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Feeds and Speeds

PostPosted: Tue Feb 05, 2019 10:27 am
by OCEdesigns
Does anyone have a simple basic guide (chart) to feeds and speeds? I'm looking for some basic starting points. I know there are many variables and I will be learning them as I go and I plan on doing something like an Excel sheet to track it all. I'm just hoping to reduce my learning curve. My Google skills may be off because I didn't find too much info. I did see the CNCcookbook site but that looks like they go way too deep into it. I may be wrong.
If it matters I am using the water cooled spindle with my HD4 Extended.

Re: Feeds and Speeds

PostPosted: Fri Feb 08, 2019 8:33 am
by bill z
I've asked a couple of but manufactures and others for suggestions on feeds and speeds but all I get is nothing also.

I was thinking it had to do with the grade of alloy steel in the bit.

Maybe, no one wants to be liable should something go wrong when setting up to specific values.

Just so you know, you are not alone in your quest. Maybe misery would like some company.

Re: Feeds and Speeds

PostPosted: Fri Feb 08, 2019 8:42 am
by OCEdesigns
bill z wrote:I've asked a couple of but manufactures and others for suggestions on feeds and speeds but all I get is nothing also.

I was thinking it had to do with the grade of alloy steel in the bit.

Maybe, no one wants to be liable should something go wrong when setting up to specific values.

Just so you know, you are not alone in your quest. Maybe misery would like some company.



LOL... Kind of what I expected. As soon as I get mt starting point figured out I'll just start my own chart.

Re: Feeds and Speeds

PostPosted: Wed Feb 20, 2019 7:30 am
by sk8nmike
no chart would ever work for someone else. Feed and Speed are based on the Material, the bit being used and rotation speed of your spindle/router. ideally you want to want to have the feed and speed set so that one point of the bit clears the material just as the second starts it's cut, but even that's not a "rule" as some materials may need more time between cuts to allow the bit to cool.

here's a place you can start with:

https://daycounter.com/Calculators/GCod ... ator.phtml

Re: Feeds and Speeds

PostPosted: Fri Feb 22, 2019 7:43 am
by OCEdesigns
sk8nmike wrote:no chart would ever work for someone else. Feed and Speed are based on the Material, the bit being used and rotation speed of your spindle/router. ideally you want to want to have the feed and speed set so that one point of the bit clears the material just as the second starts it's cut, but even that's not a "rule" as some materials may need more time between cuts to allow the bit to cool.

here's a place you can start with:

https://daycounter.com/Calculators/GCod ... ator.phtml



I have done several projects and this is what I am quickly finding out! :mrgreen: I have looked at the link you shared and even that doesn't help too much but it can get you in the right direction.

Re: Feeds and Speeds

PostPosted: Thu Mar 14, 2019 11:07 am
by gdon_2003
I had posted about replacing my Bosch router on the Shark Pro Plus HD and one of the forum members sent me some pdf documents about his upgrades over time. It was very good information but either in the email he sent or the pdf he recommended the following:

Set your router on 3 and forget it.

The Bosch speed guide for the setting 3 is 16,500 RPM

I have cut several test projects on 3 and they came out fine. They were "Chip Carving" type projects in red oak and mdf.

There are the feed and speed charts but would the setting of "3" be an agreeable universal setting for most projects on the Shark? What speeds do you typically run for 1/4" end mills for pocket cutting?

Thanks

Re: Feeds and Speeds

PostPosted: Thu Mar 14, 2019 2:34 pm
by OCEdesigns
So far everything I have done I have used between 10,000 and 14,000 RPM. The 14,000 seems pretty good for the stuff I'm doing.

Re: Feeds and Speeds

PostPosted: Mon Mar 18, 2019 4:12 pm
by Scheffy
I'm in my first few months of playing with an HD4/water spindle combo too so I'm sort of in the same boat. The end of this PDF has a pretty comprehensive table with starting points without getting too far into the weeds with anything:
https://static1.squarespace.com/static/59efc96d90badec50a4afa15/t/5a21f4b6e2c483bcf39a2c84/1512174775486/FeedsandSpeeds.pdf
I think the best guidance is on pg. 7, quoted below:

"Optimizing feed rates and speeds:
1. Start off using an RPM derived for the chip load for the material being cut (see charts).
2. Increase the cutting speed (feed rate) until the quality of the part’s finish starts to decrease or the
part is starting to move from hold downs. Then decrease speed by 10%.
3. Decrease RPM until finish deteriorates, then bring RPM back up until finish is acceptable.
4. This optimizes RPM and speed to remove the largest possible chips."

This PDF is a pretty good primer for understanding bit basics too:
http://www.woodguide.org/files/2014/07/CNCrouter_bit_basics.pdf

There's a lot in there you probably already know but it might help to fill in a few blanks like it did for me.

One thing I learned in the meantime is to be pretty cautious with any calculators on bitmaker websites. Freud for example has a pretty intuitive calculator function where you select one of their bits, put in some material info and it spits out a calculated feed rate. Problem is the calculation is for what the bit can handle and not necessarily what your machine can handle. It basically assumes minimal flex and unlimited horsepower. One of my first cuts I blindly followed their recommendations, even erring on the low side, and the bit still bound up 3" into the cut and stopped the spindle. It's probably for reasons like this why bit manufacturers are reluctant to give out recommendations. A recommended speed doesn't mean much if the machine is run by a hamster and built with wet noodles.

Re: Feeds and Speeds

PostPosted: Mon Mar 18, 2019 7:37 pm
by Bob
OCE,
If you can get the March issue of Wood magazine, there is a very brief description for cutting different materials on the cnc. It's a good starting place .
If you can't find the magazine, try here:
You can go here for the article, including a trial version of a feed and speed calculator.
https://www.woodmagazine.com/tool-revie ... o-all-that
Also, Remember that when cutting wood, the density can change a lot within just one piece. Even if you carefully calculate the recommended speeds and feeds, they may need to be adjusted for your material.
Bob

Re: Feeds and Speeds

PostPosted: Tue Mar 19, 2019 8:34 am
by OCEdesigns
Scheffy wrote:I'm in my first few months of playing with an HD4/water spindle combo too so I'm sort of in the same boat. The end of this PDF has a pretty comprehensive table with starting points without getting too far into the weeds with anything:
https://static1.squarespace.com/static/59efc96d90badec50a4afa15/t/5a21f4b6e2c483bcf39a2c84/1512174775486/FeedsandSpeeds.pdf
I think the best guidance is on pg. 7, quoted below:

"Optimizing feed rates and speeds:
1. Start off using an RPM derived for the chip load for the material being cut (see charts).
2. Increase the cutting speed (feed rate) until the quality of the part’s finish starts to decrease or the
part is starting to move from hold downs. Then decrease speed by 10%.
3. Decrease RPM until finish deteriorates, then bring RPM back up until finish is acceptable.
4. This optimizes RPM and speed to remove the largest possible chips."

This PDF is a pretty good primer for understanding bit basics too:
http://www.woodguide.org/files/2014/07/CNCrouter_bit_basics.pdf

There's a lot in there you probably already know but it might help to fill in a few blanks like it did for me.

One thing I learned in the meantime is to be pretty cautious with any calculators on bitmaker websites. Freud for example has a pretty intuitive calculator function where you select one of their bits, put in some material info and it spits out a calculated feed rate. Problem is the calculation is for what the bit can handle and not necessarily what your machine can handle. It basically assumes minimal flex and unlimited horsepower. One of my first cuts I blindly followed their recommendations, even erring on the low side, and the bit still bound up 3" into the cut and stopped the spindle. It's probably for reasons like this why bit manufacturers are reluctant to give out recommendations. A recommended speed doesn't mean much if the machine is run by a hamster and built with wet noodles.


Thanks for this! I have looked at some of this already. It does help. I have already learned to just do a little research before trying a new bit or new type of material.


Bob wrote:OCE,
If you can get the March issue of Wood magazine, there is a very brief description for cutting different materials on the cnc. It's a good starting place .
If you can't find the magazine, try here:
You can go here for the article, including a trial version of a feed and speed calculator.
https://www.woodmagazine.com/tool-revie ... o-all-that
Also, Remember that when cutting wood, the density can change a lot within just one piece. Even if you carefully calculate the recommended speeds and feeds, they may need to be adjusted for your material.
Bob


Thanks Bob! Yeah I have learned to just use trial and error. So far very little error! LOL. I'm also trying to keep a log book with notes until I get better at this. I will look at that magazine article. I'm trying to learn as much as I can.