Straightening or bending metal

[bjcsc]

Rake tips are always getting out of line. I made a tool for lining mine back up (cold). It's just a 4' piece of 1 1/2 x 1 1/2 x 1/4 angle with a piece of 1 1/2 x 1/4 tube with one side cut off welded to it about 10" or so from one end. Slip it over the tine, bend it back.

Chances are it's spring steel, even if it's welded. If you heat it enough to bend it, you'll take the hardness and the temper out. If you quench it, you'll get the hardness back, but it will be brittle and will break in that spot next time instead of bend. You could try to re-temper it, but that is difficult as a pretty precise temp. has to be maintained for a period of time. Bend it cold...

 

[jgrieve]

in manufacturing most steel parts are bent cold. Heat makes it bend easier. Spring steel will break if bent cold generally.

 

[bota7800]

Wait, are you saying that the tines on your rake are welded on? If they are then either they are not treated, or they have already been damaged by the welding.

Mike

Yes, they are bolted to a piece of square tubing that acts as the shaft. I may try to weld on some triangular reinforcements like I saw on some larger spreaders.

 

[SPYDERLK]

The rule I was always taught was don't heat treated steel, and if you do heat it, use as little heat as possible, and let it cool on its own.
Try it on a tine or two, and see what happens. You can always replace them.

This is good advice as far as it goes.
In order the make hard springy stuff move harmlessly you will need heat absolutely! Springy steel, if high quality, is hard like grade 8 bolts or even harder. In the hardening process the steel is heated very hot and quenched. Then it is reheated to the 800-1000F range and allowed to cool. This softens it a little, but makes it much tuffer. If you were to reheat this steel very hot [bright red/yellow] and allow it to cool it would anneal it and make it soft. You dont want to use enuf heat to anneal it, but 600 to 800F will not spoil the original heat treatment. You can gauge this temperature by 1st lightly abraiding the surface to put a silver shine on the metal. Then heat the area you want to bend. When the shine turns straw brown you are at around 400F. At blue you are passing 600. At purple you are at 800 or so. Do not go further. A gradual [as opposed to sharp] bend can be done harmlessly in this range.
larry

 

[bota7800]

Yes, they are bolted to a piece of square tubing that acts as the shaft. I may try to weld on some triangular reinforcements like I saw on some larger spreaders.

D-0h!! What the blank was I thinking? Sorry

No the tines on the rake are not welded on - they are clamped like normal.


Thanks Spyderlk, that is what I was looking for.

 

[bjcsc]

Spring steel will break if bent cold generally.

I'll have to respectfully disagree with that line of thinking. If that were true, his rake tines wouldn't be bent in the first place - they'd be broken. If they are severely bent, they can't be fixed or bent cold, but if they're slightly out of line (which is my experience with landscape rakes) they can be tweaked cold. I've been tweaking mine like this for years. Catching those slight color changes in the steel is an art and is quite difficult for the average DIY guy (including me)...and what a considerable effort for a $4 tine...However, to each their own!

 

[AlanB]

Not sure if it is what you are looking for, but as for heating them (and I would not, I am in the bend cold if possible camp) And you are inexperienced (which, from the question, I gather you are in this discussion) then there are what is called Tempil markers that will be available from your local welding supply house.

Apparently Tempil is a brand, but if you ask at the welding house, they will know what you are referring too.

http://www.airgas.com/browse/product_list.aspx?catID=381&Keyword=tempil

That is the easiest, accurate way to tell temps on steel if that is where you are looking to go.

The problem with heat treating / spring steel and all the other discussions we are having here, is that none of us REALLY know, what steel you have, heck, depending on where your rake was from, and who replaced the tines along the way, the manufacturer may not know either.

I am off and wandering, but if you would like to learn more about heat treating in a practical, do it in your home shop kind of way, get the Foxfire book that talks about blacksmithing and rifle making. Excellent discussion in those volumes about seeing the colors etc. Next best thing to standing next too the crusty old timer in a dank dark shop up in the mountains.

That said, depending on how accurate you want to be, make a form out of plywood etc, and make a follower and curve them around it.

On ours (wife is a landscaper) I have a big hammer and when it starts looking gangly, I raise it up and beat the things basicly back into line, when one breaks, my local small time tractor store has a pile of them at a couple bucks each.

Good luck.