Moved to New Shop to Do Real Work! #81 - Damietta, Egypt
 

Hi all,
Finally after months of reading this great forum almost on a daily basis as the addiction can’t be resisted :) I decided to start my build. I’m a mechanical Engineer form Egypt. I have some experience in construction field, maintenance of the wind turbines and some computer knowledge. As usual the electronics part seemed vague/dark to me but after spending along time reading and reading and reading I have the feeling of things and I think it can work for me with the help of this great group of people here. I’m almost confident that whatever the troubles I could face during my build it will be solved with the help of MM family. My table so far will be X=1200 and Y= 1600 I ordered some of my parts (electronics) as following:
4X G203V
4X motors KL34H295-43-8B
1X KL-5413 700 W 54VDC/13A
1X PMDX-122
Please review and let me know what you think about the compatibility of the power supply with the motors.
Laser-cut parts will be received next Monday but without bending and I have to look for another workshop to make the bends.
That’s it for now and I will keep posting my progress as I go on.
Thanks Gerald for the great forum and the plans. You made it easy for me to decide what type of CNC router I will build. Thanks all for your help.
Ahmed

Welcome Ahmed,
Its really amazing to see all the different areas of the world that are starting to build a MM. :) Hope your build goes well.

The KL34H295-43-8B motors draw 6.1A when wired parallel or 4.3A if wired unipolar (half-coil). It would not be good to use a 13A power supply if you wired the motors parallel; however, the 13A power supply would be fine if you wired the motors unipolar (half-coil).

The maximum voltage for a motor with 3.3mH inductance is about 58V, so the 53VDC power supply is very near the maximum voltage if you wire the motors either bipolar parallel or unipolar (half-coil).

My personal preference would be to wire the motors unipolar (half-coil) via a 3:1 or 3.6:1 belt-drive gearbox. By doing that, you would multiply your torque by the gear ratio and you would have 3 or 3.6 times better resolution per step.

Welcome Ahmed! There's lots to learn and even more experts out there to help you. Best of luck and keep us posted!
Scott

Mike,
unipolar (half-coil) via a 3:1 or 3.6:1 belt-drive gearbox is the plan. as with unipolar i will have another chance if I've done something wrong:p as per Gerald's recommendation beside the power supply will be smaller. I really wanted to get the OM but the price+shipping(~US$2000) was huge enough to make me go for the direct drive as a start. Thanks Mike and keep an eye on me.I'll need your help all the way :)

Thanks Heath&Scott for the warm welcome.

motors+G203+Power supply delivered
 

yesterday i received my laser cut parts great move for me:).

Today i received my 4 motors , G203 , C10 instead of PMDX-122 :mad: and unfortunately a wrong power supply 65V and 15A #$@#$&:mad::mad::mad:.
Now my motors will be worm/hot if connected unipolar so i have to change the plan to Bipolar connection.Right?

Do you think this will work with the type of motors i have (KL34H295-43-8B)?
Back to reading again i think. The answer is somewhere around.

You got a 65V power supply instead of the 53V maximum calculated for the motors. That is not so serious - just reduce the current to the motors by changing the resistor on the G203 drives.

Gerald,

I have a 63V power supply - what do you mean by changing the resistor on the 203Vs?

Scott,
By changing the current set resistor for a lower max current, you will lower the temp rise at the motor. The higher voltage will cause more motor heating effects.

If your voltage is causing the motors to get too hot, then the simplest solution is to reduce the current by changing the resistor on the drive.

(This approach is never really mentioned on the various CNC forums, probably because it is too simple. Everybody else is focussed on changing the most difficult thing (the power supply) when a motor overheats. I really can't see any harm in dropping the current by 10% when the voltage is 10% too high)

Gerald,
When i calculate the resistor to be connected to my G203 using the Gecko formula i get the value of 75Kohm as the specifications of my motor if connected unipolar is 4.3 A . As i understand from the G203V manual the volt is not an issue here as long as its more than 17VDC and less than 80VDC. Is my calculation right?

Ahmed, your question is confusing. Are you talking about:

- a volt rating for the 75 kiloOhm resistor? (resistors are not normally sold with a volt rating, but they are sold with a Watt rating. Gecko wants 0.25 Watt. See http://docs-europe.electrocomponents...6b80098b49.pdf)


- a supply voltage to the Gecko? (There Gecko talks about a max voltage of 80V, but you have already purchased a 54V dc supply. This must be matched to your motors)

Ahmed replied by PM, here is a part of that message:

"I have 4 motors KL34H295043-8B as per the data sheet if connected unipolar:
The Amp. required is 4.3A and the inductance is 3.3 mH

Req Volt = 32 X √3.3=58 V
Req. Amp= 4 motors X 4.3 X 0.67= 11.5 A
Req. VA= 58 X 11.5 = 667 watt

I ordered a power supply with 54V and 13A

Now what i have is a power supply that provides 65 V and 15 A

My understanding is this power supply can do the job but will make my motors hot.

so if I continue as planned i calculate the required resistor to the gecko using this formula:
R (in kilo-ohms) = 47 * I / (7 – I)
So R=47*4.3/(7-4.3)=75 kilo-ohms to be connected between Term.11 &12.

In this case i have extra voltage (65- 58) and you said "I really can't see any harm in dropping the current by 10% when the voltage is 10% too high)"

How can i drop the current by 10% . Increase the gecko resistor value ???"

Sorry for putting your PM here Ahmed, but I do not do technical correspondence by PM's. We can all laugh, maybe learn, or be confused, together! :)

Your voltage is too high by 65/54=1.2 times. To drop the current 1.2 times, the new reduced current is 4.3/1.2=3.6 Amp. The resistor for that is 47*3.6/(7-3.6)=49 kilo-ohms

Also, have a good look at the transformer in your power supply. It is usually quite easy to remove some turns/coils to reduce the output voltage.

Do not worry too much about this high voltage - first run your motors and check if they really get too hot. Depending on the way in which you use your router, you might not have any problems even at a the higher current and voltage. The heating up is a slow process and you can check every 5-10 minutes over 30 minutes - you have a lot of time to decide to switch off! :)

Gerald,
Thanks for the detailed clarifications. I don't mind that you added my PM here in the way you did so its clear to any one to understand.my intention was to do the same after i have a clear vision so i don't make any confusion to any one. Any way you have the right to do it the way you think is the best for the group. we all know that Gerald knows better :)

Oh, Gerald makes some mistakes too! :)

Technically your motors are getting too hot when they feel like the top edge of a pot boiling water on a stove, or like a freshly poured cup of coffee in a thin mug. About 85 degrees C on the outside of the motor is a comfortable temperature for the motor - if you feel a true 85 C with your hand you will feel pain after about 1-2 seconds.

If I was in your position, I would buy some 47k, 56k, and 68k resistors and then experiment to see the differences on the heat.

Hi all,
Today I managed to make my kitchen table project completed. All geckos green PMDX-122 led lights green and surprise surprise!!!!!!!!
all motors turn from the 1st time smoothly. This can prove to every one that all what you are looking for is mentioned here (OK 99.999999% to be fair) it took me 3 days of very careful reading for each item to make sure there is no mistakes happens and it worked out for me .I'm quite sure it will work for every one following the rich discussions of this forum.
It gives me a very good feeling to reach this point. I hope the rest of the road will be the same :)

thanks Gerald and the others. I'm proud to be a member in your group.
A small video for my motors turning(sorry for the poor quality i used my mobile - as usual your camera batteries are empty when you really need it:mad:)

Ahmed,

Congratulations on finishing the Kitchen table project.

Excellent achievement Ahmed!

Ahmed,

Great work!:) And, you started only a few weeks ago.

I remember the feeling of getting the steppers turning under the control of Mach3. A lot of things have to come together to make this happen.

Congratulations and keep up the great work. You'll be cutting before you know it.

I enjoyed the video...nothing like actual video to demonstrate your progress.

Masha-allah!

congrats

Some pictures for my parts
 

Thanks guys for your support, I really appreciate it.

I thought i should submit some pictures as i have never did.Specially that I've charged my camera batteries and the backup one also :D

resuming my build
 

Hello every one
After one & a half year I’m resuming my build again. My day job was keeping me away from continuing my MM But now i have the sometime to continue. Actually I’m feeling a little bit late as i started when there was #33 MM now i can see the Number reached #74 (what a great progress). I hope i can reserve the serial #90 :p

Started with the v-rollers, I had them done in a local workshop with the bushes and installed SKF bearing as per Gerald's instructions.

I bought L 60X60X9 for the Y rails ( I know the angle should be 6mm but i think 9mm will work, more effort on cutting/grinding will be required, right?:confused:) and started cutting using the Skate. the result of the 1st rail was 1.5mm difference on the height along the rails i had 28 mm at the two ends and 26.5mm at the middle:eek::mad::mad:.
Then i rearranged my supporting surface to an MDF piece i had for cutting the second rail and the result was 28.5mm all the way:D. I think i need to have some grinding on the 1st rail to make it even along its length and shimming the rails could help too. Today i start grinding the rails.
Merry charismas to all of you MM members.
Ahmed

Y rails grinding
 

Grinding of the Y rails almost done. The skate was excellent for the job, easy to install and adjust. Needed some small modifications but all in all it's the right way to have a good V rails.

The only problem i had was the dust covering everything around my working area :) but this was expected. Thanks JR for the 2nd important invention in history after the wheel.......... <<<<the grinding skate>>>>.
Ahmed

The rails look good.

I'm a bit confused by your skate, though. It looks like there are some bolts missing: the angle fine-tune bolts, and the height adjustment bolts.

Hmmm... :confused:

Michel.
After seeing your skate now I’m confused. I checked the angle and the height again it's all fine.

I can't explain it but it worked ok for me without these bolts. Most probably because the thickness of the angle was 9mm i had to squeeze the skate to ride the angle and it was so rigid on its position.

I need to check again as i still have the X rails to be done and i plan to use 6mm angles this time so i'll need these adjusting bolts.

Y-Car welded
 

Today i finished welding my Y-car.
I spent over a week training to have a nice welds as I've never used a welding machine before (i used to supervise only) now i know it was not that easy.

The welds are ok even if i have some small porosity on it but that can be covered in a later stage :rolleyes::o.

The Y-car is square and leveled I had some trouble to make the verticality but i used two threaded bars to do it and that helped a lot.
I can’t remember if i saw it somewhere in the forum or it’s the sense you gain from using that amount of bolts and nuts while you are building.

Next step i need to make the gantry assembled. Let’s find something to cut the metal with. Most probably I'll buy a new cutting grinder (hacksaws are not common here in Egypt unless you are looking for a monster).

Hi Ahmed
well done and hope u all success i'm starting to build a plasma cutter in SUEZ if u can help or contact.
v. thanks
adel sebaey

Finished the gantry
 

I managed to finish the gantry this week. waiting for my rack & pinions to arraive from hong kong. Next step will be the control box assembly. Table will be the last task as i need to move to a bigger place.

Adel thanks for your words. If you need any help contact me and I'll be glad to help in anything you need. you can PM me any time :)
It's nice to have more than one builder in Egypt

greetings from west coast of egypt
 

hi ahmed i am mohamed yousry from alexandria we already have a cnc machine we are now making a big renovation to it and the same time collecting the electronic parts of the mechmate . i am going to wait a little bit before making the mechmate as the guys in the forum are going to make a new design or something called mechmate 2 , whatever it will be called. i am not going to use the skates for grinding the rails when building my mechmate i will go for the linear slide as it's easy to install them and take so much weights. i know they are expensive, there is a mechmate member who made his machine using a linear slide. keep on building , good luck with your build,
we al salam alykom