Quite an Unusual one

[Boyan Silyavski]

Any progress with this machine?

I need 5 days to finish it and could not find the time from a couple of months. Either i am on a vacation with wife, very busy with orders or tired. Hopefully very soon, as i start needing it.

left long ball screw is unmounted and the ball nut needs centering. Cause the bloody Chinese made it bigger than the drawing so it did not fit right in the rotating nut. Change one servo cable and make the enclosure box

[NordicCnc]

The shop

SAMSUNG SERVO MOTOR DRIVER CSDJ-04BX2, CSMQ-04BA1ANM3 400W w/CABLE thats what i bought for Z

SAMSUNG SERVO MOTOR DRIVER CSDJ-04BX2, CSMT-04BB1ANT3 400W w/CABLE thats for the gantry

Now the first motor is shorter and fatter and the second is smaller and longer, more like a typical stepper. Both are ok. When buying servo motors and drives make sure they are 220V AC, motor is standard inertia and not some specialized motor for a special purpose, that drive works in STEP DIR mode, especially take care with Iskawa as not all will work ok for CNC control. Make sure you buy them with cables as 1 cable is >100 euro or more

I was between these and Panasonic/ a bit more expensive/ but decided on price. The best thing about these drives is Autotuning. You push the button and it starts jogging for 3 seconds and that's it-its tuned.

So my recommendation is the SAMSUNG SERVO MOTOR DRIVER CSDJ-04BX2, CSMT-04BB1ANT3 400W w/CABLE as it more standard size. and smaller shaft or servo motor plus automatic tuning.

Another good options are the Minawa /Panasonic series /


The other money wise option is Chinese servo drive drive MCAC808 and 400w servo: 60ASM400 which last i checked were ~180USD if you buy lot/4/ from Shenzhen Just Motion Control Electromechanics Co.,Ltd. Write to Molly/remove space/ molly @jmc-motion.com
Tell her Boyan from Spain send you there so my 30 email exchanges with her help you with the price.
I would use these motors in my prototype machines and hopefully later. These are probably the cheapest servos ever directly from a manufacturer. If you send me your mail i will save you needless conversations and send you some documents about these servos.

Hope that helps. There are other options but these are my conclusions as a balance of features and moneywise

Hello Boyan.

Nice machine I have to say. Looks very stiff! How is it running these days? Do you have a lot of work for it or mostly hobby stuff?

Anyway I wanted to ask how you went about auto-tuning the axis with double servo motors (Y-axis in my eyes, not the gantry). Auto-tuning is a very nice feature in any servo motor software, but I have not figured out how to tune an axis with double servo motors.

Also how did you go about calculating the servo motor size? Perhaps you have explained this in a post somewhere, but I couldn't find it! :)

Thanks!

[Boyan Silyavski]

Hello Boyan.

Nice machine I have to say. Looks very stiff! How is it running these days? Do you have a lot of work for it or mostly hobby stuff?

Anyway I wanted to ask how you went about auto-tuning the axis with double servo motors (Y-axis in my eyes, not the gantry). Auto-tuning is a very nice feature in any servo motor software, but I have not figured out how to tune an axis with double servo motors.

Also how did you go about calculating the servo motor size? Perhaps you have explained this in a post somewhere, but I couldn't find it! :)

Thanks!

Thanks!

I have sufficient work for the machine. Not as much as it deserves though. I make some product on it, sometimes for other people and sometimes cut letters for signs.

I tuned the Z and used same parameters on the other axis, as more or less motors a properly calculated for the loads on each axis, working at optimum.

Then one day i figured that if i move left or right motor 5mm, its not a problem as the gantry is like 2 meters. So there is play enough. Then i entered in Samsung software and limited the movement to 5mm each side and tuned the axis like that. With a short movement. I say 5mm just to be on the safe side, it could have been 10-15mm, on such a long gantry this is like nothing, before the other side tries to engage. In Real life if i switch off 1 motor i can move the gantry front/back even with one motor only .Of course autotuning stresses the thing, so better in the short safe range. Check all that range adjustment on the Z firts, so you dont bend something.

The servo motor size Jonathan or Dean helped me, its on the first pages somewhere. But basically 400 or 750W ac servo at 230vac are the thing for a machine like that. I went with 400w as ballnut is geared 3:2 so at 3k rpm of motor i am at 20k mm / min and my motor power is multiplied by 1.5 at that ratio. My motors support up to 6k rpm so ...

As far as i understand the things, Panasonic, Samsung or other brand servos are way better than the chinese ones, so if i was going with China servos would have went with 750w ones, as price is irrelevant also on the chinese servos. No big difference. But remember. All time i am talking about AC servos driven by 230VAC drives.

[JoeHarris]

I take it you are not going to Surface the whole bed with that cutter?!

[ImanGH]

Hi boyan
are you using epoxy for y axis? if yes how use?
thank's

[feldah]

Ok think that'll do. Maybe to be double sure sure I will also use silicone. I imagine that would be frustrating seeing your epoxy flushing in a not properly sealed hole. :-)

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[Boyan Silyavski]

First time i did it not entirely right. With time discovered new ways and next time i did it welded 6mm or 8mm bar stock, distance 40mm between. Have to check if it was 8mm as it may touch the Hiwin 20 block. Better read my second build log to see how i poured a couple of times epoxy on a 3m machine untill i figure the perfect way. iin short i discovered that the most important part is to make the damned dam longer like 15 cm at least than the actual machine to compensate for the shrink and that way only one bridge is enough, and the bridge must be then outside the machine. So when all dries and shrinks, the bridge will not eat from the actual ways but from the extra length. If you know what i mean

[feldah]

Yes thanks. I read that post already. I will follow it. I have a vacuum chamber where I can stir epoxy under vacuum. I am excited to see if it will make a difference in accuracy. Good job btw.

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[Boyan Silyavski]

Yes thanks. I read that post already. I will follow it. I have a vacuum chamber where I can stir epoxy under vacuum. I am excited to see if it will make a difference in accuracy. Good job btw.

Sent from my MI 6X using Tapatalk

No difference if you stir it properly, without introducing too much air. Remember you torch it later also. But i agree that vacuum is best

[NordicCnc]

Sounds good that you have work for the machine!

Thanks Boyan, for all the answers.

I like your idea and it makes sense to perform auto-tuning like that.

Myself I have build log (build in real life not started yet) if you are interrested to check it out.

Anyway I was thinking about those servo sizes as well. I will take your advice and get Delta 750W servos! Perhaps also 2020 (plan was 2010 with 400W servos) ballscrews to get a crazy speed of 30-40m/min, depending on what gear ratio I choose (3:2 or 2:1).

Not sure if I ever will need that speed but nice to have some room for experimenting.



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