# Turning weld metal?



## Aqua-Andy (Dec 16, 2017)

So in the past couple of months I have had to repair some parts and on a few occasions it was decided that we would build up wend on the part and then turn down the weld to the correct dimensions.  I have been having an issue with the weld metal ruining the cutting tools.  I have tried both HSS and carbide tooling.  It just seems that the weld metal is so too hard, most of the filler metal we use is in the 70K PSI strength range.  Also the welds are not cooled rapidly, they are just left to cool down naturally in the air.  I was thinking next time I could maybe wrap some insulation around the part so that it cools slower.  One particularly nasty part was a pulley that was spun on a shaft.  The pulley was welded on the id and I had to turn the weld metal to the required ID.  I had a heck of a time as the weld was so hard that the 3/4" boring bar would just flex and chatter while trying to cut.  How have other dealt with these issues?


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## Terrywerm (Dec 16, 2017)

I anneal the part by heating it up to cherry red then burying it in a bucket of barn lime to let it cool slowly. After that I can usually turn the weld down without any trouble using a HSS tool.


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## 34_40 (Dec 16, 2017)

Barn Lime???   I've never heard of this.  Is it just regular Lime or something special?


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## Cactus Farmer (Dec 16, 2017)

Sifted fireplace/stove ashes work as well. I sift it through 1/8" hardware cloth. I do a lot of part making and keep a sifted bucket in the shop all the time. Plus I may need to make soap someday!


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## 4GSR (Dec 16, 2017)

If that pulley spun on the shaft once, it's going to do it again.  If this is a standard vee belt pulley, replace it with one that has a taper lock bushing. I guarantee it won't spin.  Or modify the existing one to receive a split taper bushing.


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## Sylvainmom (Dec 16, 2017)

When rebuilding a part , I usually pre heat before welding since we cant be 100% sure of which alloy the part is made of. Especially rebuild carbon steel , for example 1045, the dilution with base material hardened the welds. I do a simple test by welding with 7018 electrode 1 single pass then I try to file it down. If the file doesnt goes through , it means that you'll have hard time machining...


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## kd4gij (Dec 16, 2017)

What welding proses are you using?


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## Uglydog (Dec 16, 2017)

Would ashes have a high carbon content and potentially contribute to the hardness?
Looks like Barn Lime is carbon neutral, and cheap. 
https://www.farmandfleet.com/blog/what-is-barn-lime-why-do-i-need-it/
https://www.tractorsupply.com/tsc/product/waukesha-lime-barnlime-50-lb-bag

Daryl
MN


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## Technical Ted (Dec 16, 2017)

When the weather is cold I have put welded and burnt out pieces right into the fire in my wood stove. They will get a nice cherry red and sometimes even more orange. I just let it cool with the fire and remove it the next day. The only thing is the parts are typically covered with a scale after doing this so it might not work out for some parts that are already to size or have a good finish you are trying to preserve. It does a nice job of softening burnt edges from a cutting torch when I burn out a piece of stock for something making it from scratch. 

Ted


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## Technical Ted (Dec 16, 2017)

Uglydog said:


> Would ashes have a high carbon content and potentially contribute to the hardness?
> Looks like Barn Lime is carbon neutral, and cheap.
> https://www.farmandfleet.com/blog/what-is-barn-lime-why-do-i-need-it/
> https://www.tractorsupply.com/tsc/product/waukesha-lime-barnlime-50-lb-bag
> ...



I personally have not found this using my wood stove technique. But, it might harden them if you removed while hot and did a quick quench... interesting. I'll have to try that to see if I can case harden that way. That would be awesome!

Ted


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## Terrywerm (Dec 16, 2017)

34_40 said:


> Barn Lime???   I've never heard of this.  Is it just regular Lime or something special?



It is also known as ag lime and is used in dairy barns to help reduce the slipperyness of concrete floors and to reduce the potential for bacteria growth. It is also used to raise the pH level in acidic soils. It is simply limestone that has been ground to a coarse powder. It should not be confused with quicklime or slaked lime which are very caustic and poisonous. If the bag says calcium carbonate you've got the right stuff, but stay away from calcium hydroxide or hydrated lime, which are the same thing and also the same as quicklime and slaked lime.


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## Aqua-Andy (Dec 16, 2017)

I agree that not having a key or some other locking device is not optimal but as long as the retaining bolt is torqued properly there is more than enough clamping force to hold the pulley from spinning on the shaft.  On this particular machine the bolt was not torqued properly.   I'll have to pick up some barn lime and try this trick out.  The process used was was GMAW.


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## Terrywerm (Dec 16, 2017)

Barn lime is also great if you happen to have a dog that kills part of your lawn by urinating in the same place all the time. Spread a healthy sprinkling of barn lime over the affected area and water it in once or twice a year.

As previously mentioned ashes will work also. Fine sand will also work but not as well as barn lime.


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## kd4gij (Dec 16, 2017)

Are you using mig or tig for welding?


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## Ray C (Dec 16, 2017)

Are you working on known base metal?   There are several options.  If possible, pre-heat the entire area around the weld at least several inches away from the junction.   The pre-heat temperature varies according to base metal but for mild to low/medium carbon steel, it's about 500F.   The total area you pre-heat depends on the shape/size of the part.  In some cases, the entire part must be pre-heated.  After you perform the weld, make sure the surrounding area is at least at your pre-heat temperature.  Re-heat if necessary.   Wrap the part in a glass thermal blanket and toss it in a suitable container so it cools down naturally and very slowly.    If you have a HT oven, ramp the part down below martensetic temp (typically 350 F) over a 5-6 hour period.  This will make a huge difference and the weld will be easy to cut.

Next option is to normalize the entire part after welding and heat-treat as necessary.  Of course this may not be possible on a finished part that is being modified with a weldment.

Ray C.


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## tq60 (Dec 17, 2017)

How stout is your machine?

One trick we have used end mills as a boring bar when we needed to do a shallow or small hole.

A chipped end mill may not be good for milling but great for boring.

You can either come in as a boring bar or go sideways and cut full depth shaving it so to speak to smooth out the high spots.


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## NortonDommi (Dec 17, 2017)

Change the weld wire. Use FCAW and the appropriate electrode or for that particular application Bronze welding would work fine.


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## epanzella (Dec 27, 2017)

I just weld and then machine. The only hardness problem I've ever encountered was with a torch cut edge and carbide took care of it.


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## savarin (Dec 27, 2017)

Have a look at post 10 here
http://www.hobby-machinist.com/threads/the-giant-binocular.55688/
this was just stick weld on hot rolled steel.
I used a braised carbide tool that was sharpened as if it was HSS ie. very sharp.
It didnt chip even with that interrupted cut.
No annealing just went at it as soon as it was cold enough.


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## Silverbullet (Dec 28, 2017)

One of my jobs during my apprenticeship was turning journal ends on rollers for a steel mill in Pennsylvania. They were welded with rod on an old worn out lathe head layered to build up the wear . I had a big lathe slow turning ill say it was between 500-750 rpms. Now the diameter was about ten inches by sixteen inches on each end , I used a carbide round tool , insert type. For cutting the weld till it wasn't interrupted then I used a HSS  tool bit with a slight radius and good rake angle on top , enough bottom and side clearance not to rub . The breakthrough cutting is the hardest use a little more course feed then you normally use its course material and needs course action to cut it . Yes we used up some inserts but it worked well. Even in castings on the planer and boring mill ,, from the dark ages even in the 70s ,,,.


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## Gwil (Jan 2, 2018)

A simple bit of help in this situation is CAREFUL use of a grinder or a Dremel type tool before machining. This gets rid of the roughness of the weld bead.

A steady hand can really do a good pre machining cleanup, and give your lathe tools a much easier time.


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## Ray C (Jan 2, 2018)

Gwil said:


> A simple bit of help in this situation is CAREFUL use of a grinder or a Dremel type tool before machining. This gets rid of the roughness of the weld bead.
> 
> A steady hand can really do a good pre machining cleanup, and give your lathe tools a much easier time.




Yep, agree.   The metal around the weld is hard but, the outermost part where you can see the ripples in the bead, is the hardest.  That's because that area cools off first and faster than all the rest of the area nearby.  That rapid cooling is basically a quench -which is how metal is hardened in the first place.

Regards

Ray C.


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## neilking (Jan 2, 2018)

Aqua-Andy said:


> So in the past couple of months I have had to repair some parts and on a few occasions it was decided that we would build up wend on the part and then turn down the weld to the correct dimensions. I have been having an issue with the weld metal ruining the cutting tools. I have tried both HSS and carbide tooling. It just seems that the weld metal is so too hard, most of the filler metal we use is in the 70K PSI strength range. Also the welds are not cooled rapidly, they are just left to cool down naturally in the air. I was thinking next time I could maybe wrap some insulation around the part so that it cools slower. One particularly nasty part was a pulley that was spun on a shaft. The pulley was welded on the id and I had to turn the weld metal to the required ID. I had a heck of a time as the weld was so hard that the 3/4" boring bar would just flex and chatter while trying to cut. How have other dealt with these issues?


a lot of pulleys and motor sheaves are cast iron. Any welding on that is goin to be hard as ****

Sent from my SM-G920P using Tapatalk


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## Gwil (Jan 3, 2018)

Anyone not familiar with taper lock type pulleys may be unaware what a huge range is out there, and how solid are these fittings. And if you need it there are some neat interlocking dog type couplings with rubber inserts to cater for small amounts of misalignment and shock loads/vibration. 

Not only can it save a lot of machining but also allow for very precise adjustment and alignment.


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