Tapping a stainless steel rod.

[willy3486]

I hope I can explain this as I am not a machinist and just learning. Years ago I picked up a Craftsman 109 metal lathe at a good price. Yes its not the best reputation as far as lathes go but for what I need it for it would do. The one issue that it has and is a known issue is the shaft the head fits on bends easy. Mine is like that. I ran across a page a fellow made a shaft for his and he said it worked a lot better. He found out the shaft was 14 mm which translates to .551".

So I ordered a stainless steel rod to replace it. What I found out is the threads on mine is 1/2 inch with 20 teeth per inch. I have a tap that size but it will not go on. I figure I need to mill the rod down for the tap to go on. So I am thinking I need to mill it down on the end I want the threads to about .490" to .495" . Does this sound like a good size to tap it using a 1/2 inch tap with 20TPI ? If not what would be a good size? Here is a picture after I had taken it apart, oiled and put it back together.

 

[Packard V8]

FWIW, you do not want to thread a lathe spindle with a hand tap. It's impossible to get it straight enough. You're going to have to pay/beg/bribe someone with a lathe to cut the threads.

Another FWIW, it's theoretically possible to thread it on the lathe you have, but from the way your question was posed, maybe you shouldn't go there just yet.

jack vines

 

[The Cobbler]

and stainless is not the material to use

 

[Firebrick43]

Taps are for internal holes.

What I think you’re talking about is called a Die for cutting external threads.

And Mr 1955 and the shoe maker both have it right

Have some one else machine it out of at least 4140.

 

[MushCreek]

I'm trying to understand- Are you talking about making a new lathe spindle? As others have said, stainless is not the right material. It is hard to cut, but is actually a fairly soft material. The threads have to be perfect- not a job for a die.

 

[willy3486]

Yes I believe it is called the spindle maybe. Its the shaft that has the pulley the belt goes on and the other end holds the chuck. I always get taps and dies mixed up. As far as the original shaft the metal its made of is really soft, its not tool steel. These were the cheapest lathes you could get from Craftsman at the time. The steel rod I got was listed that it could be used for shafts and such, I thought it was stainless but it may not be. If I could find someone local I would pay to have one made but I live in a rural area, a lot of farms and meth heads so not a lot here. As far as the lathe goes it was cheap so it was a offer I couldn't pass. I would like to upgrade to one of the nicer lathes they sold but I don't need a full size one. I am the type that likes to try to learn a new skill. As far as what I would mill I think it would be mostly soft steel and aluminum.

Usually if I see some new machine I might think I need I don't go out and find something used or cheap, like HF stuff. That way I don't have much in it and if I see I will use it I can upgrade. As it sets now the shaft is so bent it can't be used. There was a fellow who use to produce these new spindles but he was elderly and quit completely. I do see used ones pop up from time to time on ebay but I don't want to chance getting one and then it be in the same shape. I have had this one for about ten years and I am finally getting around to try to fix the issue and try it out. I restore old tube items like radios,jukeboxes and guitar amps. So it would be handy to make new dial or volume control shafts for oddball stuff. Anyway I was tinkering around with it to see if I could actually use it some to see if I would have a need for a lathe.

 

[helterskelter]

Stainless is the wrong material. And you're not going to be able to cut those threads with a threading die (they won't come out concentric). So go ahead and return the stainless shaft.

Can you post a detailed drawing of your spindle so we can see the part you're trying to make? There might be some creative solutions if we can see the part. The best way would be to make a new spindle on a larger lathe. But if you just want something to run and have fun with maybe something can be figured out.

 

[willy3486]

Here is a link to the article someone posted about making a new one. He does excellent work to me so I thought I might try it as well. As far as this "fix" goes keep in mind its just a temp fix. I mainly want to do something to make it usable somewhat until I see I really have no need for one or I see I really need one and then upgrade. As far as this rod goes I thought it was stainless but it may not be. The description said it could be used for making parts like this. Hopefully its ok to post this blog.

Craftsman 109 Lathe - New Homemade Spindle

I have known that the spindle on my lathe is old and worn out. I am not sure if it is bent, but I like to replace it. There are spindles av...

adamli.blogspot.com

 

[MushCreek]

It's odd that an old Craftsman lathe has a metric spindle. If I were making it, I'd find a piece of 14mm drill rod (not hardened), and proceed like the guy in the blog. Is the original spindle solid or hollow? I've never seen a lathe with a solid spindle, but that's a really small spindle. That's a bit of work with the woodruff key slots and need for accurate threads. First I would accurately measure the original spindle. It might be 9/16 in diameter (.5625) instead of 14 mm. Metric dimensions aren't often seen in older American iron unless it rides in ball bearings, many of which are metric. It also needs a really good fit in the spindle bearings, or else the spindle will move around when you try to take a cut.

 

[andyvh1959]

I agree that stainless steel is not the right choice. Tool steel is a better choice and likely machines better. I wonder if trying to cut threads on stainless steel has galling issues like when treading S/S threads together? When threading S/S hydraulic fittings togeher, JIC flare or O-ring face seal, anit-seize is required on the threads and sealing faces (for JIC) to avoid galling and ruining the connection.