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Spindle material for rocket tools, stainless, brass or bronze


mabuse00

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It seems like stainless steel is somewhat stronger than brass, what would make it the proper choice for smaller tools with longer spindles, where spindles are easily bent and the forces to extract the motors are not too great.

 

But on my old 1lb tool I found the force needed to extract the motor dangerously high. Getting the motor off was a real challenge, and I suspect some CATOS have their causes in the removal process...

 

Anyway, how great is the advantage of the more slippery brass compared to the rather sticky stainless?

How much greater is the risk of bending the spindle?

 

What is the better tradeoff?

 

For a rather skinny BP or nozzleless spindle at 8oz or above, what would you choose?

 

 

 

And what particular brass formula is advisable?

Wouldn't bronze be even better (but maybe to brittle?)

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I like beryllium bronze for spindles. It is nearly as 'slippery' as brass, is NOT brittle, but friction-durable, resisting abrasive wear much better than common 360-brass.

 

And it machines VERY nicely!

 

Lloyd

Edited by lloyd
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It seems that the dust from beryllium alloys is a known carcinogen, but the bulk metal isn't hazardous. I'd wear a dust mask for machining beryllium bronze.

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Phhhttt! If you're 'machining' (not 'grinding'), you're not raising any dust. CHIPS come off a lathe, not dust. <Grin!>

 

In addition to what other tasks I must do, I have a full machine shop for building tools for customers. Beryllium bronze comes off in nice small 'curls' on the lathe. It doesn't come away as long 'worms', but also doesn't make dust.

 

Lloyd

Edited by lloyd
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I and many others find that polished stainless is the cat's meow. I've been making replacement spindles for lots of folks that are switching out their naval brass.
It might just be the stainless doesn't get scratched up like other stuff does.

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I and many others find that polished stainless is the cat's meow. I've been making replacement spindles for lots of folks that are switching out their naval brass.

It might just be the stainless doesn't get scratched up like other stuff does.

Unless you're a dumb newbie like I was!

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I like them both, brass is nice to work and SET is durable. I'll pass on the Beryllium, it has to be sanded or filed to smooth it, turning alone doesn't make it rocket ready.
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"I'll pass on the Beryllium, it has to be sanded or filed to smooth it, turning alone doesn't make it rocket ready."

-------------

In fact, you've hit on one of its "strong points" (if you'll excuse the pun).

 

(FWIW, with the right geometry cutters that also have the correct back-rake, you CAN get a smooth finish in one pass. But an ordinary cutter designed for steel or aluminum won't do for either copper or beryllium bronze)

 

Lloyd

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If you have a sharp-edged tool with a positive rake angle, you can get very nice finishes on the various bronzes. You just need to run high SFM and a slow feed.

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If you have a sharp-edged tool with a positive rake angle, you can get very nice finishes on the various bronzes. You just need to run high SFM and a slow feed.

But I think you would still have to polish it afterwards.

 

 

I and many others find that polished stainless is the cat's meow. I've been making replacement spindles for lots of folks that are switching out their naval brass.

It might just be the stainless doesn't get scratched up like other stuff does.

The thing is, I cannot polish stainless so well, because I dont have lathe access. A cannot turn this evenly. All power drills I could use for it have to small chucks.

I could just take the tool and well, start wanking.

 

PS:

What would you use here? Something like NEVR DULL...?

Edited by mabuse00
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But I think you would still have to polish it afterwards.

-----------------

I don't; ever. I will 'feel' the length of the spindle for burrs or roughness, and will file off sharp shoulders at H/V transition points... but that's all.

 

All my bronze spindles have gone right to work off the lathe.

 

Lloyd

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I sand all mine with 180 and 320 and then for the good stuff..

Mothers Mag Aluminum Polish on a scotch brite pad. Then finish it off with a paper towel.

If I still see any cut marks I start again. :)

Edited by calebkessinger
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Caleb,

If I may... you're making them (MUST make them) just as much for appearance as functionality. All mine ever had to do was 'work right' in production tooling.

 

To that end, I found that the bronze spindles sort-of 'polished themselves' after just a few dozens of pressings and extractions. Even just lathe-turned (with the right cutter and speeds/feeds), we never had any withdrawal issues or comp collecting in surface defects.

 

Lloyd

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I polish my spindles with 600 grit paper then oxalic acid (bar keepers friend). They are like mirrors when I'm done. A battery drill works good enough to spin it up. If I can't grab the spindle at the base then I grab the holddown screw.
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Yep lloyd,

 

I cut some gerb spindles this morning on my cnc and they come off "almost perfect" If i didn't miss a cut by .001 thou they wouldn't have needed anything other than a polish to make them shiny. A quick 320 wet sand and polish made them shine like diamonds. :)

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