was waiting for someone to come up with spider web. First catch your spider and put him in a box on his own. Then you starve him ! why, because when he craps it is attached to the web like a round object. After starving for a while get the spider onto a wire frame, wind the web he issues around the frame spaced apart so you can lay the strand across the cell where you want the cross wires. Fix in place with shellac.

Some backgrounnd, spidere web graticules absorb the shock of recoil in the telescope on the artillery piece. Mostly used on coastal artillery. All superceded now by etched graticules or photo etched and coated. One time they were drawn finely on beeswax on the surface of the glass and placed over an open mouth of a bottle of Flouric acid. Nasty!
13 October 2018 at 22:54 #375840
Michael Gilligan
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@michaelgilligan61133
Posted by John Reese on 13/10/2018 22:32:13:

You could go "old school" and use spider silk for the crosshairs. I believe silk from the Black Widow spider was the preferred material.

.

But unless the spider is uncommonly co-operative, it's unlikely to produce the circles that Gray would like.

MichaelG.
14 October 2018 at 00:28 #375848
Mark Rand
Participant
@markrand96270
Just weigh his clogs down on one side, so he walks in circles?
14 October 2018 at 10:59 #375875
daveb
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@daveb17630
Posted by Clive Hartland on 13/10/2018 22:53:25:

I was waiting for someone to come up with spider web. First catch your spider and put him in a box on his own. Then you starve him ! why, because when he craps it is attached to the web like a round object. After starving for a while get the spider onto a wire frame, wind the web he issues around the frame spaced apart so you can lay the strand across the cell where you want the cross wires. Fix in place with shellac.

Yes! That's exactly how I did it nearly 60 years ago but we used to buy the web ready wound on cardboard frames. I always checked to make sure there were no spiders in the box. I should think the web winding trade has died out by now, so if you need to do this, you will probably have to catch you own Black Widow. I believe it needs to be female, they're a bit bigger than the males. Daveb

Edited By daveb on 14/10/2018 11:00:38
14 October 2018 at 21:47 #375984
Mick B1
Participant
@mickb1
Posted by Clive Hartland on 13/10/2018 22:53:25:

…

Some backgrounnd, spidere web graticules absorb the shock of recoil in the telescope on the artillery piece. Mostly used on coastal artillery.

…

I knew they were used in telescope graticules, but not gunsights. I think it will be because that was the easiest way to make them. In point of fact the recoil shock on an artillery piece has lower g-force than small arms – muzzle velocities are in similar ranges and the barrel length, and therefore time, for acceleration are very much greater. The snap of a good air-rifle's spring piston bottoming imposes the most severe reticule shock of all – scope creep and even breakage has required specialised design effort to resolve.

Added to that, artillery scope sights are generally mounted on the fixed carriage, further decoupling the shock.
14 October 2018 at 22:34 #375996
Clive Hartland
Participant
@clivehartland94829
I would look at this as an old time method, as said earlier the technique of making fine graticules was not developed and as Artillery telescopes were of a medium power big fat scored graticules filled with black were not accurate enough.

Making the grat. from spiders web gave a very thin graticule which suited the application fine..Consider that in older guns the gun was bore sighted using horse hair across the muzzle and the telscope aligned with it by looking through the barrel from the vent tube. Targets were church steeples or any other well difined object more than 400 yards away. Nowadays they set up a big board with the sighting marks on the board for the bore and the telescope and even the small bore weapons. Any minor adjustments are then made on the range. Thats why i am deaf!
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