OLFA LBB vs. disposable microtome blades

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hans
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OLFA LBB vs. disposable microtome blades

#1 Post by hans » Thu Mar 11, 2021 1:17 am

Started playing around with hand sectioning a bit but none of the various inexpensive utility knife or single-edge razor blades I have around are particularly sharp. I see MicroBob has recommended OLFA LBB blades in the past which are ~$0.50 to $1 per blade depending on quantity. It looks like there is also new surplus of some reputable brands of disposable microtome blades sometimes available on eBay in that price range, but typically only in quantities of 50 or more. How do they compare?

BramHuntingNematodes
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Re: OLFA LBB vs. disposable microtome blades

#2 Post by BramHuntingNematodes » Thu Mar 11, 2021 5:12 am

I don't know about OLFA LBB but here are some edge profiles:

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Reichert/ Jung Model 818 Disposable Microtome Blades, typical vintage microtome knives. A human hair is draped over it for size comparison. All pictures taken with a Zeiss-Winkel(!) 25x/.4 epi-darkfield lens.

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Xacto blade lightly used.

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Xacto straight from pack.

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I believe a vintage Hyde brand single-edge razor blade.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

BramHuntingNematodes
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Re: OLFA LBB vs. disposable microtome blades

#3 Post by BramHuntingNematodes » Thu Mar 11, 2021 5:18 am

Also something to consider is that the microtome blade has two discrete bevels while the other blades don't. The single-edge razor has its edge buffed or burnished at its extremity, however.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

MicroBob
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Re: OLFA LBB vs. disposable microtome blades

#4 Post by MicroBob » Thu Mar 11, 2021 11:17 am

Hi together,
OLFA offers a blade type that probably fits better into the holders for 8mm wide blades: The OLFA ABB with 9mm width. It is from the same super sharp series but I haven't tested it.
I don't have holders to do a 1:1 comparison so I compared my Leica 818 with the OLFA LBB blades by cutting through paper tissue, starting with a stretched edge. Here the OLFA blade cut into the tissue much more easily while the Leica blade appeared blunt at first. After entering the tissue both blades cut equally well. Reason is not that the Leica blades are blunt but they are teflon coated whicht blunts the edge to some degree. I'm not sure how hard the Leica blades are, they seem to dull quickly. The OLFA blades are fairly hard an I have cut hundered of sections with half of one blade with only light stropping on plain leather before use. The OLFA LBB are a lot sharper and smoother than ordinary blades and still a good bit sharper than the best Tajima blades. I think the OLFA LBB blades have two bevels and the Leica 818 three.

The best blade won't help you though without a fitting holder that clamps the blade right behind the edge. There are microtome blades with 35° included angle and I think 22° or so.

Bob

hans
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Re: OLFA LBB vs. disposable microtome blades

#5 Post by hans » Fri Mar 12, 2021 5:53 am

Interesting photos, Bram, the edge on the R-J blade looks very nice
BramHuntingNematodes wrote:
Thu Mar 11, 2021 5:18 am
Also something to consider is that the microtome blade has two discrete bevels while the other blades don't. The single-edge razor has its edge buffed or burnished at its extremity, however.
When counting bevels, is that including the main wedge or just small bevels near the cutting edge from final sharpening? I have a few X-acto brand blades with a single bevel after the main wedge that are noticeably sharper than my Irwin snap-off blades and Stanley utility blades. They slice nicely but I was looking for some larger blades to try out the AO table microtome I bought.
MicroBob wrote:
Thu Mar 11, 2021 11:17 am
The best blade won't help you though without a fitting holder that clamps the blade right behind the edge.
Makes sense, I saw your 3D-printed holder. I haven't worked out a good blade holding solution to use with the table microtome yet. Have you tried sticking disposable blades to a more substantial wedge of metal with thin double-sided adhesive tape?
MicroBob wrote:
Thu Mar 11, 2021 11:17 am
There are microtome blades with 35° included angle and I think 22° or so.
Yeah some of the disposable ones I saw were 35 degrees. I didn't see angle anywhere on OLFA's site but some retail sites list 59 degrees. If correct that is quite a difference, maybe helps explain why the Leica blades dull quickly compared to LBB?

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Re: OLFA LBB vs. disposable microtome blades

#6 Post by MicroBob » Fri Mar 12, 2021 8:45 am

A metal wedge would have to have an included angle of half the edge angle, so be knife like thin. Machining such a wedge is not easy as internal stresses in the material lead to warping. And gluoeing the blade on wouldn't allow quick changes. Perhaps you can build a mould and cast a holder from reinforced epoxy?

The 60° angle of cutter blades is at the top, blade seen from the side. The micro bevels of the OLFA LBB seem to have an included angle of a little less than 35° according to my experiments. I haven't ground a blade and inspected it under a measuring microscope as there was no need.
If I would sell microtome blades I would try to offer a blade that cuts well but has an edge of limited life. :mrgreen:
The cutter blades have to stand the practical minded judgement of craftsmen and logistics people and quick dulling blades would sell well.

hans
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Re: OLFA LBB vs. disposable microtome blades

#7 Post by hans » Fri Mar 12, 2021 6:06 pm

MicroBob wrote:
Fri Mar 12, 2021 8:45 am
A metal wedge would have to have an included angle of half the edge angle, so be knife like thin.
Good point, I hadn't carefully thought through, but since blades are ground symmetric there is only room for half the included angle (plus the clearance angle if there is slight overhang of the blade?) on the specimen side. I have read suggestions in 5-10 degree range for clearance angle between the back of the blade and specimen... is that what you use with the LBB?

I wonder if it would be possible to support the blade from the front with a larger angle wedge as long as the transition from blade to wedge was smooth? Or would the transition interfere too much with the sections sliding off?
MicroBob wrote:
Fri Mar 12, 2021 8:45 am
The 60° angle of cutter blades is at the top, blade seen from the side. The micro bevels of the OLFA LBB seem to have an included angle of a little less than 35° according to my experiments. I haven't ground a blade and inspected it under a measuring microscope as there was no need.
This makes more sense, I was thinking 59 sounded too high for a very sharp edge.
MicroBob wrote:
Fri Mar 12, 2021 8:45 am
If I would sell microtome blades I would try to offer a blade that cuts well but has an edge of limited life.
Sounds familiar... how long until we get $99 rotary microtomes accepting proprietary 7-blade sectioning cartridges?

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Re: OLFA LBB vs. disposable microtome blades

#8 Post by BramHuntingNematodes » Fri Mar 12, 2021 7:19 pm

hans wrote:
Fri Mar 12, 2021 5:53 am

When counting bevels, is that including the main wedge or just small bevels near the cutting edge from final sharpening? I have a few X-acto brand blades with a single bevel after the main wedge that are noticeably sharper than my Irwin snap-off blades and Stanley utility blades. They slice nicely but I was looking for some larger blades to try out the AO table microtome I bought.
Image
Microtome Blade: this has a secondary bevel cut into the side well away from the point. Note the primary bevel continues on for some distance off camera before meeting with the flats. The microtome blade is perhaps twice as thick as the typical single edge razor.

Image
Single Edge Razor: this has a more obtuse secondary micro-bevel honed much closer to the point. Here you can see the primary bevel end and the flats proceed readily.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

MicroBob
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Re: OLFA LBB vs. disposable microtome blades

#9 Post by MicroBob » Fri Mar 12, 2021 8:14 pm

Hi Hans,
in theory one always would use a clearance angle. For paraffin sectioning i know of angles between 1 and 5 even 8?°. In practice things can be different. The 35° angle is only between tiny micro bevels that can be ignored in some cases. For sectioning fresh material with cylinder microtome it is proven that an inclination of 14° cuts slightly better than 17,5° or more. Actually a negative clearance angle! Shocking but true. :D
Can you make a sketch of your intended wedges? Anc can you show a picture of your microtome?

Bob

hans
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Re: OLFA LBB vs. disposable microtome blades

#10 Post by hans » Mon Mar 15, 2021 6:19 pm

I currently have the jack screw, parallel bar linkage, and specimen vise removed for relubrication but here is what the frame with glass knife slides looks like. Also attaching a picture from "Effective Use and Proper Care of the AO Microtome" which only mentions the model 900 briefly. I didn't find a manual for the 900 but it seems pretty self-explanatory. The little thumb wheel on the bottom of the jack screw is graduated in 5 um increments. The unsupported length of blade between the two glass slides is 45 mm. That AO document also has a diagram defining various blade angles which I had been referencing, attached below. Is the 14° inclination you are referring to what is labeled "FC" in that diagram?

Interesting photos again, Bram. Have you tried making an impressions of an edge in some softer material? That AO diagram shows the shape of an impression but I am not sure if that is just how they are illustrating it or if taking impressions of the edge to check angles is actually something that is commonly done.
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MicroBob
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Re: OLFA LBB vs. disposable microtome blades

#11 Post by MicroBob » Mon Mar 15, 2021 6:47 pm

hans wrote:
Mon Mar 15, 2021 6:19 pm
Is the 14° inclination you are referring to what is labeled "FC" in that diagram?
The AO knife has a wedge shape while the cutter blade is rectangular over most of it's depth. This makes comparison a bit difficult. The 14° are the angle between holder gliding surface and center axis of the blade (which is parallel to the contact surface between blade and holder).
For paraffin cuts you will need a little free angle "H" of a few degrees. For sectioning fresh material with a cutter blade "H" could be a little negative in relation to the very fine micro bevel. For sectioning fresh material you will need a slicing cut, of a ratio of slide 5 to 10, cut 1. Since your microtome is rather wide and has a lot of distance between the glass guides you would need a stiff and long blade holder for this. I think it is made for embedded objects rather than fresh object sectioning. What does the manual say?

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Re: OLFA LBB vs. disposable microtome blades

#12 Post by hans » Mon Mar 15, 2021 7:36 pm

I did not find a manual specific to the model 900. The more general microtome guide I linked only has a short description:
The table microtome is a hand microtome with a clamp for fastening it to the edge of a table. Fresh materials are mounted in the table microtome in a manner similar to a hand microtome and are sectioned in the same manner. Harder materials are usually sectioned with a chisel shaped knife. A plane bit sharpened to a keen edge is satisfactory when very thin sections are not required. ln cutting hard material the handle of the knife is held against the hip and the cut made by swaying the body. This gives a very firm hold and frozen sections may be cut. The table microtome, Fig. 16, is arranged to take the ordinary specimen holder and it is possible to cut paraffin and celloidin embedded material, although this is more difficult than with the larger microtomes.
The pack of 10 LBB I ordered just arrived and they are indeed very sharp, much sharper than the Irwin blades I already had.

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Re: OLFA LBB vs. disposable microtome blades

#13 Post by MicroBob » Mon Mar 15, 2021 7:43 pm

And after using them for microtomy they go to the work shop...

Greg Howald
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Re: OLFA LBB vs. disposable microtome blades

#14 Post by Greg Howald » Tue Mar 16, 2021 4:03 am

I wonder who is going to develope a high enough quality ceramic blade?
For myself I have a very simple microtome. I make my own to make specimens of varying thickness using two double edge blades with a spacer between. The specimen gets stuck between the blades and I fish it out with a needle. But even a single layer of scotch tape between the blades can result in a specimen being too thick. There must be a spacer or the specimen has no place to go and is crushed. I use the thinnest material I can find.
Greg

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Re: OLFA LBB vs. disposable microtome blades

#15 Post by MicroBob » Tue Mar 16, 2021 10:21 am

Hi Greg,
I think that on the finest level ceramics are too coarse for such fine cutting. The grain structure of steel is probaly finer. The edge is also under some load and brittle ceramics edges might wear by grain that breaks away. For ultra-microtomy freshly broken glass knives are used - very interesting.

Tony has recently shown convincing sections made with Walter Diony's method: https://www.microbehunter.com/microscop ... ons#p99670
I have tried the method and it worked well for leaves, but I can't remember how I kept the blades apart,

Bob

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Re: OLFA LBB vs. disposable microtome blades

#16 Post by hans » Wed Mar 17, 2021 1:51 am

What is a good brand/source for those very thin double-edge blades? Walter Dioni's article shows a 100 um thick blade. The single-edge blades I have are more like 300 um so would give pretty thick sections if used that way.

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Re: OLFA LBB vs. disposable microtome blades

#17 Post by MicroBob » Wed Mar 17, 2021 6:57 am

The classic disposable double edge razor blades are about 0,1mm thick. So typically you would get a section of 0,1mm plus spacer, not thin but usable. Depending on your dexterity you might also try free hand sectioning.

Edit: "Wilkinson Sword" is the brand I bought recently and measured for you. But I think they are all around 0,1mm.

hans
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Re: OLFA LBB vs. disposable microtome blades

#18 Post by hans » Thu Mar 18, 2021 3:13 am

Thanks Bob, I did try some free hand slicing with the other blades I had, haven't tried with the LBBs yet. May try getting some of the double-edge shaving razors also out of curiosity. One difficulty was getting the blade to bite at the start of the cut very close to the end of the stem without deflecting the corner and sliding off. I was hoping the sharper blades might help with that.

Still not sure about using the LBB blades on the AO table microtome, maybe a longer-term project. In the mean time I made lowball offers on a couple old-style microtome knives (with handles) and one was accepted. So I will play around with sharpening that (not too easy, I understand) and maybe also try using it as a support taped to the front side of the LBB blades and see if the slices can make the transition from the LBB bevel onto the the microtome knife ok.

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Re: OLFA LBB vs. disposable microtome blades

#19 Post by MicroBob » Fri Mar 19, 2021 10:28 am

For free hand sections the right strategy is important: Better not try to acheive a full and even section as this will likely become too thick. Better cut a wedge, starting either from the outside and become narrover or from the surface and slowly enter it. Then parts of the section will be just right.

For you AO microtom you could make a blade holder from a positive model (e.g.wood) in a plaster mould. Filling it with degreased all-thread of different diameters and epoxy will ead to a stiff wedge of the right angle.
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hans
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Re: OLFA LBB vs. disposable microtome blades

#20 Post by hans » Sat Mar 20, 2021 12:20 am

Good ideas, I will try cutting thin wedges starting or ending on the face next time.

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