The rubber band shim

#1
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.
 
#2
I tried this today as like yourself, I had one single band that was approximately the right size (though a bit narrower than yours so it only covered half the spine.) Result? Best 1912 shave to date. Blade chatter greatly reduced and the razor gave no neck irritation at all which is usually my only issue with it, even with a regular half spine shim.
 
#4
A bicycle inner tube could be a good source for bands? Just need to find the right width and cut into strips.
I did look into that possibility, but the information on inner tubes on the web is frustrating. They don't ever tell you the actual dimension of the rubes, just which tyres they fit. You get helpful advice like:
  • 700 x 23-28c (for road bike tubes)
  • 29 x 1.75-2.4" (for mountain bike tubes)
That doesn't help me.
The width of the blade is 38.9 mm, the circumference of the tube needs to be less than twice that: 77.8mm
So the diameter of the tube needs to be less than 77.8/Pi = 24.7mm, but not much less.
A wall thickness of 0.5mm would be ideal, but probably a bit thin for bike tubes.
Which tube fits the bill? I have no idea and I'm not going to buy a bunch of inner tubes to find one that fits. I have a feeling the shop won't let me return them once I've sliced them up :D
If anyone finds a tube that fits the above description, just send me 20cm or so.
 
#6
Which tube fits the bill? I have no idea and I'm not going to buy a bunch of inner tubes to find one that fits. I have a feeling the shop won't let me return them once I've sliced them up :D
Ask at a proper bike shop for ones that are going in the bin. Depressingly, an awful lot of people either don't know how to fix a puncture, or can't be a***d. So they take the bike to the bike shop for a new tube.

HTH, John
 
#7
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.
I found this place but I think the minimum order would be a bit excessive and they are in the US. They do have a handy size chart though.

http://www.lee-rubber.com/sizes.htm
 
#12
I got my rubber band from the odds-n-sods dish. I reckon it came as one of those small bands that tie up micro-USB cables when you get a new gadget.
Using my calipers I measure the spine to be 0.98mm thick and with the rubber band attached 1.91mm. So the extra thickness is 0.93mm or 0.47mm extra each side of the spine. That's about the same as half a spine shim added under the spine which seems about right to me.
Sounds promising but the proof is in the pudding - which will be tomorrow's shave.
 
#13
31mm ish flat
And less than 1mm
That sounds OK - the rubber band I have been using is 25mm and a bit of a stretch...
If you can spare a bit of old inner tube, I'd love to have some - whatever fits flat into an envelope - 15cm should keep me going for years...
I promise to report back and mention you in my article about shimming... :D
I'll send you a PM...

So it's a 27 x 1 1/4" tube. 27 is the wheel diameter I assume (in non-metric).
1 1/4" in real money is about 32 mm, so I assume that's the diameter of the tyre it fits rather than that of the tube itself?
Who comes up with this shit? Mathematicians don't ride bikes I assume....
 
#14
I got my rubber band from the odds-n-sods dish. I reckon it came as one of those small bands that tie up micro-USB cables when you get a new gadget.
Using my calipers I measure the spine to be 0.98mm thick and with the rubber band attached 1.91mm. So the extra thickness is 0.93mm or 0.47mm extra each side of the spine. That's about the same as half a spine shim added under the spine which seems about right to me.
Sounds promising but the proof is in the pudding - which will be tomorrow's shave.
I think my rubber band came with a router, maybe around some cable, but I'm not sure.
If you like your blades shimmed, a rubber band should be even better. I love the way it quiets down the blade. Some people love the sound of "buttering toast" when shaving with a 1912 - I don't. I reminds me that the blade is not intended for the razor...
Enjoy tomorrow's shave.
 
#15
Well I've had my shave with my 1912 razor and the rubber band shim and although it was smooth I'm not sure if I can really tell if it made much difference.
I could still hear the rasping action (which I like) and it provided a very good shave but would I have had just as a good a shave without the band?

I've never really been convinced that raising the spine of the Gem blade by 0.5mm or even 1mm actually changes the shaving angle by any noticeable measure. Surely it's only a degree or two.
My schoolboy trig says... tan-1 (0.5/19.5) = 1.5 deg

Shimming a DE is different as you're increasing the gap between the cap and the baseplate but shimming a Gem is just altering the angle a touch.

Anyway, maybe it was smoother, I don't know. I'll try it again tomorrow (in another razor) and see.



 
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