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Thread: how to make flat spring?? Newbie
05-02-2007, 11:08 PM #1
Any advice on books that describe how to make flat springs?
I need to make a somewhat flat spring with about 3/8 inch of deflection fron one end to the other end.
Its measurements need to be 6 inch long, 1/2 inch wide and something between 1/16 to 1/8 inch thick
I have some brownells spring stock which is annealed and I have no instructions on how to use it. It is not springy enough the way it is.
I'm basically trying to make a small leaf type spring
05-02-2007, 11:29 PM #2
Annealed spring stock will have to be hardened before using it as a spring. Depending on what machining has to be done you may be able to use pre-hardened stock which machines fine with carbide tools. ...or you can harden the piece you have. McMaster sells a wide variety of spring steel. I have a spring design book but I can't find it. Machinery's handbook has formulas for force and deflection of leaf springs though.
There's a spring design forum here if you need more help:
05-02-2007, 11:33 PM #3
You might send an email to Brownell's tech support. They are very helpful answering questions like this.
05-02-2007, 11:48 PM #4
Ordinary O1 ground flat stock can be used for making springs. It is available in 18" x 1/2" x different thicknesses by 64ths of an inch. It is oil hardening and possibly a little easier to heat treat than the Brownell stuff, which is probably similar to W1 tool steel.
You can also buy ready to use hardened spring steel in various size long strips. Not heat treating it saves some headaches. See the listing of clock spring steel on P. 36 of the Coles Power Models price list. Coles price list
By the way, you can stack two or more layers of thin strips of spring steel to get the effect of a single thick spring. Trucks do it all the time.
05-03-2007, 12:04 AM #5
Place a couple of bricks together.Maybe 4.Make them into an inside corner shape to keep heat from escaping too quickly from mapp gas torches.Heat the finished spring by laying it in the "corner".you might want to use 2 mapp gas torches.Heat it evenly all over,keep the torches moving over the spring,until it changes from red into an orange color. If it is 01 steel,quench it in vegetable oil. If W1,use water that is not freezing cold..Quickly take tongs and submerge the spring vertically into about a 2 gallon water,or oil quench. Have it enter the quench end first,vertically. Stir the spring around in a circle as quickly as you can once it is completely submerged. The spring will now be very hard and should be treated like it is glass.Polish off the spring with wet or dry paper. Keep the spring free of oil. Place it back into your brick corner,and very slowly,and by degrees do your best to draw it to an even dark blue color.it is easy to get the spring too hot in one area,and have it go above blue to a gray color.Then,it is too soft and must be hardened again.If you get one part of the spring to a blue color before the other parts,quench it while it is still blue,wipe it off,and heat the other areas to blue. It might just be best to take the hardened spring and place it into a metal bowl with maybe an inch of motor oil in it,light the oil,and remove the spring after the fire goes out.No need to quench after this last oil heat proceedure. It should be a spring unless you got it too hot during the initial hardening. Any sign of blisters on the steel after the initial hardening means you burnt the steel and ruined it. The oil heating process will not make the blue appear,as the burning oil just leaves a black coating on the metal. The oil fire does give the same temperature as the bluing process. the spring will only break if you got it too hot,or if your design is wrong,has thin spots,holes drilled in it,etc.. I hope this posting isn't too confusing. P.S.,if you ruin the piece by overheating it drawing it to blue,you must normalize the steel. I take a pile of sand and get it good and hot with the torch. Heat the steel bright red,and shove it buried into the hot sand. Let the whole mass cool slowly. The spring should then be as soft to a file as when it was new. It has been re-annealed. Then,repeat the hardening and drawing processes. Be careful of your eyes when bending the new spring. They burst violently when they fail,sometimes they throw pieces at high velocity. I would not try using pre hardened stock,unless it is blue spring steel stock. Pre hard 4140 is too soft. The Brownell's stuff is water hardening. The only thing wrong with water hardening is that it can distort more than any other type of steel. All of the 19th.C. springs were made from it,though. If your spring must have a hole,pack steel wool into the hole tightly with a hammer and flat nosed punch. That keeps it from cracking from the hole. Avoid stamping figures on the annealed spring,too. that invites cracks also.
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05-03-2007, 01:12 AM #6
if i may add to Mr. Wilsons advice if you use molten lead at 600* or 620* whatever it melts at this will temper to spring easily...jim
05-03-2007, 07:21 AM #7
i have some spring steel 1095 if i remember right, it is .160x.875x10 oal i can part with a couple for you to experiment with
05-03-2007, 02:26 PM #8
Could O-1 be use to make a round strip spring for a compass,caliper or similar type of legged tool that needs inward tention? I have been wanting to make my own compass for a while,I figured this would be a good time to ask.
05-03-2007, 02:39 PM #9
05-03-2007, 03:53 PM #10
I have made quite a few springs out of 01. The trouble is,01 has a bit more carbon than 1095,and 1075,which makes it a little trickier to temper so it won't snap. I would advise use of the 1095 or 1075 if you can get it. 1075 would be the easiest to use to avoid breakage.