First build. Old equipment + new technology= FUN???

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ShawnM
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Re: First build. Old equipment + new technology= FUN???

Post by ShawnM »

tblough wrote: Thu Sep 29, 2022 7:39 am This should be required reading: https://centroidcncforum.com/viewtopic.php?f=63&t=1801

Final turns ratio will probably be a little different.

+1 to this being required reading.
cnckeith
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Re: First build. Old equipment + new technology= FUN???

Post by cnckeith »

yep! and page 51 and 52 and 78-81 of the Acorn Installation manual. :-)
https://centroidcncforum.com/viewtopic.php?f=60&t=3397
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mikecowhey
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Re: First build. Old equipment + new technology= FUN???

Post by mikecowhey »

So been playing with the mill for the last couple weeks. Ended up taking apart the z and y axis and doing a couple of upgrades to them in order to reduce the mechanical backlash as much as posible. Z turned out really nice, mostly do to it being spring preloaded if I am not mistaken. Buy y on the other hand.... Holy crap... and x is almost twice as bad....anyway. that aside I just want to make sure I am trying to dial in the movement. Ran thru the process of adjusting the turn ratio several times and thought I had it dialed in untill I added backlash comp. My mill doesn't have a tone of movement to it x is 9", y Is a tad more than 3",, so setting up the turn ratio I moved all the way to theimit switch then turned back the other way about .300 inches. 0'd an indicator Then moved the table 3 inches.did this a few times and had the table moving 3 inches as the indicator showed over the 123 blocks. Did the same an the other 2 axis then proceeded to dial in backlash. I got backlash figured in and now my question....

Now that turn ratio and backlash are dialed in I can command y to move back and forth from 0 to 1 inch and back multiple times. Every time I go from 0 to 1 the dial indicator reads .998 inch. But it is dead on .998 every time. So is it a turn ratio or backlash issue?

I think I need to change from 1 inch to 3 inche of movement and indicate off a 123 block. If the indicator reads .006 inches off that would be a turn ratio correction? If it is still .002 backlash????

Let me know if I am getting warm.

Thanks.
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Re: First build. Old equipment + new technology= FUN???

Post by cncsnw »

I think I need to change from 1 inch to 3 inche of movement and indicate off a 123 block. If the indicator reads .006 inches off that would be a turn ratio correction? If it is still .002 backlash????
Correct. If you just do a 1" back and forth movement (which includes changing direction), it is impossible to tell whether errors are due to backlash or to an incorrect turns ratio.

If you compare the 1" move to the 3" move, then the portion of the error that scales with the distance is due to turns ratio; and the remainder is backlash.
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Re: First build. Old equipment + new technology= FUN???

Post by mikecowhey »

That's what seamed to make to most since to me anyway.

Good news..... I have it working... I had to go back thru all the settings once again, part of the problem I was having was in the configuration. For some reason I thought my stepper drivers were capable of 4000 steps per rev and they aren't. They can do 2000 steps or 5000 bot not 4000. Although for what it is worth having the software thinking that the steppers rotate twice what they should and the tables moves the same with half the actual needed achieves the same results, more less... error isn't too far off either, Y axis is so little I cant really see it in the dial indicator when I go from 0 to 3 inches, I am well within a couple of 10000's. The X axis I cant seam to dial in better than .001 over a 6 inch movement (I tell the table to move 6 inches and the measured travel is actually 5.999. for this mill I am totally ok with that... I try to dial it in better than that and I just go several thou over that or several thou under. I might give it another shot later

I still need to get pictures off my phone of the mods I have done so far on the mill to knock down as much backlash as possible. but as of right know it works... Actually made some chips with it last night even, kind of... more like acrylic worms than chips. AND.. yesterday was the first time freehanding g-code also... I was trying to run a pattern so I could glue a couple of pieces of corian together to make a block out of for milling. I have give it a try again tonight...
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Re: First build. Old equipment + new technology= FUN???

Post by cnckeith »

mikecowhey wrote: Tue Oct 11, 2022 10:23 am That's what seamed to make to most since to me anyway.

Good news..... I have it working... I had to go back thru all the settings once again, part of the problem I was having was in the configuration. For some reason I thought my stepper drivers were capable of 4000 steps per rev and they aren't. They can do 2000 steps or 5000 bot not 4000. Although for what it is worth having the software thinking that the steppers rotate twice what they should and the tables moves the same with half the actual needed achieves the same results, more less... error isn't too far off either, Y axis is so little I cant really see it in the dial indicator when I go from 0 to 3 inches, I am well within a couple of 10000's. The X axis I cant seam to dial in better than .001 over a 6 inch movement (I tell the table to move 6 inches and the measured travel is actually 5.999. for this mill I am totally ok with that... I try to dial it in better than that and I just go several thou over that or several thou under. I might give it another shot later

I still need to get pictures off my phone of the mods I have done so far on the mill to knock down as much backlash as possible. but as of right know it works... Actually made some chips with it last night even, kind of... more like acrylic worms than chips. AND.. yesterday was the first time freehanding g-code also... I was trying to run a pattern so I could glue a couple of pieces of corian together to make a block out of for milling. I have give it a try again tonight...
gald you figure it out.. always best to have the Wizard steps per rev and overall turns ratio set to what they really are so definitely make those adjustments.
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
cnckeith
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Re: First build. Old equipment + new technology= FUN???

Post by cnckeith »

mikecowhey wrote: Tue Oct 11, 2022 10:23 am That's what seamed to make to most since to me anyway.

Good news..... I have it working... I had to go back thru all the settings once again, part of the problem I was having was in the configuration. For some reason I thought my stepper drivers were capable of 4000 steps per rev and they aren't. They can do 2000 steps or 5000 bot not 4000. Although for what it is worth having the software thinking that the steppers rotate twice what they should and the tables moves the same with half the actual needed achieves the same results, more less... error isn't too far off either, Y axis is so little I cant really see it in the dial indicator when I go from 0 to 3 inches, I am well within a couple of 10000's. The X axis I cant seam to dial in better than .001 over a 6 inch movement (I tell the table to move 6 inches and the measured travel is actually 5.999. for this mill I am totally ok with that... I try to dial it in better than that and I just go several thou over that or several thou under. I might give it another shot later

I still need to get pictures off my phone of the mods I have done so far on the mill to knock down as much backlash as possible. but as of right know it works... Actually made some chips with it last night even, kind of... more like acrylic worms than chips. AND.. yesterday was the first time freehanding g-code also... I was trying to run a pattern so I could glue a couple of pieces of corian together to make a block out of for milling. I have give it a try again tonight...
gald you figure it out.. always best to have the Wizard steps per rev and overall turns ratio set to what they really are so definitely make those adjustments.

related post. https://centroidcncforum.com/viewtopic.php?f=63&t=1801
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
mikecowhey
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Re: First build. Old equipment + new technology= FUN???

Post by mikecowhey »

So with a limited schedule of time that I can play with my newly converted toy I have definitely have learned a few things. First my mill is defiantly not up to the challenge of making a good CNC machine without some major upgrades... But I already knew that. Second I now know how to set up and get things going with an Acorn controller... It is time to start stepping things up. I will be picking up a PM-833TV mill on Monday. unfortunately the CNC conversion kit from heavy metal is no longer available and another company AizonaCNC has picked up and will be doing the kits. unfortunately they wont be available for a bit so it will be a bit before the conversion will happen on this mill. That and I am trying to get the carport-garage conversion done first so I have somewhere to put it. So in the mean time, got a few questions.

first what are your thoughts on adding 4 pin panel mount connectors for the steppers? my steppers have about 4ish feet of wire off the back of the motor. Is extending the wires on the motor a foot or two reasonable?

Second what are some recommendations for good limit switches? I have seen a couple of people using proximity switches not sure I like them the idea that they trip when they get close to a piece of metal I feel like other things can interfere with them and cause a problem,, maybe I am over thinking it...

last, More of a PM specific question for controlling the spindle. on a mill with a VFD so I need an additional controller/signal conditioner to control the spindle?

Thanks
Mike
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Re: First build. Old equipment + new technology= FUN???

Post by cnckeith »

VFD's are 'controlled' with the Acorn analog output speed command and Acorn relay outputs for Forward, Reverse direction command.

I'd install home switches and use travel limits.
triggered home switch during a cut doesn't stop the machine (a limit switch does) so using a prox switch is not a concern.

the mill in this video is using prox switches.

https://centroidcncforum.com/viewtopic.php?f=57&t=3376
Need support? READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043
All Acorn Documentation is located here: viewtopic.php?f=60&t=3397
Answers to common questions: viewforum.php?f=63
and here viewforum.php?f=61
Gear we use but don't sell. https://www.centroidcnc.com/centroid_di ... _gear.html
mikecowhey
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Re: First build. Old equipment + new technology= FUN???

Post by mikecowhey »

cnckeith wrote: Sat Nov 05, 2022 1:49 pm VFD's are 'controlled' with the Acorn analog output speed command and Acorn relay outputs for Forward, Reverse direction command.
Gotcha, but my question is, with a VFD do I connect directly from the ACORN spindle speed control output directly to the VD input or do I need an additional controller to interface between the two. I ask only because I was thinking of connecting my ACORN to the CD motor control I am using on my current mill setup but it was highly recommended not to do so without an intermediate device to act as a "buffer". Apparently treadmill motor controllers can provide the ACORN with enough back signal or spikes to burn up the boards spindle output circuit.

As for proxy switches I have also watched a couple of Dr D-flo's videos as he has the same mill I will be picking up. He also uses the proxy switches on his setup. I was just curious how reliability was on them and if there were any real benefit to using them other than that I assume they are completely sealed so using them in a flood coolant system would be a no brainier. My current mill does not move the table fast enough to do any damage to its self unless I use the override and move the table the wrong direction however the CNC plasma table I have access to does when moving in rapid mode, and there have been a couple of times where rapid has been activated and the table moved the wrong direction resulting in a loud noise in the shop. That said I can see having something like a proxy switch would be nice as so that I don't have something I am physically hitting. I have seen a couple of spring loaded plunger stops that would work also but I am still relying on physical contact. But I can see your point using home switches and movement limits. A piece of metal getting thrown in the wrong direction during could possible bring the system to a halt, that is why I asked the question about their reliability.

I will say this though. I am defiantly digging that counter balanced mill head. I will probably have to do something similar with mine.
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