Author Topic: Sieg X2 CNC conversion  (Read 56293 times)

Offline Imagineering

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Re: Sieg X2 CNC conversion
« Reply #50 on: October 19, 2010, 04:39:17 PM »


What Switch settings would you recommend to start with?

I'll be running 24VDC @ 100Amp PSU.
Stepper Motors are NEMA 24 rated at 4.2Amps 4.5Nm, (650 OzIn).
Running a Sieg SX3 under Mach3.
Steppers are driving the LeadScrews at 2:1 ratio. LeadScrews are the original Acme at present. BallScrews will happen after Financial Recovery  :ddb:

.

I'm not too sure what you mean by switch settings, the dip switches on the Stepper drivers? or switch relay ratings? or switches like I have for individually switching the power to each axis?

I forgot to say earlier, but if you want even bigger versions of any of my pics you can just click on them and it will take you to my photo site where larger versions are available. ( just so you can see my mistakes and cockups in even greater detail )

Tim

Sorry, I meant the DIP Switches on the Stepper Driver Boards.

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Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #51 on: October 19, 2010, 04:56:20 PM »
I would start off by setting the current for 4.2Amps. Because you only have 24Volts available, your steppers will not be generating their maximum strength, so keep the amps to the max acceptable for the motors, especially as you have plenty of amps to spare.

As you are gearing down the stepper motors, and are using the stock screws which have a finer pitch than ballscrews have, I would stick to 400 steps per revolution, unless you find that that is not giving you enough resolution when running.

If you find that the motors are running too hot, or the drivers are getting too hot then switch the auto half-current mode on.


I think that covers it all, but these are just my semi-deranged musings, all the standard disclaimers apply and remember that your home is at risk if you leave the doors open.


Tim
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Offline picclock

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Re: Sieg X2 CNC conversion
« Reply #52 on: October 20, 2010, 04:31:51 AM »
Power (torque) of stepping motors is related to current not voltage. 
Speed is related to Voltage not current.

So if powering your stepper at 12Volts and 4.2A Its torque will be the same as at 48V at 4.2A. In terms of supply current, as the voltage increases the supply current tends to reduce although the current in the motor winding remains constant (subject to how good the controller is).

In order to maintain the 4.2A current at higher speeds the controller needs to switch the current from one winding to another (or reverse the winding current direction). The speed with which it can do this is limited by the inductance of the winding (its resistance to current change) and the voltage applied to it. So higher voltage, higher speed of switching, faster motor.

Heating of the motor is, for the most part, related to the electrical resistance of the winding. Power (heating effect) is equal to the square of the current x resistance. Additional heating caused by induced switching losses in the magnetic material are normally far lower than this and can be largely ignored.

Hope this helps a bit.

Thanks for the pictures, they are very informative. I first used a similar chargepump design 48 years ago on a pdp mini computer, memory lane again .. .


picclock



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Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #53 on: October 20, 2010, 07:47:06 AM »
Power (torque) of stepping motors is related to current not voltage. 
Speed is related to Voltage not current.

So if powering your stepper at 12Volts and 4.2A Its torque will be the same as at 48V at 4.2A. In terms of supply current, as the voltage increases the supply current tends to reduce although the current in the motor winding remains constant (subject to how good the controller is).

In order to maintain the 4.2A current at higher speeds the controller needs to switch the current from one winding to another (or reverse the winding current direction). The speed with which it can do this is limited by the inductance of the winding (its resistance to current change) and the voltage applied to it. So higher voltage, higher speed of switching, faster motor.

You are right, the voltage effects the speed and the current effects the power. But the thing is, with at least 200 steps per revolution, you are really going to need a good supply of voltage in order to turn at any sort of useful speed. With a lower voltage you can have the full power at very slow speeds, but as you stated the higher speed of switching needs a higher voltage in order to drive the needed current.

It's not like we are talking about some super speeds of table movement. If you think that 1 revolution takes at least 200 steps or switches, then think that a ballscrew may have a pitch of 5 TPI, and a standard acme leadscrew may be 14TPI. That means for a direct driven Ballscrew you would need at least 1000 steps to move an inch and 2800 steps with a acme leadscrew. That is without any micro-stepping or any gearing down which could easily take you to over 10,000 steps or switches to move just one inch.


Just some food for thought.


I got some more done today on the stepper motor mounting hardware. The 1st problem was the raised ring on the stepper motor.






So I set up my boring bar on my mill and cut out the needed part. I didnt really calculate it out but just marked out where the edge of the ring should be, then marked the centre and then just edged the boring bar very slightly into the work and adjusted it by eye to be centered.




Then I did it again for the other support.







Next will be drilling and tapping for fixings, boring out the thicker plate for the bearing and mounting holes to attach to the mill table.


Tim
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Offline Imagineering

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Re: Sieg X2 CNC conversion
« Reply #54 on: October 26, 2010, 02:11:42 AM »
Tim, a question for you.

I've hooked the BOB to Stepper Controllers as such;
P2 X - Step
P3 X - Dir
P4 Y - Step
P5 Y - Dir
P6 Z - Step
P7 Z - Dir
P8 A - Step
P9 A - Dir

I have setup Mach3 Output Pins as above, but only my Y - Axis moves.
I've checked all My Wiring, which is identical for all four 'BOB - Controller - Cords - Stepper' setups.

Instead of playing around trying to find which Pins are which, ( I don't like seeing Expensive Smoke) :zap:, I thought that I would get lazy and ask you what your Mach3 'Pin Selection' is?

Murray

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Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #55 on: October 26, 2010, 11:36:06 AM »
Tim, a question for you.

Hi Murray, I havent got my controller pc hooked up at the moment, but I do remember that when I first applied power I couldnt get any of my axis' working. The reason turned out to be that I needed to check (or uncheck, I cant remember which, but it had to be changed from it's initial setting) the option in the "ports and pins" menu for "Active Low" on each axis. That sorted it for me, it may be worth trying to change the setting and seeing if it works for you. Also make sure that each axis is also Enabled in the same "ports and pins" menu.

I'll try and take a screengrab of my settings when I get back into the workshop, but that may be tomorrow or friday though :(


Tim
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Offline Simon0362

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Re: Sieg X2 CNC conversion
« Reply #56 on: October 26, 2010, 02:12:30 PM »
Murray,
One problem that I had that may be similar is that I had to increase the pulse width significantly - I am not near my system at the moment but I think I increased it to Mach3's maximum (is that 15ms??) and that cured many problems. So did esuring that the 25 way D connector was mounted the correct way up on the breakout board - but that is another story... :bang:

Tim,a question since I am now going through the upgrade path from leadscrew to ballscrews - when you described how you replaced the balls into the ballscrew nut, were they replaced through the removed PTFE end cover? I assume that this was the case but your description seems at odds with many other accounts of the difficulties of returning the balls into a ballscrew. Also I recall that there is a 'magic diameter' for a keeper that replaces the ballscrew itself - does anyone know what this is for a 16mm thread please?

Simon (generally a lurker...)

Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #57 on: October 26, 2010, 02:39:14 PM »
Tim,a question since I am now going through the upgrade path from leadscrew to ballscrews - when you described how you replaced the balls into the ballscrew nut, were they replaced through the removed PTFE end cover?

......................

Simon (generally a lurker...)
Hi Simon, yes you have it spot on, I removed the ptfe end cover thing on the non-flanged end in order to re-pack the balls. If you try packing from the other end on these ballscrews it is an exercise in futility that could teach you to utter words that your mother would not approve of  :bang:

On these ballnuts that I have, they have split the nut into 3 re-circulating sections, so if you empty out all the balls and want to re-pack them, you just divide the balls into 3 piles and then ( with the PTFE wiper removed from the unflanged end only ) screw the ballscrew into the other end a little bit, then put a third of the balls in and gently rotate the ballscrew back and forth, gradually moving it further into the nut until it has got past the 1st recirculation point, then add the next set of balls and repeat, then the remaining balls.

If you find the the ballscrew will screw in to the flanged end but is pretty sticky when trying to go the opposite direction, this may well mean that there is one or more balls that have got into the section of the ballnut that is between the PTFE wiper at the flanged end and the 1st recirculation loop.


From what I have seen, other ( probably more expensive and higher quality ) ballnuts are so much easier to re-load, with external re-circulation tubes that are removable, making it easy to feed in the ball bearings.

Another tip with reloading the type of ballnuts that I have is to chamfer the end of the ballscrew that first goes into the ballnut, this helps the balls to naturally go into the channels in the ballnut.

Hope this helps


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Imagineering

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Re: Sieg X2 CNC conversion
« Reply #58 on: October 26, 2010, 03:52:54 PM »
Tim, a question for you.

Hi Murray, I havent got my controller pc hooked up at the moment, but I do remember that when I first applied power I couldnt get any of my axis' working. The reason turned out to be that I needed to check (or uncheck, I cant remember which, but it had to be changed from it's initial setting) the option in the "ports and pins" menu for "Active Low" on each axis. That sorted it for me, it may be worth trying to change the setting and seeing if it works for you. Also make sure that each axis is also Enabled in the same "ports and pins" menu.

I'll try and take a screengrab of my settings when I get back into the workshop, but that may be tomorrow or friday though :(


Tim



Thanks Tim but all my settings are the same for all Steppers, (except the Pin Assignations), Y-Axis is working but the other three are not.
This indicates to me that all my settings are correct except my Output Pin Assignations for X, Z & A.
My BOB came fully built, so the DB25 is correctly mounted.

Your Pin Assignments may be helpfull.

Murray.
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Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #59 on: October 27, 2010, 11:13:52 AM »
Your Pin Assignments may be helpfull.

Ok, here they are,













Tim
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Offline Imagineering

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Re: Sieg X2 CNC conversion
« Reply #60 on: October 27, 2010, 03:45:46 PM »
 :mmr: WOW, thanks Tim, I'll try these settings later on & let you know.  :mmr:

Offline Imagineering

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Re: Sieg X2 CNC conversion
« Reply #61 on: October 28, 2010, 12:59:33 AM »
Thanks Tim,

Y, Z & A are now all working.
I've just got to chase down why the X-Axis isn't. :scratch:
Is there anything missing on your Screen Shots that might be hiding below the Scroll-Bar?

Murray

.

Edit; X-Axis is now up & running - the 'Resident Workshop Gremlin' wired a Stepper Motor the wrong way. :wack:


.
« Last Edit: October 28, 2010, 02:09:34 AM by Imagineering »

Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #62 on: November 05, 2010, 11:55:23 AM »
A little update, I havent forgotten this one, just not had much workshop time lately. But I have managed to get out there for a couple of hours this week.

I got started on the thicker mounting plate, boring out the pocket for the Angular Contact bearing, and wonder of wonders, I managed to get a really nice snug, "finger-press" fit. I bored it to the depth of the bearing minus about 0.5mm.

I then made up a bracket to hold the bearing into the pocket out of some 1/8" steel plate, drilled it for 4 mounting screws and drilled and tapped the corresponding holes in the mounting plate.

I then marked up, drilled and counterbored the mounting plate for the side support plates. Then the corresponding holes were drilled and tapped in the side plates.

Then I drilled and counterbored the mounting holes for attaching the whole assembly to the mill table.

Here's a pic of all the parts as they stand today.




And a mockup of them





Closer view of the coupling (minus the lock nuts on the ballscrew)




Next will be a trial fit on the mill itself, and if that goes well it will be on to the Y-axis.

Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Brass_Machine

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Re: Sieg X2 CNC conversion
« Reply #63 on: November 05, 2010, 02:38:23 PM »
Very nice Tim.

I have actually started on mine again... Thanks for the inspiration!

Eric
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Offline j45on

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Re: Sieg X2 CNC conversion
« Reply #64 on: November 05, 2010, 05:16:28 PM »
 :offtopic: but we have the same work bench  :lol:
yes I have idiot stickers on my mill

Excellent work  :thumbup: I'm watching with great interest   :thumbup:

Jason

Offline Imagineering

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Re: Sieg X2 CNC conversion
« Reply #65 on: November 05, 2010, 05:19:45 PM »
This is my next step once I've financially recovered from the CNC Conversion. Thanks for all the updates.

Murray.

Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #66 on: November 06, 2010, 03:33:44 AM »
Thanks Eric :thumbup:

:offtopic: but we have the same work bench  :lol:

It's a good bench innit  :thumbup: But I have a custom bench on the other side of the workshop, it is half beech and half black-leftover-kitchen-worktop with an attractive white joining stripe of silicone sealant.



This is my next step once I've financially recovered from the CNC Conversion. Thanks for all the updates.

Murray.

You're welcome Murray. It is surprising just where the costs mount up, not on the obvious parts like the steppers and drivers, but all the smaller fixings and fittings, bearings and couplings. I've been collecting bits and pieces for over a year before starting on this conversion, I figured that getting the bits gradually would soften the financial blow.


Tim
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Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #67 on: November 29, 2010, 09:59:52 AM »
Crumbs, dont time fly by, hard to believe that it is not far off a month since my last update.

I have been working on this, but it has been a bit stop-start (more stop than start) as I have been just grabbing a bit of time where I can to work on it, so this post covers a few weeks of stop-starts.

I mounted the x-axis on the mill and it worked great, all it needed was a couple of 1-2mm thick packing pieces to go either side of the ballnut flange to fit neatly into the pocket from the old acme nut, then jsut tighten up the 2 grub screws and it was fine. Testing went exceedingly well and I am very happy with it.

That being done I replaced the X-axis back to the original manual acme nut and screw, and set about making the Y-axis stepper mounting, which is basically identical to the X-axis, so see the earlier pics for the details. Then I mounted the Y-axis stepper and mount onto the mill.




As you can see, there was a slight design flaw in that the gib screws of the x-axis would crash into the stepper mount, therefore limiting the x-axis by about 4-5mm. So as a quick and easy solution I just cut a little ledge into the mount with the bandsaw.




And here's a shot of both axis's





So now I can use the X and Y axis as computer controlled to help make the Z-Axis mount. It certainly is easier to just type in a command to move one direction by 72.3mm than counting turns of the handwheel. And being able to spot-drill all the holes at once and then go back to drill all the holes without worrying that you are drilling in the wrong place is just great. I guess it is like having a DRO, but instead of reading off the coordinates of where you want to be, you just type in where you want it to be.


So, onwards and ummm ....... sideways?!?!?


Tim
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Offline Brass_Machine

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Re: Sieg X2 CNC conversion
« Reply #68 on: November 29, 2010, 10:08:26 AM »
Very good Tim!

Getting there. How's the backlash?

Eric
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Offline spuddevans

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Re: Sieg X2 CNC conversion
« Reply #69 on: November 29, 2010, 10:38:39 AM »
Very good Tim!

Getting there. How's the backlash?

Eric

Thanks Eric :thumbup:

Backlash seems to be pretty low, in my initial tests and setting of steps-per-inch/mm in Mach3, I found that there was about 0.02-0.03mm when changing direction. I dont know if that is final or whether it can be reduced further by proper adjustment of the gibs and making sure that everything is properly tightened up. And if that's not good enough, I believe that Mach3 has backlash compensation that is quite effective.

All I can say is that it is a darn sight better than the backlash under the acme screws!!!


Tim
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Offline Brass_Machine

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Re: Sieg X2 CNC conversion
« Reply #70 on: November 29, 2010, 10:43:48 AM »
Yup it is. Unfortunately, I am going to be stuck with the Acme Screws for a little while. Making some anti-backlash nuts to take it up some. Mach3 will have to take the rest by adjustment.

I hope to have X and Y done in a week or so.

Exciting isn't it?

Eric
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Offline Brass_Machine

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Re: Sieg X2 CNC conversion
« Reply #71 on: November 30, 2010, 10:32:37 AM »
Tim,

Have you given thought to upgrading the motor controller for the spindle? This THREAD Has a link to what I am talking about. I am going to do this as well as a spacer for the column, Will get a little more range out of the Y axis.

Eric
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Re: Sieg X2 CNC conversion
« Reply #72 on: November 30, 2010, 10:46:19 AM »
Tim,

Have you given thought to upgrading the motor controller for the spindle? This THREAD Has a link to what I am talking about. I am going to do this as well as a spacer for the column, Will get a little more range out of the Y axis.

Eric

To be honest, I havent thought about it, I am pretty happy with the standard controller, and I have the C6 speed control board from CNC4PC that will give speed control via Mach3. Until it goes  :zap: I'll stick with it I think. If I need more speed I might just make a new pulley for the motor.


I have had an idea about getting more Y range, it involves changing the tilting base part of the column with a fixed block of steel/CI with a dovetail in it that the column fits into, thus allowing the whole assembly to be moved back on the base a bit further. That coupled with getting a little more travel to the front should mean getting away without spacing the head out more and gains about 1" of travel.


Tim
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Offline Imagineering

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Re: Sieg X2 CNC conversion
« Reply #73 on: November 30, 2010, 02:29:07 PM »
Hi Tim,

What are the two holes for, that mysteriously appeared when you did the Bandsawing?
Are they for a Swarf Cover to protect the Stepper Coupling?

Murray.

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Re: Sieg X2 CNC conversion
« Reply #74 on: November 30, 2010, 05:34:07 PM »
Hi Tim,

What are the two holes for, that mysteriously appeared when you did the Bandsawing?
Are they for a Swarf Cover to protect the Stepper Coupling?

Murray.

Ah ha!! we have an eagle eyed member here :D Thanks for pointing that out, I had completely forgot to mention it. I drilled the holes with just a cordless drill handheld ( yea I know, not the "proper" way, but it saved having to replace the acme screws just to drill 2 non-critical holes ) and then tapped them M6, also using the cordless drill.

They are for fitting the original folding "bellows" cover for protecting the ways of the mill, but will also be used to attach a cover to also protect the stepper coupling.


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME