Atlas 618 leadscrew question

Hi,
first of all, I'm not familiar with lathe vocabulary and use primary french as language, so excuse me the poor "text" that fallow.
I just bought my first late yesterday, an Atlas 618, serial number 011801 (if that change something, considering they build this particular model many years)
The only problem I see for now is that the leadscrew has a flat spot in the middle. This flat spot (about 6 inches) prevent the "tool carrier" to continue to move, so it stop.
In my complete newbie mind, I see three ways to solve this problem.
1. buy a new part. I read somewhere that we can still buy new atlas parts. Does this part is still available? If yes, does any one know the price?
2. machine a new one on a bigger lathe. This seem pretty easy to do, considering that a retired machinist that still have access to a shop will teach me some "lathe basic", but, as I have no experience, maybe it is harder than I think.
3. buy a treaded bar, so I will only have to machine the two ends. I think I should be able to do this on my lathe.
I would prefer the third option, if possible.
Any comments or hints?
Thanks a lot
Francois in Montreal
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These leadscrews are often available on E-Bay.
Pete Stanaitis ------------------
Francois wrote:

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Francois wrote:

Flat spot? - like it was struck with something? You should be able to fix this with some careful filing. Ken.
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hi Ken
It's more like if the top of the tread is wider and flat, like if the top of the tread was gone, maybe after 50 years of use.? or abuse? it is the same think all around the screw, for the central part, so it don't look like it was struck.

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    You are doing far better with English than I would be able to do with French. (I don't think that I could even do as well with Spanish, which I have studied.)

    [ ... ]

    Oh! That is not a *problem*. That is what is known as an Acme thread. The bottom of the thread will also be flat. The shape is sort of like this (within the limits of ASCII graphics, and it will look distorted if you don't have a fixed-pitch font selected when you read it. A good choice would be Courier, which is present on almost all systems which can change fonts.) ___ ___ / \ / \ / \ / \ _/ \___/ \___
    Except that the sides should be closer to vertical. The angle between the sides is 29 degrees, or 14-1/2 degrees from vertical on each side.
    This style of screw is able to deliver more force, and to wear longer before failing. It is *far* better than a typical V-form thread for the purpose. So -- nothing is wrong -- leave it alone.
    And as a way to check whether something is due to wear or is normal, check at various places. Most wear on a lathe occurs with the carriage near the chuck, so the end of the leadscrew near the tailstock should be a pretty good example of what an unworn one should look like. A *badly* worn leadscrew will look more like this:
/\ /\ / \ / \ _/ \______/ \______
That is -- the width at the top will have become a sharp edge, and the width at the bottom will have increased significantly. I found this in the middle of travel of the cross-feed leadscrew on my Clausing. (Note that the Atlas 6x18" lathe which you have (and which I have a very old example of) does *not* use Acme threads in the compound leadscrew, though if I remember correctly, it *does* use Acme threads in the cross-feed leadscrew.
    Good Luck,         DoN.
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french
many
the
I
http://www.atlas-press.com/service.htm
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