Spine wear

manly49

manly49

Joined
Sunday January 26, 2014
Location
South Wales or Nottinghamshire
I have got a second hand dovo that I picked up for a song. The blade is in good condition, although dull and in need of honing, but there is evidence of previous honing on the spine. At what point does it become useless? Can this razor be honed and stropped effectively with a slightly worn (and I mean slightly) spine?
 
Electrical tape is a wonderful thing. New razor 1 layer, 30£ razor 2 layers, 20£ razor 3 layers, 10and < 4 layers.
Makes the old new again.
 
John is right about the tape. There's a calculation tool that tells you the number of layers of tape required to achieve the correct bevel angle if you feed in spine width and blade width.

Generally speaking, spine wear will not make the blade unusable. You are allowed to upload photos - this would give a much better chance of getting the right advice.
 
Yes post a few close up photo's. if there is substantial hone wear of the spine then this creates a wider bevel below when you hone the razor making your edge angle more acute and the only way to rectify this is by more tape, why don't people tape the spine from the word go the number of razors ruined from not carrying out a simple task such as placing a small piece of tape on the spine makes me scratch my head in disbelief.
 
If the edge and the spine wear at the same rate, the bevel angle will remain the same - spine wear is not a fault, it is designed to wear at the same rate as the edge in order to keep the bevel constant. In fact, if you hone the edge back over time but do not put any wear on the spine (eg through taping), then the bevel angle will inevitably become steeper - it's just simple geometry.

The only way honing will change the bevel angle is if the edge and the spine are worn at different rates, and in my experience that is pretty rare. You can measure the spine thickness and the blade width and calculate the bevel angle if you want, but the chances are it's just fine.

Spine wear does not indicate the end of a razor's life - as long as you can still get an edge that will shave, it's fine. I have some old Sheffield razors that are more than 100 years old with probably 1/4 inch honed off the edge and a lot of wear on the spine, and the bevel angle is still perfect - precisely because they have not been honed with tape.

Some people like to use tape, and sure, if that's what you want then go ahead. But the effect is usually only cosmetic - it is using tape that alters the bevel angle, not not using tape.

My recommendation is to forget all of this and just use the razor - it will almost certainly be fine!


pugh-the-special-one said:
why don't people tape the spine from the word go the number of razors ruined from not carrying out a simple task such as placing a small piece of tape on the spine makes me scratch my head in disbelief.
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Stop scratching, dude, you'll get a sore head :cool:

The reason people don't do that is because they want the edge and the spine to wear at the same rate so as to keep the bevel angle constant, the way the makers intended.

If you hone the edge back but do not change the spine thickness, the blade width will reduce and by simple geometry the bevel angle will increase - razors with spine wear are not ruined, they are simply wearing as designed.

Cheers,
Alan
 
I shall take a couple of detailed photos over the weekend and post them on monday. I am not a nutter, but I work away from home and go home on the weekend. I don't take my razor home because I am worried my 13 year old will get hold of it and have a go unsupervised thus needing a trip to casualty to reattach an ear or lip! The tape thing is something I have seen used before, but as an Engineer, the constant wear and bevel angle makes more sense to me. Thanks gents, I shall upload photos on monday.
 
Oscroft said:
If the edge and the spine wear at the same rate, the bevel angle will remain the same - spine wear is not a fault, it is designed to wear at the same rate as the edge in order to keep the bevel constant. Cheers,
Alan
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Hi Al. Have to disagree here. If the spine is wearing at the same rate as the edge, the whole geometry of the blade is thrown out and you end up with what Jamie said - a wide bevel. In reality, the wear on an edge is minimal, therefore taping maintains a more accurate bevel than not taping.

You will have seen enough wide bevels to know this is the case.
 
UKRob said:
Oscroft said:
If the edge and the spine wear at the same rate, the bevel angle will remain the same - spine wear is not a fault, it is designed to wear at the same rate as the edge in order to keep the bevel constant. Cheers,
Alan
Click to expand...

Hi Al. Have to disagree here. If the spine is wearing at the same rate as the edge, the whole geometry of the blade is thrown out and you end up with what Jamie said - a wide bevel. In reality, the wear on an edge is minimal, therefore taping maintains a more accurate bevel than not taping.
Click to expand...

Maybe we do disagree, but I'll do a diagram of what I mean later.

Oh, and I really do have blades with 1/8 or even 1/4 off their width due to honing - over more than a century, admittedly.

Cheers,
Alan
 
I don't want to make enemies before I've made any friends here but I disagree with a lot of what has been said about electrical tape. In the main I agree with Oscroft.

Hone wear does not change the bevel angle assuming steel has been removed from both the edge and the spine. Yes it results in a wider bevel but this is due to thickening of the edge which can't be avoided unless you don't sharpen the razor! Putting electrical tape on the spine will give a slightly thinner bevel but only by increasing the sharpening angle. Besides electrical tape is only about 0.09mm thick so how much difference can it really make.

By all means use tape to avoid scratching the spine but in my opinion that is all you will be doing.

Just to illustrate this, if you ground a 6mm thick piece of steel to a sharp edge at 20 degrees per side the resulting bevel would be 8.242mm wide. If you added one piece of electrical tape to give a thickness of 6.09mm and maintained the same grinding angle, the bevel would be 8.366mm wide. That's a .124mm difference! On something as thin as a razor we are talking about even smaller changes.

Of course, I could be wrong about this! I'm just going on my own experience :)
 
I wouldn't worry about makng enemies here Mike, everybody seems very friendly, helpful and pleasant. Plus, everybody seems to value other peoples opinions as nobody is ever 100% correct. However, as I stated above, as an Engineer, I agree with you and Oscroft from a purely mathematical standpoint. I have never honed a razor yet, it's on my list of things to learn, but at the moment I am more concerned with getting the shaving technique correct, so I can't talk from experience on this matter and I bow to the superior knowledge of such things on this site.
 
Well you are both wrong and here's a simple experiment you can carry out on a old razor of course, put two layers of tape on now set the bevel have a look how small the bevel looks, now remove the tape and keep on resetting the bevel low and behold your bevel as just become large to large in fact. and that's what happens everytime you hone a razor with with excessive hone wear to the spine, and I've honed enough old Wade & Butchers to realise that hone wear to the spine doesn't match up to your theory of the blade wearing down at the same rate it simply doesn't work that way regardless of diagrams, Rob and myself hone a fair amount of razor on a monthly basis between us to say theoretically it simply doesn't happen this way. PS I also forgot to add the blade edge is much smaller than the spine so there's a hell of of a lot more material touching the hone on the spine for a start.
 
In my opinion the theory of some of the above is incorrect. Honing say a new 6/8" blade without tape takes far more off the spine than the edge - simply because the spine is at 90 degrees to the hone and the bevel is at 20 or less. It takes not a great deal for the original geometry to change so that the bevel starts to get wider.

Taking Jamie's suggestion but the other way round, take a spine worn blade and put a new bevel on it without tape then repeat using a quality 3M tape that is more wear resistant than cheap electrical. Re-set the bevel and you will see with a naked eye just what a difference it makes to the width of the bevel.

One thing no-one has mentioned is the reason for using tape to overcome a problem spine. We have all come across blades with kinks or other problems - using tape can help here because it enables a more consistent bevel as the tape wears unevenly i.e. it's helping to straightem out the kink.

Just so that this doesn't become a thread of people taking sides, I would add that I tend to use tape on 1k and sometimes 4k hones (depending on the blade) and then remove when moving up the grits. It doesn't take a lot to change the initial bevel angle as the difference is only about 1%. However, this applies to blades in reasonable condition where the bevel is small to start with. Any older blade showing signs of more significant spine wear gets tape - because I don't like bevels approaching 2mm.
 
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