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Merkur HD dimensional issue, does it equal shaving issue?

In another thread I questioned the quality of my new Merkur HD-G, that I've had three weeks, two of which I've shaved with it. I've had a wide range of shaving experiences, which I initially thought was just me being a noob.

Add to that different blades, started off with Walmart Persona's, 1st blade okay, 2nd blade was treacherous. Then changeover to Derby and it definitely was an improvement.

But since receiving my new DE I've thought something wasn't right. First off the blade exposure was uneven - meaning I could see more blade sticking out one side than the other, add to this that it seemed the blade clamp (the part you tighten the handle to pull down to hold the blade on the head) looked to be not square to the razor's head.

So I took my digital Mitutoyo caliper which displays in increments of .0005" and via checking it on a few "Jo" blocks (high accuracy measuring standards) I confirmed my caliper was indeed reading very accurately.

So the blade clamp measures .754" on one end and .762" on the other, so a different of .008", not a big deal if you split it, .004" a side, so a little more than a human hair.

Now the head itself measures .996" on one side and .993" on the other, again not bad, that is only .003" parallelism across a length of 1.650". So split that in half and it's only .0015", pretty good.

Here is the rub, the .754" end of the blade clamp is on the .996" end of the head, for a total difference of .242" or .121" per side of blade exposure. The other side is .762"/.993" respectively, equating to a difference of .231" or .1155" blade exposure per side. (Granted it's not really blade exposure since the blade is not straight, but curved to match the clamping surface machined on the two main components - the head and the clamp.

So if I flip the clamp around 180 degrees it would .996"/762" = .234" blade exposure and .993/.754 = .239" blade exposure. Using these differential numbers and dividing by 2 would be .117" and .1195 per side, for a end to end difference of .0025".

To me this is a trivial number, and when I factor in that the pins on the bottom of the clamp are .183" in diameter (with a slight taper towards their points) and the receiving holes in the head are .192"/.194" in diameter. This would allow a side shift up to .0055" which adds to the differential numbers listed above. Factor in that these pins are on 1.455" centers, which limits the total side shift to under .0022" at either end, so again too small to be concerned with it.

Lesson is that I onced asked about the HD and that if it's head was directionally mated, like the Progressive's, everyone thought no and I too thought that way. But it is clear to equalize the shaving conditions of the razor from side to side I need to spin the clamp around 180 degrees.

Just an FYI, from a someone looking to improve his personal shaving process.
 
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I neglected one other variable and that is the openings in the razor blade itself that the clamp's pin go through. I haven't tried measuring the blade itself, since it's is too flexible to get a good reading using a caliper. I would need to use an optical comparator to do a more accurate job, so clamping deflection would not enter into the equation.

All and all I think they can only make it, we can only set it up so accurately and ultimately it all comes down to good technique and feeling where the blade is when you shave.

I'm sure this is the easy part, just like writing the words, the hard part will be doing the shave well allowing for an even wider human tolerance.
 
The HD isn't directional. That doesn't mean that there won't be variances due to manufacturing discrepancies. The Progress is intended to be aligned in a certain way and the HD has no such requirement.

Your HD sounds wonky. I'm not breaking out the calipers but I can tell you that mine is pretty damn even.
 
J

Jarmo P

I am going to shave today with my Feather Portable. It aint perfect either but gives me a good shave as same as my Merkurs and Gillettes.

Bic Sensitive disposable is also now in my rotation :tongue_sm

The razors, they all have their distinct differences, we love them cause of that.
 
Fortunately, as long as the discrepancy in blade exposure isn't too lopsided, you can still get a very nice shave from a Merkur.

On some specimens, flipping the head around 180 degrees will help. On others, it makes no difference. It seems to vary from razor to razor.
 
But how does it shave? Can you feel a difference between the two sides when you flip the razor around? Do both sides feel the same?

I'm particularly interested, as I'm considering buying a new HD, but I don't want to drop the $ for something that's less even than any of my Gillettes.
 
But how does it shave? Can you feel a difference between the two sides when you flip the razor around? Do both sides feel the same?

I'm particularly interested, as I'm considering buying a new HD, but I don't want to drop the $ for something that's less even than any of my Gillettes.

My HD is very even. If you get an uneven one you should contact the vendor you bought it from and ask them about it. The commonly used vendors here all have great customer service and know what to do when manufacturers defects are encountered.
 
Well after flipping the clamp 180 degrees the shave this morning was much better. It equalized, meaning both sides feel the same. I think this may of been some of my problem. Maybe a more veteran DE shaver would of more easily adapted to this issue, but the shave this morning was BBS and no nicks.

Makes me think that if the 2nd Persona blade was not as bad as the shaves it resulted in, but was compounded by the machining errors of the clamp to head sizes.

Oh and by the way Geo Trumpers Violet shaving creme is the stuff! What a smell, made buckets of thick slimey lather that was warm in my Moss scuttle. A better day has been started.
 
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