lines left from turning steel (striations)

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Dan
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lines left from turning steel (striations)

Post by Dan »

While turning steel round stock, it is leaving some pretty bad striations.


The piece is hanging out to far but can't get a live center close enough and part won't fit in chuck beyond the jaws.

Any thoughts? And thanks for reading. :D
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Larry turning striations.jpg
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Re: lines left from turning steel (striations)

Post by Harold_V »

From my vantage point, I'd suggest to you that the problem isn't how far the material is projected, but the alloy in question. Mild steel tends to tear when being machined, depending on the type of cut. Simple turning is often difficult, yielding exactly what I see in the picture.

If surface finish is critical, you have a couple options. One of them is to investigate the use of a different alloy. A move to leaded stock is very helpful, as would be a switch to a material known in the industry as Stressproof. Those choices machine without tearing. A free machining grade of stainless is also an option. You can select 303 or 416, each of which is a pleasure to machine.

Alternately, you can improve the existing finish by spin polishing. It's an acceptable procedure, and can yield excellent results with just a little care. If you wish to pursue this process, you'd be well served to procure some strip abrasives, graduating from coarse to fine. The wider the selection, the better the finish that can be achieved.

Harold
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warmstrong1955
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Re: lines left from turning steel (striations)

Post by warmstrong1955 »

Welcome to the world of mild steel.....

I agree with Harold, but there are some things you can do to make the finish on low carbon steels tolerable.
My first machine was a 3 in 1, less than rigid machines they are, so here's my 2 cents....

Tune up your machine. Tighten up the gibs as much as you can, and still be able to turn the handles with one hand. That includes the compound....and lock it down if you are not turning a taper.

Not sure what tool you are using. Whatever it is, HSS, carbide, get the tip on center, or a touch below center.
For low carbon steels, the smaller the radius, the better. Positive rake is important as well, and make sure you have enough relief.

Play with some speeds & feeds. Higher SFM, as well as feed rates work better for me. Finish cuts, I use oil....whatever is cheapest, and multiple passes.

No matter what you do, low carbon steels will not look as pretty as leaded, stressproof, alloys, stainless, and other more fun things to work with.. You can make it look quite acceptable though. It'll take some polishing, and like Harold says, no harm in that.

So....some comparison. I was looking for pics of identical parts I have made out of low to medium or high carbon steels. Best I have.....I think I posted these before.....

I made this test shaft from 1018 or 1020, to make sure it fit the laser.
Note all the ugly lines....I didn't try too hard for a good finish, I did no polishing, I was just testing out my hand ground rad tool, to make sure the end result fit the tool.
Test.jpg
Same thing, in 1045 medium carbon steel. Again no polishing yet. Quite nice when I polished them up with some emery cloth. Sorry I don't have a close-up.
Prism Shafts.jpg
The ones I made from stainless....again....sorry...I have no pics....required no polishing at all.

Play around a bit....see what works, and what doesn't. That includes trying some different materials.

Bill
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Dan
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Re: lines left from turning steel (striations)

Post by Dan »

Thank you, Harold & Bill, so much for the information! Purty cool. Picking up more materials Monday so the advice on that front is very much appreciated.

This part is for a prototype/experiment sleeve from a 5/8 engine PTO to increase the shaft size to 3/4.
(Dunno why they are called "shaft reducers" seems it functions in the opposite?) It will need an internal key. So I am planning on milling a slit and welding one in. Got no clue if it will work but is all an experiment, anyway.

The cap shaped sleeve will be concealed under a clutch bushing and finish is of no consequence other than how product will look to the end consumer during installation. I chose mild steel out of just not knowing. Was mighty impressed you both looked at a picture and knew what was wrong.

Unless for this purpose, some other material should be used, am gonna go with the stainless option? Or 1045 medium carbon steel.

Seriously, thanks for taking the time, guys.

:mrgreen:




(note to self; "stainless is also an option. You can select 303 or 416")((So I can find it later))
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warmstrong1955
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Re: lines left from turning steel (striations)

Post by warmstrong1955 »

Are you talking simply a sleeve, 3/4" OD x 5/8" ID?

If that's the case, I'd skip any welding, and make a sleeve with a groove, actually a slot, to fit the width of the key, which should be 3/16". Picture a roll pin.
I'd use some oversize key stock....without doing the math...I'd say you need 3/16" x 3/8". You'd need to check that....it's a SWAG.

Only other thing you need is a method to make sure the sleeve can't migrate off the end of the shaft. A setscrew in the pulley, or coupling, or whatever fits to ithe OD would be easiest. You could also have a flange at the inboard end if you had to. Maybe the end of the shaft is threaded, and a bolt & washer to hold it in? Loctite would do it too. Not sure what you have.

I've bought these before, as I've described....much larger though. I think from Browning. Been a while....
If I was going to make my own, I'd pick any material that was machining friendly, as torsional load is not in play. It's only a bushing.
Steel....I'd use 12L14. Stressproof, 1144, would be a good one, and tougher. Both easy to turn.
Stainless steel....303. 416 a good choice too, not as corrosion resistant, but tougher than 303.

Bill
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warmstrong1955
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Re: lines left from turning steel (striations)

Post by warmstrong1955 »

Like this..... http://www.ebay.com/itm/5-8-X-3-4-X-3-S ... 566cf7c124

Appears to be bronze of some sort....but gives you the picture.

:)

Bill
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Re: lines left from turning steel (striations)

Post by Dan »

Man Bill, that would make life easy. But the clutch that will accept the bushing has a key manufactured in. So I'm trying to make a rock solid sleeve/bushing that is one piece. It is also longer than the PTO. So using that opportunity to add strength by not drilling through except for the set screw. Not sure it is not over kill.

Could probably use a sleeve as you so kindly linked to but ,and have thought about it, might be to weakened after milling a keyway into it and then it would be 2 pieces.

Could try it but just seems it would be sloppy with the torque involved.
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internal key.jpg
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Last edited by Dan on Sun Nov 23, 2014 9:42 am, edited 1 time in total.
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Re: lines left from turning steel (striations)

Post by Harold_V »

In haste, and I'm a bit confused.
Welding is a part of the project?

If it is, don't use either of those grades of stainless (303 or 416). 303 is not recommended for welding (S contains sulfur, and Se contains selenium), and 416 is a heat treatable alloy, so both would be troublesome.

If the part is subjected to high torque, 416 would be the better choice, assuming there's no welding involved, but it would be best applied heat treated.

If welding is involved, leaded materials aren't acceptable, so that eliminates pretty much all of the free machining mild steel alloys. Stressproof, like 416, is heat treatable, so, again, welding isn't an option.

304 stainless would be acceptable, but it's not fun to machine. To its credit, it finishes quite nicely, however.

Any particular reason you're trying to avoid cutting a keyway?

Harold
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Re: lines left from turning steel (striations)

Post by Torch »

Dan wrote:Image
It appears to me that the key is separate but retained by an insert pressed or threaded into the bore. If the key was ground at an angle at each end then such a retainer would prevent it from falling out of a broached keyway with no welding required.
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Re: lines left from turning steel (striations)

Post by Dan »

The key in the clutch (3/4 ID) is intrinsic and machined into the part. The only way to remove it, would be to bore it out. The clutch operates by a portion sliding in and out and using the keyway that acts as a guide way. #8 in the diagram is the part that moves in and out horizontally on the key & shaft. So have to cut a key way for it to drive and travel on. That is the OD. The welding is to create a key inside a blind hole to adapt to the 5/8 PTO. So am cutting one keyway and making another intrinsic/permanent key in the sleeve/shaft reducer.

So welding the one key in, is the only way I can think of accomplishing this on the equipment I have. But am sure there is always more than one way to feed a cat.

Really trying to translate from my odd wording to proper descriptions, but think I might be losing some thing in the translation. Thanks for putting up with it, fer sure. Pictures, diagram below. (did resize them but seem huge for 800 pxls)

Pic of shaft and back plate is with the key sitting out side the keyway.

The only engines available for this application only have 5/8 shafts/PTOs. And the clutches all come in 3/4. No real options for already mass produced parts.
That would take all the fun out of it anyway, snork.

Edit; Picture is part #12 from diagram. Sitting on shaft and off keyway.


(note to self; "304 stainless would be acceptable, but it's not fun to machine. To its credit, it finishes quite nicely, however")
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drive unit.gif
SVT back plate on PTO.jpg
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Re: lines left from turning steel (striations)

Post by warmstrong1955 »

You need to build something almost like this.
Without the key protruding thru the OD of the bore. [edit....I wrote ID originally]

http://www.andymark.com/product-p/am-0996.htm

You'll need to make some weld jigs. You will have to consider distortion & shrinkage when you make this thing, and a little stress relief after welding will be necessary. (no....not a cold beer...that's for later)
If you use stainless, you'll need a adapter to purge the inside of the sleeve with argon as you weld it, otherwise, you'll have 'crusties' of oxidized stainless along the ID of the bore, opposite of the welds.

What is the width of the key in the hub? Standard would be 3/16"....but a lot of things aren't standard. I see a potential problem with the key in the hub interfering with the OD of the sleeve. See attached. You may need to ream a portion on the integral hub key away.

Shown with 3/16" key. Red is the hub.
Doodle.pdf
(8.73 KiB) Downloaded 331 times
Have you considered a custom broach? Just a thought.....

Bill
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Re: lines left from turning steel (striations)

Post by Dan »

That is almost exactly, except for the blind hole/cap, the part, Bill.
Could use a borach but want to keep the cap.

Waiting on holding tools but part is all but done. (Ya just can't call this work. So much dang fun)

Sleeve fits the PTO perfectly and am very happy with it.

The only problem is the choice of raw materials & striations. Gonna try, as suggested, the 304 SS. Also try and make another with the mild steel and try polishing it.


Having so much fun with this I am sitting here in the shop drinking coffee and watching the sunrise every morning I can in the shop and quit about 7 or 8 at night.
Dan
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