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Heating brass

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Hukshawn

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#1
IMG_20171103_220212.jpg

Above is a brass (I think) gear from the fine feed of my mill. One of the many gears that need replacing/fixing.
Notice the teeth laying over. I'd like to straighten those up. I was pounding on a few last night with a chisel and a hammer and I'm worried about shearing then right off.
Can I heat it up to soften it? Will that harden it? Will it just melt?
What will happen if I put a torch on this gear?
 

RJSakowski

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#2
Heating brass will soften it. You harden it by work hardening. Considering the distortion in the teeth,m the gear is probably soft already. You could heat the affected teeth but there is a possibility that they would just bend again under a load. TRhere isw a fairly good margin between the softening temperature and the melting point so you should be OK there. Brass will anneal between 600 and 800ºF. This is below a red heat. It melts somewhere around 1600ºF which would be a bright orange. You may want to immerse the gear in water except for the teeth you are trying to work.. An oxyacteylene torch or similar woould be cpable of the localized heating. Barring that, heating the entire gear up with a propane torch should work except it will soften the entire gear.

If it were my machine, I would consider replacing the gear.
 

Hukshawn

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#4
I completely understand wanting to replace it. But the combined cost to fix all of the broken/missing parts in the quill power feed on this mill is over $1000 usd, and I'm in Canada... So as 25% minimum.
Just not an option to replace everything. Some items I can fix, such as this, some items I can make, other items like stacked gears, and the clutch, I will have to purchase.
 

RJSakowski

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#5
Several decades ago, the back gear on my 6 x 18 lathe stripped some teeth. I was able to buy cast iron gears and fabricate a new back gear. It is still working after many decades. SPI/SI (http://www.sdp-si.com/products/Gears/Index.php) sells both inch and metric gears at a reasonable price.

Stacked gears can be assembled by pinning two simple gears together.
 

markba633csi

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#6
Judging from the picture the gear should have been made of cast iron to better withstand the forces involved
I would not expect you will be able to salvage that brass gear but you can certainly try.
Mark S.
 

dave_r_1

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#7
That could be the sacrificial gear (ie, the one that is supposed to bust when things go wrong, vs some other bits that are more expensive/difficult to replace).
 

Billh50

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#8
Judging from the pic, you can straighten the teeth. But the tooth form will not be correct and cause other problems. Replace the gear.
 

chips&more

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#9
A clockmakers experience would tell you that trying to straighten the teeth would result in the subject teeth cracking off. They typically bend OK in one direction, but when you try and go back the other way the teeth crack off. A clockmaker type repair would just cut out the bad section and replace with good teeth…Dave
 
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