Hello Guest it is April 24, 2019, 12:40:00 PM

Author Topic: My First Mill and first CNC upgrade  (Read 8017 times)

0 Members and 1 Guest are viewing this topic.

Offline Tef9

*
  •  89 89
    • View Profile
My First Mill and first CNC upgrade
« on: February 10, 2009, 06:08:09 PM »
I am about to buy a Milling Machine, I have selected which one I want however due to its lack of CNC I plan to convert it almost immediately.

It is an Eastern Mill so I was planning to replace the leadscrews for ball screws and then fit ... servo motors on each axis.

Two questions:

1)  I am only looking at Servos due to our 'workshop guy' at work recomending them over steppermotors...is there a real gain?

2) Can mach3 controll Servos?  If not what would be a good set of stepper motors? (I am in the UK)

Thanks,

Andy
Re: My First Mill and first CNC upgrade
« Reply #1 on: February 10, 2009, 06:18:00 PM »
I am about to buy a Milling Machine, I have selected which one I want however due to its lack of CNC I plan to convert it almost immediately.

It is an Eastern Mill so I was planning to replace the leadscrews for ball screws and then fit ... servo motors on each axis.

Two questions:

1)  I am only looking at Servos due to our 'workshop guy' at work recomending them over steppermotors...is there a real gain?

2) Can mach3 controll Servos?  If not what would be a good set of stepper motors? (I am in the UK)

Thanks,

Andy

Mach is perfectly happy with either steppers or servos, as the interface between the PC and the motor driver is the same for either.
How big is the mill?  For small (table-top) machines, steppers are every bit as good as servos, and generally a bit cheaper.  For large machines (knee mills) servos *may* make more sense.  But, really, outside a production environment, it's more a religious question than anything else.  Up to and including a Bridgeport-sized machine, you can get perfectly acceptable results with either.  There are pros and cons to both, but the functional differences are generally rather minor, and often not good for much more than bragging rights (My mill will rapid faster than your mill!).  By far the most important things, no matter which you use, are to size them properly, gear them properly, and power them properly.  Most beginners tend to start with steppers, and grossly under-size them.  Then based on the poor outcome, they decide steppers are inherently no good, and will always lose steps.  This is simply not true.  Mariss Freimanis, the owner of Gecko (www.geckodrive.com) has a good rule of thumb:  Up to 100W, use steppers.  Above 200W, use servos.  Between 100W and 200W, use either.  You'll find some good information on stepper sizing, and power supply spec'ing on his site as well.  Whichever you decide on, I'd strongly recommend Gecko drivers - they are first-rate, reasonably priced, and well supported.

Regards,
Ray L.
Regards,
Ray L.
Re: My First Mill and first CNC upgrade
« Reply #2 on: February 10, 2009, 11:57:23 PM »
Well said Ray, I couldn't agree more!

I run a Lagun knee mill, (Brigdeport clone) every day powered with steppers and it works absolutely great! The knee is powered for the Z with a rapid speed of 25 IPM, X and Y rapids are 100 IPM. That's plenty fast enough for the milling we do so selling me the idea servos are needed for big iron would be tough, especially when I watch that super heavy knee zip up and down.

I purchased my steppers from www.homeshopcnc.com after Rick LaLonde, who i think may be the owner there, advised me what sizes to buy. Like you I was really unsure what to do since that was my first conversion but decided to trust Rick's advice and I am 100% satisfied. Matter fact I just recently purchased steppers for my upcoming lathe conversion based again on his advice.

As for drives, again I agree with Ray. Gecko G203V drives have been happily powering my steppers and I have yet to have even one problem.

My suggestion would be to contact Rick and see what he recommends for your application. Bet you won't be sorry.

Good luck on your conversion.

Kerry
Re: My First Mill and first CNC upgrade
« Reply #3 on: February 11, 2009, 12:19:50 AM »
Well said Ray, I couldn't agree more!

I run a Lagun knee mill, (Brigdeport clone) every day powered with steppers and it works absolutely great! The knee is powered for the Z with a rapid speed of 25 IPM, X and Y rapids are 100 IPM. That's plenty fast enough for the milling we do so selling me the idea servos are needed for big iron would be tough, especially when I watch that super heavy knee zip up and down.

I purchased my steppers from www.homeshopcnc.com after Rick LaLonde, who i think may be the owner there, advised me what sizes to buy. Like you I was really unsure what to do since that was my first conversion but decided to trust Rick's advice and I am 100% satisfied. Matter fact I just recently purchased steppers for my upcoming lathe conversion based again on his advice.

As for drives, again I agree with Ray. Gecko G203V drives have been happily powering my steppers and I have yet to have even one problem.

My suggestion would be to contact Rick and see what he recommends for your application. Bet you won't be sorry.

Good luck on your conversion.

Kerry

Yup, I bought most of my stuff from HomeShopCNC as well.  I did go with servos this time, and don't regret it, but also don't see a clear, practical advantage.  With the SmoothStepper, I can get 400 IPM rapids on X/Y, and 75 IPM on Z, but seeing that big sucker flying around at 400 IPM is downright scary!  So, I backed it off to 150IPM for actual use.

I agree with everything you said about Rick.  He was a huge help in my first conversion (an X2), and on this one.  Great products, great prices, and great support.  What more can you ask?

Regards,
Ray L.
Regards,
Ray L.

Offline olf20

*
  •  317 317
    • View Profile
Re: My First Mill and first CNC upgrade
« Reply #4 on: February 11, 2009, 07:20:27 AM »
Here is a item number on ebay for some crydom solid state relays that
 I used to turn on/off my router - dust collector.
They have worked great!
260356186971 
Hope this helps!
olf20
 
Mach3, Atlas Knee Mill, 4th Axis, VcarvePro, ESS, Super PID.
Been Heating with corn since 1998
Re: My First Mill and first CNC upgrade
« Reply #5 on: February 11, 2009, 10:18:06 AM »
Kerry, Ray,
  Mind to say which model motors you used for the X,Y and Z....and the ratios ?
Thanks,
RC
Re: My First Mill and first CNC upgrade
« Reply #6 on: February 11, 2009, 11:27:48 AM »
Kerry, Ray,
  Mind to say which model motors you used for the X,Y and Z....and the ratios ?
Thanks,
RC

RC,

I used the HomeShopCNC 850 oz-in servos, with 500 line encoders, Gecko G320s, 70V/20A power supply.  X and Y have 2.5:1 GT2 belt reducers, Z has a 4.8:1 XL belt reducer, all of my own design.  Were I doing it over, I'd use the 4.8:1 on all three, as I can't get the motors up to full RPM with the 2.5:1.  There's more than plenty of power with the 2.5:1, but max rapid speed is >400 IPM, which SCARY fast for a machine this size.  I normally run 150 IPM rapids on X/Y, and 75 nIPM on Z.

Regards,
Ray L.
Regards,
Ray L.
Re: My First Mill and first CNC upgrade
« Reply #7 on: February 11, 2009, 02:19:52 PM »
My HomeShopCNC steppers are as follows:

RHT34-1200 oz/in $258.00 For X and Y. Geared 1:1
RS34-2550 oz/in   for Z geared 2:1
RHT34-740 oz/in  for A direct coupled to the rotary table shaft so it's 1:1

Are are run with Gecko G203V drives.

Steppers are the most powerfull at slow speeds so that's the reason for the low gear ratios.

Ray, Are you powering the knee or the quill for the Z axis?

Regards,
Kerry
Re: My First Mill and first CNC upgrade
« Reply #8 on: February 11, 2009, 03:00:51 PM »
My HomeShopCNC steppers are as follows:

RHT34-1200 oz/in $258.00 For X and Y. Geared 1:1
RS34-2550 oz/in   for Z geared 2:1
RHT34-740 oz/in  for A direct coupled to the rotary table shaft so it's 1:1

Are are run with Gecko G203V drives.

Steppers are the most powerfull at slow speeds so that's the reason for the low gear ratios.

Ray, Are you powering the knee or the quill for the Z axis?

Regards,
Kerry

Kerry,

Right now, I'm using the knee for Z, but I'm in the process of designing a quill drive.  Once that's on, I'll use the knee for tool length compensation, and the quill for the "active" Z axis.

Regards,
Ray L.
Regards,
Ray L.
Re: My First Mill and first CNC upgrade
« Reply #9 on: February 11, 2009, 03:55:54 PM »
Thanks guys,
RC