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Totally green need help

FreediveShop_hb

Plastic
Joined
May 2, 2009
Location
CA
Hey guys I'm sure you probably answer the same questions over and over from new guys but I know next to nothing and need it answered.

I run a small spearfishing shop and I want to thread steel shafts up to 5/16 or 8mm as cheaply as possible.

The thing I can't figure out is can a mini lathe handle spring steel or heat treated shaft up to 160cm long? If not what will?

What can I say I never took only took woodshop in HS. Any help would be greatly appreciated
 
This would typically be done on a thread grinder. Lathe or no lathe heat treated spring steel would not be easy to thread. In that case it becomes about the particular specification of steel and just exactly how hard it is and how big and how stiff the lathe is. The question asked is really the wrong question. Should be something like: I've got steel type SAE XXXX and it's heat treated to rockwell C XX and I want to cut threads 0.XX deep in N of them; what machine and tool do I need? That's a question we could answer.

Are these shafts solid or hollow? Would it compromise the performance to anneal the end first? What is the finish on the shaft? What finish do you want on the finished threads?
 
This would typically be done on a thread grinder. Lathe or no lathe heat treated spring steel would not be easy to thread. In that case it becomes about the particular specification of steel and just exactly how hard it is and how big and how stiff the lathe is. The question asked is really the wrong question. Should be something like: I've got steel type SAE XXXX and it's heat treated to rockwell C XX and I want to cut threads 0.XX deep in N of them; what machine and tool do I need? That's a question we could answer.

Are these shafts solid or hollow? Would it compromise the performance to anneal the end first? What is the finish on the shaft? What finish do you want on the finished threads?

Ummmmm yeah like I said totally green I really thought I could just get a machine set it up and there were pre set threading paterns or something and you just control how fast/deep each pass is made.

How about a new question......

Anyone know of a good school, college where one can take a class to learn how to thread material in the Los Angeles Area?
 
Why are you using spring steel? That seems like tremendous overkill and it will corrode like a mother in salt water. All you really need is a material harder than the fish. Plain aluminum will do just fine. I you really want to be fancy, you can use a stainless. Either one will reisist corrosion in salt water as long as you rinse them off when you get back to shore. I'd use thick wall tubing in either case to provide adequate stiffness and save weight. You can use a plain old Craftsman die to do that job. Any cheap lathe will cut the tubing down to the right diameter. In fact
 
How many parts do you want to thread? If it is a dozen use a hand die and a vise. If it is a thousand a month there are machines that will do it no problem. A Haas tool room lathe has canned programs for threading and a Haas sales place will demonstrate how it works on one of your pieces. If you have a job worth spending $20-30K on a brand new small smart lathe like that you have a solution for doing a 100 parts a day probably. If you need 1000 parts a day you might have it done in China.
 
All you really need is a material harder than the fish. Plain aluminum will do just fine.

What about Rockfish :crazy: ?

Anyhoo, I'm fairly certain he means stainless. Fancy SS like 15-5 or 17-4 maybe, but stainless nonetheless. I think Al wouldn't work not because it wouldn't stick a fish right through, but because I bet these things get tossed around with other gear and otherwise treated roughly. Maybe there's a mass component to it as well - an Al shaft might slow down too much between the sticker and the stickee.

OK, so now I recall the "Threading SS with a die" thread. I forget the thread title, but it's all about using dies on SS.

Regards.

Finegrain
 
Why are you using spring steel? That seems like tremendous overkill and it will corrode like a mother in salt water. All you really need is a material harder than the fish. Plain aluminum will do just fine. I you really want to be fancy, you can use a stainless. Either one will reisist corrosion in salt water as long as you rinse them off when you get back to shore. I'd use thick wall tubing in either case to provide adequate stiffness and save weight. You can use a plain old Craftsman die to do that job. Any cheap lathe will cut the tubing down to the right diameter. In fact

you obviously never shot any big fish.....they'll bend even good SS shafts, especially if you have a line on it....
 
I hope you aren't referring to the "overseas" mini mill ... if you are the thread will be closed pronto by the moderator. You are better off posting the question to the home shop machinist forum where you can discuss the "overseas" machine tools more openly.

Oh, btw ... see the forum rules and you'll see what I'm referring to.

http://www.practicalmachinist.com/vb/showthread.php?t=137724

and this kinda stuff on the computer torques me off too.....some guy comes on with an honest question, and the first thing you get from one of the 'keyboard kommandoes' is this kinda krap......"well, we're really smart, and professional, and gotta lot of posts on the forum, and we know all these rules, and....blah, blah, blah..."......pretty pathetic.....amazing what bravery anonymity breeds....
 
I think the cheapest method to get good threads on those shafts would be to take them to a machine shop. You could spend a lot of time and money getting to the end result you're looking for, considering the material you're working with, experience level, and that fact you're starting from scratch tool-wise. If you do a batch of them it'll be cheaper per unit. If you do it yourself plan on making making scrap out of some spears.
 
and this kinda stuff on the computer torques me off too.....some guy comes on with an honest question, and the first thing you get from one of the 'keyboard kommandoes' is this kinda krap......"well, we're really smart, and professional, and gotta lot of posts on the forum, and we know all these rules, and....blah, blah, blah..."......pretty pathetic.....amazing what bravery anonymity breeds....

I do understand the frustration, but I think it was a friendly warning rather than a commando attitude. Like it or not, this is NOT a publicly owned forum -- it is owned and maintained by Milacron, and he sets the rules. His rules say no discussion of small asian-import hobby level machines ... period.

FWIW, his rules have "bitten" me a time or two, to my own frustration. But I also appreciate the very high level of experience and information that is available here ... partly as a result of limiting "home shop" type discussions. Bottom line is that it is Milacron's sandbox, so if I want to play here, I gotta play by his rules, like it or not ...
 
"well, we're really smart, and professional, and gotta lot of posts on the forum, and we know all these rules, and....blah, blah, blah..."......pretty pathetic.....amazing what bravery anonymity breeds....

C'mon Bigsax, The first thing anyone should do when joining a forum is read the rules. Most (all?) forums have at least a few, it's common courtesy to know and follow them.
 
Finegrain: Hardy har har! But you forgot stonefish and steelhead trout!

Actually, from what I understand, real spearfishermen take very good care of their rig. And I don't think we're talking about spearguns here. The guys I'm thinking about take down a loooong spear with a line on it and they don't use SCUBA gear. They're a lot like bow hunters who view it as a matter of pride to just use lungs and good eyes to snag dinner. At least that's what I think he's talking about.
 
OK, so the question was: can you use a small lathe to thread stainless or spring steel? Answer is: yes. However, there are extenuating circumstances. Simply put, for the beginner, if you can cut your material with a file, you have a good chance of generating some decent threads with a single point cutter on a thread cutting lathe. To start, you will need to know how to sharpen a carbide tool bit to 60 degrees with the proper clearance angles. You will need a silicon carbide grinding wheel and a diamond sharpening stone like the type used to sharpen kitchen knives. OK, you will need to determine whether your lathe will cut the threads you need. If it has a quick change feed box, look at the numbers on the instruction panel. If you only have change gears, you will need to consult a standard reference to determine what gears to use. Yes, going to a class will get the job done, so will getting a a few good books and figuring it out for yourself. The books will take a little longer, but the info will stick in your head a lot better. Best deal is to go to a local machine shop and talk to someone who does this stuff for a living. Most guys who love this stuff are more than willing to share their secrets. Most times when someone told me I couldn't do something because it was too much trouble, I just dug in deeper. Man it's dark down here. WWQ
 
alternate approaches, soldering or welding end on, or, if shaft is hollow, a stud can be shrunk into end with some loctite on it. a custom made stud with a shoulder on it so the shoulder is resting on the tubular wall, would be very strong and durable. heat tube, press in
 
Yes

IMHO I think that the OP is trying to make a living in his profession. His question is more about how to cut threads in spring stainless with a small, low power lathe as opposed to an attempt to discuss the lathe itself. I believe he deserves a respectful answer to his question.

Hello FreediveShop,

I have been diving for over fifty years in the ocean; first with spear guns and then with slings. I turn my shafts all the time with HSS. Without more information, I presume that you are using spring SS. You say that your shaft is 5/16 by approximately 63 inches long. I also presume that the length of the thread you want to cut would be about an inch or so based on my experience with spear shafts. If so, that should be no problem. All you have to do is use a lighter cut than one would use with a heavier lathe. You may need to support it with a spider (see attachment) on the left side of your spindle to keep it from whipping; or thread it at a lower speed. You can make the spider yourself. If need be, support it farther out to the left with something like a steady rest on a pedestal. Keep a sharp HSS 60 degree cutter and you can cut any kind of thread you want.

As a caveat, depending on how many you are doing, this may not be the best use of your time. Cutting threads on a lathe is slow compared to other methods. If you need to do alot, farm it out. If you need to do a few, use a die. It's much less expensive than any lathe I know of.

If you go the lathe route and you are really new to cutting threads, I suggest that you look at this thread, especially if you are cutting up to a shoulder.

http://www.practicalmachinist.com/vb/showthread.php?t=177089

Best of luck,

Drew
 

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