Glenn Posted November 29, 2009 Share Posted November 29, 2009 I have a couple of hooks on pulleys that have been overloaded and stretched out of shape. The first is on a 4 inch diameter or so wire rope block with a 10k pound rating, the other on a 3 pulley rope block. What is the best way to bend these back into shape? Cold with lots of pressure? Hot which would be the easy way. Should the hot bent hook be tempered or let air cool? What does either method do the the performance of the hook? Would it still have the original load rating? Quote Link to comment Share on other sites More sharing options...
JNewman Posted November 29, 2009 Share Posted November 29, 2009 (edited) Are these hooks for a lifting device Glenn? What is the material? Without knowing the material it is imposible to say how they should be heat treated. Usually it is much better to be soft because a gradual bending is better that breaking. If it is for a lifting device in a commercial application I would be very careful. The hooks I just finished had to be magnetic particle tested and sample material had to be impact tested. I also had to provide documentation from my heat treater. Often hooks have to be x-rayed on a regular basis. If these are standard hooks replacing them will probably be cheaper than all the testing. Are you willing to bet your house on your repair? Edited November 29, 2009 by JNewman Quote Link to comment Share on other sites More sharing options...
Glenn Posted November 29, 2009 Author Share Posted November 29, 2009 These would be used on a personal basis for pulling, lifting, or as needed. I have no idea of the parent material specs. The wire rope pulley was out on load and came back stretched. I ask how and got the run-a-round. The deal was 2 ea. 3 pulley wooden blocks and a 2 pulley wooden block. Even if you discount one of the blocks you still have enough pulleys to form a block and tackle. The one block has some damage to the side of the wooden frame and the hook is stretched but could be repaired with new wood, hook repair, or a new hook, if needed. Quote Link to comment Share on other sites More sharing options...
CBrann Posted November 29, 2009 Share Posted November 29, 2009 I would adjust them hot. First because it is easier, and second because it would cause less work hardening to the hooks.... However that being said, since these blocks have been overloaded, they may need to be taken apart, checked for wear, fatigue and abuse.... cooked bearings or bushings, cracked wheels, and bent axles can all make work harder than it needs to be.... and can cause injury and death... You know this already... It sounds like you just want them for light lifting.,... a little spray paint with a with a low working load might be a good idea... just so someone who is not you doesn't get into trouble.... Just a suggestion... good luck and be safe.. Cliff Quote Link to comment Share on other sites More sharing options...
JNewman Posted November 29, 2009 Share Posted November 29, 2009 I would agree with what CBrann just posted and would definately not use them near there rated capacity. Quote Link to comment Share on other sites More sharing options...
Frank Turley Posted November 29, 2009 Share Posted November 29, 2009 I have made a number of light duty slip hooks out of mild steel according to Schwarzkopf's* directions. I let them normalize. Nowadays, however, I understand that hooks are manufactured of medium carbon steel or alloy steel and are hardened and tempered at the factory. I think that when used for repeated hoisting and the hooks begin to open (stretch), that is a sign of failure, and they are discarded. P.S. It is best to have them open slowly rather than suddenly shearing in two. In some industrial applications, they have a discard schedule, and all hooks are thrown out and replaced at certain times of the year. The idea has to do with safety, and not all plants have heat treatment departments. I agree with Newman's above post re not knowing the type of iron or steel. I don't think that one should guess about how to reforge and heat treat. A friend from Toronto was researching old records at the library. He ran across an obsolete law stating that all wood hooks were to be brought to the blacksmith on an annual basis to be annealed. We assumed that the wood hooks were of wrought iron and were used in logging. The annealing would somewhat refine the grain structure of the wrought iron. *Ernst Schwarzkopf, "Plain and Ornamental Forging," Astragal Press reprint 2000AD.Turley Forge and Blacksmithing School Quote Link to comment Share on other sites More sharing options...
bigfootnampa Posted November 29, 2009 Share Posted November 29, 2009 Being that you are a smith Glenn, if I were you I'd forge new hooks. Just too much to worry about with ones that have been overloaded and damaged. It's not that hard to do. 4140 or something with even a little more carbon would be good. Loaning tools is a pain! I do it rarely and reluctantly (I am usually sorry afterwards too). It is real amazing how careless people can be with other peoples tools. If they were responsible people they would have their own tools. Quote Link to comment Share on other sites More sharing options...
Glenn Posted November 29, 2009 Author Share Posted November 29, 2009 Thanks for the replies thus far, keep them coming. Quote Link to comment Share on other sites More sharing options...
jimmy seale Posted November 29, 2009 Share Posted November 29, 2009 can you loose the hook and maybe replace with a shackle/clevis set up? or maybe replace the hook with one off of a chain? what ever you do be careful,jimmy Quote Link to comment Share on other sites More sharing options...
petere76 Posted November 29, 2009 Share Posted November 29, 2009 Glen, I work with lifting devices. The paper trail on everything connected to the load side is tremendous. We can't use slings that don't have cert tags attached. Lifting wires are calendar timed for replacement, not hours. Overloaded or even bad looking hooks get canned. That being said and I understand this a personal use (risk) item, work the hook hot and heat treat it the same as you would for proof chain. I would not attempt to re-bend the hook cold. As a safety recomendation, when you are done, de-rate the lifting load by 25percent of capacity. That should give you more than enough of an operational safety margin. Be safe and best regards, Peter Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.