Shimming a Merkur 34c Razor

[MM879]

I am looking for information on how many shims and positions to use on a Merkur 34c. My goal is to use the Derby Extra blade which I have a large supply. I did a test on this razor with four shims inserted under the blade. The shave received was improved. There was still blade feedback but , razor burn was eliminated. Any experience shiming a Merkur 34c razor with Derby Extra would be greatly appreciated.



MM879

 

[nemo]

Four shims is a heck of a rise, any more than that and you may have trouble engaging the threads! I don't shim my razors any longer as I feel if you need to change it that much you may want to use some other less mild razors.

You may want to give a Mühle R41 a try. How long have you been using a double edge?

 

[MM879]

Four shims is a heck of a rise, any more than that and you may have trouble engaging the threads! I don't shim my razors any longer as I feel if you need to change it that much you may want to use some other less mild razors.

You may want to give a Mühle R41 a try. How long have you been using a double edge?

I tried the four shims as a test. It was very successful. I am now looking for data, numbers, positions for shims. I am not interested in different razors or blades.
MM879

 

[Atinofpeas]

Grind off the safety bar perhaps?

 

[Invicta]

Any experience shiming a Merkur 34c razor with Derby Extra would be greatly appreciated.

You can shim the razor with any blade but four shims is a lot. It occurs to me that improved technique may get you a better shave rather than adding shims.
It would be interesting to know what blade angle you prefer (shallow, neutral, steep)?

 

[MM879]

You can shim the razor with any blade but four shims is a lot. It occurs to me that improved technique may get you a better shave rather than adding shims.
It would be interesting to know what blade angle you prefer (shallow, neutral, steep)?

The four shims was just a starting point. I wanted proof of concept for the shimming process. The four shims worked, but also increased the risk for a cut. My plan is to remove one shim at a time and evaluate the shave. The ideal function will be a close shave. The variables will be the shim count and position. I will calculate a signal to noise ratio for each variable. Once the variable with the lowest signal to noise ratio is identified it will have the gain increased or reduced to bring it closest to ideal function, "a close shave".
MM879

 

[Atinofpeas]

A Q shave adjustable can be had for $5. They are decent tbh

 

[MM879]

A Q shave adjustable can be had for $5. They are decent tbh

There are many razors that address the blade gap question with different configurations, plates, adjustable, slant. I'll probably get an adjustable someday. When I do it will be a Gillette vintage. Until then I want to explore the 34c out of respect for the brand. With the right blade there isn't much to complain about with the 34c.

I'm getting great test results using the Derby Extra.

The results are as follow:
4-shim below= close shave no irritation. Weeper cut on chin
3-shim below= close shave, no irritation. minor blade feedback
2-shim below= close shave, no irritation. blade feedback
1-shim below=TBD
0-shim below= irritation, mild razor burn. Blade feedback and overall tugging
2-shim below, 1-shim above= TBD

After testing is complete a configuration will be selected and tested for one week. Then a premium blade will be tested in that configuration.

MM879

 

[santamariasteve]

By coincidence I shaved last week with my Merkur 34c and I used 2 shims under the blade. That was perfect for me. I don't notice much difference between brands of reasonably good quality blades.

The stock 34c was too mild for my tough beard. One shim was better. But 2 shims were perfect!

What do you mean by "blade feedback?" Is that good or bad?

 

[MM879]

By coincidence I shaved last week with my Merkur 34c and I used 2 shims under the blade. That was perfect for me. I don't notice much difference between brands of reasonably good quality blades.

The stock 34c was too mild for my tough beard. One shim was better. But 2 shims were perfect!

What do you mean by "blade feedback?" Is that good or bad?

When I say "blade feedback" I mean it in an acceptable way. I know that my blade choice, Derby Extra is not the sharpest. My 2 shims under the blade shave was very good irritation free shave. I think that I am very close to a setting for this razor. I want to complete the test matrix and then try a premium blade to confirm.
MM879

 

[MM879]

By coincidence I shaved last week with my Merkur 34c and I used 2 shims under the blade. That was perfect for me. I don't notice much difference between brands of reasonably good quality blades.

The stock 34c was too mild for my tough beard. One shim was better. But 2 shims were perfect!

What do you mean by "blade feedback?" Is that good or bad?

Yes, I tried the one shim under the blade before these tests and couldn't tell if it the shave was was improved. That is why I went to the four shims to prove proof of concept.
MM879

 

[MM879]

I am having more thoughts about this shimming process. I believe that the primary function that is changing is skin tension between the guide bar and razor cap. The whole process is no different from the manual skin pulling when using a straight razor. If this hypothesis is true I should see an improvement when a shim is added to the top of blade. The increased height of the razor cap should improve the skin tension. This explains the increased irritation at the base of the neck where there is excess aged skin…turkey neck! No skin tension at the end of the razor stroke.

MM879

 

[rabidus]

There are razors that support the blade fully making it very rigid, the 34C is not one of those razors. When you add a shim or more, you are stiffening up the cutting blade, especially if the shims are wide.

Prewar Tech + one Shim =...

If you cut one shim narrow and place it between the cap and blade, you will increase the blade gap making the razor more efficient.

 

[BigJ]

To go at this from another direction, “Have you tried anything besides Derby blades?” My guess is that you would do better with something sharper.

 

[MM879]

To go at this from another direction, “Have you tried anything besides Derby blades?” My guess is that you would do better with something sharper.

That is the plan. See reply #10.
MM879

 

[rabidus]

If you cut one shim narrow and place it between the cap and blade, you will increase the blade gap making the razor more efficient.

I meant exposure...not gap...

 

[Atinofpeas]

That is the plan. See reply #10.
MM879

The two are not mutually exclusive

 

[AimlessWanderer]

I've never shimmed a razor. I prefer to appreciate the razor as it was designed to be used, and tweak my technique and handling accordingly. I've never used a razor where technique adjustments didn't lead to a great shave. I have had incompatible blades, which is an easy fix if you have a few different types to hand, but never had a razor that needed shimming in order to shave well.

 

[MM879]

The two are not mutually exclusive

I've decided not to insert a shim under the cap. My ability to accurately cut a shim might cause a distortion in the blade. I'm doing the 2 shims under with the Derby extended testing. The two shim setting is working quite well. I think that 34c benefits from a little more blade gap.

MM879

 

[Atinofpeas]

I've decided not to insert a shim under the cap. My ability to accurately cut a shim might cause a distortion in the blade. I'm doing the 2 shims under with the Derby extended testing. The two shim setting is working quite well. I think that 34c benefits from a little more blade gap.

MM879

The Derby is one of the mildest blades going. I think you do better by putting a sharper blade in the murkur before shiming it. The Merkur is a daily shaver. If you are shaving only once or twice a week, it is perhaps the wrong razor period. Either get an adjustable or go aggressive with a Muhle R41