Two-blades method - possible to improve?

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patta
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Two-blades method - possible to improve?

#1 Post by patta » Wed May 05, 2021 12:03 pm

I tried the two-razor blades method for making thin sections;
It works but is fiddly and I cut myself..

I had this idea to improve it, if somebody has a 3D printer and time/ideas to design it.
It consist in holding the blades at an angle, so the thin slices in the middle don't get clumped, and should be possible to cut thinner sections a bit more reliably.

The 3D-printer object is just an holder to keep the two blades in place; each blade sits in a support, the two supports are connected by braces. Plus a short handle to use the tool. Basically it is like a modified disposable multiblade razor, the main difference is that the blades are much nearer, slightly angled to each other and held firmly so won't flex ad open/close the gap.
It would benefit some fine adjustment method to get the blades aligned and at the desired distance. Using the flexure of properly designed 3D parts may be the way to achieve the fine adjustment.

Just drop the idea, if somebody is interested!
Which blades, I don't know, either the Olfa, or straight razor blades... some standard mount.

Links:
the two-blades method
http://www.microscopy-uk.org.uk/mag/art ... plants.pdf
there should be some thread in this forum, but couldn't find them
The OpenFlexure microscope, for how to get precise movement from 3D-printed parts:
https://openflexure.org/projects/blockstage/
Two-blade holder for thin section
Two-blade holder for thin section
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One example of fine adjustment with elastic 3D printed parts, like OpenFlexure
One example of fine adjustment with elastic 3D printed parts, like OpenFlexure
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wstenberg
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Re: Two-blades method - possible to improve?

#2 Post by wstenberg » Wed May 05, 2021 1:47 pm

There is a double scalpel knife, used in periodontology. It's often called a Harris knife, after the author who first described the surgical technique. They come in a variety of widths. I wonder if they would be useful for thin sections? Both blades are parallel, though, not angled like your description... At least it keeps your fingers away from the sharp ends!
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Greg Howald
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Re: Two-blades method - possible to improve?

#3 Post by Greg Howald » Wed May 05, 2021 2:01 pm

I mount the two blades between two microscope slides and carefully tape it together so I have a handle.
Greg

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Re: Two-blades method - possible to improve?

#4 Post by MicroBob » Wed May 05, 2021 4:23 pm

Angling the blades could improve the quality of the sections. The included angle of the micro bevels of one blade will be around 35°. So the inclination would be 17,5° plus clearance angle. For fresh sectioning it has shown that the back of the microbevel can slide above the section a bit without doing harm, so a good starting point for the inclination of a single blade would be 14°, leading to 28° included angle between blades. The disadvantage of this is that the outer angle will be 14°+35°=49° so it will not enter easily and far into the specimen and leave damages that will be a problem for the following section. For leaves it will work well though.

I would suggest to better make a blade holder that holds the blade and move it over a cylinder microtome of some kind. This is much more versatile.
There is a fairly cheap but still usable cylinder microtome available from china: https://www.aliexpress.com/item/1005001 ... web201603_

Not "Approved by MicroBob" but usable.

Bob

Greg Howald
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Re: Two-blades method - possible to improve?

#5 Post by Greg Howald » Thu May 06, 2021 10:46 am

I like the idea of angled blades and will try that In the future. But it will be a while. My current schedule is in the field of mineralogy for the next couple of months.
I suppose that during this time My pond water will die off too. So many subjects. So little time. A great hobby and profession. Nothing like enjoying your work. 😃
Greg

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Re: Two-blades method - possible to improve?

#6 Post by patta » Fri May 07, 2021 8:49 am

Thanks for the replies!
but at a check with reality, it didn't work.
I tried to cut sections with the "two angled blades", either glued or kept in position by two microscope slides, as Greg suggested.

As Bob wrote, they form a wedge; this wedge actually wedges in the specimen, making the cut difficult, and worse, the two blades get pushed against each other.
The few-micrometers gap that I've carefully left between the two blades, when I'm cutting, gets closed immediately by the wedging force (the blades are thin and flexible), so no thin section comes out from it, it makes only one cut, instead of the two I was dreaming of.

Try before speaking.... Maybe with smaller wedge angle, less than the micro-bevel. That is how the original two-blade method works. I'll try again. Or just order the cylinder microtome.

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Re: Two-blades method - possible to improve?

#7 Post by MicroBob » Sat May 08, 2021 7:16 am

I think the two-blade method is best for flat specimen like leaves. As soon as the specimen are round and bigger or harder the struggle will increase. So I wouldn't spend too much energy into optimising this method.
If you look for alternative solutions: A well sharpened wood plane can take of chips of down to 0,01mm. So depending on the specimen and the way it is held this might work too.

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