Need help - press drill spring

[rendoman]

Hi all!

I'm searching for good advice about how to install the coil spring in my press drill.
I bought this spring, the internal diameter is 22mm, perfect size for the shaft. The trouble is the external diameter, the round seat for pin prevents the spring from going into place.
The spring has enough force, it's quite hard to turn by hand, it's even difficult to use the left threaded alu case.

I'm thinking to build a sort of frame jig in order to compress the spring and then tie again with wire, but maybe there is a better way

Any advice welcome, thank you for your suggestions

[olderdan]

From your picture it would appear that the spring has to many coils than is necessary and you would have to wind it up a lot to reduce the diameter enough, making it difficult to assemble. I think I would try halving the amount of coils and re forming the end loop curling outwards.

[thehomeengineer]

Hi
When I have fitted return springs in the past they have been supplied with a c-shape 3/16"-1/4” diameter ring which is slightly smaller diameter than the housing so it can be slid in place (safely) and once in place the ring can be discarded. I have not seen this type with a wire is wound to hold the coiled spring.
Be very careful as there is a lot of stored energy and when they go can take you by surprise. You could roll a ring and re wind the spring to fit the new ring, again be very careful if you chose to rewind the spring. Also make sure the spring is fitted the correct away around. So annoying when it is fitted and you realise it is in the wrong way and you have to remove it and rewind. Hope this helps.



The Home Engineer

[rendoman]

Thank you all for the advices!

It's nice this C shape ring,it seems better than the wire!

I just fixed the spring! As olderan said, I had to cut the spring and re forming the stop loop with oxy torch. I cut more or less 60cm, in order to put the spring inside the bobbin. With surprise I noticed that the energy stored was high (when I cut the wire), but to be honest it was perfectly manageable with leather gloves. I added a little pre-loading of 2 turns. The spindle axis returns fluid, the descent is light. I hope this spring will last !

[owen moore]

My suggestion would be to throw the entire spring assembly away and purchase a gas spring cylinder. I used two of these on a hydraulic press that I built. they are the the "pull" type( they have specific pull forces when retracting). You can select one that will fit your needs for both stroke length and force. I bought mine from Mcmaster Carr in Chicago, Ill.
I have not seen this done on a drill press, so be the first guy! I like the ones I put on my hydraulic press, and they solved a lot of space problems and eliminated two bulky return springs that were any ones guess as how much force they had.
Hope my reply was useful.

[Beserkleyboy]

I can't second the safety issue enough. As the homeengineeer said, heaps of stored energy, enough to require 4 stitches in the fleshy part below the thumb! I still curse that spring when I look at it (nearly every day)...Glad all worked out in the end. Cheers

Jim in the sunny South Coast NSW, Australia

[Toolmaker51]

I'm in full agreement with ALL of the details mentioned, especially that it looked far too long. 2 turns are a good preload setting. I frequently alter setting in accord with depth and certain operations, including occasional oiling of the spring. Really smoothes out binding on deeper work.