Honing My First SR

[Slash McCoy]

I will be ordering some lapping film from Japan early next year. That will be used on my Titan - if needed. I will be away overseas during Christmas/New Year.

That is good news. Film is a game changer, for honing on a tight budget. Be sure to get full size sheets and plain back, not sticky back. And an acrylic block. It is the absolute best. A calibrated granite plate is flatter, but you won't be holding that in hand, and you won't get it cheap. 3/4" acrylic is very flat, light, and durable. It won't warp under normal conditions and it is too stiff to flex on you. It is also thick enough to keep fingertips below the path of the razor. 1" is maybe even better. Anyway, one plate is all you need for film. You can simply change the film, rinsing the plate well, of course. You could reserve the other side for glueing sandpaper to it, for bevel setting, if desired. Later you will want to up your game with the balsa but that can wait a while. The acrylic makes an excellent backing for the balsa, helping to prevent flex and warp, and you will want a separate plate for each of the three grits used in The Method. The balsa will do you no good until you are getting a good 1u or 12k level edge, though, so it can wait until you have a nice paycheck to work with.

Lately I have been running a file along the top edges of my acrylic plates. Usually not needed, but depends on who is doing the cutting. I have found a few proud edges that needed to be knocked town a few thou.

Spray adhesive works good for sandpaper or balsa to acrylic. Don't use Gorilla Glue. Spray adhesive (Loctite or 3M brand) works best. Next best is common rubber cement, applied sparingly though uneven coating could be a problem with sandpaper. Not so important with balsa since you will lap it after gluing anyway. Spray adhesive residue cleans off easily with acetone. One cheap source for small amounts is fingernail polish remover but some polish removers do not contain acetone, so read the label. And I would not let acetone stand for long on your acrylic. Brief contact won't hurt it, though.

 

[rbscebu]

Yes, I have realised that my first USD5 SR is really a RSO. Still, it has been interesting to play with and I have learned a lot from it.

There hass been some discussion in the forum on taping the spine while honing. As I am looking to tape the spine of my RSO to try and set a reasonable bevel, I decided to first perform some tests to see how much the tape compressed while honing and how that would affect the bevel angle.

I first measured the force I would apply to the blade while honing. I found that with my honing style, this force varied from about 200N to 350Ns so I decided to measure the tape compression on my RSO at 500N and 1,000N using 1 to 5 layers of tape on each side of the spine. Three sets of tests were performed using new tape for each of the 5 x 3 = 15 tests. The tape was applied separately to each side of the spine (i.e., not wrapped over the spine which would have affected the results due to the "fold") and both sides of the spine were compressed together.

Before each test, the taped blade was loaded to 50N to set a zero reading. Here are the results:

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The compression readings were fairly constant per layer of tape and reasonable relevant to the load applied. Things that would change the results include; type of tape used, temperature, humidity, and even on how will you applied the tape. I was able to keep the first three of these variables constant and tried my best to keep the last variable constant.

The results show that on a 5/8 (15mm) blade with 5 layers of tape on each side of the spine, the included bevel angle would change by about 0.18deg at 500N load and about 0.39deg at 1,000N load

Included Angle Change = sin^-1 (compression (mm)/15)

How this variation in included bevel angle affects the edge performance, I do not know.

With this information, I am now more inclined to try and set the edge bevel on my RSO using 5 or 6 layers of tape.

My Titan with ACRM-2 blade should also be arriving today (USD28 including delivery). Hopefully it will be in near shave-ready condition so that I can try it out. I will still practice my stropping and honing skills with the RSO and then gently apply them to the Titan as needed.