Today I recieved this PM.

Desperated newbe

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Hello Benny:



Well, i don´t know more what to do.... I started 3 CNCs, but always stucked by same thing: how to fix screw and stepper together... something is not centered... ALWAYS, in all my 16 motors!

I´m trying to make it with NYLON, i made a hole with 6mm full (crossing the nylon) then i remake the hole with 9.5 or 9mm to put the 10mm screw using a homemade tool to make the screw line into the nylon (maybe could br on this time i´m doing wrong)

Please help me, i bet all my extra money on the projects and now i have 3 machines and one command box (controlers etc...) but no CNC working...

Sorry about my english, i´m from Brazil.

Please help, i have not who to ask heare and no much more money to use on it...

It became an obsecion, i worked 3 days full time (16 hours a day) trying to solve, making other machine, trying to solve, etc etc... all the time i stoped by the same problem: fix motor and screw.

thanks anyway !

Ito.

I have suggested that he use two pulleys and a timing belt, or the hose coupling method. Does anyone else have some further suggestions?

Thanks

Ito, I just found this in the photo gallery.
http://www.cnczone.com/gallery/data/500/medium/Afbeelding_137.jpg
EDIT: all of a sudden it has been removed from the phot gallery. I wonder why?

Could work:
:rolleyes:
If i make a homemade "lovejoy" ? i will use 20mm diam NYLON and some floppy disk parts.

see the pics.

What do you think?

Ito.

Opps, one more picture...

Ito,
Try taking a short piece piece of rubber hose the size of the motor shaft or the scre shaft. Automotive gas or vacuum line will work. The on the other side make a nylon piece the size of the other shaft. Use automotive hose clamps to secure.

Phil

What you just drew is a homemade U-Joint, like the one in your socket wrench set. It'll probably work, but you might want to mock it up and see how much flex is present in it.

I think the hose coupling is a much better, and definitely simpler method for shafts of even remotely similar size.

-- Chuck Knight

The rubber hose idea may sound crude, but in practice it works rather well, especially for a lighter hobby use table..
I did this one as a 'temporary' joint, and haven't found any reason to upgrade it yet..
the red rubber hose is from an auto air conditioning recycling unit, just under 1/4" , and is fairly well reinforced with virtually no twist, easy to cut, and the clamps are single use crimp clamps, again designed for air conditioning ewuipment, and just crimp tight with a pair of end cutters..
the stepper ouput shaft is 1/4" and the all thread rod is 1/4x20tpi, at least the rod is one step above 'cheap' grade...

sorry about the poor photo..

Is that the correct type? It is used on air pressured...

Thanks a lot!
The entusiasm came with full power!
:cheers:

I would suggest turning the ends to a diameter such as 1/4" and getting some real couplers from mcmaster, I use the helical beam couplers for my cnc kits, I got a couple spider couplers, those have a small amount of play but will work just fine unless your using absolutely zero backlash screws.

Jon

Well, i wish i have money to get real stuffs to my machine...

As you know, heare in 3rd world thing are so much more expensive. Multiply by 3 or 4 the costs.

I bought today the rubber hose. I worked 4 hours on the new coupling system. It seems to be OK :D !
Tomorrow i will make a test, but moving by the fingers i can see the rubber hose work, really amazing. I should made this at first time... :o

The mounting stoped as the pictures show.

Thanks guys, you are good guys !!!!!

Way to go ITO !

Phil

I an happy for you mate, you have made a great effort of your machine :)
Thanks for posting the pictures

There's a lot to be said for simple solutions. My dad taught me this saying when I was a little boy -- it's stuck with me ever since. BTW, he was a mechanical engineer.

"Complicated is easy...simple takes genius."

-- Chuck Knight

If it's ordinary air line [air compressor] hose, it may have a bit of flex [or twist], the stuff that I used was higher pressure and had a fair bit of braiding inside it..
easy way to check is to try and twist it with pliers or similar..

The one you used may have a little extra 'give' but at least the table is under it's own power now, and 'improvements' can come later on...

enjoy..

Yes you are right Vlad,
I guess for Ito, since he has not yet seen one of his creations working yet, his main aim is to just get movement first, and at least cut something even if the hose does twist fractionly. Later on he can edit his machine a bit further.

When I first started here, there seemed to be so much talk about a poofteenth of an inch, and high tolerances, that I figured the whole thing was out of my league. These days I realise that fine tolerances are not needed for every machine. Just do the best you can with the limited tools you have. What ever the results, you will be super impressed that you made it yourself.

I recon Ito's next major hurdle will be making some gcode for it. I recon making the machine is easy, its learning software, and finding cheap/free programs to use.

What is the cutting area of your machine Ito? I recon a few of us could make some test gcode for you, if you wanted.

Definitely..accuracy is an extreme variable...
for an MDF hobby machine 0.010" is more than acceptable,
for a toolroom machine...0.0001 is max for smaller [or more demanding] items..

On the tractor with 31 feet of tillage, I'm glad to stay within 6" of the power line poles, only managed to 'scuff' one once, and 7200 volts sure does throw pretty sparkles at night...

a lot of different type of equipment here, as well as budgets..:)

WOW! :rainfro:

of course i acept, thank you very much!

My table has trully Y=300 mm ; X= 250 mm; Z=100 mm ;
Those steppers are cheap: 7.5 deg (48 steps/rotation) ;
screws are M10 (10mm) ;
I gess the resolution will be like 0,03125 mm/step. Is that correct ? :confused:
I´m trying the TurboCNC to control my steppers.

Oh please tell me how to do Gcodes too...

I can start from VECTOR or CAD softwares ?

Well, what can i say...
I tested at the shop by trying to twist the rubber hose by hands and after that i bouth it because my steppers are very small and never will twist it as i tryed...

When i was mounting the screw on the rubber hose (screwing into the hose) i used some hard tools and the hose twisted a little.

I think it will not be a problem, cos i´m using small steppers and the table is not so heavy...

please you guys take a look at the hose to see what type is it... :(
I´m newbe and i´m an advertizer. I don´t know taht much about tecnical stuffs, hehehe.

Thanks a lot!

Here you can try this out.
You will need to set Z zero at the top of your material.
You will need a Vbit for carving.
It will varve 1mm into your material
The material should be 250mm x 250mm
Dont worry, I didnt spend much time on this, it is an adaptation of a job I did for a friend.

EDIT: For best results paint your material black b4 you do the cut. This will give contrast. Or you could use a bit of clear plastic and shine a light up the sides so as to illuminate the sign.

You could do something like this.

http://www.cnczone.com/gallery/data/500/748929031_29255_524a.jpg

Wow benny, thanx! But where will be the ZERO XY ?

Hello guys:
I didn´t tested yet, but rolling by fingers, the stepper seems that are not rotating freely, it´s a little blocked...

Anyone have an idea ?

thanks ! :o

Ito the steppers will have a rough feel to them as you turn them by hand. It has to do with the number of steps per turn. If you turn one very slowly you can feel each step.

Mike

Turmite:
I know about the steps, but thanks anyway..
What i can say is when i put the stepper on rubber hose an fixed it on the table, the stepper cant roll very easy, like it was doing before the rubber hose... What am i´m making worng?

If you just have the leads of the stepper hanging free and they are touching you will get an electric braking action which will make the shaft more difficult to turn.

Pete C.

I released then fixed the clamps and the stepper rotated lightly! :idea:

Next step: mount the electronics and test the Y axis !!!!!!!

Thanks guys!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Finlly i finished the Y axis :p !!!!

But i´m tired it´s 23:45 heare....
Tomorrow i will test it, but the stepper moves very nice, even without grease on screw.

The problem is sleep ! The machine is ready to test!!!!!!! hahahhah.

Thanks guys! Your help is all !!!!

Ito, the X,Y zero is the bottom left hand side of your machine. I guess that depends on how you have setup your machine.
Will you be using mach2 to drive your machine?
You will need to configure mach2 so that it knows the orintation of your machine.
I suspect you may need to ask a few questions about how to do that, when you get up to that point.
If you are using the demo version of mach2, you will only be able to cut 1000 lines of code. I didnt check how many lines of code the file was that I posted.

:D YEAH !!!!!!!!

Thanks a lot, guys! i gess the problem is solved !!!!
I will construct the X-axis today and maybe Z-axis tomorrow.
I a on full power now!

I tested it on FKEYBIT.EXE then tested on TurboCNC. All successfull at 8 kHz !
:banana:

Tnanks, thanks, thanks! :cheers:

Yo guys, how to calculate the resolution on a M10 (10mm) screw on a 7.5 deg/step motor (48 steps/ 360 deg) ???

Thanks!

You need to measure the "pitch" of your screw. That is, how far is it from one thread to the next one. Suppose, it is 1.5 millimeters. That's how far your axis will travel with one rotation of the screw. If your steppers are hooked up direct, with no belt/gear reduction, and you are using full steps on your stepper drive, you just divide the pitch by the number of steps per rotation (you said 48). So, it's 1.5mm / 48 steps = .03125 mm per step. (You came up with this number, too in an earlier post in this thread)

--Brian ;)

Thanks Drawbar, i measured the pitch, but i need more precise information... I will try on the tools shop too...
Thanks Anyway!

By the way the screws are M10 (10mm) and the steppsr hocked direct to it, 7.5 deg (48 steps/360 deg) ; if the screws pitch is 1.5, will the resolution be
1.5 / 48 = 0.03125 right?

And at 8kHz will the speed be 8000 x 0.03125 = 250 mm / minute ?
Is that right, and... Is that good ?

There is a forum with this title:
stepper coupling
Maximebleu

May we can move this tread to there, so we can help other newbes with stepper coupling...

What about this idea ?

:cheers:

About speed, 8 kHz = 8000 pulses/second, not pulses/minute. So speed at 8kHz will be 250 mm/second! And 250 mm/second X 60 sec/minute = 15000 mm/minute. Wowee Zowee!!!!! :eek:

About moving the thread, I think you get a Moderator to do that. Anyone?

--Brian

8000 per second? Wow! i gess i´m doing something wrong so, i´m just using jog features on TurboCNC that´s configured to upto 16kHz... But seems like 250 mm per minute.. I can´t see my machine "running", just walking good...
:confused:

Hey GUYS:

This is the last picture from friday night.
I think the X axis will be tested today.

Thanks for everything.

Ito.

This was taken on the line 951 :cheers:

Guys, i would like to thank very much all of you.
Really. I started this project with no knowledge about CNC, steppers, G-code, milling etc... IN ONE YEAR i could do a machine that works at 750 Hz! WOW, it´s amazing, you guys are amazing...

I just can´t stop, i´m planning the 2nd, the 3rd, the 4rt machine !!! I´m really addicted!

Tomorrow i will make a real piece of acrilic. :rainfro:

Thanks guys :banana:

ZZZZZZ...ZZZZZ..zzzzz.zzzz.zz.z...... :banana:

What a picture, electronics, mechanics, sushi and a beer. Now thats the way to work.

I thoug the machine was 250 x 250, but it is 240 x 230 hahhahahaa

G-code is oversized!

Thanks anyway!
:p

That´s the way, a-ha, a-ha, i like it :rainfro:

Well guys, i forgot to thank you for all help and support. I forgot to say sorry disturb with newbe stuffs and i forgot to say that my machine is very nice now! :cheers:

I´m helping other brazilians that searched for me on this forum and i like to thank them to for let me help them, cos helping i learned mucha and fast.

I´m building now 2 other machines, a large one and a hard one.

And i´m doing other improvemens on electris and electronics. You guys will know it soon.

See ya and thanks , really thanks!

Did you get the step size set Ito? In TurboCNC, where it asks for Step increment, you can type CALC and a little wizard comes up prompting for screw pitch, gear ratio, number of steps, microstep etc.

Yeah, My machine has 0,0075 mm resolution per step.
Screw 1,5 mm per round, motor with 200 steps / 360 deg. No gears.

Thanks for the tip.