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04-11-2018 07:23:22  #1


Low mainspring tension in QDL

While cleaning, my 1939 QDL developed low spring tension that now only moves the carriage about halfway before running out of steam.
When I try to rewind the spring drum, the spring tightens for like three turns then slips back inside the drum.
Before I remove the drum to investigate I thought I better ask for an assessment.

 

04-11-2018 18:30:06  #2


Re: Low mainspring tension in QDL

If you are lucky, the mainspring has become detached inside the spring drum.  If you are not, the spring will have broken (but usually near one end so that it can be softened and re-drilled).  If you are really unlucky, the spring will have broken in the middle and you will need to get a new one.  Best have a look inside the spring drum !

 

11-11-2018 17:21:06  #3


Re: Low mainspring tension in QDL

Alas, my spring is broken -- a shame as this Royal is in excellent condition otherwise.
While a search for a new drum, has anyone had success mending a spring by spot welding or with rivets? I am without experience working with spring steel and wonder if heat or drilling would make the effort useless.
https://i.imgur.com/JMvxUUi.jpg

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12-11-2018 04:14:11  #4


Re: Low mainspring tension in QDL

If someone on here has a complete spring drum for you, that would be the easiest.  The next option is to open your drum up to see exactly where the spring is broken.  On most typewriters, the spring is attached by means of hooks in the drum and the mainshaft  through holes in either end of the spring.  Sometimes the end of the spring itself is formed into a hook.  Most springs break within a few inches of the end, so there is plenty of spring left to re-attach.  To make a new hole, you need soften the end of the spring first by heating.  In its hardened state, the drill will just glide off.  Sometimes you may need to shape the new hole into a slot using a needle file.  If you are unsure of this process, seek someone out who is used to this sort of work.  An old-fashioned clockmaker would know what to do for instance.  Clock springs are very similar.

 

12-11-2018 07:33:04  #5


Re: Low mainspring tension in QDL

Alas, this spring broke smack-dab in the middle.
I suppose any attempt to spot weld or rivet the two pieces together would be for naught, due to the nature of spring steel. 
So I begin the long search for a replacement...

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12-11-2018 09:29:59  #6


Re: Low mainspring tension in QDL

Don't give up !  Two possible strategies :  1. Find a clockmaker and see if he can supply a similar spring.  2. soften the broken spring ends by heating, then drill and rivet.  I know that  2. has been used to repair the much larger spring found in wind-up gramaphones, so should work. 

 

12-11-2018 10:47:27  #7


Re: Low mainspring tension in QDL

Oh, I won't give up on this beauty!
https://lh3.googleusercontent.com/mE9c9EPxCEfgWMPjJuUIyIFJ0ciNT5TZXu08dBNZTLFkL35oGi_4BtijzWyjnnNAbwp6C4qJXjfJWL0ggoJHOwdkJhnyiA7moAQ-8ysE2N7oxaA35HkpXgIKzbx9iHbv6KYSlgI_Ei2SLzTVl0U36WU8IEQqlxSqlDkuGDS60PMbywQr6PSMXToguucZnHHvOhy687SojU1zKa5gJiiWcjuj7i5YdWyViyQZUEGjqxWV_A5QLIe2XRRYLP0tA-kF7iQhmBG5iUARW7CCPDCfNTcCdMeRYOG5zuhNF2gWRT3qV2NbXXfOD3ZQYOYeSU5RYIWlVnhVKxXOzbRxlYX5yE3G8-r8UGHnimr8JLLBeuYTPuBy_MajPCKuzhg1rIDJaldjQ91ACeTc7FGliQkUzFf8KFVr3mvHMOIUEvVJFcQUkzfez0Q0nEeUQQWF9pCtHYZOIcI2ldUOd6DT3ND2ezcDzIKJNbipKGtyzsZKozObSkxolXKHSzg_VHinqWxz4TsA_bWvqkiQQ6gdKvF-R2QaZb3wFDoLqDvinmhNYuifepXr3Vy0YrHOOe4nTU6WKHE8EKlPs7qdKVOl3pevN2_urrwKcqeh8KvbzSIRbpl909eZcVIZS-tdfQ519BCQjEvrkkgvP8mOKsehHV2cBkAwbjW2Xe35ZjFKPdqIEyF6=s720-no

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