The rubber band shim

sɐǝɹpu∀

riverrun
Shimming modern GEM blades for use in vintage razors is nothing new and I have written about it ↪here.

Here's another way of doing it and one I quite like - the rubber band shim:
The rubber band in the following pictures is 1 inch long (when laid flat) and ¼ inch wide (rubber bands seem to be measured in inches). The blade with the rubber band is 2.19mm thick, which is slightly more than required, but it works really well. The rubber has the added advantage that it properly removes any blade chatter. One thing to keep in mind when using the rubber band shim is that the rubber band stops the blade from sliding around in the head, so you shouldn't rely on the spring in the head moving the blade towards the blade stops. Just make sure the blade is seated properly when closing the head.




One disadvantage of the rubber band shim is the availability of suitable rubber bands. I have one rubber band of the correct size and no idea where it came from. If you know of a good source of 1 (maybe 1¼) inch long, ¼ inch wide rubber bands, please let me know.
 

Gordy

Legendary Member
I was trying to find different bits of material to suit but I found bike tyre tubes cut to size to work. My calipers have vanished so I've no idea on the dimensions, they just look right.
 

sɐǝɹpu∀

riverrun
I was trying to find different bits of material to suit but I found bike tyre tubes cut to size to work. My calipers have vanished so I've no idea on the dimensions, they just look right.
Interesting idea... How big/thick are bike tyre tubes? I can't believe they are small/thin enough... will look into this...
 

sɐǝɹpu∀

riverrun
I thought about that but then str8s caught my attention.
I would try with the road bike (23mm) tubes.
23mm what? Diameter? That would yield a 'rubber band length' of 23mm*PI/2 ≅36mm. A GEM blade is 38.9mm wide, so that should work out OK... How thick are those tubes? Are some thicker than others? Intriguing...
 
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lloydrm

Forum GOD!
Alright, off my comfy zero-gravity chair I go ...

23mm actually refers to the tire size the tube fits in. This used to be the most popular ti(y)er size. So if you got to your local bike shop, you would ask for a tube for a 23mm ti(y)re, even though they fit different sizes.

IMG_1829.JPG


So actually it is a bit small for the blade. Fitting is was a don´t try this at home kids kind of thing.
This is a repurposed blade so I used pliers to hold it while fitting the rubber band.

IMG_1830.JPG

IMG_1832.JPG


So maybe, if you are going to get a tube just for that, you could get one for a 25 or even a 28 mm tire. Maybe that will make the fitting process a bit easier/safer.
Now, tube thickness is like politician performance: there are differences but for the purpose and for practical reasons, we are safe assuming they are all the same.

Here are the comparison thicknesses.

Just the blade
IMG_1833.JPG


Rubber band

IMG_1831.JPG


And my standard half spine shim

IMG_1834.JPG


Now, since I am now into straight razors, this got me thinking: what if you tape the spine with electrical tape? That would give you the additional benefit of thickness adjustability.
 

sɐǝɹpu∀

riverrun
Alright, off my comfy zero-gravity chair I go ...

23mm actually refers to the tire size the tube fits in. This used to be the most popular ti(y)er size. So if you got to your local bike shop, you would ask for a tube for a 23mm ti(y)re, even though they fit different sizes.

View attachment 19302

So actually it is a bit small for the blade. Fitting is was a don´t try this at home kids kind of thing.
This is a repurposed blade so I used pliers to hold it while fitting the rubber band.

View attachment 19303
View attachment 19305

So maybe, if you are going to get a tube just for that, you could get one for a 25 or even a 28 mm tire. Maybe that will make the fitting process a bit easier/safer.
Now, tube thickness is like politician performance: there are differences but for the purpose and for practical reasons, we are safe assuming they are all the same.

Here are the comparison thicknesses.

Just the blade
View attachment 19306

Rubber band

View attachment 19307

And my standard half spine shim

View attachment 19308

Now, since I am now into straight razors, this got me thinking: what if you tape the spine with electrical tape? That would give you the additional benefit of thickness adjustability.
I'm having trouble reading the values...
Is that a medieval (pre-metric) micrometer gauge? What does it say in mm?
:p:
The tube looks rather thin though... If I'd go to my local bike shop I'd ask for a punctured tube out of the bin they'd give me for free, right?
 

Grarea

Forum Plod
Good idea.
You are right to ask the question though.
Different makes of inner tube have different thicknesses.
 

lloydrm

Forum GOD!
I'm having trouble reading the values...
Is that a medieval (pre-metric) micrometer gauge? What does it say in mm?
:p:
The tube looks rather thin though... If I'd go to my local bike shop I'd ask for a punctured tube out of the bin they'd give me for free, right?
I hate the reading system on that thing so I use it as a reference more than actual measures. Roughly speaking, you get te same thickness with the spine shim than the tube.
Yes, maybe they have one and hopefully they are nice enough to give it for free. There are so many tube sizes now a days that coming by the one you need might be hard. Good luck.
 

R181

Grumpy old man
Now, since I am now into straight razors, this got me thinking: what if you tape the spine with electrical tape? That would give you the additional benefit of thickness adjustability.
Yes, using electrical tape on the spine of a straight razor has two main uses. The first being to keep the spine wear or damage if you are rookie honer to a minimum with 1 layer of tape. The other reason is to adjust the spine width to compensate for excessive hone wear using at times up to 3 or so layers of tape. That helps bring the blade's geometry back towards producing a 17 degree(iirc), +/- 2 degrees, standard. Since there is a +/- tolerance using a single layer of tape an a brand new razor is of no consequence as it makes about 1/2 degree difference in bevel angle.

Bob

Apologies for the above post. I had forgotten that some people refer to shavettes as straight razors which they are similar to but not the same as a traditional straight razor. A young male barber told me he was using a straight razor recently. I told him it was a shavette not a straight razor. He only believed me when a female barber set him straight, sorry for the pun. Even among professionals the lines seem blurred.

To me it is a simple distinction. A shavette is a razor with a disposable blade that may also fold. A straight razor is a razor with a non disposable blade that may fold. Key distinction being the type of blade.

Bob
 
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sɐǝɹpu∀

riverrun
I hate the reading system on that thing so I use it as a reference more than actual measures. Roughly speaking, you get te same thickness with the spine shim than the tube.
Yes, maybe they have one and hopefully they are nice enough to give it for free. There are so many tube sizes now a days that coming by the one you need might be hard. Good luck.
So, as the tube is on both sides of the blade it's only half the required thickness...
 

Gordy

Legendary Member
The inner tube I have is not as thin as the one pictured, I bought it out of Lidl a while back so I'm assuming it was for a mountain bike. I certainly wouldn't need it around the blade, as on both sides. I thought about tape, just not electrical, with regard to building it up, but the rubber takes more chatter out of the blade. I used duct tape the last time I tried because that's what my wife uses to help hold them, after we're finished shaving with them.
 

sɐǝɹpu∀

riverrun
No. One tube rubber band = one whole spine (two sides). Sorry for my rubbish choice of words.
To clarify: The blade with a half blade shim (on one side) is the same thickness as a blade with the rubber tube (on both sides)?
Then the rubber tube would be too thin...
 
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