Coverglass Clamp

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ldflan
Posts: 21
Joined: Wed May 22, 2019 11:36 pm

Coverglass Clamp

#1 Post by ldflan » Thu Oct 21, 2021 12:09 am

I frequently make wholemounts of leaves and vibratome thick sections. It's often helpful to clamp the coverglass in place while the mounting media sets up. Over the past several years I have really struggled to find a good way to do that. I've tried weights of various sorts, clothes pins, bent wires, IV tubing clamps -- a whole host of things various authors have suggested or I have thought up, and until recently none worked really well.

So I thought I would share what I eventually came up with. While not perfect, it is by far the best clamping mechanism I have used.

The absolutely necessary core component is a set of cheap carbon fiber anti-static fishbone tweezers from China. I don't know who actually makes them, but they are black plastic and marked "93304." They can usually be found on Amazon or Ebay, or certainly on Alibaba in packages of 10, 20 or 300, or as part of a set of different shaped forceps. I think I paid $10 with shipping for 20 of them. THESE FISHBONE TYPE ARE THE ONLY SHAPE THAT WILL WORK. Don't even bother with the others.

Next, take two hardwood boards, approximately 20mm x 50mm, place a 1cm spacer at each end (a stack of washers will do) and then screw them together through the spacers at each end. You're done.

The picture shows how it is used. The amount of pressure applied is readily adjustable by simply sliding the forceps further in or further out.
IMG_20211020_163933.JPG
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If you come up with an improvement, let me know!

Leonard

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mrsonchus
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Location: Cumbria, UK

Re: Coverglass Clamp

#2 Post by mrsonchus » Thu Oct 21, 2021 12:29 am

Love this idea, always a problem with as you say thicker mounts.
Just ordered a pack of 20 from you know where, <£7 delivered to the U.K.....
Thanks for the tip.

Great for permanent hand-section mounts not to mention smaller whole-mounts.

Ordered these, they look identical to yours,
tweezers.jpeg
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John B

PeteM
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Location: N. California

Re: Coverglass Clamp

#3 Post by PeteM » Thu Oct 21, 2021 1:43 am

One could also make a ring to fit over the forceps - slide it up to vary the compression as needed. A right-sized o-ring would work. The bottom of the slide could rest on a short piece of similar board (say, 3" long), with a cutout to clear the forceps on the underside of the slide.

ldflan
Posts: 21
Joined: Wed May 22, 2019 11:36 pm

Re: Coverglass Clamp

#4 Post by ldflan » Thu Oct 21, 2021 2:27 am

A good thought, but unfortunately the ring idea doesn't work - tried every size I could find, but the shape of the forceps is such that you can't get a consistent variation on the pressure by sliding it up or down.

Leonard

PeteM
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Location: N. California

Re: Coverglass Clamp

#5 Post by PeteM » Thu Oct 21, 2021 5:42 am

ldflan wrote:
Thu Oct 21, 2021 2:27 am
A good thought, but . . .Leonard

Bummer. I like the idea of plastic tweezers you've discovered.

FWIW, I've also had luck -- but with metal tweezers meant for holding parts for soldering and gluing -- using a custom-wire ring (squared shape) or a bit of surgical tubing of the right ID and cut a couple cm. long. The tubing will stay put where it's positioned.

ldflan
Posts: 21
Joined: Wed May 22, 2019 11:36 pm

Re: Coverglass Clamp

#6 Post by ldflan » Thu Oct 21, 2021 11:08 am

Yes, a square wire ring or maybe a chain link of just the right size would probably work. On the other hand, you don't really want them to move around and dislodge anyway, so the board assembly facilitates that.

Leonard

MichaelG.
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Re: Coverglass Clamp

#7 Post by MichaelG. » Thu Oct 21, 2021 10:14 pm

Looks an excellent idea … I’ve just ordered some.

MichaelG.
Too many 'projects'

MichaelG.
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Re: Coverglass Clamp

#8 Post by MichaelG. » Thu Nov 04, 2021 2:15 pm

No fault of yours, Idflan … but I am very disappointed with my purchase :(

Of 20 pairs … 7 arrived broken, and another 7 with badly-chipped tips

MichaelG.

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Edit: __ and here’s an example of a chipped tip :
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A37FE96F-3462-4C8D-B4ED-F05F7303B8E7.jpeg
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This clearly not ‘carbon fibre reinforced plastic’ as we usually know it !
Too many 'projects'

ldflan
Posts: 21
Joined: Wed May 22, 2019 11:36 pm

Re: Coverglass Clamp

#9 Post by ldflan » Mon Nov 08, 2021 5:06 pm

Wow, those are garbage! How frustrating and what a waste. The past several months I have had a record number of similar "bait and switch" purchases, attempts to sell me items that have clearly already been returned as defective, etc. I guess it's probably ramifications of the pandemic shutdowns. I'm not sure the ones that I have are really carbon reinforced, but at least none of them are defective, and none have broken. :(

MichaelG.
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Re: Coverglass Clamp

#10 Post by MichaelG. » Mon Nov 08, 2021 8:19 pm

Thanks for your empathy

With a little persuasion, the seller has refunded 70% … so I have only paid for the six that arrived intact.

… Whether they are any good at all remains to be seen.

They appear to have gone through some sort of Postal handling machine, and [being brittle], just snapped !

MichaelG.

.

P.S. I had a problem a couple of years ago : Bought a very good mount for putting the iPad on a tripod.
… It was so good that I rushed back to ebay to buy a couple more.
Seller apologised that he had no more of them.
Found another seller of apparently the same item, but when they arrived; the design was the same, but the material was much more flexible.

As John Ruskin is reputed to have said :
There is hardly anything in the world that some man cannot make a little worse …
Too many 'projects'

PeteM
Posts: 2008
Joined: Tue Dec 06, 2016 6:22 am
Location: N. California

Re: Coverglass Clamp

#11 Post by PeteM » Wed Nov 24, 2021 6:53 am

My small assortment of cheap tweezers finally arrived today. In this case, unbroken. FWIW, this batch was nicely molded, unlike the rough finish inside in the batch Michael received.

Another clamping option is to run a tap thread drill through both sides, then a clearance drill on one side, and tap it for a small thumbscrew. The "carbon fiber" (?) plastic threads OK. It takes little more than a minute to run the drills and a tap through.

There's enough "meat" to go a bit larger with the thumbscrew (this one a 4-40, with its coarser threads better suited to plastic than something like an M3) and to move the hole location closer to the working end where it would be easier to operate with one hand.

On edit: second thumbscrew size (6-32) and placement below. Thanks to idflan for alerting us to these tweezers.
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Tweezer.jpg
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Tweezer2.jpg
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ldflan
Posts: 21
Joined: Wed May 22, 2019 11:36 pm

Re: Coverglass Clamp

#12 Post by ldflan » Wed Nov 24, 2021 6:32 pm

Hi, Pete.

The ones you have there aren't the fishbone type, from what I can see, but another similar configuration that are made by the same factory and often sold in sets with the fishbone variety. They don't work as well as the fishbone shape because the clamping surface is larger on the ones you have, and mounting media can get on it more easily. You should try to lay hands on the fishbone version if you can!

The fishbone shaped ones are marked "93304."

Love the thumbscrew idea!

Leonard

PeteM
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Joined: Tue Dec 06, 2016 6:22 am
Location: N. California

Re: Coverglass Clamp

#13 Post by PeteM » Wed Nov 24, 2021 7:23 pm

Leonard, The assortment I got had one of the fishbone version, which I intend to use. Thought I'd mess with the others first, before getting to that one. Cheers, Pete

ldflan
Posts: 21
Joined: Wed May 22, 2019 11:36 pm

Re: Coverglass Clamp

#14 Post by ldflan » Wed Nov 24, 2021 9:32 pm

Ah, good! I see there are a number of sellers in China offering a set of 20 of the fishbone version on eBay at $12 and change right now.

I am definitely going to give your thumbscrew idea a try, but I think the two boards just might end up working better. I do know that getting the pressure just right with the board arrangement is really easy and goes smoothly -- just slide the forceps in until the media hits the edge of the slip -- no fiddling or fussing with a screw mechanism. Also with the boards, the slide stays at the same angle throughout the adjustment operation, so there is perhaps less chance of the cover slip shifting out of place by accidentally tilting it without enough pressure applied.

Leonard

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