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Reprofiling an edge (aka fixing a chip)

OpusX

OpusX

TSC’s Master of Warp Cores, Alchemy, Ale, & Cider
The straight razor bug has bit, and now I'm already getting into projects. I just picked up a K.W. & Co. razor locally, as overall I liked the look, specifally the scales. As I was looking at it during the meetup I noticed a pretty nasty chip in the blade. I thought to myself "ah...I can reprofile that edge all the way up to the chip and see if we can work from there". Granted I've not done such a thing on a razor, but I have a touch of experience with making edges from steel.

I wanted to work to document what I'm doing, as well as see what feedback and tips the cadre has at large for such a task.

My current plan:
  1. Glass the edge to take it down so I don't oopsy myself
  2. Get out the fine metal files and hand grind the blade edge perpendicular to the file until we have hit the chip depth
    1. I have concern that this is a dangerous step that may cause more chipping as that is some thin steel
  3. Tape up the spine and start a 500/1000/2000 wet sand profile on the edge
  4. Progress to burr method lapping paper progression
  5. Strop
  6. Shave
Some pics of the razor we're working with:
20210108_131822.jpg

The blade chip we're going to try and remove

20210108_131844.jpg


Also for the heck of it and reference, here is a fun dashi style knife I made from a water jet scrap (I think I made 3-4 of these) from the knife shop (when I did such things)

tgwdashi.jpeg
 
Watching with interest! Wouldn’t it just be safer to tape the spine and use the lower grit hones to work the edge down to remove the chip? A file sounds like it would cause too much vibration and make more problems. (More of an inquisitive question...definitely not a “I know what I’m talking about” question - cause I don’t) 😂


OpusX said:
Also for the heck of it and reference, here is a fun dashi style knife I made from a water jet scrap (I think I made 3-4 of these) from the knife shop (when I did such things)
Click to expand...
That is cool! 😎
 
You don't need the metal files. 220 grit WD sandpaper will take the chip out.

There are a few videos on YouTube that will show you how to do it. One of them is on the Maggard Razors channel.

I have used this sandpaper technique to some success. I have a Hess Hair Milk which had a small chip out of the edge. WD sandpaper removed it real quick.
 
When "reprofiling" or fixing a chip the biggest thing to be aware of is the final geometry of the edge. how you achieve the repair is up to you but if you don't end up with a bevel edge with the right angle you won't have a shaving razor. Depending on the overall size of the chip and the thickness od the spine you will need to take some metal off the cutting edge AND the spine. There is a tool called "bevel calc" that will help with the math. You basically measure the thickness of the spine and the width of the blade to get the angle of the cutting edge, then you can play "what if". What if I leave the spine untouched and file the blade to clean metal, what will the new cutting edge angle be? will it be within an acceptable range? if so, you can do exactly what you described. Too shallow (small) an angle and you risk turning your blade into a fillet knife, too steep and it won't cut. I've got a blade with a 13-14 degree edge that is WAAY wicked. If memory serves I think you want 18-20 but 16-22 range works too. I'll find the link to the bevel calc tool in my google drive and send it to you. worst case you need to work the spine and the edge at the same time
 
If you want to use Excel to do the math here is the formula. Imagine Column A is where the labels are and column b is where the values are and Spine is 1 and Bevel is 2
Spine Width4
Bevel Width13
Bevel Angle17.7

=(ASIN(((B1/2))/B2)*180/PI())*2
 
So 1st, due to geometry, even a glassed edge will slice the heck out of you very easily.

as for the reprofiling, the most important thing is that you want to try to keep the ratio of spine/blade width within the 0.275 to 0.325 range(16 to 19 degree bevel angle). removing that much of the blade may put you at a 20+ degree angle and that is less likely to give you a good edge for shaving comfortably.

I would use a file on the edge a SR. that will likely case more chipping/cracking in the blade. When i need to take out something like that i use a diamond plate or low grit stone/sandpaper. and again, don't tape the spine so you preserve the edge profile.
 
See I knew if I just tossed out my random thoughts, I'd get proper feedback. Thanks all for the starting points. Keeping the spine to edge ratio consistent makes sense, as it is the future reference point for the entire edge. I'll work through some papers on this one then to get things moving along.
 
The first BIG chip I removed was on a Wade and Butcher, I used a power sander (dragster), the same one I use to modify gold dollars and the like. Wade and Butcher's come to find have very some metal by comparison so the work was very fast. My large chipped blade quickly became an average sized clean blade. In the end I think luck played a bigger role than skill but the big take away was a trust in the process and the knowledge that by working the spine and edge in the same proportion I would be ok. I knew NOTHING when I did my first 2 repairs but both of my repairs (my second one was fixing a huge frown and heel drop by grinding of the shoulder so I could hone it into submission) required nothing more than doing the same thing to BOTH sides of the razor in roughly equal amounts.

If you are going to use power tools or aggressive abrasives because you don't have anything else, always do spine leading strokes until you get to something you would be willing to rub on your face and Always keep your blade/spine flat and make sure whatever you are rubbing your blade on is flat) the rest will figure itself out. next thing you know you will be looking at every rock you see wondering what kind of edge it would put on your blades. Your think I'm kidding. I'm not. Ask anyone here that hones or is a recovering rock addict.
 
I wouldn’t use a file. The first chip I removed was with lapping film. I used a 30u and 20u, but you could use W/D sandpaper also. When using tape, be mindful of your geometry.
 
Well I do already have lapping film in bound for the overal straight razor honing process. I did stop by Lowes and grab two marble edge tiles and some wet/dry 220, 600, 1000 and 2000 paper to fix this and set a bevel.

20210108_171730.jpg
 
late to the party, but Yes with all that has been said, throw the files in the drawer and take a zoom picture as best you can of the chip to make sure there are no micro cracks and if you hit that with 200 out of the gate without the inspection disaster can occur. Dont ask me how I know
 
CBLindsay said:
If you want to use Excel to do the math here is the formula. Imagine Column A is where the labels are and column b is where the values are and Spine is 1 and Bevel is 2
Spine Width4
Bevel Width13
Bevel Angle17.7

=(ASIN(((B1/2))/B2)*180/PI())*2
Click to expand...
A quick and dirty that will get you within .1º (your errors in measurement will likely be of more consequence than the math error) is spine thickness/active width X 57.3 =__ º .

Notice 'active' width. This it the distance from the edge to the top of the hone contact on the spine. Often a bit smaller that the full width of the razor.
 
Definitely looking good so far. Nothing beats a vintage razor you whipped into shaving shape yourself. You’ll learn a lot (good and bad) with this project and you’ll be better because of it.
 
CBLindsay said:
Definitely looking good so far. Nothing beats a vintage razor you whipped into shaving shape yourself. You’ll learn a lot (good and bad) with this project and you’ll be better because of it.
Click to expand...
That was whole plan. This is all skill building. I mean thats the fun of it.

Rocked the 600 and now all I can say is "What chip?"

20210109_113056.jpg
 
Well this is as far as I can take it today, at least untill my lapping film shows up (..."arriving late" uugghh).

After setting the bevel and running draw passes at 1k I can shave some arm hair. Then ran a set at 2k. It certainly isnt the smoothest yet, but I think this shows that this one will eventually be a shaver again.

20210109_123150.jpg
 
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