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Tenson
29-01-2012, 02:00 PM
Hi Guys,

I got my first CNC machine working yesterday. It is a CNC3040 from eBay and although I had lots of problems with broken parts I finally got it going and cut a roadrunner :)

New as I am to this stuff I have a few questions I hope you can help with:

1) I got a TB6560 controll board from eBay* and it has 3 banks of 6 DIP switches. The PDF for the board seems to expect there is just one bank of 6 switches. Can anybody explain the extra ones, please?

2) Micro-step. What is it?

3) The machine accepts 3mm shank tool bits. Where can I get tools with 3mm shank? My usual router has 6mm shank bits.

4) It would be nice to add a turning axis to do metal lathe work (wood too if possible). Can anyone advise the easiest way to do this? I guess I don't need stepper control of the turning, just a speed control. I assume I can then install a lathe cutting tool in place of the usual spindle motor.

Thanks! I'm sure I'll be back here soon as I will need lots of help!

Simon

Swarfing
29-01-2012, 06:00 PM
Assuming you are talking about the dip switches that control the step resolution (full, 1/2, 1/4 etc) then there should be a set for each axis. Assuming again all the screws and motors are the same then you want to set them all same.

Hope that helps

Tenson
29-01-2012, 06:35 PM
Assuming you are talking about the dip switches that control the step resolution (full, 1/2, 1/4 etc) then there should be a set for each axis. Assuming again all the screws and motors are the same then you want to set them all same.

Hope that helps


Thanks, that makes more sense now :)

Also I notice the motors make a fair noise even when they are not moving, but just under control of the board. Is this normal?

blackburn mark
29-01-2012, 07:07 PM
Also I notice the motors make a fair noise even when they are not moving, but just under control of the board. Is this normal?

yep, thats pretty normal for that board

iv also had a ponder on the idea of adding a lathe head of some sort
in theory you could have a row of turning tools on the bottom of your Z axis for and easy tool change, might be worth the effort if your making a big batch of parts
iv not fleashed the idea out yet (depends on a job) ill post if i have a crack at it :)

Swarfing
29-01-2012, 07:09 PM
If you use micro stepping the noise will be less, just make sure that you have the board setup to the same as it is in the software you are using.

Tenson
29-01-2012, 07:11 PM
If you use micro stepping the noise will be less, just make sure that you have the board setup to the same as it is in the software you are using.

Hi,

I'm using Mach3. Where do I set this, please?

Swarfing
29-01-2012, 07:14 PM
Ah! all wrong all wrong....Only joking

Wait for one of the wondoze Mach3 guru's for that answer i'm an EMC patriot i'm afraid..

JAZZCNC
29-01-2012, 07:23 PM
Also I notice the motors make a fair noise even when they are not moving, but just under control of the board. Is this normal?

Yes it's normal and they will get hot as well when stood still.! They are actually drawing more current when stood still than when moving without load.

Please note that if you change the step dip switch's you will have to retune the motors in the control software.


The machine accepts 3mm shank tool bits. Where can I get tools with 3mm shank? My usual router has 6mm shank bits.
Cutweltools.co.uk mainly for milling but metal carbide tools cut wood ok.



4) It would be nice to add a turning axis to do metal lathe work (wood too if possible). Can anyone advise the easiest way to do this? I guess I don't need stepper control of the turning, just a speed control. I assume I can then install a lathe cutting tool in place of the usual spindle motor.


Forget it the machines not up to cutting metal.!

You can buy purpose built 4th axis from Arceurotrade or make your own using a stepper and pulleys. Then use the spindle to cut material while the 4th axis rotates or holds the material as an indexer for engraving/carving. This is the common setup for wood turning.
Also On bigger stronger machines it's possible to put the metal to be turned in the spindle and mount cutting tool on the frame then program then Y or X axis to move the spinning material into the static tool. . . . just youtube mill as lathe and you'll find examples.

JAZZCNC
29-01-2012, 07:57 PM
Hi,

I'm using Mach3. Where do I set this, please?

Config menu then motortuning. On the motor tuning screen theres an input box that says STEPS PER make a note of this number. Now on the right you will see Axis selection X,Y,Z click on which ever axis you want to change then enter the new number then and THIS IS IMPORTANT else it's any changes are not saved click on the SAVE AXIS SETTINGS button.

Depending whether you step up or down will determine the new steps per amount, so if original was 1/2 step and say 80 steps per and you go to 1/4 then just multiply the steps per x2 so would be 160. If 1/8 would be x 4.

Then re adjust the Accelleration and velocity sliders to tune the motors for best performance. TIP: Dont raise the Accelleration too high else will miss steps.
Just play around with the sliders untill your happy with it's performance BUT REMEMBER you must Click on the Axis then save every time you make a change.

Edit: The Steps per amount is the amount of steps it takes to move 1 measurement unit, not per revolution.
So if Mach set to metric units then it's steps per millimeter, if imperial then steps per inch
It's not steps per revolution.

JAZZCNC
29-01-2012, 08:06 PM
Ah! all wrong all wrong....Only joking

Wait for one of the wondoze Mach3 guru's for that answer i'm an EMC patriot i'm afraid..

Nissan girl Does my last post make me A "Wondoze guru" and do I get an official badge. .:joker:

Swarfing
29-01-2012, 08:14 PM
I will consult the linux hierarchy to find out :rofl:

blackburn mark
30-01-2012, 08:32 AM
You can buy purpose built 4th axis from Arceurotrade or make your own using a stepper and pulleys. Then use the spindle to cut material while the 4th axis rotates or holds the material as an indexer for engraving/carving. This is the common setup for wood turning

maybe i read his post wrong?..... not sure he was asking for a classic 4th axis/indexer jazz

Jonathan
30-01-2012, 12:19 PM
You can buy purpose built 4th axis from Arceurotrade or make your own using a stepper and pulleys. Then use the spindle to cut material while the 4th axis rotates or holds the material as an indexer for engraving/carving. This is the common setup for wood turning.
Also On bigger stronger machines it's possible to put the metal to be turned in the spindle and mount cutting tool on the frame then program then Y or X axis to move the spinning material into the static tool. . . . just youtube mill as lathe and you'll find examples.

If only it were that easy.

I tried exactly what I think Tenson wants using my milling machine and a 4th axis I made, see here:

http://www.mycncuk.com/forums/showthread.php/3341-4th-Axis-running-as-CNC-lathe-using-milling-machine

Even in my milling machine, which is obviously significantly stronger than that router it was hard to get a good finish. A more rigid toolpost would help, but still play in the quill/slides will ultimately limit it. The wood lathe I have will fit along the bed of my CNC Router if I drop the bed down so I've considered doing the same with my router. I think it is strong enough, but not yet needed to try it.

I tried the other way here:

http://www.youtube.com/watch?v=4wGDMSiZpyg

That worked very nicely...

You could probably sharpen pencils with it:

http://www.youtube.com/watch?v=W37MySCl82E&feature=mfu_in_order&list=UL

But you'd have to cut the pencil in half first as the critical speed of a pencil is... oh nevermind.

JAZZCNC
30-01-2012, 01:58 PM
maybe i read his post wrong?..... not sure he was asking for a classic 4th axis/indexer jazz

Ye I know mark but was pointing out that he won't cut Metal with this machine no matter which way he goes about it and that if he did want to go with turning wood then the classic way is to use 4th Axis and let the spindle do the cutting rather than spin the material fast with static cutter.



If only it were that easy.


Yes it is that easy You pay the money they send you a 4th Axis . . .Simplizzzz

Now if you meaning turning metal you obviously missed this bit . . .
Forget it the machines not up to cutting metal.!

Tenson
30-01-2012, 06:18 PM
Hi Everyone, thanks for all your advice!

It seems like the best solution for me would be to put a different spindle with chuck on the machine and then have that move in to a static cutting tool fixed to the table. Like the second link Joanthan gave cutting the chess piece. However, I take the point about needing to hold the piece very still for a good finish on the cut. I think this alteration will be something to come back to later.

Now, as far as I can tell this CNC3040 has one main weak area and that is the (I don't know what you call it?) part that fixes the moving parts to the trapezoidal rod. It is made of plastic, looks like nylon and one actually got broken in the post with the weight of the spindle being thrown around on it. So, any advice of upgrading this part, if it is worth doing?

I originally thought of getting some metal ones but I wondered if it needs the contact area with the rod to be nylon for low friction? Anyway then I saw it is possible to get ball-screw rods and nuts which I get the impression are better, and I could replace the shafts with that. Why is a ball-screw system better, and anything else I should know?

The stepper motors on this machine seem quite slow (100 steps per mm, 1800 velocity), but they do seem pretty strong. The spindle (accidentally) hole-punched a 3mm end mill about 10mm directly in to a piece of melamine chip-board!

Tenson
30-01-2012, 10:04 PM
Can you guys see my post? I was obviously posting okay but then it said I need my post approved by a mod?

Hmm seems okay again :)

So I'll probably put the lathe idea to the side for now, but it does seem like attaching a more meaty motor and chuck to the spindle bracket and then having a fixed tool clamped to the table will work best.


Now, the weakest part of this CNC machine seems to be the plastic (I don't know what it's called?) that links the trapezoidal rod to the moving arm/spindle. Everything in this machine is nice strong metal except this nylon part.

Is it worth changing them for metal ones or does it need to be nylon for low friction on the rod?

Alternatively I've seen ball-screw rods and ball-nuts for sale and I consider upgrading with these. What makes ball-screw better than the more normal screw thread I already have?

You can see the plastic bit in my picture here.

http://img641.imageshack.us/img641/2439/cncplasticpart.jpg (http://imageshack.us/photo/my-images/641/cncplasticpart.jpg/)


Uploaded with ImageShack.us (http://imageshack.us)


Oh! Also I tried changing the setting on the control board from the default 75% current to 100% and it makes the motor jerk. Why would this be? 50% also makes it jerk. Best settings seem to be 75% current with 1/2 micro-step.

baccus61
05-03-2012, 04:45 AM
Hi Tenson (Simon),
If you go on over to the GeckoDrive web site you will find a lot of info there that Mariss Friemanis has put up to teach people about steppers and their associated quirks. It makes for an interesting read when you are first starting out with CNC things and it explains a lot of details on how they work.

Here is the link

http://www.geckodrive.com/ark-2/support.html

There is a lot to digest when you first start up and the good people here on the forum will guide you on the right path to success.
Rich.

baccus61
05-03-2012, 05:35 AM
Can you guys see my post? I was obviously posting okay but then it said I need my post approved by a mod?

Hmm seems okay again :)

So I'll probably put the lathe idea to the side for now, but it does seem like attaching a more meaty motor and chuck to the spindle bracket and then having a fixed tool clamped to the table will work best.


Now, the weakest part of this CNC machine seems to be the plastic (I don't know what it's called?) that links the trapezoidal rod to the moving arm/spindle. Everything in this machine is nice strong metal except this nylon part.

Is it worth changing them for metal ones or does it need to be nylon for low friction on the rod?

Alternatively I've seen ball-screw rods and ball-nuts for sale and I consider upgrading with these. What makes ball-screw better than the more normal screw thread I already have?

You can see the plastic bit in my picture here.


If you remove the screws and slide out the plastic nut does it have a long shaft cut into 3 separate pieces with a spring mounted over them? This is designed to push radially down onto the screw with slight force to keep the threads engaged and reduce the amount of backlash. If it has then it is an anti-backlash nut and is perfectly ok to use for a wood router. The plastic is self lubricating and has very good wearing properties. This nut looks to be Delrin. Correct me if I am wrong.
If it is just a standard nut with a thread then you will have backlash on the screw and your positional accuracy will be thrown out.
These type of screws are very good with all the dust and fibres thrown around when cutting wood and are self cleaning to a certain degree. It pays to keep them clean as wear and tear will occur if material is left to build up on them. A few drops of oil occasionally will help keep them smooth but will also attract dust. Some people just keep them dry. After all, they are self lubricating :-)
Ball screws are also very good but keeping the crap out of them is another story due to the small tolerances involved. Some manufacturers of high end machines blow compressed air through them with a small amount of lubricating oil to keep out the crud and other more simple set-up's have fibre washers or felt washers at either end to seal them from debris. There are some good spring steel covers on the market now that cover both sides of the screws and keep out nearly all of the dust etc but they are very expensive. They are like the spring inside a tape measure but much wider and pull out from the centre.
It's your choice and other people here will let you know how they fare with their set up's being good or bad.
Here is a bit of info on some types of plastics you may come across in your travels. Just a bit more ammo to chew on.
http://www.mcmaster.com/#plastics/=gix8tt

I hope all this helps you somewhat.
Rich.

Tenson
08-03-2012, 03:51 PM
The plastic nut has no spring, it is just a plastic shaft with a screw thread on the inside.