RPM and Chipload Calculator

[andrewm]

I wanted a quick way of calculating chiploads so I created a little windows program that will quickly compute chiploads based on feedrate, flutes, and RPMs. There are sliders to quickly change these values so you can home in on your desired chipload. Runs in Windows. Pretty simple and easy to use. Let me know if you have any problems or if you find it usefull.

Chipload Calculator
ChiploadCalculator.zip (http://www.talkshopbot.com/forum/messages/29/ChiploadCalculator-3483.zip) (8.8 k)

[garbob]

Pretty nifty program Andrew!

[kerrazy]

Andrew that is great!!!!!!!!!!
Dale

[miker@xmission.com]

Andrew,

Your program will save a lot of time with a calculator; however, could you give my old eyes a break and change either the background color or the foreground color so that there is more contrast between the two - like black type on a light blue background?

[andrewm]

Wow Mike! Is that what I get to look forward to? The type is 24pt to make it easy to read on my 14" shop monitor. You must have a devil of a time reading the stuff on this forum. All kidding aside, as I know we are all heading in that direction, here is a version with more contrast. Enjoy!
Chipload calculator with different colors
ChiploadCalculator.zip (http://www.talkshopbot.com/forum/messages/29/ChiploadCalculator-3497.zip) (8.7 k)

[gerald_d]

Nice calculator for the inch-inclined. Can someone tell me what chipload is and why I should be calculating it?

[Mayo]

Chipload as I define it, is the amount either in number or in weight, of chocolate chips which is sufficient to produce the effect of having consumed just the right quantity of cookies.

Personally, I never have "calculated" this because it will vary at different times of the day and can also be affected by consumption of beverages such as milk or coffee but nevertheless, I do know when maximum chipload has been reached.

[gerald_d]

- my sentiment exactly.

[slendon]

"Maximum chipload" and "just the right quantity of cookies" are just another example of the male female perspective.
In my maths:just the right quantity of cookies = maximum chipload minus two.
I find this works well in metric or imperial.

Steve

[gerald_d]

Dang, I never remember to eat two less the next time . . . . .

[richards]

Andrew,

Thanks for changing the contrast for me. The new program is great.

You're right, reading the forum on a Windows computer gives me a headache from the eye strain, but normally I use one of my Linux boxes, which allows me to zoom the text to 120% or larger.

Getting old is an adventure, especially when it's mixed with MS.

[evan]

ChocolateChips aside (mmmmm, they're GOOD), I'm with Gerald-
"Nice calculator for the inch-inclined. Can someone tell me what chipload is and why I should be calculating it?"

[gerald_d]

Copied from Onsrud's FAQ's (http://www.onsrud.com/faqs.html):

What is chipload and why is it important?
Chipload is the actual thickness of chip that is produced in the machining process. Chipload is measured in thousandths (i.e.: 0.010) and is influenced by the spindle speed and the feedrate of a CNC machine. The number of cutting edges on a router bit determines how the chipload is divided. A single edge tool takes all the chipload during a revolution, while a double edge tool divides the load over two edges. Chipload is an important factor in tool life because it dictates how much heat will be carried away from the cutting edge. Better heat dissipation directly relates to increased tool life. The formula for determining chipload is: chipload= feedrate/(rpm x #cutting edges).

[evan]

Thank You!

[grant@shopbottools.com]

Andrew, you're my hero. That thing is awesome! I think it would be a great thing to have on the website, or possibly even include in the software. I'd like to talk to you about it when you get a chance, why don't you give me a ring at the shop!

Grant Bailey

[harold_weber]

I don't think this little program is giving the correct answers for any case but a single flute router bit. Try these two cases:

Input 12000 rpm, 2 inches per second feed rate, and get 0.010 inch chip load for a single flute bit. That's OK.

Now keep rpm and feed rate the same and increase the number of flutes to two. The answer from the program is 0.020 inch chip load. It should be 0.005 inch chip load. Perhaps you have the number of flutes in the numerator and it should be in the denominator. Or, maybe either my computer or I are having a "Senior Moment"???

[harold_weber]

Also, it sure would be nice to be able to type in the rpm, or have the slide bar increment it by 100 rpm steps.

[andrewm]

Its good to have beta testers! Beat my head against the wall on this one. I had the equation exactly as it should be in the code...except... one set of parenthesis around the (RPM x Flute). Attached is version 2 with the correction.

By the way, if you click on the < or > on the scroll bar it will change in increments of 10. If you click in the area between the slider and the < > it will change in increments of 100.

Added in a box to enter RPM.

Let me know if you find any other problems.


Chipload Calculator v2_1
RPM Chipload Calculator v2_1.zip (http://www.talkshopbot.com/forum/messages/29/RPM_Chipload_Calculator_v2_1-3513.zip) (9.2 k)

[gerald_d]

That's why I could not initially make sense of these funny "chiploads" I was supposed to be calculating!

[slendon]

Hi Andrew

It's getting good, however I get a run time error when I try to change the number of flutes "run time error 11. division with zeros"
Thanks for the work so far....

Steve

[andrewm]

Thanks Steve,
It works when you highlight it and change it. The run time error occures when you zero out the blank first. Made a correction and got it working even when it is zeroed out for you.

This thing started out to be just be something that I needed to try and speed up a single flute project I was working on without breaking bits. Not single line of error handling code. Its now getting to be a real program.

Let me know if you guys find any other bugs or options it could use and I will add them in as I get a chance.

Andrew


Chipload Calculator V2_2
Chipload Calculator V2_2.zip (http://www.talkshopbot.com/forum/messages/29/Chipload_Calculator_V2_2-3534.zip) (9.5 k)

[slendon]

Hi Andrew,

That was quick!! Works fine now..........if you weren't 3500 miles away I'd buy you a drink. Cheers anyway.....

Steve

[slendon]

Got a feeling that tip speed (therefore cutter dia) must have some part to play in the practical relevance of chipload?
Any answers?

Steve

Rather like smaller chocolate cookies increases the maximum (per unit) chipload.

[richards]

Steve,

I had the same impression when I first used the program; however, I'm fairly certain that if we realize that chip load is not the same as volume of wood removed, we would realize that the chip load remains constant regardless of the cutter diameter.

It helped me to visualize the cutting process by assuming that I had already advanced a 1/2-inch cutter about one inch into a piece of wood. Then I assumed that the Shopbot would advance the cutter 1/1000th of an inch for each revolution of the cutter. It's easy to visualize that the cutter would remove a ribbon of wood 1/1000th of an inch thick. Next, assume that the cutter was replaced with a 1/4-inch cutter, but that the feed rate remained at 1/1000th of an inch per revolution of the cutter. The ribbon of wood would still be 1/1000th of an inch thick, but the ribbon would be shorter. Thus the chip load would be constant, but the volume of wood removed would depend on the diameter of the cutter.

[gerald_d]

Two identical "chiploads":


4887

The second cutter, being twice the diameter, will produce double the chip volume, or double the chip weight.

[slendon]

As I understand it chipload (via info from geralds link to onsrud) is a variable related to the heat generated by a cutter and carried away by the chipload. Surely the friction created on the tip of a large cutter is higher if the feed rate and rpm remain the same as for a small cutter? doesn't this variation in tip speed generated heat(caused by bit dia) need to be factored in to give a set of variables(rpm and feed rate)that protect the cutter from overheating? I suspect I'm missing something, or running on too far.....
Steve

[slendon]

Is the key to this that the mass of a chip removed by a bigger cutter, the leading edge of each flute being longer in contact with the cut material, is larger, and is therefor able to carry away more heat? so the whole system is self regulating?
Steve

[gerald_d]

Steve, you are completely over-complicating this issue, and quite rightly so, because the "load" in chipload gives all sorts of expectations of work / heat / energy. However, the "load" is misleading, because the chipload is simply the chip thickness, nothing more, nothing less.

Thicker chips carry away more heat. Thin chips need to be cut more often, generating more heat.

[richards]

Here's a Java version of the Chipload program patterned after the program written by Andrew McClary. If you're a Linux user (like I am) having a program that runs in Java works better than booting up a Windows box every time I need to check the chipload.

To those of you who use Andrew McClary's Chipload Calculator, I extend my most profound regrets. His program is better than mine in every respect except for the fact that mine runs on any computer that uses Java.

Basically my program allows you to enter the spindle/router speed, the machine feed speed, and the number of flutes on the cutter. Press the calculate button to compute the chipload.

This is a Jar file. Place it in whatever directory best suits your needs. Run it with the command "java -jar /directory/Chipload.jar" (substitute your directory path for 'directory'). If you're lazy like I am, write an executable script to facilitate the process; however, please don't ask me to do it for you. This program is best used by those of us who are inconvienienced by Windows, not by those who already have and use Windows regularly.

Of course you may extract the source code from the jar file and modify it to your heart's content (after all, Linux is Open Source).

One last note: If you're using a Windows machine, don't waste your time trying this program. Andrew's program is better.

Mike


Java Chipload Calculator

4888 (6.1 k)

[richards]

I assumed a little too much from the Forum's upload/download feature. Instead of using the name that I'd selected, the filename 'Chipload-3916.unk' was substituded for the default download name. (By the way, using that name, or whatever name appears as the default download file name, works just as good as Chipload.jar.)

If you're using Mozilla (like I am), right click on Chipload.jar and select 'Save Link Target As' and then enter whatever file name you desire ( I use Chipload.jar). In any case use the command 'java -jar /directory/file.name' substituting your directory name and file name as needed.

Mike

[johnny_s]

Michael- are you running your bot from a linux machine?

[richards]

John,

I wish it were possible to run a Shopbot with Linux; however, until then, I'll struggle with the constant viruses, blue screens of death, and other Windows induced/allowed interruptions whenever I have to run a Windows based box. (This is not suggest that the Shopbot software is faulty, but the underlying Windows OS is a cesspool filled with bugs and assorted viri)

(Side note: I've installed hundreds of desktop computers over the last twenty years as data handlers for the process control computers that I design and program. The DOS computers, the Novell computers and the Linux computers run 24/7 with downtime limited to preventative hardware maintenance. The Windows computers rarely run long enough to require preventative maintenance. When I have to write programs on a Windows machine, I've learned to hit the enter key at the end of each line, and then to hit the pre-programmed hotkey to save the file.)

Mike

[johnny_s]

LOL - you sound just like every linux user I know - they despise windows. Do you think it is compicated to port the control software to linux? It wont work under windows emulation?

-John

[richards]

John,

Porting a process control program from one operating system (OS) to another is difficult and certainly not something to be taken lightly.

Several years ago I stopped directly driving any process from any general purpose computer - including those running Linux as the OS. Forcing a general purpose OS to act as a Real Time Operating System usually leads to problems. However, there is another way to get around that problem. By using slave computers to control each part of the process and by connecting those slave computers to a master computer via TCP/IP sockets, the slave computers can effectively control the process while the master computer interacts with the equipment operator. The slave computers that I use cost between $50 and $100 each, depending on memory and I/O ports. They are programmed in 'C' and enhanced Z80 Assembly Language.

As far as being 'uncomfortable' with Windows as an OS and with Microsoft as a company, I really do despise their buggy software and the various FUD (fear, uncertainty, and doubt) campaigns that they have run since Bill Gates first chastised the world for stealing his version of BASIC and continuing until the present when funding for SCO's multi-billion dollar lawsuit against IBM was funded - through a third party - by Microsoft. Their way of doing business is the antithesis of the Shopbot way. Thank God for forums and people who are willing to help each other.

My advice to anyone who wants to know the best OS is to first determine what OS is required by the programs that will be run. In the case of Shopbot software, that OS is Windows - making mute the discussion on what OS is best.

My apologies to Shopbot and to the forum members for ranting and standing high on my soapbox to castigate an OS; however, having seen my customers loose literally hundreds of thousands of dollers every year due to buggy, error prone Windows software should be factored into the equation.

Mike

[bruce_clark (Unregistered Guest)]

Mike,

Not to start an OS war, but say Microsoft is at fault for buggy software written by a third party is like blaiming ShopBot (the company) for not getting a large cabinet contract. They only make the tools.

As for their business practices, yes, I agree they are heavy handed and designed to squash the little guy (heck, even the other BIG guys). BUT, name me ONE company that would not do the same (or worse) if they were in Microsoft's position?

Lastly, while I personally think Linux is neat, it is not EASY. My grandmom can run windows software, but would be calling me every 5 minutes if she had to run Linux. Also, Linux is so "stable" because it does not do much. I can crash my X windows system pretty easily. Sure, it doesn't bring down the whole computer, but it still causes me to loose all the stuff I was doing. So, it is not the blue screen of death, but a black screen with a blinking caret. Which is worse?

Again, I am not defending MS or putting down Linux, but I see them as two separate OS for two separate type of people. People who like keyboards and typing and those who do not. The first catagory are more likely to want Linux, the second type are more likely to run Windows.

Just my $.02,

Bruce Clark

[richards]

Bruce,

I think I may have started something that shouldn't be in this forum. Although we have differing opinions on computers, I hope that we both agree that Shopbot makes a terrific machine.

Mike

[bruce_clark (Unregistered Guest)]

Michael,

I agree on both points. Funny thing, I don't disagree with you either, to an extent.

Also, not only is ShopBot a great machine but they are also a GREAT company! Just for the record, I have been a ShopBotter since '98, starting out with a cable drive ShopBot.

Bruce Clark