Turning Shafts

Kenny G

Kenny G

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My name is Ken and I'm so green I make grass look yellow. I have a used 7x14 microlux lathe that I bought several months ago it was an impulse buy and now I find myself facinated with it and working on tooling it up. I have several projects i n mind for my other hobby lapidary. The first project I have in mind is making stainless steel shafts for grinding and polishing drums. The through hole in the spindle will only accept up to 13/16 stock which will limit me to 3/4" and less shafts(which is fine) unless I turn between centers which limits me to less than 14 inches when you take into count the lathe dog. My thoughts are that if I can pass the work through the head stock I can gain a few more inches hopefully around 20" total. This would mean that I would have to turn it in two sections I have a feeling it may be hard to get it uniform the entire length this way before I do it stainless is pretty pricey, can you give me any tips on how to do it right?
 
An interesting setup problem and not a real easy one to solve. I guess I would face and center drill each end of the shaft, then stick the shaft out as far as possible and turn that section. Then turn the shaft around and work on the other end, with as much sticking out of the chuck as possible, supported with the tail stock of course. Working near the tail stock may minimize any runout in the work. If you have a 4 jaw chuck, then the runout should be near zero. If you only have a 3 jaw chuck, shimming under the low jaw can bring the part in true. Blend the transition as best you can, maybe with a file and some emery cloth.
 
Could you expand on this project a bit?
Are you talking about something akin to a line finisher? A shaft with a series of drums covered in abrasive or compound for hand grinding and polishing?

You can buy ground shaft. Plain cold rolled might fit standard drums as is with no turning needed.
You can then turn the ends down to accommodate bearings or pulleys.
Trying to turn a 3/4" shaft 10" long in stainless on a mini lathe is maybe not the best first project for a pure novice.
The work will want to flex a great deal away from the tool. If you use carbide, the problem will be even worse.
With some practice and a small bit of experience, you should be able to manage it. I would want to use a follow rest, but you can do it with out.

A word of caution. Long stock through the head stock = recipe for injury and disaster. The work will need support on the outboard side of the head stock.
 
Thanks that is sort of the way I expected I would have to do it good idea on the transition. After turning the first section would replacing the tail stock with a steady rest and feed it thru or would that not be rigid enough? As to using a follower rest I would definitely do that I have already found that to help in my practising . I found out about not supporting a piece through the head stock.I couldn't get it shut down fast enough so for now I would be happy to not go past the end of the spindle until I can make a steady rest for support there. To the question about the drums yes you are right on, for the most part the sanding drums are made of light material like plastic or carbon fibre usually 8" in diameter by 3" wide covered with a diamond impregnated resin of various grits.
 
Last edited:
Kenny G said:
After turning the first section would replacing the tail stock with a steady rest and feed it thru or would that not be rigid enough?
Click to expand...

I have done that on long shafts, and yes it works. It just takes a bit more setup to get everything right. As @joshua43214 said, make sure the shaft is well supported to keep the ends from ''whipping''.
 
Any reason not to use drill rod or a stainless rod for the shaft? Both have close tolerances over the length. Enco has either for under $50 and cheaper with the sales they have. You might only have to turn the ends to attach a coupling.
 
Check out speedy metals. It is a online metal supplier that ships anywhere. I have purchased 1144 stress proof steel that is turned polished and ground. Drill rod would be even tougher. Check and see if they have the same in a grade of stainless if you really need it to be stainless. If it is available in the diameters you need it will save you a ton of work. Then you just stick out enough from the chuck to thread or whatever you need to do.
UPDATE: Just checked and they have turned, ground, and polished 4140 also.
 
Grinding and polishing stone requires using water, so they need to be corrosive resistant. Well I have a lathe now and just thought that I should be able to do something like this. .8125 303 stainless is relatively hard to find but I did find some on Amazon and ordered it I am very retired so the work isn't a factor. Here is another thought if I turn between centres then centre drill one end and tap it then thread the end of the other I could screw them together but am wondering about runout each half would be supported in it's own pillow block with a riser and the pulley would be offset to the left half eliminating the need for left hand threads.
 
Might as just make it all modular rather than trying to screw the ends together. Just connect segments together with a coupler, they come in a huge variety and price ranges or can be shop made.

Speedy metals sells 3/4" ground 303 stainless bearing shaft for $81.00 for 72", or $48.00 for the same length in 303 cold rolled.
 
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