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View Full Version : CNC Router with Servo motors & belt drives (non-MechMate) - Bangalore, India


Irfanulla
Mon 12 February 2007, 02:46
Hi all,

I am intending to start a thread pertaining the build of my machine which will use PMDC motors converted to servos using US Digital optical encoders and UHU controllers, so far the controller has been built and awaiting the mounting on the machine.

The machine i am getting together is based on teh mechmate and thats why I want the thread to be on this forum. Yup there are variations to the design but only in areas where i needed the motors to be mounted and so on....

I hope this thread has the right location.

So far I have done my design in Solidworks - only X axis and the y car which I still think are incomplete a few pics for ref.

Irfanulla
Mon 12 February 2007, 03:09
http://www.mechmate.com/Forum/messages/329/3358.jpg
http://www.mechmate.com/Forum/messages/329/3359.jpg

Gerald_D
Mon 12 February 2007, 04:05
Interesting...

Mike Richards
Mon 12 February 2007, 06:25
It took a minute to realize how your design worked. Am I guessing right that you are using a single servo to turn a jack-shaft that has spur gears on each end?

Gerald_D
Mon 12 February 2007, 06:33
I thought those "spur-gears" were belt pulleys, with the final pulley and pinion still to be shown?...

I have a scheme for mounting the stepper motors roughly where the "spurs" are now (motors pointing inboard) and then running toothed belts down to the pinions....

How will the y-car drive work? How will the y-car hold-downs work if the x-jackshaft is in the way? Lots of curious questions to take me on a dangerous side-track, but I promise I will resist. http://www.mechmate.com/Forum/clipart/happy.gif

Irfanulla
Mon 12 February 2007, 06:44
Mike, Geral is right, i mentioned that these are just incomplete pictures and I am working on them yet, as I am going to get it done at one of the fabrication houses here. The reason I will be posting the images is to get more out of you there so that i correct my mistakes as well...

Let me finish the 3d modelling and then post it so that there is some clarity.

Gerald U have mentioned a scheme with motors running the spur with toothed belts kindly provide me with images or links

the x jack shaft will not come in the way, for the work , its on the same height as the cross member tube for the y car is.

Regards
Irfan

Irfanulla
Mon 12 February 2007, 11:43
some more
http://www.mechmate.com/Forum/messages/329/3369.jpg
http://www.mechmate.com/Forum/messages/329/3370.jpg
http://www.mechmate.com/Forum/messages/329/3371.jpg

Irfanulla
Wed 14 February 2007, 10:19
My V rollers are in.
http://www.mechmate.com/Forum/messages/329/3382.jpg

Ali Ahmad
Wed 14 February 2007, 10:39
Hello Irfanulla
Your design looks interesting.I am just getting started in solidworks myself.Where did you get your V rollers?
thanx Ali

Mike Richards
Wed 14 February 2007, 17:35
Irfanulla,

That design is very interesting. It's given me a few new ideas. I am wondering, however, how much effort would be required to replace a wornout or broken belt?

Gerald_D
Wed 14 February 2007, 21:43
Mike, the old trick in this situation is to hang one or two spare belts over the through shaft from the beginning. (Tied out of the way with wire or nylon ties). And then 10 years later when you need the first replacement, you find the spare has gone hard through lack of exercise and it breaks in a few days. But, if you don't hang a spare there, the first one only lasts one year...

Irfanulla
Thu 15 February 2007, 10:42
Ali,

I got the V rollers turned at a friends place, he got it heat treated and ground too.......

Mike nice Q well initially i did want to go with a gear box, but ruled out due to the costs......U can say that the pain in replacing the belts is a necessary evil......any idea out of it is welcome

Gerald ur idea might work but i am thinking of using gates poly chain belt which i suppose has a long life span....

Thats it for now
CYA

Irfanulla
Thu 01 March 2007, 09:33
Hi all,

Finally from Manjeet's idea I got a automotive timing belt from gates for 3.5USD thats INR 165 its length is around 24 inches and a 3/4" wide, I even got the timimg belt pulleys which are from a suzuki car called teh Maruti 800 in India with a idler pulley. the only thing is that both the timing pulleys have a bore of 24mm diameter and my motor has a shaft size of 19 mm dia......but the positive thing I got all the three for a prize of around INR300 thats under 7 USD....well teh smaller pulley does have two threaded holes through thm planning to use thm in some way.

http://www.mechmate.com/Forum/messages/329/3572.jpg

Gerald_D
Thu 01 March 2007, 09:54
The only snag with that is your ratio is only 2:1 - you need a much bigger difference in pulley sizes to make it really worthwhile. Looks like the small pulley is about 20 teeth while the big one is 40 teeth? (if it is from a car engine the big one will be exactly double the small one)

Irfanulla
Thu 01 March 2007, 10:41
Gerald,

what would be teh correct ratio, the motors are rated at 2000rpm @ 110v, each motor is 625watts.

U are right its 20 and 40, iam planning for a bigger wheel probably 80 teeth at the pinion end...what do you suggest.

Thanks and Regards
Irfan

Gerald_D
Thu 01 March 2007, 10:54
Gut feel says around 8:1 in total - if you only have 2:1 at the motor, then you need another 4:1 at the gantry ends. I just mentioned the numbers for a feeling of how it works, you need to do all the calcs yourself.

Remember, if you only do 2:1 at the motor, then your long shaft and heavy couplings turn relatively fast. You might get flywheel effects - lots of torque needed to accelerate the inertias.

Mike Richards
Thu 01 March 2007, 10:56
If we assume that you want a top jog speed of 1500-inches per minute (25-inches per second) and that your final pinion gear is 30 tooth (20-pitch, 20-degree rack), then each revolution of the pinion gear will move the axis 4.71 inches. The formula to compute the gear ratio is (RPM * distance traveled per RPM) / inches per minute; therefore, (2000 * 4.71) / 1,500 = 6.28. A ratio of about 6:1 would be a good starting point.

(Edited: Gerald, you posted while I was thinking, but it looks like we're generally in agreement.)

Gerald_D
Thu 01 March 2007, 10:59
Mike, my mental calcs also said about 6:1 but I didn't trust the torque from that single motor to budge the gantry, so I inflated it a bit. http://www.mechmate.com/Forum/clipart/happy.gif

Irfanulla
Thu 01 March 2007, 11:10
Mike and Gerald,

The torque on my motors is 3Nm, and if the ratio is 6:1 then the torque gets multiplied right, thats 3x8=21 Nm, probably a lot of torque......right?

Regards
Irfan

Gerald_D
Thu 01 March 2007, 11:28
Multiplying the torque by the ratio is right. But, if 21Nm is a lot, is like like asking me how long is a piece of string....http://www.mechmate.com/Forum/clipart/happy.gif

Have a look at what the recommended stepper motors can do for torque.

Irfanulla
Thu 01 March 2007, 11:37
Gerald I got my multiplication wrong its 6x3=18Nm,a bit of confusion, i think the lot i might spend on the belts and pulleys may as well get me new steppers...........and their drivers what say....let me try the costs involved first, tomorrow i am gonna find the costs.

Good night....

Mike Richards
Thu 01 March 2007, 11:40
Gerald, you're right. I saw the 625-watt figure for the servo (slightly higher than the 560-watts that a Gecko can produce at full current and full voltage (7A at 80VDC) and didn't stop to think that the 625-watt rating is probably the PEAK rating and not the continuous rating.

I'm just guessing, but the continuous rating for a motor that size is probably between 50 and 75 watts, which would make an 8:1 or 10:1 ratio more practical. Using the figures from my post above, a 10:1 ratio would still give you about 940 inches per minute - or over 15-ips. That's faster than I jog my Alpha. (Although the Alpha can jog at 30-ips, I have mine set at 12-ips.)

(Edited: Boy you guys are fast. It takes a white-haired old man like me forever to run computations.)

Gerald_D
Thu 01 March 2007, 11:46
Mike, I'm cheating, I'm just sucking my thumb and sending Irfan to do the legwork. http://www.mechmate.com/Forum/clipart/happy.gif

Mike Richards
Thu 01 March 2007, 12:02
Conversion utilities on the web show that 1 Nm = ~140 oz*in. So 3Nm X 140 = 420 oz*in. Then, with an 8:1 gearbox, you'd get 8 X 420 = 3360 oz*in, which is roughly what the holding torque rating is for the TWO Oriental Motor Alpha steppers geared 3:1 that I have running my X-axis on my Alpha.

However, I'm still concerned whether the servo's rating is PEAK or CONTINUOUS.

Irfanulla
Thu 01 March 2007, 12:03
Gerald Mike having a nice time on my expense LOL...

Well teh motors are rated 625Watts contineous, they are huge PMDC motors with US Digital Encoders.....huge in my sence.......and are rated at 3Nm continuous...and powered by UHU servo controllers..

Now what say........

I do know my motors are a overkill already...

http://www.mechmate.com/Forum/messages/329/3578.jpg
http://www.mechmate.com/Forum/messages/329/3579.jpg
http://www.mechmate.com/Forum/messages/329/3580.jpg

Gerald_D
Thu 01 March 2007, 12:06
A motor shaft of 19mm (mentioned in the pulley photo post) indicates more than a 625Watt peak motor? Lot's of vague guessing in the absence of real specs.

Edit: Oh, I thought you had gone to bed! Didn't see the last two posts before I did this one.

Mike Richards
Thu 01 March 2007, 12:14
It looks like we're posting on top of each other - which is good. It shows lots of interest.

If I were doing the project, and had those motors, my only real concern would be whether I could build a practical gear reduction unit. Using the jack-shaft approach gives two places that you could easily add gears. Two 3:1 reducers would give you 9:1 overall.

You know, it just might work.

Gerald_D
Thu 01 March 2007, 12:16
With these HUGE motors, you might get away with a 4:1 ratio total. Go and break up two more Maruti 800's and you are done! Go and get some sleep now.

Irfanulla
Thu 01 March 2007, 12:20
Gerald

check the specs of these motors here on the cnc zone link
http://www.cnczone.com/forums/showpost.php?p=190804&postcount=572

Gerald_D
Thu 01 March 2007, 23:23
Out of curiousity, how do you plan to use the other two motors on the other axes? Belts, pulleys, shafts, screws....?

Irfanulla
Thu 01 March 2007, 23:37
I will use belts for Y and a ball screw for the Z

Irfanulla
Fri 02 March 2007, 10:49
Some more images for comments and suggestions
http://www.mechmate.com/Forum/messages/329/3590.jpg
http://www.mechmate.com/Forum/messages/329/3591.jpg
http://www.mechmate.com/Forum/messages/329/3592.jpg

Irfanulla
Fri 02 March 2007, 10:50
http://www.mechmate.com/Forum/messages/329/3595.jpg

Gerald_D
Fri 02 March 2007, 11:01
Swing the Y-motor to the inside, next to the router. (The motor can be off-center, while the belts run back to the center)

Irfanulla
Wed 14 March 2007, 11:06
Hi Gerald

See the pic below

http://www.mechmate.com/Forum/messages/329/3664.jpg

Comments please....

and thanks in Advance

Gerald_D
Wed 14 March 2007, 12:19
The line between the middle pulley (hinge point) and the last/pinion pulley must be more horizontal. As you drew it above, when the motor drives the y-car to the right the pinion may jump out of the rack. To the left, the pinion jams tightly into the rack.

Irfanulla
Wed 14 March 2007, 20:40
Gerald,

I plan to load it as in your machine with a spring which is not shown here, the final drive pulley sits on a spindle which is mounted on the swing arm, the swing arm will be tensioned by a spring which will hold the pinion and the rack together......
what say...........

Gerald_D
Wed 14 March 2007, 23:01
I understand about the spring. The problem is that the hinge point of the swing arm must be more in a horizontal line with the pinion.

Realise that the pinion must push/pull the car. It must push/pull against the hinge point as much as possible, and against the spring as little as possible. As you have drawn it, the pinion push/pulls mostly against the spring - in one direction it tightens the spring and in the other direction it loosens the spring.

Irfanulla
Thu 15 March 2007, 01:11
Yup Gerald now i got your point, do you mean the hinge and the pinoin centres should be on a horizontal line, O------O this way or
O
|
|
|
|
O
This way, yup gerald i know what it means by horizontal....but i just wanted to confirm...

http://www.mechmate.com/Forum/clipart/happy.gif

Gerald_D
Thu 15 March 2007, 01:41
We speak the same language!

It does not have to be exactly horizontal. The MechMate is at 45 degrees. But it must not be vertical.

In other words, horizontal=best, vertical=not acceptable, 45 degrees=acceptable

Irfanulla
Sat 17 March 2007, 03:56
Gerald See the new configuration.........of the belts for Y.....think i have a problem to do a similar thing to the X axis......mean getting it to the horizontal.

http://www.mechmate.com/Forum/messages/329/3676.jpg

http://www.mechmate.com/Forum/messages/329/3677.jpg

Irfanulla
Mon 19 March 2007, 19:55
Gerald,

Still no comments, any one any help.

Thanks and regards
Irfan

Gerald_D
Mon 19 March 2007, 23:07
I didn't think you want to hear my honest comment, so I thought it is better to keep quiet....

Looks like the back of my washing machine. Stepper motors will be so much cleaner...

Irfanulla
Mon 19 March 2007, 23:55
Gerald:

I appreciate your honest comments, but you know i am sort of stuck with the motors and controllers thats why i want to use em all. I cannot keep them aside and think of steppers as I have already spent an amount which for me is pretty handsome.

What ever it looks like I would be happy if it works......

AND BTW how did you change the color for the font

and the question again......will this work..... http://www.mechmate.com/Forum/clipart/happy.gif

Regards
Irfan.......

Gerald_D
Tue 20 March 2007, 07:45
In principle, it will work

javeria
Wed 19 September 2007, 09:06
The pictures tell the tale of my router bed, presently used to tie up the cattle, the gantry is also ready,
have to assemble the rack to the X and need to purchase the timing pulley's and belts.

Will keep posted .... Regards
IRfan

373

374

javeria
Wed 19 September 2007, 10:23
Thats the smooth gantry on You tube

http://www.youtube.com/watch?v=nUtYt6XM7-Y

(tried embedding the video .... not possible)

Gerald D
Wed 19 September 2007, 12:32
Wonderful! :):)

(I am very glad that you could not embed the video! We have a limit of 3GB of downloads per month, and embedded videos can kill that quota very quickly)

javeria
Wed 19 September 2007, 17:26
Wonderful! :):)

(I am very glad that you could not embed the video! We have a limit of 3GB of downloads per month, and embedded videos can kill that quota very quickly)

Gerald,

Actually it will not,the video will be played from youtube direct and will not take out your bandwidth. Only that the video will be telecast on the thread! It only like posting a link.

RGD's
Irfan

Gerald D
Wed 19 September 2007, 20:54
When I say "we have a limit", I meant it as all people in South Africa. I can not send & receive more than 3GB per month from my broadband connection to my pc. (I know it is not problem to host youtube, but I want to make this site friendly to everybody, even with poor internet connections)

javeria
Sun 23 September 2007, 09:04
Hi Gerald and others.

You can see my Jack shaft arrangement. its overweight on one side, the gantry is more than 30kg I think! and I require that sort of motor to drive it, but a small tap and it will tilt. have to find ways to balance it! ANY suggestions,BTW look at the limit switch arrangements and the jack shaft itself.

RGDS
Irfan

Manjeet
Sun 23 September 2007, 09:17
Hi Irfan,

Good progress. Keep it up

Manjeet

javeria
Sun 23 September 2007, 09:27
Hi Irfan,

Good progress. Keep it up

Manjeet

Yes Manjeet there is progress but the Gantry is very heavy, so I am a bit worried!

Regards
IRfan

Gerald D
Sun 23 September 2007, 09:30
30kg is not much. Our gantry, with router and z-slide assembly is 80kg. Your balance should be okay when you add the z-slide and the tool. You can also put your Y-motor to the "better" side.

Marc Shlaes
Sun 23 September 2007, 10:31
Irfan,

I have been to Bangalore twice and 4 times to India total. I enjoy your country very much and I really miss the food.

You are showing everyone that ingenuity and determination can produce very interesting results. You are also showing the do-it-yourselfer without a complete machine shop can, in fact, end up with a production machine.

Best of luck!

javeria
Sun 23 September 2007, 17:20
Irfan,

I have been to Bangalore twice and 4 times to India total. I enjoy your country very much and I really miss the food.

You are showing everyone that ingenuity and determination can produce very interesting results. You are also showing the do-it-yourselfer without a complete machine shop can, in fact, end up with a production machine.

Best of luck!

Thanks Marc,

I really get motivated by your words!

RGDS
Irfan

bbreaker
Mon 24 September 2007, 00:55
I Irfan, I think the same tan Marc, I like the way you follow and I think your country is an example of doing the best with nothing or a little hardware, go go go, I continue to look your thread and see you advance from me.

javeria
Mon 24 September 2007, 01:11
I Irfan, I think the same tan Marc, I like the way you follow and I think your country is an example of doing the best with nothing or a little hardware, go go go, I continue to look your thread and see you advance from me.

Gee. ThnX,

Appreciate it! , it all makes me think positive toward doin it good!

RGDS
Irfan

cbboatworks
Mon 24 September 2007, 05:14
Hello Irfan

Keep up the great work,You have showed alot of people that they can build whatever they put there minds to with the least amount of materials available in there country. I see in a few other post that people Can not get materials in the country they live in. I can clearly see you have adapted to what is available to you what an inspiration to others.keep up the great work.Thanks

Gee. ThnX,

Appreciate it! , it all makes me think positive toward doin it good!

RGDS
Irfan

javeria
Mon 24 September 2007, 08:52
Hello Irfan

Keep up the great work,You have showed alot of people that they can build whatever they put there minds to with the least amount of materials available in there country. I see in a few other post that people Can not get materials in the country they live in. I can clearly see you have adapted to what is available to you what an inspiration to others.keep up the great work.Thanks

Hi CB, thanks for the kind words,

Actually lot of material and infrastructure is available here, for me teh only constrain was that of finance which drove me to use most commonly available material and there is a shortage of skilled labour to weld and finish......so all this circus!

lets hope with all these constraints teh router turns out good!

Regards
IRfan

Hugo Carradini
Mon 24 September 2007, 09:19
Hello Irfan.
I bet your having a great time, no matter the doubts you can get. Keep going.
I like your solution to the limits switches. I was thinking in involving them in a very soft plastic to protect them from the powder.

javeria
Mon 24 September 2007, 19:20
Hello Irfan.
I bet your having a great time, no matter the doubts you can get. Keep going.
I like your solution to the limits switches. I was thinking in involving them in a very soft plastic to protect them from the powder.

No Hugo, I think the limit switches just need to be maintained, enclosing them in soft plastic may result in more dust accumulating within it. Any wayz if you have a proper dust evacuation system then there is no need to protect the limit switches.

RGDS
Irfan

Gerald D
Mon 24 September 2007, 20:42
Irfan & Hugo, all dust evacuation systems have a problem to work correctly at the edge of the board. When you are right on the end of a board, the cutter gets exposed.

Irfan, you have the right idea to lift a mechanical switch up, away from a flat surface where dust will collect. Also, the holes in the switch must point downwards (like you have it) so that the dust will fall out.

javeria
Tue 25 September 2007, 08:31
Hi Gerald and All,

I had a Q

1. for the timing pulleys which i will be using to drive the pinion can i use just the grub screws to hold the pulley's in place or is it necessary to have a key to bind it with the shaft.

2. If only grub screws can be used tehn how many, I was about to put 3 each 120 degree apart........is it OK

3. I expecting a center distance of 325mm, will that matter much?

4. I will be using a HTD 8 mm pitch belt. is it OK

Regards
Irfan

javeria
Wed 26 September 2007, 00:44
Hi,

Any answers to my previous questions

RGDS
Irfan

Gerald D
Wed 26 September 2007, 04:30
CNCzone

javeria
Wed 26 September 2007, 09:47
CNCzone

Righto Gerald,

I moved my thread to the CNC Zone, I will keep posting updates on this forum when ever there are major updates on my thread at CNC Zone,

Gerald, thanks for all the inspiration.

Next a mechmate in in my mind. I already have the vampires. So see you all guys later

at CNC Zone my address will be http://www.cnczone.com/forums/showthread.php?p=347147#post347147

Thanks for all the help!
RGDS
Irfan

javeria
Mon 01 October 2007, 12:11
http://www.cnczone.com/forums/showthread.php?p=349138#post349138

Updated with Pics and ideas