Triac with servo's

[sneakym8]

Has anyone converted an old triac to servo's , if you have what size motors did you use. I have the chance of some 240oz max torque servo motors ,do you think they are good enough.

col

[sneakym8]

Hey, I fitted those motors on and ran them just off my power supply andd they look like they are gona work just fine, reckon i should get around 6m/min rapid. I'll let you know when the drives arrive

[funkstar]

Interresting, sort of thinking of doing this myself to my 86-triac.
What drives are you looking at and what config for control, mach3?.
Keep updating and if you can post some pic;s

Per

[sneakym8]

I'll keep you up to date,
I have some rutex drives, a bob campbell breakout board and going to run mach3.
I have run the motors on the rutex drives just for the purpose of tuning the drives and they seem smooth.I have not had them under mach control yet.
I am trying to put the drive cabinet together first, if i run it off the bench it will probably stay like that ( i've done it before ) so i am trying to do the boring stuff first .
I'll post some pics soon .

[carloramon1]

hey there, im newbie here, well i have a few ideas send me a reply or pm ! bye

Has anyone converted an old triac to servo's , if you have what size motors did you use. I have the chance of some 240oz max torque servo motors ,do you think they are good enough.

col

[sneakym8]

Sorry it took so long, as you can see it is still very much "on the bench" but its getting there, I am cutting the apertures into the cabinet now so i should be mounting the drives onto the machine shortly.

[funkstar]

Wow, nice work.
What kind of encoders do you use, have learnt that there are a range of different types other than optical?
Are the excentrical placment of the motor in the bracket to be able to adjust belt tention?
I see three Rutex drives but two motors, I guess that you left the Z motor out in the pics?
How will you control the spindle, mach and an additional frequency converter?

Interesting project, keep the good work up.


Per

[sneakym8]

Hi
The encoders are hp 512 ppr optical with a mechanical gearing of 2.5-1 on the motors, this will give an resolution of 4um if i don't use the encoder in quadrature.

I could, sacrifice rapid speed for resolution but i think it will be quite good to see it doing 6m/min and 4um is not that bad.
You like the eccentric idea for belt tension,the motors are placed 5mm out of centre.
I will be using mach 3 and there is a frequency converter onboard the breakout board to control a vfd.

The power supply is 55v and the motors are 60v max, so this is going to limit my fast travis a little but i should still reach 6m/min if my maths are correct.
I could do with about 70v to really get the best out of the motors, maybe I will come across another transformer sometime.

I'll keep you posted.

col

[funkstar]

Ahh, theres the Z-axis.
But as you mention 4um, how are you ballscrews doing? I have about 0.02 - 0.04 mm backlash in my axes (is that the correct plural form of axis in english?). From reading some in this forum the backlash could, and often are, source from the axial bearings rather than the ballscrews. Have you measured this, and have you made some effort to get rid of this?

I follow the progress with great interest.

P.-

[sneakym8]

I measured the backlash when it was on steppers and got about the same as you mentioned on all axes. I never tried to get rid of it yet.
I will get it up and running under mach3 control first and see how it goes.
That might be a job for the next winter nights.

[sneakym8]

I mounted the drives in the control box and had the axis running using the tuning software

[sneakym8]

Well there you go!!
I had it running under mach3 control today, talk about smooth axis control, they were smooth as silk.
The maths worked too. 6m/min rapid travis and it looks awesome.

No spindle control yet and no home switches wired up, this is probably the next task

[funkstar]

GOOD WORK!
I would love to see it run.
Myself, I was running stepper and old PNC3 today... it really starts to tick me off. Next big proj may be this servo mod. You made it look so simple:-)
Will be interesting to see a test report on accuracy and repetability and so on in the future, and also if you find the torque enough and just the general machining feel of it.

But as said, good work!

P.-

[sneakym8]

I'll see if i can upload a video sometime, I may get time over the weekend .
I did some preliminary accuracy tests , just running a piece of program and returning to a position where a d.t.i. was parking at "0" against the side of the
head and the repeatability was excellent, I ran the feedrate up to 3000mm/min on a circular pocketing program which probably took about a couple of minutes to complete and i repeated it continuously for 30 minutes and it returned to the same park position every time, I know this says nothing for accuracy but the repeatability looks good, for a first test anyway.

[sneakym8]

Here goes , Try this link its only short but you can get the general idea.I need to do some accuracy tests soon. i got the home switches wired and working at the weekend.The next job might have to be the spindle drive or maybe put the door on the control cabinet


https://www.youtube.com/watch?v=zDf5ExPcNo8

col

[sneakym8]

I got the spindle running under mach3 control tonight at last, I had a bit of a fight with it today but she's working good now.

[sneakym8]

I did some accuracy tests today .
I machined the outside dia. of an aluminium bar at 100mm/min , the bar was within .05 mm of being round, considering the backlash in the machine i thought this was very good.

I then did the same test at 500mm/min and similar results.

I then did the test at 1500mm/min , the surface finish was not as good and the roundness was .08mm .

I ran the 1500mm/min test over and over for about an hour with no ovality appearing i presume that the repeatability is good too. There was no metal cut on these repeat tests the cutter just went around the same already cut piece of aluminium so any repeatability problems would have been seen as ovality

If i could get rid of the backlash which is about .04 and .02 on X and Y respectively this would be very acceptable, it seems like the drives are doing there job very well. Nice one RUTEX, Now lets see how long they last.

[funkstar]

fantastic job. Loved the vid. Your machine is awsome now. A very inspirational thread. Good to see someone actually do the conversion.
Quest: how much have you put into this project, roughly?

[sneakym8]

hi
including the cost of the machine which i got for £200 and disregarding a few failed attempts with different breakout boards and driver boards about £1000 this includes things like filters , I also had some stuff laid around, like power supply's, relays,cabinet,wiring and switches etc.

I intend to keep adding to it, i have a little 4th axis which i will start modifying as soon as i have the machine running to my liking .
I need to build a control panel, I have an ipaq with 56 inputs that i am going to use for the inputs from the control panel buttons and digital pots,I have not decided weather to build a hand held pendant type or a fixed to the machine type, a lot of people seem to go for the hand held one but i can't help thinking the machine isn't really big enough to warrant a mobile pendant. I would appreciate your thoughts on this !!

I will try to post some more vids soon

[sneakym8]

Here is a video of a digitizing program running in mach3 on a fan blade .
I will try to post a picture of the model created from the point cloud. Its not perfect as the fan was moving slightly and i used quite a large stepover but you can see the possibilities .

https://www.youtube.com/watch?v=3srDezBlwL0