[Damo]

One of the drive gears my lathe's quick change gearbox is worn and needs a new bush pressed into it. Where can I get some bronze to make the bush?

The shaft is a bit sad too but with a bit of a clean up it might be OK I think. Worst comes to worst I can machine the shaft down and make the bush to suit.

[royce]

bearing shops, Faegestera metals (dunno how to spell it )

[appsie]

id be going with the last option and skim a bit off the shaft,just so you know its right.

Gotta love machining bronze,nice and easy

[Damo]

appsie wrote:

id be going with the last option and skim a bit off the shaft,just so you know its right.

Yep i'm with you on that

appsie wrote:

Gotta love machining bronze,nice and easy

That's good to know! I'm a very amateur "machinist", do you have any tips for me?

[kreecha]

Damo wrote:

appsie wrote:

Gotta love machining bronze,nice and easy

That's good to know! I'm a very amateur "machinist", do you have any tips for me?

fast shallow cuts.
get some material to practice on,
too shallow and the work may vibrate and leave 'corrugations' in the work.
too deep with a soft non-ferrous metal and you will create a bundle of heat (I am guessing a small-lathe without coolant??).
And clamp the work in (I am guessing a 3-jaw chuck??) copper jaws so that jaws do not affect the finish of the material even if you part it off.



It is a finite science.

[Fluffy]

Damo wrote:

That's good to know! I'm a very amateur "machinist", do you have any tips for me?

be carefull when u drill bronze...go slow and reduce the rake on the back of your drill .other wise it will grab and pull it out of the chuck..

steve

[ball]

Any decent bearing shop should have bronze.

It is possible to buy pre-made bushes if the bore and shaft are standard sizes. They are available in short lengths that you just cut to size.

Pine Rivers Bearings on South Pine road used to stock some sizes of these bushes but would order anything in you needed.

[Damo]

Does anyone have a chart that lists surface feet per min. for different materials? I am using cheap, shitty, chinese carbide tooling.

[Bruce]

Damo wrote:

Does anyone have a chart that lists surface feet per min. for different materials? I am using cheap, shitty, chinese carbide tooling.

I do Damo but it's at work. Remind me on Mon and I'll scan it and post up mate.

[Damo]

Bruce wrote:

Damo wrote:

Does anyone have a chart that lists surface feet per min. for different materials? I am using cheap, shitty, chinese carbide tooling.

I do Damo but it's at work. Remind me on Mon and I'll scan it and post up mate.

Thanks Bruce!

[ball]

Just make it up as you go along

You soon get a feel for what is right.

I did all the correct speeds and feeds at trade school but in real life it doesn't usually work out that way.

Machine rigidity and setup count towards achieving the correct surface finish not just cutting speed and feed alone.

[Damo]

ball wrote:

Just make it up as you go along

You soon get a feel for what is right.

I did all the correct speeds and feeds at trade school but in real life it doesn't usually work out that way.

Machine rigidity and setup count towards achieving the correct surface finish not just cutting speed and feed alone.

Thanks Ball, from what i've been reading it tells me the same thing. Being a rank amatuer I just wanted something as a starting point that's all.

[steak_knife]

I was taught "more speed, more feed" by an engineer.

Not 100% sure if he should of taught me that tho.

[ball]

Try this link

http://littlemachineshop.com/Reference/ ... Speeds.php

They look about right I think but it has been a long time since I bothered to calculate RPM for the material.

Once you get a feel for your machine you will soon know if the speed is right.

Most small lathes don't have enough RPM to turn small aluminium jobs at the correct speed, so you just run them flat out

You just have to be careful when facing something of all the way into the centre. The surface speed decreases and becomes far too slow. If you are not aware of this then the carbide usually breaks. If you can drill the job for a center then you will have less chance of breaking inserts.

[ball]

steknig wrote:

I was taught "more speed, more feed" by an engineer.

Not 100% sure if he should of taught me that tho.

Not always, sometimes you need to increase the feed and reduce the speed.

It all depends on the material, the machine and how it's held in the machine.