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Donniev

How to keep wide flat stock flat

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I have a friend who wants me to make a coat rack for him, he wants 3" wide flat stock to be used...I'm wondering if it would be better one way or the other to get 1/4" thick or 3/16" and also the best way to go about keeping it flat and straight...it's going to be 36" long end to end, and aside from working it in the vise I'm just not sure how to have my finished piece not have some wobble when it's laid on the table. My anvil has slight swayback, it's not a lot but enough that I can't just use my anvil as a guage to see how flat it is/ hammer it back flat

Any thoughts appreciated

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This will sound odd; but "Take up knifemaking!"  you spend a lot of time staring down the edge of blades checking their straightness and straightening them. Also a sway on an anvil is *BETTER* for straightening than a dead flat one.  If you need a dead flat surface to trial against a piece of RR rail is usually pretty flat over reasonable differences. (and you can check it before you haul it home from the scrapyard.)

I generally find that the thinner long wide pieces of metal are the harder it's to keep them flat and straight while working them---how much will you be forging the back plate?  Have you checked for where the studs are where the coatrack will be mounted?  You may need to factor in the mounting holes into the coat hook pattern.

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Flat stock will do any or all of 3 things.  Bend the easy way, bend the hard way, or twist (which is technically a combination of the first 2).  To fix the bends, flip it over and hammer down on the high spot of the bend.  To fix a twist clamp one end in a vise, sight the length, and muscle a bending fork, twisting wrench, tongs, adjustable wrench, etc the opposite way.  Combination bend/twists are easier to fix if you correct the twist first.  It is possible to hammer out a twist but it's more trouble than it's worth if you have a vise.

Cold twisting tip:  Scale pops off cold mild steel at around the same time you pass the yeild strength.  Often when you see the scale start to jump off a bar it will have taken a new "set" and stay where you put it.  YMMV

In my opinion a swaybacked anvil is fine for hobby work but inferior for high quality professional work.  You can straighten a bar on a flat anvil as easily as you can on a swaybacked one, but a flat anvil also allows the smith to instantly index the work piece to a flat surface, even the zone that would be up in the air on a swayback. No wasted steps to a secondary flat work surface or "eyeballing" while the piece cools.  Energy costs money. 

99% of the professional smiths I know or have seen working have a dead flat primary working surface. 

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Thank you, Judson Yaggy, for your opinion on swaybacked anvils. Agreed. I find sway turns a simple straightening process into a back-and-forth time wasting endeavor. I only frequent one professional shop; both anvils have chewed faces from cold work but are dead flat. The owner describes an anvil with any sway as "worn out."

In my shop, an otherwise excellent Hay-Budden has a barely discernable sway that makes it far less useful than the marred, but straight, Badger. 

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Using 3" flat stock for the backer plate on a coat rack is pretty easy.  Just keep it cold.  You can add dings to give it that "old" look even though it's cold, so keep it cold and it will stay as flat as it was when you bought it.

As for putting holes in it, use a drill rather than try punching them.   I prefer to drill since I don't have to worry about the holes being lined up right.

Also, you can use your driveway or a curb to act as your straight edge.  Hot steel is far softer than concrete, so a little light hammering on the stuff won't bother it.

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On 2017-06-30 at 2:35 AM, Judson Yaggy said:

  You can straighten a bar on a flat anvil as easily as you can on a swaybacked one, but a flat anvil also allows the smith to instantly index the work piece to a flat surface, even the zone that would be up in the air on a swayback. No wasted steps to a secondary flat work surface or "eyeballing" while the piece cools.  Energy costs money. 

99% of the professional smiths I know or have seen working have a dead flat primary working surface. 

hear hear!

I have no difficulty whatsoever in straigthening on a dead flat anvil

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If you need a straight edge to lay the item on to see if it's flat (by looking for daylight gaps underneath), just buy more flat stock than you need for the job and use that as a guide. 1/4" x 3" is not likely to bend on the hard axis, so just cut a bit of that off and clamp it in your vise vertically, then move your coat rack around on it and look for daylight. Laying it on lengths ways will show one set of valleys and peaks, rotating it through 90 degrees and running it back and forth perpindicular to it will show up twists. You're probably more likely to feel them than see them using that method.

You're not going to need a very larger area to check for flatness in the coat rack, other than my flat-bar-in-vise method you could just find a small bit of RSJ and move it around on that. Make do and bend!

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I have been using the same slightly swayed Hay Budden for my entire career.

I make a great many colonial style strap hinges, often 3 feet long or longer.

I have no problem getting/ keeping them dead flat. 

As Thomas said a slight sway helps immensely. 

My last year on the road I spent at the shop of a well known smith with nothing but the best of everything.

I did a LOT of straightening on heavily hammered pieces.

It was much more difficult for me to do a large volume of straightening on dead flat anvils.

I entirely disagree that a slightly swayed anvil is worn out.

I have anvils that were worked all the way through the top plate.

Perhaps used on a sole task yet for the majority of the lifespan they were "worn out". 

 

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I have a sway-back just for the purpose of straightening bent tractor and equipment parts and pieces,,,heat and beat  then back to work

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I got both racks finished up yesterday. The small one is 20" long, and I was laying it flat in the coal forge to heat an entire section up, but it starting twisting pretty badly. After 30 minutes fighting it back flat, I stood the steel straight up in the fire so I would get about a 1"*6" area hot, and just chisel and work one side at a time. This went much better, after the chiseling was done I easily got it back flat with 2-3 blows since I was only working one side, as opposed to heating a section of the 3" wide steel. Also went with Thomas' suggestion and used 1/4" stock, I do agree that it's easier to keep flat than 3/16 (what I'd used for the last one I made)

IMG_20170727_210606509~2.jpg

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