Help the newbie, or laugh at silly questions :)

[Sentinel]

I've been in computer/network/telecoms area, for a long time. Then I 'cracked', and decided to move to something completely different.

So, here I am, having a CNC machine in my room (just arrived few days ago), too scared to even think about assembling it (well, almost).

I have no knowledge about CNC, nor do I have any knowledge about machining, but I've definitelly decided to learn. So, I've spent past 2 months reading and reading and reading, and reached 'information overload' stage, where I ended up knowing lots of things, but not actually understanding them

To make things even more complicated for myself, I live in a place where you don't find CNC stuff in shops (milling bits, collets, etc, etc) - I have to order things from abroad, so I have to really know what I need in advance.

Therefore, at risk of being laughed at, I am going to ask some very stupid and basic questions. Hope I'll get some responses.

(yeah, I know - there are no stupid questions, only stupid answers )

1. How do you people know what speeds (spindle) to use for what materials, and for which milling bits? This has been puzzling me for some time now. Is there a resource (table, list, ...) that shows combination of speeds/materials, or it all depends on experience and "trial & error"?

2. CNC machine that I've bough came with Kress 1050 FME spindle/motor. It has a 'slider' on the back (from 1 to 6), which is supposed to control speed of the motor. However, manual doesn't explain how do I set the speed. So, how do you know at what speed spindle runs, and how do you 'finetune' spindle speed (for example, you want it to run at 17,000RPM)? Before machine actually arrived, I thought (for some reason) that software controls spindle speed. Seems it's the case on more expensive machines only, right?

3. Machine came with controlling software (WinPC-NC Light), which turns out not to be able to load G-Code files. As if I've bought a car without an engine. Although I can upgrade to version which can open G-Code files, it is going to be annoying process (due to way I have to order things and pay, then do customs procedure, blah, blah). Now, I'd like to try EMC2 or some other controller software, but I am not sure if it'll work with controller I have.

Controller is here:

http://www.cnc-router-routers.com/ht...nel_2_1am.html

Is there a way to know if EMC2 would work with it properly, without opening the controller box and looking inside for parts details? Or I should simply try EMC2 and see what happens?

Btw, machine which I have is CNC-STEP High-Z S-1000/T (more details here: http://www.cnc-router-routers.com/html/t-series_with_ball_screws_cnc_.html), so if anyone has it and successfuly used other control software than WinPC-NC, I'd be happy to know about it.

4. Ok, funniest question. If spindle runs at high speed, and miling bit breaks - can it be dangerous in case broken piece decides to fly in my direction?

5. After browsing many sites (milling bits manufacturers), I have often seen milling bits being recommended for metal work. Would such bits work with wood (and other 'lighter' materials) as well, or I should be trying to find bits specifically made for cutting 'softer' materials?

6. Nut and collets are driving me crazy. Basically, there is this part (collet):

https://ssl.kundenserver.de/s8472815...2049080%253D29

and it goes into this part (nut):

https://ssl.kundenserver.de/s8472815...2821208%253D29

Once it's fit, it's a nightmare to take it out and replace with other collet. Do you take out collets from nuts by hand, or you use pliers, or you just have spare nuts loaded with different collets, so you don't have to bother with changing collets all the time?

Although I am planning to order some spare nuts, I have to order them from Germany, so I am bit worried that I don't break existing nut (or collet, for that matter) before I get spares. Any guidelines on preferred nut/collet 'replacement' procedure is welcome (even if it only involves 'brute force').

Well, that's it for now.

Any help is much appreciated

[SORCHEROR]

ok,ill answer some of the questions you posted,the others i will have to think on or look at the sites you posted more,
first off,yes the cutters can break and hit you,always wear safety glasses,always!!!,second,you could use mach 2 or mach 3 to control the machine,its a free download and gives you up 1000 lines of g code,any more and you need to buy the license,third,im not familar with the collets you have ,but most of them to get out of the nut,theres a flat spot on the muts lock ring,you need to hold the nut and pull the collet side ways away from the flat,should just pop out,pliers or forcing it will damage the collet
cutting speeds and feeds know from expericne,but there a machinist book that has all that in it for starters,not sure where you find online,but could buy from book store maybe,ill check into it
steve

[jackson]

this may help on the feeds and speeds

[NC Cams]

Get a copy of the "Machinist's Handbook". It has tons of information and answers to questions that you haven't even dreamed up of yet. Even an older one will do as many of the formulae never change.

Cutters are a hard thing to give generic replies to. SOme of the info comes with experience and others can come right out of the handbook and/or from the machine tool cutter maker's applications pamphlets.

Some of your CNC specific questions can be solved/learned/studied via the CNC ZOne search engine. In many cases, the info/question has been asked and answered a number of times before.

IF you can do network programming in Unix/Linux/NT and/or Windoze, a lot of the CNC stuff will be realatively easy to pick up on. Finally, before you ask some specific question (like how do I use MACH On a laptop? Try the search engine. You'll be surprised at the results.

[SRT Mike]

Originally Posted by Sentinel I have no knowledge about CNC, nor do I have any knowledge about machining, but I've definitelly decided to learn. So, I've spent past 2 months reading and reading and reading, and reached 'information overload' stage, where I ended up knowing lots of things, but not actually understanding them

Welcome!

Everyone started somewhere. Every person on this site, no matter how much they know, knew nothing about machining at one time, so don't feel bad at all about newbie questions.

1. How do you people know what speeds (spindle) to use for what materials, and for which milling bits? This has been puzzling me for some time now. Is there a resource (table, list, ...) that shows combination of speeds/materials, or it all depends on experience and "trial & error"?

Do a google search on "feeds and speeds" and you will find tons of information. There are also some free programs you can download that will tell you the correct spindle RPM and feedrate (feed is the speed the table moves - or more exactly the speed at which the part is fed into the cutter). The Machinists Handbook also has this information and I believe you can order it on a CD now.

2. CNC machine that I've bough came with Kress 1050 FME spindle/motor. It has a 'slider' on the back (from 1 to 6), which is supposed to control speed of the motor. However, manual doesn't explain how do I set the speed. So, how do you know at what speed spindle runs, and how do you 'finetune' spindle speed (for example, you want it to run at 17,000RPM)? Before machine actually arrived, I thought (for some reason) that software controls spindle speed. Seems it's the case on more expensive machines only, right?

Feed and speed isn't an exact science, so if you calculate that your spindle speed should be 15,000rpm (for example), and you only can get it to 14,500rpm, you should be OK. You can tell when you got things right based on the sound and surface finish, so you can adjust until you get the results you want/expect. But, if the numbers do not correlate to anything, then you can easily get a "tachometer" that will tell you an exact spindle RPM. Its not a bad thing to have anyway... you can probably find a tach suitable for a milling machine spindle for quite a cheap price on eBay.com

3. Machine came with controlling software (WinPC-NC Light), which turns out not to be able to load G-Code files. As if I've bought a car without an engine. Although I can upgrade to version which can open G-Code files, it is going to be annoying process (due to way I have to order things and pay, then do customs procedure, blah, blah). Now, I'd like to try EMC2 or some other controller software, but I am not sure if it'll work with controller I have. Controller is here: http://www.cnc-router-routers.com/ht...nel_2_1am.html Is there a way to know if EMC2 would work with it properly, without opening the controller box and looking inside for parts details? Or I should simply try EMC2 and see what happens?

It looks like this controller just goes into the PC parallel port, so you should be able to use almost any NC control software that you like. We were using EMC2 at our shop for a bridgeport that had been converted to a PC control using Geckodrives. It was OK, but if we could do it again we would use Mach instead of EMC. But you can try both - I think there are free versions of both you can try.

4. Ok, funniest question. If spindle runs at high speed, and miling bit breaks - can it be dangerous in case broken piece decides to fly in my direction?

It could fly your way, so be careful! Always always use safety glasses at a minimum. You could also get a plastic shield (I have seen them at Enco www.useenco.com) that have a magnetic base and you can stick them to the table. Not a bad idea and if you start using coolant you may want to build a shield/enclosure anyway. But to begin, definitely safety glasses and remember that if the bit catches your part, it can throw it very fast and hard across the room. Also be careful of chips - as they grow they can spin around and fly too - always pay attention and be careful at all times.

5. After browsing many sites (milling bits manufacturers), I have often seen milling bits being recommended for metal work. Would such bits work with wood (and other 'lighter' materials) as well, or I should be trying to find bits specifically made for cutting 'softer' materials?

My experience is metal cutters work OK in wood, but wood cutters do not work in metal. Wood is actually quite abrasive from what I understand, so it will dull your cutters quickly. Its not a bad idea to have one set for wood and one set for metal (and one set for plastic, if you do plastic). But if you are just occasionally cutting wood, I wouldn't be too concerned with using your metal bits for that.

The other guy above answered about the collet. Good luck and enjoy yourself!

[afh]

To SRT Mike

It was OK, but if we could do it again we would use Mach instead of EMC.

why? What was wrong with EMC?

To Sentinel

Well. I am planning to use EMC too - http://www.linuxcnc.org/
Mostly because Mach is limited and Windows only, and I prefer unix.

If you have experience with Linux, it would be nice with EMC2.
Mach is not bad, and Windows works fine with it.
if you have zero experience with Linux, it would be better to stay away from
it, if you are busy or does not want to learn an another OS.

I suppose that you only need to feed STEP/DIR from parallell port to each motorconnection. Did you get some documentation? Call/send email.

Then you must feed EMC/Mach with pitch of your ballscrews.
Very important, since your CNC and controller works as one, and they must fit like a glove - together!

That's why I have found a surprisely big enjoyement in DIY CNC - software and hardware works together as one beautiful unit, and one must be careful to all details.

[SRT Mike]

Originally Posted by afh To SRT Mike why? What was wrong with EMC?

The main problem was that tool offsets just did not work. So every time a tool was changed it had to be re-zeroed on the workpiece. This was supposedly changed in the newer version but we had tried out Mach and found the interface to be nice and the software easy to use.

The newest version of EMC supposedly fixed this but we moved away from that machine and up to a full VMC so never tried it with the newest EMC.

[cixco]

Hi everybody

i am new at this so please forgive my ignorance.

Here is my problem:

I have purchased a new a new machine, complete with winpc-nc light software.
parameters as per manufacturer.

my "z" and "x" axe work perfectly the "y" does not move.

so i have tried the following.

new pc, new cables, re-installing program, new parallel / pci port,
nothing works.

when i plug the "y" cable in any other plug (Z or X) the Y works perfectly
when i plug the Z or X in the Y plug they dont work.

i believe their night be a bad connection in the control box but the shop (in Germany) say they test drived the machine before shipping and it ran perfectly, am i nissing something?

need Help Please.


cixco(Portugal)

[The White Fox]

Some beginner formulas - "food-for-thought":

( SFM X 3.82 ) / Dia = RPM

SFM = Surface Feet per Minute
3.82 = approx 12 / pi = (12 inches per foot / 3.14156)
Dia = tool diameter

some starting Surface feeds (these are easy going to moderate) for drilling H.S.S.
Alimn - 350
Soft steel - 60
Hard steel - 50
soft stainless - 30
hard stainless - 20

.125 inch dia. drill approx .004 chip load
.250 inch dia. drill approx .006
.500 inch dia. drill approx .010

So drilling into a block of 303 s.s. with a 1/4 inch drill

(30 x 3.82 ) / .250 = 458.4 = 450rpm (round down to the nearest 50rpm will be PLENTY accurate) 450 x .006 = 2.7

so for 303 stainless steel I'd run a feed of 3 @ 450 RPM
for Aluminum F32. @ S 5300

Some rules of thumb:

"Speed kills" - watch your RPM
"Don't Rub the material away, cut it" - always try to have at least a cut of .001 inch per tooth, and harder materials need a heavier minimal cut to prevent tool deflection.

When starting off, good quality sharp High Speed Steel tools will get the job done for now, don't woory so much about carbide until you start to get comfortable with what you're doing. Use multi flut (at least 3 cutting edges) if you are concerned with bottom fininsh.

A "Machinist Hand book" is that to a machinist what a holy book is to a priest and other holy people. It contains everything, but remember, it is a book - books are for referance. I wish you the best.