# Earning Myself Some Beer Money



## GCM (May 8, 2015)

As a "self trained" hobby machinist I have recently finished this project for a friend of a friend. Some serious abused pulleys were brought to me and as you can see his workers do not care when something is not theirs.
I have not seen the unit where these pulleys are used in, but as I understand it is used to put tension on cables for
pre-stressed concrete casting and it does not turn at high speed. I am hoping by using bearings instead of the pulley running directly on the shaft, it would cause less friction and last a bit longer.
When I did the shaft I machined the one half and thread it. Then turned it around to do the other side. I was worried the chuck would leave marks on the shaft and first tried some paper around the shaft but then realized
it is too difficult to get it centered again. I did not clamp it tight enough and during threading it slipped and left
a mark. When I redid it I machined a thinner extension on the one side and when I turned it around I clamped
the extension and cut it off when finished. It worked but is there a better method ?
What do you guys use to protect the service of the shaft in the chuck ?
I am not even sure if the way I machined it is correct. I thought of maybe finding some thin
copper plate to put between the shaft and chuck but would that make it solid enough during machining.


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## thomas s (May 8, 2015)

Nice job on the pulleys they should last a long time.


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## brino (May 8, 2015)

Hi GCM,

Wow, nice upgrade to those pulleys.....you have built them much better than the originals.

That's the kind of project that I enjoy too. Working on a part of a system that you've never heard of before, let alone operated. Coming up with solutions to the problems of the original design.

Your trick of leaving a removable stub for the chuck to grab sounds like the correct method to me. Otherwise, maybe turn between centres, and use a "deep" lathe dog to drive it near the middle, you could even have a flat spot between the two bearings for positive drive.

You did a great job on implementation!

-brino
PS: great high quality photos too, much appreciated.


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## mzayd3 (May 8, 2015)

Nice work!  I would suggest between centers as well.


Sent from my iPhone using Tapatalk


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## kvt (May 8, 2015)

Looks like a great solution,  In fact you may get repeat business as they prob has others that need the repair once they see this one.  Leave it to people that do not respect others tools and equipment, They will find a way to break it then you will have to do it again.


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## JimDawson (May 8, 2015)

GCM said:


> I was worried the chuck would leave marks on the shaft and first tried some paper around the shaft but then realized
> it is too difficult to get it centered again. I did not clamp it tight enough and during threading it slipped and left
> a mark. When I redid it I machined a thinner extension on the one side and when I turned it around I clamped
> the extension and cut it off when finished. It worked but is there a better method ?
> What do you guys use to protect the service of the shaft in the chuck ?




Many times I use emery cloth wrapped around the shaft.  I doesn't slip and protects the work.


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## TomS (May 8, 2015)

I've used emery cloth a lot and it works great.  I also use 1/8" x 1/2" aluminum strips about 1-1/2" inches long under each jaw to protect the part.  Another option s to take a set collar of the appropriate ID for the part being clamped, remove the set screw and saw cut through the set screw hole.  You now have a split collar that you slip over the shaft to protect it.

Tom S


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## RJSakowski (May 8, 2015)

An expanding mandrel would have worked as well.  I have also used custom turned arbors with a threaded end and screw or nut arrangement to provide axial compression (much like mounting a grinding wheel).


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## Karl_T (May 8, 2015)

GCM said:


> ...
> the extension and cut it off when finished. It worked but is there a better method ?
> What do you guys use to protect the service of the shaft in the chuck ?...



You're done. Good job. My solution for both hold the pulley and the shaft would have been soft jaws.

If you're not aware, you can put sacrificial jaws on in place of the hard jaws in the lathe. Normally made of Aluminum.  Then turn them to fit what you're holding. Two big advantages are getting perfectly on center and being able to clamp with significant force and not mar the product.


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## Ulma Doctor (May 9, 2015)

Nice work on the pulleys, !!!


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## Micke S (May 9, 2015)

Nice work but how does they pull with a bearing in the center?


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## RJSakowski (May 9, 2015)

Micke S said:


> Nice work but how does they pull with a bearing in the center?


They are idler pulleys.  They don't pull. They just change the direction of the cable.


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## f350ca (May 9, 2015)

Very nice work. How much tension is on the cable? For prestressing concrete it could be considerable, is the static load rating of the bearings high enough? 

Greg


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## GCM (May 10, 2015)

f350ca said:


> Very nice work. How much tension is on the cable? For prestressing concrete it could be considerable, is the static load rating of the bearings high enough?
> 
> Greg



I met the guy who I did this for on Friday afternoon. He explained to me that there are two sides and they tension rebar between two ends to cast prefab wall panels. The tension is not very high and more to straiten and mount the rebar. It is well within the bearing rating considering that they are putting tension on this by hand.
He already installed the pulleys and said the workers are very happy because it takes less "elbow grease" to get the tension on the rebar. They feel the bearings are a good improvement. All he need to do now is to monitor it over a few months and then maybe improve two more units with the bearing option ;-) Hopefully more beer money on the horizon


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## uncle harry (May 10, 2015)

GCM said:


> I met the guy who I did this for on Friday afternoon. He explained to me that there are two sides and they tension rebar between two ends to cast prefab wall panels. The tension is not very high and more to straiten and mount the rebar. It is well within the bearing rating considering that they are putting tension on this by hand.
> He already installed the pulleys and said the workers are very happy because it takes less "elbow grease" to get the tension on the rebar. They feel the bearings are a good improvement. All he need to do now is to monitor it over a few months and then maybe improve two more units with the bearing option ;-) Hopefully more beer money on the horizon



You might consider needle roller bearings for a better load rating if it ever becomes necessary.


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## GCM (May 13, 2015)

uncle harry said:


> You might consider needle roller bearings for a better load rating if it ever becomes necessary.


Thanx for the feedback. Yes, needle roller bearings would have been a better option as it will spread the load over the width of the pulley. I did actually consider it but the problem I ran into was that I were unable to find needle roller bearings which are sealed. All agents I asked, said sealed roller bearings does not exist locally here in South Africa. I think one of the main reasons for the wear on the old pulleys are the dust and sand in the environment they are used. 

Thank you to everybody for the ideas and feedback.


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## chips&more (May 13, 2015)

When you use a chuck the jaws have only so much clamping area. The jaws exert a lot of force in a very small area. And yes, the jaws can leave a mark(s) in your work because of this. IMHO, the best way to avoid this possible mark problem is to use a collet. Its clamping area is almost 100% surface contact with the part. But it could be another $ addition to your shop. My rationalization to the $ is… I have none, I just buy the stuff I need, you only live once, be happy in your shop!...Good Luck, Dave.

PS; and the jaws have a fixed radii at their clamping faces that does not always match the parts diameter making it an even more unmatched clamping area.


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## Peter Dahlman (May 13, 2015)

Nice work!


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## catskinner (May 14, 2015)

kvt said:


> Looks like a great solution, In fact you may get repeat business as they prob has others that need the repair once they see this one. Leave it to people that do not respect others tools and equipment, They will find a way to break it then you will have to do it again.



I refer to that as the iron ball in the plowed field syndrome there are a number of employees that can manage that feat.


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## Guv (May 14, 2015)

A job well done!


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## jimcisme (May 14, 2015)

To prevent chuck marks on your work try using .02~.03 brass shim stock. The chuck jaws will bite into the brass and the brass will hold the work well if you make sure to get the jaws tight enough. Never use paper, as you have discovered it simply does not work.

Jim C.


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