Aftermarket Recoil Spring Adapter

[bamaboilermaker]

Recently when i was rebuilding the basket case of a Super Mini VI, i tried to use a Rotary Brand recoil spring to replace the long broken original.  i quickly realized that the aftermarket version would not work with the original spring catch and i "borrowed" a spring from another recoil assembly.  Having purchased 2 of these springs some time ago (i forget when and where), i thought it would be a simple task to design and print an adapter which can be used with the aftermarket spring.



i took some simple measurements of the inner diameter of the replacement spring and compared to an original Homelite 65107


i designed and printed a simple adapter.  I added two 2 mm steel dowel pins to aid the plastic in withstanding the shear load from the spring on the spool.  i also noted that this design would not work with the very early version of the spool (12041), but has clearance for the mid 70's version (65094)


Here is the aftermarket spring with adapter in the spring assembly


i then assembled to a side cover and pretensioned the spring.  Everything seemed to work just as good as the original aluminum part.  I have not put this recoil on a saw yet ( i think i have enough parts left over from the basket case to build another SEZ)
i will attach the .STL in another post if anyone is interested in doing this.  Note the dowel pins can be substituted with panel nails, roll pins, etc.  Just something to stiffen the section which goes into the spool.

Attachments:

[bamaboilermaker]

rotary zb.pdf (40.48 KB)ROTARY RECOIL SEZ REV2.STL (193.83 KB)
 Attached is the drawing and .STL file if you are interested.

[blythkd]

So why wouldn't the Rotary spring work with the original lock?

Cool project and I'm envious of guys that design and build stuff like this but why not just buy a Homelite spring?

[bamaboilermaker]

The rotary spring inner diameter was too big to catch the original lock. I designed this so that i could use the aftermarket springs which is had already purchased. it seems like there are a lot of SEZ's with broken springs, i guess the temptation is there to overwind them more than needed.

[edju1958]

I don't think it's overwinding the spring that breaks them as much as trying to start the saw without using the compression release.

[onlyhomelites]

There's a lot of those rotary springs that ended up with that large loop...almost like they mixed up the Super 2 spring specs with the Super EZ at some point. I like your adapter idea!

[blythkd]

I just have one more question. Did you check how many turns of preload you could put on the spring before pulling the rope to full extension stacks up the spring? The large diameter of the custom made lock will limit the total number of revolutions the pulley can turn before the spring stacks up vs the much smaller OEM lock.

The larger lock diameter is probably actually a little easier on the spring.

Just don't want to see you break your spring!

[5terrysupersaws]

Mar 13, 2024 22:02:10 GMT -5 onlyhomelites said:

There's a lot of those rotary springs that ended up with that large loop...almost like they mixed up the Super 2 spring specs with the Super EZ at some point. I like your adapter idea!

  
   True !

   The early Super-EZ, pre-LOT:0277 ( October 3rd 1980) used rewind spring->65107, that had the tighter wound inner loop. 

   Later built units with the plastic starter housing used rewind spring->69217 ( larger inner loop ).                                                                     
   Same 69217 spring was also used on the Super-2. 


   Example of a proper Rotary: 37-1701 ( Homelite: 65107 )    www.ebay.com/itm/125655987216

   Homelite: 69217 spring ( Rotary: 37-3009 )     www.ebay.com/itm/362271647992

   

[bamaboilermaker]

Excellent detective work, it clearly looks like OLD (pre 1998) rotary 37-1701 will work with original homelite lock, but the later (made in Taiwan) version will need the adapter lock. Classic example of an attempt to commonize service (aftermarket) part numbers with no verification of functionality.

The other idea was the E bay listing showed it was made in the USA, my spring was made in Taiwan. Maybe the drawing specs got confused. I will have to fill the spool with line and see if my adapter will even work at full extension.

The moral of this story is: use NOS Homelite parts whenever possible!