Feed rate

[Maker]

The feed rate calculators all ask for the "feed per tooth", "chip load" or "feed per revolution". My question is; How do I know what this is? Does it vary for different cutters?

I think I understand how spindle speed works now; for steel, the velocity at the outside of the cutter should be 120 fpm, whether you're drilling, milling, lathing or even cold-sawing?

 

[shedfull]

Have u seen this from Sandvik ?

https://tu-academy.csod.com/catalog/CustomPage.aspx?id=20000170

I haven't had the time to do it yet myself

http://yarchive.net/metal/empirical_feed_rates.html

 

[Maker]

What is it, it want's a username and password but nowhere to sign up.

 

[711jrp]

What they are talking about is how far the saddle advances per rpm of the work on a lathe, or how fast the bed moves on a mill. You get to pick these with what gear you engage on the power feed.

 

[shedfull]

The first link I gave you is Sandviks distance learning course, deals with cutting speeds depth of cut etc etc but its a bit long winded.

If your after rules of thumb then

http://yarchive.net/metal/empirical_feed_rates.html

 

[Maker]

So you really just go as fast as you can without the machine grumbling?
I can't adjust the powerfeed on my mill as easily as the guy in your link because I have to stop the machine and swap out a couple of gears.

From Wikipedia:

Where:

• FR = the calculated feed rate in inches per minute or mm per minute.
• RPM = is the calculated speed for the cutter.
• T = Number of teeth on the cutter.
• CL = The chip load or feed per tooth. This is the size of chip that each tooth of the cutter takes.

When I buy a new cutter, will the manufacturer tell me the chip load or do I have to try it and find out?

 

[shedfull]

So you really just go as fast as you can without the machine grumbling?
I can't adjust the powerfeed on my mill as easily as the guy in your link because I have to stop the machine and swap out a couple of gears.

On my mill I just start the cutter into the job and turn the variable feed rate up.

Found this,
http://its.foxvalleytech.com/MachShop3/speedCalc/feedratecalc.htm

 

[Bill Edwards]

Particularly for low volume work just go by what feels right.
You don't want the thing chattering away because the book figure says it's right. But it isn't too much of an issue if you're going a little slower than you could be, you aren't on piece work are you?

 

[Maker]

On my mill I just start the cutter into the job and turn the variable feed rate up.

Found this,
http://its.foxvalleytech.com/MachShop3/speedCalc/feedratecalc.htm

That's exactly what I was after, thanks.

 

[Maker]

Particularly for low volume work just go by what feels right.
You don't want the thing chattering away because the book figure says it's right. But it isn't too much of an issue if you're going a little slower than you could be, you aren't on piece work are you?

So it's fine to go too slow, just not too fast. No, I'm not doing anything at the moment, I haven't even sorted my motor yet, but I will get it going soon.

 

[shedfull]

Dont go too slow, youll rub the cutter and blunt it,

 

[Spark plug]

Dont go too slow, youll rub the cutter and blunt it,

View attachment 57715

What's the book if you don't mind me asking?

 

[Maker]

What's the book if you don't mind me asking?

I don't think it is this but "Caxton Engineering Workshop Practice" is excellent if you're after some books. I'm sure the answer to my question is in one of them (3 parts) but I'm not at home this weekend so I couldn't check.

 

[shedfull]

I think that picture was from model engineers data book

 

[Bill Edwards]

You'll get a feel for what is right and what isn't. As I say, if it's chattering and sounds horrible just go slower.
That doesn't mean crawl along at tortoise speed for everything, just go with what seems sensible.