# Thread: Need help working on FEED rates!!

1. ## Need help working on FEED rates!!

Hey guys, new to the forum! first thread for me

basicly, im a BTEC student, in mechanical engineering, and currently working on a specified work peice to create, using a virtual CNC programme, known as "CUTVIWER" bacisly, we as a class have finished writing up our G code Etc.. but we have been told to find the feed rate forumulas for ourselves!!! Can any one tell me how to work out the feed rates for straight cuts, going round specified diameter curves ETC.(Have not had good luck at all yet with this! eek) thanks for reading this and any help that any one offers!

2. Originally Posted by LiamRatedRKO
Hey guys, new to the forum! first thread for me

basicly, im a BTEC student, in mechanical engineering, and currently working on a specified work peice to create, using a virtual CNC programme, known as "CUTVIWER" bacisly, we as a class have finished writing up our G code Etc.. but we have been told to find the feed rate forumulas for ourselves!!! Can any one tell me how to work out the feed rates for straight cuts, going round specified diameter curves ETC.(Have not had good luck at all yet with this! eek) thanks for reading this and any help that any one offers!
Hi,

There is formula for feed rates but first you have to decide the cutting speed. Which can be decided by experience or there is standard chart which shows Cutting speed for specific material. This information you will get in any engineers hand book.

Thanks.

3. Oh right i see, Thanks lol
sorry to sound such a newbie and all, just we have not been told this from our teachers in college! there lazy in my view and make us find things out, and realy its them who should be teaching us! Ok cheers any way

4. These rather nice chaps will send you a free speed/ feed calculator (like a slide rule thingy), or you can download it from their site.

http://www.lovejoytool.com/speedcal.htm

Click on the "FREE" tag up the top of the screen (in the middle).

5. Thanks alot for that IManCarrrot
i sent off for it and The Millworks calculator is a great programme, great find !

6. Are you going to call your teacher when you run into something you weren't spoon fed when you're in the real world?

Engineers. Atleast they're making would be engineers learn a little bit about the shop floor goings on. That's more than I can say about the ME's at my day job.

Here's the formula for figuring out feed rates at the endmills' periphery while going around corners:

Internal:
Straight line feedrate in IPM x (bore dia - cutter dia) / bore dia = feed rate in IPM to program.

External:
Straight line feedrate in IPM x (corner or boss dia + cutter dia) / corner or boss dia = feed rate in IPM to program.

You still need to figure out what your feedrate will need to be in a straight line based on chip load. Go to this page and check out all the formulas they have.

7. Oh, and since you're in the UK like me you'll have to multiply by 25.4 since we use proper dimensions like mm, not inches. Which, if I remember rightly was based on the dimensions of somebody's thumb (from the knuckle to the thumb tip).

Incidentaly, the metre was invented by the French and was one ten millionth of the distance from the North Pole to the equator.

Sorry for going off at a tangent there, I'm working on my own on a Saturday and am bored senseless, the machine's all set up and working properly and all I got to do is push the big green button every now and then

And my IPod's just packed up

8. Originally Posted by Matt@RFR
Are you going to call your teacher when you run into something you weren't spoon fed when you're in the real world?

Engineers. Atleast they're making would be engineers learn a little bit about the shop floor goings on. That's more than I can say about the ME's at my day job.

Here's the formula for figuring out feed rates at the endmills' periphery while going around corners:

Internal:
Straight line feedrate in IPM x (bore dia - cutter dia) / bore dia = feed rate in IPM to program.

External:
Straight line feedrate in IPM x (corner or boss dia + cutter dia) / corner or boss dia = feed rate in IPM to program.

You still need to figure out what your feedrate will need to be in a straight line based on chip load. Go to this page and check out all the formulas they have.
Nice to see someone else understands radial chip thinning and actually apllies it. I've seen too many "veteran" machinists and programmers who don't even understand the concept let alone adjust for it.....

9. IManCarrot, again thannks alot for the help:P andd yeahh i knew Lol
soz 2 hear about the Ipod man that realy does suck!

All done and dusted now guys cheers for the help