[Magnum164]

Geez... And I thought being married was rough...

You asked a very legitimate question: How to determine the speeds and feeds for the tools. You got a very legitimate answer: With very few exceptions, we all use GWizard.

If you wish to do it without such a software tool, then you will have to spend time doing all of the calculations by hand. There are many variables to take into account that you will need to account for. It is tedious, requires digging through charts and graphs from manufacturers, evaluting the materials you are cutting, calculating tool deflection based on the amount of stickout from the tool, evaluating how much horsepower is available on your spindle, and much more.

You did state that you cut back to 12F and had no problems. If you had started with GWizard, you would have started at 12F and had, well, no problems.

Not trying to sell you anything. You can drive a nail into wood with your thumb, a rock, or a bowling ball. We are suggesting you use a hammer like the rest of us!

Kevin

[kevinro]

Geez... And I thought being married was rough...

I don't get it.

You ask a great question, and then are pretty rude to us when we answer honestly. Sorry I was unable to help you.

Kevin

[300sniper]

maybe i missed it. magnum, how did you come up with your initial rpm/ipm?

[Magnum164]

maybe i missed it. magnum, how did you come up with your initial rpm/ipm?

I think you and TXfred may very well have hit on my frustration. While you can enter any RPM and chipload and get numbers to enter into a program. How should I select them.

The 4K RPM was a starting point just to get the parts I had done... I generally try and use between 525 and the 10K (I think) RPM to keep from having to change my belt since I generally use smaller than 1/4EM's.

So based on what TXfred had suggested, perhaps I should have found a good surface speed to start with? BTW, I checked and the end mills were Interstate, so probably can work backwards from there and determine how I should have started.

[dertsap]

Now on to the RPM issue. I can increase my RPM, but the runout issue has me concerned. I am not 100% sure my ER20 holders are balanced..

i never realized the tormach runs at 10k i thought it was only 4k , it takes a lot of aluminum parts to dull a tool so if you want your parts done faster then run the spindle at its max , don't worry about balanced holders ,because your not running fast enough for that to be a concern , try starting at 10,000 rpm at 15 ipm (with the hss) and bump up the feed as you see fit , two key figures to know if your tool is cutting proper is sight and sound , if it sounds good and all looks good then it's probably good , then try speeding up the feed rate and see how it goes . depth of cut and engagement are always the variables that will determine the proper speeds and feeds , so there is no one set speed and feed rate that will be carved in stone

[rbw1313]

Thanks.. I have some ordered, I will look at the 55 degree helix as well. Would there be a concern with them pulling the material up out of the way I hold them with mitee-bite clamps? I can always order the ones with grooved sides.

Actually they were supposed to be ramped. It made me cringe as well I think I missed something in one of my settings.. But getting there..

The small end mills really like high rpm, but if you are not able to get up to speed take your highest rpm x flutes x chip load. If I were doing the 1/8 end mill it would be two flute for plunging and chip clearence and would not take more than the diameter in thousands for chip load. Lets say you can run 2500rpm x 2(flute) x .00125(dia.in thou.)=6.25 as your feed rate. I also would not plow in more than .015 to start. From here you can make any adjustment to your feed but I would limit your cut per tooth to .002. Go for the cobalt end mills you will get some deflection but progam to do finish passes. You don't have the speed to use carbide tools.
I have used this and taught this to my trainees for years, even with the higher rpm spindles you still have the same relevant speed and feed and we would use cobalt tools for 2ooo or more parts.

[flyinchips]

Magnum164

You sound new to milling with small tools and using your Tormach. You are exactly the kind of person that needs to consider GWizard!!! It will help you get the feel you are asking us to provide. More importantly, it will save you money. How many end mills do you need to break to afford the subscription? 3? 4? From what I have read, you are well on your way on this payment plan.

You can (and will) develop this feel and skill, even without the use of GWizard, but in the end you'll pay way more than the subscription.

I apologize for being another "salesman". Just because you use the crutch, doesn't mean you can't review every GWizard result and understand the reasons for the result, thereby making you smarter. The software to facilitate CNC machining is just another tool to make the job efficient. Imagine cutting this job without the use of G Code. You would have more control and hence more of an opportunity to make mistakes, It's the same thing with other software, including GWizard.

Marriage is difficult: YES!. So is CNC machining without the right tools.

Again, Mea Culpa.

[rowbare]

Now on to the RPM issue. I can increase my RPM, but the runout issue has me concerned. I am not 100% sure my ER20 holders are balanced. I will have to go back and see what Tormach states about the higher RPMs and how to make sure everything is still in balance. I know they sell balanced ER20 collets for that reason.

The rule of thumb that I see mentioned most often is that you only need to worry about balanced tooling above 10,000 rpm though this varies depending on toolholder size, with the rpm being lower for larger toolholders.

From Tormach's web site:
"Unique to the PCNC 770 is a dynamically balanced spindle cartridge which allows the PCNC 770 to achieve a spindle speed of 10000 RPM, making it a perfect choice for engraving and light finishing with small diameter cutters."

The machine is designed to run 10K so if you need it use it. With a small cutter, you should be using the highest speed you can.

As many have mentioned, a good feed and speed calculator is invaluable. There are several online: Milling Speed and Feed Calculator is one.

bob

[Magnum164]

Thanks Bob,

I think that is part of my problem looking at what others are doing on a slower machine and not taking advantage of my higher RPMs on smaller bits. I'll look at the site you posted, looks good. I need to replace a bad belt as it shredded some the other day when I got a 2MM up to 8K RPM.. Still works but Tormach had already sent me a replacement. So time to crank up the speed and see what happens...

I'll post back on the results.

The rule of thumb that I see mentioned most often is that you only need to worry about balanced tooling above 10,000 rpm though this varies depending on toolholder size, with the rpm being lower for larger toolholders.

From Tormach's web site:
"Unique to the PCNC 770 is a dynamically balanced spindle cartridge which allows the PCNC 770 to achieve a spindle speed of 10000 RPM, making it a perfect choice for engraving and light finishing with small diameter cutters."

The machine is designed to run 10K so if you need it use it. With a small cutter, you should be using the highest speed you can.

As many have mentioned, a good feed and speed calculator is invaluable. There are several online: Milling Speed and Feed Calculator is one.

bob

[Magnum164]

Yea, and everyone has told me to use SprutCAM as well, I have switched to Visual Mill and have never been happier.

And just for the record I own Gwizard as well and do not like it. Just like SprutCAM and VisualMill, there are other programs out there that will do the job just fine.

Have you been following the actual helpful posts?

Magnum164

You sound new to milling with small tools and using your Tormach. You are exactly the kind of person that needs to consider GWizard!!! It will help you get the feel you are asking us to provide. More importantly, it will save you money. How many end mills do you need to break to afford the subscription? 3? 4? From what I have read, you are well on your way on this payment plan.

You can (and will) develop this feel and skill, even without the use of GWizard, but in the end you'll pay way more than the subscription.

I apologize for being another "salesman". Just because you use the crutch, doesn't mean you can't review every GWizard result and understand the reasons for the result, thereby making you smarter. The software to facilitate CNC machining is just another tool to make the job efficient. Imagine cutting this job without the use of G Code. You would have more control and hence more of an opportunity to make mistakes, It's the same thing with other software, including GWizard.

Marriage is difficult: YES!. So is CNC machining without the right tools.

Again, Mea Culpa.

[MichaelHenry]

i never realized the tormach runs at 10k i thought it was only 4k

The PCNC 1100 goes to 5100 rpm and the PCNC 700 (which Magnum164 has) goes to 10,000 rpm. Tormach sells a 3x speeder that will take the 1100 to 15,000 rpm and an auxiliary spindle (router motor) that will do 20,000 rpm. There's no TTS tooling for the auxiliary spindle so that's probably best used for jobs that need only one cutter, like engraving.

Mike

[TXFred]

Have you been following the actual helpful posts?

You know what? Nobody here owes you anything.

You come here, asking us for advice.

We offered our best advice, for free!

And you're telling us that we're not being helpful?

Since we're the ones who are taking our time to help you, and you're the one who cannot seem to cut a part without breaking an end mill, perhaps you should try a little humility, a lot less attitude, and maybe even an occasional "Thank you."

If you don't like the advice that you're given, don't follow it. But don't think that you have the right to insult those who are trying to help you because you don't like the advice that they have given.

Frederic

[Magnum164]

You may have missed this....

http://www.cnczone.com/forums/995702-post24.html

It was sort kinda a thank you.

You know what? Nobody here owes you anything.

You come here, asking us for advice.

We offered our best advice, for free!

And you're telling us that we're not being helpful?

Since we're the ones who are taking our time to help you, and you're the one who cannot seem to cut a part without breaking an end mill, perhaps you should try a little humility, a lot less attitude, and maybe even an occasional "Thank you."

If you don't like the advice that you're given, don't follow it. But don't think that you have the right to insult those who are trying to help you because you don't like the advice that they have given.

Frederic

[RTP_Burnsville]

Several toolbit makers also have basic speed and feed programs available to get you started without having to dig through manuals. However, with any software tool, I find it best to have an understanding of how the calculations are being made. Software tools are great but an understanding of what you are doing is priceless.

Robert

[Magnum164]

Several toolbit makers also have basic speed and feed programs available to get you started without having to dig through manuals. However, with any software tool, I find it best to have an understanding of how the calculations are being made. Software tools are great but an understanding of what you are doing is priceless.

Robert

+1 At work we call this going back to the basics. Double checking your process to make sure you are sure you doing things correctly. Then again, there are lives at stake at work..

[Magnum164]

The PCNC 1100 goes to 5100 rpm and the PCNC 700 (which Magnum164 has) goes to 10,000 rpm. Tormach sells a 3x speeder that will take the 1100 to 15,000 rpm and an auxiliary spindle (router motor) that will do 20,000 rpm. There's no TTS tooling for the auxiliary spindle so that's probably best used for jobs that need only one cutter, like engraving.

Mike

I have been saving up for the speeder. I think it can go 30K on the 770, granted they do not recommend that RPM for prolonged use. But I think it would be much better than the spindle router attachment. Hopefully, they will soon get more in stock.

[flyinchips]

I think the speeder is on back order.

[Magnum164]

I think the speeder is on back order.

It is..... Another post suggested manufacturing issues.... But not real sure.

[Magnum164]

I watched your videos the other night but had to think about them a bit. Good info to know, but i don't think I have a runout problem as I would think it would also show up in my final part as a tolerance issue? Currently bearing holes and other tight fit holes have not been an issue.

I'm thinking your breaking end mills because the chip load is pretty heavy at .0015 per tooth. Thats typical for for a 1/4 EM. The chip load per tooth I see suggested for 1/8" EM in aluminum is .0005 - .001"

It's also good to check the tool run out for such a small tool. The slotting parameters I listed has a chip load of .0006". If theres something like .002" of run out, that can break EMs.

Here's 2 videos I did on runout if interested.
TTS Runout - R8 Collet.wmv - YouTube

[dertsap]

have you taken into consideration that a 4 flute may be beneficial ? the tool will have more rigidity and you'd have double the cutting edges , which will gain you twice the feed rate .
i realizes that 4 flutes on aluminum seems to have become a false taboo , but considering the light chip load on such a small tool then chip welding isn't much of an issue if there is ample coolant .
I got an aluminum production job up and running today which I needed to use a 3/16 for a lot of slotting , in order to speed up the process I threw in a 4 flute and it works great at 10000 rpm , 50 ipm , .125 depth of cut .
needs a quick finish pass but its to be expected with a small tool