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Tempering or Hardening or...


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Hello All-
Apologies if I seem unfamiliar with the terms of hardening metal- I'm pretty new to this whole thing, so..

Here's my conundrum:
I am building a device to roll 3/4" fire hose. Currently it's done by hand and can be rather tedious. We double-roll it, so the middle is found, it's folded over on itself & the roll started from there.

Now my idea is to take a piece of 5/16 round stock & cut a slot down the middle as seen in this drawing:

hoseRollerNose.jpg

Attach a handle to this piece like a crank and with the appropriate mount & such, one side of the hose is placed in the slot, the handle turned, and the hose will wind itself around the 'business end' of the device.

Only one problem (so far) and here's where I need your advice: As the hose is rolled, the tension created will tend to crush the 'fork' together. I'd like to overcome this- as if that fork is smashed together the roller becomes useless.

I'm hoping to harden or temper the forks so they can't be bent easily.. But I'm not sure how to do that. I have heard about "case hardening" where (I believe) the pieces are placed in an air-tight can full of charcoal or bone, heated to a red heat & left to cool in the forge. Is this an option?
I have also heard of using a propane torch to heat the piece one wishes to harden untill the color changes to .. "Straw" I believe, then quickly quenching the item in water or oil. If this is my best option, can anyone suggest which liquid to use?

Now of cource I don't want the forks to become brittle and break off, but I don't want them to mash together either.

Thanks in advance for any help- and apologies (again) if I've mis-used any of the terminology.

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Krstopher:

First let me tell you that hardening and tempering are not one and the same. Tempering is actually the removal of a selective amount of hardness and brittleness. Second Case Hardening only imparts a hardness to a very thin layer at the surface of the metal usually a few thousandsths of an inch thick it is not what you want in this case.

All steels are not created equal. The properties that make a steel hardenable are first the carbon content of the steel and second the alloy metals that are added to the steel. I assume that you are using mild steel from a local steel supplier. This may be suitable for your purpose but you may have to use a type of steel with a higher carbon content to get the desired results. I would recommend that you try the following if this steel is in fact mild steel:

Heat the forked end of the shaft and check with a magnet. When the magnet will no longer stick to the metal it should be a cherry red color, quench the end in iced salt water. This will make the metal as hard as it will get. Now you need to temper the end, that is remove some of the hardness and brittleness without letting the metal get too soft. First sand the end to remove any scale and get the surface back to a bright condition. Then heat the end slowly with a propane torch or other burner watching the color of the steel. It will first turn a pale straw color, then a dark straw color at this point if it is mild steel, quench it in cool water. The temperature at which you temper this piece will be around 450 to 475 degrees F. If the piece is small enough you can simply put it in the oven and bake it at that temperature for an hour or so then take it out and let it air cool.

Without knowing the exact type of steel used in your tool, it is almost impossible to give you exact instructions on the proper heat treating of the piece and it may take several attempts to get it right. If you are using a piece of junkyard steel or unknown composition, and you know what it's original application was, i.e. motor shaft, spring, etc. email me, I have quite a list of junkyard steels and their types I can help you identify the material and then recommend the proper heat treating and tempering process.

Woody

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Let me add the fact that the tecmperature at which steel becomes non-magnetic is about 1430F. A steel with a carbon content of about .8% is fully austenitic at about 1340F. Heating a .8% carbon steel to non-magnetic will also mean it is fully austenitic. HOWEVER.....a steel with less carbon, and mild steel has MUCH less carbon, needs to be heated well ABOVE non-magnetic to make if fully austenitic and ready to quench. The reason for this is found on the BP on Heat treating for Blacksmiths over on iforgeiron. Why not fabricate this piece from two pieces of 1/2" or 3/4" rod? If you want to prevent the fork from collapsing and you can't heat treat it, make the forks thicker. :lol:

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Thanks for the input you guys-
I can use pretty much any steel I want, as long as it's 5/16 as that's what fits the bearings.. So it can't be any bigger. Also, if it was then the hole in the middle of the roll would be too big and the roll would probably unravel.

I'm trying to find 5/16 spring steel, as that's already a spring so even if it gets mashed it will bounce back. Pretty hard to find that size tho- At least so far. From what I understand most of the time round spring steel comes raw in coils & is then wound into a spring.. And .3125 would make a fairly big spring, so it's not stocked much.

Going to have the notch cut by the local water-jet shop.. So there's no limit to what metal I use. It's just ease of making the forks stay durable that I'm really concerned with. The pieces will be 3" long when done so I can easily fit a bunch of them in the oven- That's a really good idea.

So for now I'll probably use 4130 cold roll or somesuch. I just went to onlinemetals.com & pulled that from the sky- So if there's a better option don't be afraid to tell me ok?

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I would love to see a picture of this when your done. Spring steel that small might be found at a local garage door co. Some of thiers are small but very long. It can be heated and straitened but the heat treating will have to be done when finished. Consider bending the 5/16 into a U shape as close and as long as you want and not splitting it. Spring steel is hard to split, and small round, harder. The U can be welded to the crank. If I'm visioning this right, the legs of the U would only be 1 1/2 to 2 inches long? If this is so I would think working the steel when hot, letting cool naturaly,welding the U to the crank and letting cool naturaly should be plenty strong without any further hardening. This type of spring steel is realy hard without hardening. Probably the weld will be the weak point and thats pretty hard. I've used this system and it works. Tilt the side plate on the roler twards the crank and the hose will lay there till removed. Try it. Its cool. Brad

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Hello,
Go to your nearest salvage yard, and find a coilover shock on a old car and buy it. Most of those coilover springs are 5/16" spring steel. Take it home, remove the spring from the outside of the shock, heat to forging temps and uncoil the spring until you get the lenght you need for your project. This is what most of us do, for spring steel. Most of us get our steels from scrap piles.

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Krstofer:

You can use any diameter you want if you want to go bigger than the 5/16" that has to go through the bearings. Think like a blacksmith here...If you are concerned about the prongs being squeezed together get some 3/4" round for that section and forge in a 5/16" diameter tennon for the shafting that has to go through the bearings. A good 60 Pt. C steel like 5160, 9260 or even good old 1060, drawn back to say a full brown to temper should do it.

This would be a great excerise in working a tennon, splitting and thermal treating.

Hope this helps..

JPH

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If you start with 5/16 round stock and remove the center 1/3 there is no steel alloy that won't be pushed together---or break, just too small I would think such a small diameter bend would be hard on the hose too!.

When looking for high carbon steels call up hardware stores and ask if they have "drill rod",

Often O1 steel and found in many sizes---but I'm with the prior suggestion buy thick and forge the end down to fit 5/16---but remember that isn't a very strong dimension and hose is *heavy*.

Thomas

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Krstofer-

The real questions should be more about the material that this fork is to be used to roll. What is this 3/4" fire hose? That sound really small to me. Is this for a model or models? What type of material is it (rubber, nylon, poly, canvas), and what is the actual dimension of it when flat? What will the finished roll size be(outer diameter) and what will it weigh? What and where are these bearings that you spoke of? Are they in an existing roller or piece of equipment or are they something that you are in the process of designing/building?

If you could supply these tidbits and any others that you may have, perhaps we could work something up or suggest something more fitting about the fork.

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Hey Guys-
Here's some 3/4" "toy hose" used in the Fire indusrty to "mop up" the woods after the main front of the fire is past. That's a 50' roll in my hand.


toyhose2.jpg

It's called "liteweight" because it is.. I could carry 3 to 400' in my pack no problem.

It folds right over & is very thin when empty-
toyhose1.jpg

And it only weighs ... 4 oz or so.

The problem with this particular roll is when you unroll it, the other end is 50' away. You have to go get it then attach more hose or a nozzle or whatever. Easier to have it double-rolled, so when you throw it you have both ends in your hand still.

The bearings for the new rolling device are from "rollerblade" wheels.. Less than a buck a piece.

Here's an old prototype-
oldroller.jpg
I made it from stuff I found in the hardware store.
Tested for a year by the Plumas Hotshots.
They broke it. But that's what "in the field" type testing is for.

You put the hose in like this:
rolling.jpg

And it makes this:
rolled.jpg

From "ball of hose" to rolled & ready in under 45 secconds- When rolling by hand takes at least 5 minutes. NOt much time, except when you have 20,000 feet of hose to roll & take with you at the end of the day, and only 2 guys tasked to do it. I used to be one of those guys- And after about 2 afternoons of hose rolling tedium, I built the first prototype roller.

As I continue to think about the new roller- I'm not absolutely sure the "business" part needs to be a spring, or very hard.. As I'm not terribly sure it will get mashed together very hard. BUt I like to build things that are"bomber".. I know alot of the gorillas who will be using my stuff and trust me- If it *can* be broken, they'll do it.

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Oh and if the fork for the roller is longer than the width of the roll you can put a spacer and a cap or pin to keep the spacer in place, the spacer being used to keep the fork from collapsing. It then could be made out of any material , hard or soft.

Here is one possible configuration for the spacer/fork, you can make the spacer disk as large as the roll if wanted.


forkedtongue.jpg

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In fact if you made both sides of the fork fitted with a disk of say 10 or 12 inches it would help form the roll better than the "blades" that you have in your prototype. One would be the spacer.

I wish you could see in my head, i have a complete design to give you. I'll try to post some more as it leaks out of my sponge head.

I used to be a fireman(twenty years ago) and I should have remembered the backpack hose. Seems to me we had a winder, although I never had to use it myself.

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Why not think bending forks here. Weld a piece of 1/4 x 1 flatbar to the end of a 1" pipe, making a T. Weld 2 pieces of 1/2 round (gorilla proof) about 1 to 1-1/4" long to the flat bar. They could be as close as 1/2" apart. Loop the hose over either pin and start rotating. It will make it a bit oval instead of perfectly round, but the idea is to get the cat skinned and the hose rolled.

If your worried about the hose not tracking, put a BIG washer say 6-8" dia of 1/8" plate on the 1" pipe and slide it up to the backside of the flat bar and weld. Then insert the assembly into a 1-1/4 inch pipe. (The 1" will fit inside a piece of 1-1/4" pipe that can be held stationary) A 90 degree pipe fitting will give you the throw you need to wind and another 90 degree pipe fitting for the handle. Tack weld the fittings in place to make it gorilla proof.

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Go powered, geared down motor with a foot switch control, takes only one guy to roll it as you can guide it while your foot is doing the power control.

With light weight small hose I'd go with hardened pins press fitted into a disk and the disk have the axle that goes through the bearings. Nylon "guide" disks would be easy to fabricate too.

Have you talked with the local VoTech about doing this as a class project?

Thomas

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