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.
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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