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02-8-2020 09:55:38  #1


SM4 type action

Hello all,

I acquired my first SM4, it is in really good condition. The first part of the key stroke is light, but for the last part I need to put in more effort. Because of the noticeable resistance at the end of the keystroke, typing is heavier than I expected. Is this normal?

Lau

 

02-8-2020 11:59:41  #2


Re: SM4 type action

It doesn't sound normal to me. The stroke should be consistent throughout. There could be a few reasons for this, but most obvious might be to check the touch control mechanism and make sure that the segment is free and clear of debris and corrosion. 


Stay Safe! 
 

02-8-2020 13:33:26  #3


Re: SM4 type action

There may be something wrong with your machine. My SM4 has the lightest touch out of all my portable machines. I write faster on no other portable. Its action should be light and bouncy and consistent throughout. Writing on it should normally be effortless. If its otherwise clean, there may still be old lubricant which could be at fault. In that case the machine will have to be de-greased, cleaned and re-lubricated.

However I will say that the problem you describe does not sound to be consistent with the problems caused by hardened lubricant. 

 


Learned watchmaker and office machine enthusiast from Germany.

 
 

02-8-2020 13:37:02  #4


Re: SM4 type action

Thanks Uwe, I have checked the touch control and segment, everything is fine.

I have taken another look, the resistance at the end of the key stroke is caused by the crescent shaped part at the back of the segment. This part actuates the escapement and the ribbon drive, and is moved by the type arms.

I do not notice the resistance when I use a short, fierce key stroke. But it is almost impossible to touch type. Does this sound familiar to you?






 

     Thread Starter
 

02-8-2020 13:43:20  #5


Re: SM4 type action

Maschinengeschrieben wrote:

My SM4 has the lightest touch out of all my portable machines. I write faster on no other portable.

That is exactly what I expected, but it is not the case. I have a 1955 Triumph Perfekt and a 1956 Norm and these have a far more lighter touch than the SM4.

Maschinengeschrieben wrote:

However I will say that the problem you describe does not sound to be consistent with the problems caused by hardened lubricant. 

I have cleaned everything and the type arms move freely all the way.

     Thread Starter
 

03-8-2020 10:40:22  #6


Re: SM4 type action

Laurenz van Gaalen wrote:

I have taken another look, the resistance at the end of the key stroke is caused by the crescent shaped part at the back of the segment. This part actuates the escapement and the ribbon drive, and is moved by the type arms. 

At first I thought you were describing the Universal Bar, but it's underneath the machine. The Universal Bar trips the escapement. You need to make sure it isn't bent/deformed. There are adjustments for it, if that is the part you were referring to.

However, when you mentioned the 'back of the segment', I began to wonder if you meant the segment Ring. The ring stops the type bar just short of the platen, and a whipping action completes the stroke. There are adjustments screws for the carriage that will control the distance between  the slug and platen (this is called a Ring and Cylinder adjustment). The exact distance is very important; I use a thick piece of paper as a feeler gauge to make sure that the correct distance is established.

I hope some of that makes sense. Tom will undoubtedly be able to describe this procedure better, but this will give you a rough idea as to what the issue might be. 


Stay Safe! 
 

03-8-2020 15:27:00  #7


Re: SM4 type action

Hi Uwe, I have taken some pictures from the ring I was referring to. The pictures are from the left side of the segment, the end of the ring is visible in the center of the red circle.

http://laurenzvangaalen.nl/public/olympia-sm-4-segment-left-1.jpg

The ring is moving backwards at the end of each key stroke. It is attached to the bar that trips the escapement.
The rings position can be adjusted with the gray rubber washer you can see in the background. It has its hole off center, by rotating it the ring is moved away or towards the segment.
See the picture below.

http://laurenzvangaalen.nl/public/olympia-sm-4-segment-left-2.jpg

By moving the ring away from the segment the resistance I felt is reduced significant, and the key action becomes light and snappy.
A friend of my who owns two SM3's checked his machines, both have the ring adjusted as in the picture above.

The adjustment screws and gray washers are almost impossible to reach (there are two of them).
I damaged the screw heads in the process. To do it right the carriage must be removed.

The only question that remains is how on earth the ring was adjusted the way it was.

 

     Thread Starter
 

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