Best "Affordable" 4th Axis

Status
Not open for further replies.
RBC said:
Now, if we go back to my statement about using a servo (clearpath) on the Harmonic drive, I was referring to backlash during reversing. This is where the micro stepping really comes in to play. When you stop somewhere in between 2 full step positions and then reverse the direction, something unique happens. Quite often you will need to execute several small microsteps before you get any motor movement. I've done this with just an arm attached directly to the stepper motor shaft. I found it very strange that the control could be commanding movement, but the motor did not move. My belief is that it has something to do with micro steps. It may be that when you back up it goes immediately to the previous full step position, and then builds the micro steps from there. Whatever the reason, I believe that the tiny amount of reversing delay I experienced would be gone with a clearpath motor.




Royce
Click to expand...
Whats most likely actually happening there is the stepper drive missing the step. This happens a LOT with gecko drives and mach3 at lower speeds. The stepper timing needs to be set to sherline mode, which is a 50% dutycycle per step and the problem goes away. basically geckos, and other drives, are extremely finicky about the timing of steps from the control, and mach 3 is extremely bad at timing steps correctly. emc2 is much better for this.

Most controllers up til the last 10 years or so were analogue velocity or torque control, and the loop was most definitely controlled by the control. It HAD to be. There was no other way because the drive only knows how to make the motor spin at a certain speed. it has no clue where the motor actually is.

Emc2 can also be made to do this when using servos, kflop definitely does this (you tube the motors with the control). On analogue drives its mandatory. On digital (step and direction) its optional.

Mach3 does NOT facilitate any modal encoder feedback except for a lathe spindle. This is why it can’t rigid tap in mill mode without a dodgy hack. it is entirely open loop. You could likely write a macro to read an encoder and display it, but that’s more or less pointless except to show the true spindle rpm (which is a feature).

If all the control was doing was following error, it can get that from the fault line of the drive. You do NOT want the drive doing any compensation for errors on its own if you can avoid it (obviously you can’t avoid it with basic steppers or in mach3). You want the drive to only do what it’s told. that’s why drives with motion controllers, jerk compensation, etc are basically pointless on a CNC machine. The main control needs to precisely control everything in coordination. If you turn on jerk compensation on a drive, you’ll get a corner that’s not sharp, or a circle that’s not round.
 
Last edited:
George,

I tell you what. I really want to discuss these things with you, but we have to do them one at a time.

So far, you've mentioned at least 3 or 4 different topics. Pick one. You pick one and we can discuss that one topic. No switching or changing. We can stay on topic until we have both played it out. Then, you can choose a new topic and we can discuss that one until it's done. I won't keep trying to chase you down when you throw out accuracy and then follow it up with something else.

So, you choose the topic:

Servos versus steppers with regards to accuracy.
What encoder feedback to the control really does and whether or not it's more accurate.
The issues of micro stepping and how it relates to change of direction.
Just exactly what a cross roller bearing is and whether or not a Harmonic drive must have one.
Whether or not Royce actually knows what a harmonic drive really is.
Whether or not a belt driven 4th axis is suitable for intricate inlay work on cues.
Just exactly what a threaded connection on a ball screw really is.
Just exactly what a pressed fit ball screw connection really is.
How accurate do you need to be with a router.

I'm happy to debate these thing with you, as well as others, but I'm not going to get involved in a merry go round where the explanation for this question is really based on that question.


Royce
 
RBC said:
George,

I tell you what. I really want to discuss these things with you, but we have to do them one at a time.

So far, you've mentioned at least 3 or 4 different topics. Pick one. You pick one and we can discuss that one topic. No switching or changing. We can stay on topic until we have both played it out. Then, you can choose a new topic and we can discuss that one until it's done. I won't keep trying to chase you down when you throw out accuracy and then follow it up with something else.

So, you choose the topic:

Servos versus steppers with regards to accuracy.
What encoder feedback to the control really does and whether or not it's more accurate.
The issues of micro stepping and how it relates to change of direction.
Just exactly what a cross roller bearing is and whether or not a Harmonic drive must have one.
Whether or not Royce actually knows what a harmonic drive really is.
Whether or not a belt driven 4th axis is suitable for intricate inlay work on cues.
Just exactly what a threaded connection on a ball screw really is.
Just exactly what a pressed fit ball screw connection really is.
How accurate do you need to be with a router.

I'm happy to debate these thing with you, as well as others, but I'm not going to get involved in a merry go round where the explanation for this question is really based on that question.


Royce
Click to expand...
LOL I replied to what was said, i don't ask. I do not want to debate anything.
Only thing i asked about was what it looks like in 4th axis you have, looking for parts for 5th and 6th axis spindle.

Ballscrew threading was ask to me, i replied.
Was told Clearpath was best choice to me . its not, is wrong choice. Any high speed servo with out reduction is a bad choice
Harmonic drive is the best for rotatory.
On a router, would you notice much accuracy from servo VS stepper. Most likely nothing. On a pick and place machine. steppers would be a nightmare. All depends on machine being used.
Anyways, i post here to help people out or to give info on posted info that was not right. I deal in controllers , linear components everyday and servos/steppers . I do a lot of factory automation and designed a lot of factory machines that have nothing to do with my machines. I don't come here filling forum with my machines.
On the lathe for pool cues i have had about 25 people if not more asking if finished.
Time wasted here on gibberish i could have had it finished lol

For info on lathe or machines and new stuff coming out. it will be on new site or the forums i am on most of the time, I will be deleting this account and will not get PM no more sorry .
Thanks, talk to you later
 
gio-XZero said:
LOL I replied to what was said, i don't ask. I do not want to debate anything.
Only thing i asked about was what it looks like in 4th axis you have, looking for parts for 5th and 6th axis spindle.

Ballscrew threading was ask to me, i replied.
Was told Clearpath was best choice to me . its not, is wrong choice. Any high speed servo with out reduction is a bad choice
Harmonic drive is the best for rotatory.
On a router, would you notice much accuracy from servo VS stepper. Most likely nothing. On a pick and place machine. steppers would be a nightmare. All depends on machine being used.
Anyways, i post here to help people out or to give info on posted info that was not right. I deal in controllers , linear components everyday and servos/steppers . I do a lot of factory automation and designed a lot of factory machines that have nothing to do with my machines. I don't come here filling forum with my machines.
On the lathe for pool cues i have had about 25 people if not more asking if finished.
Time wasted here on gibberish i could have had it finished lol

For info on lathe or machines and new stuff coming out. it will be on new site or the forums i am on most of the time, I will be deleting this account and will not get PM no more sorry .
Thanks, talk to you later
Click to expand...


Well, you know George, all I wanted was to hear some of the reasoning behind some of your statements.

Each time you were questioned about a position you took, you're justification was from a completely different topic. It's just not possible to have a real conversation that way.

I mentioned that the rotary that was sent to me was a Harmonic Drive. You told me it was not. To be honest, that offended me. I'm not stupid, and I do know what a harmonic drive is. I really don't know your reasoning for telling me that I was wrong. I'm certainly not the smartest guy in the world, but I'm certainly not stupid either.

So as I said, I'd really like to understand your position on some of these topics. I don't care to change your position, just understand your logic behind those positions. It's quite possible that I may change and take the same position as you. But I can't do that just because you said one thing is better than another. I have to have some reasoning as to why one thing is better than another.

So if you choose to go, that's fine. If you would like to share your insight with me I'd like that. We could communicate here on this forum, through email, or through your forum as well. If you're interested, let me know.

Respectfully

Royce Bunnell
 
Whether or not a belt driven 4th axis is suitable for intricate inlay work on cues.
Just exactly what a threaded connection on a ball screw really is.
Just exactly what a pressed fit ball screw connection really is.

I'd like for these to be discussed. I wondered myself why the bearings aren't really a press fit. As for the threaded connection, I simply don't know any better and would like to understand the pros and cons of George avoiding them..
 
gio-XZero said:
I know what Jake was saying. Yes the new ballscrew are threaded like i used ti have before. Ballscrews are now dropped shipped. So they are now slip fit and threaded.
On coupling, which is the same as collar clamp. Has 100x more surface holding area then nut. I have to get handbook out and recalculate it . It done to cut down on shipping cost now as to why they are dropped shipped . The company i deal with are getting bigger and bigger and order are now moving into 2 to 3 weeks to get machined .So it speeds things up

Ballscrew which are press fit are machined. 9.98 -0 +0.005 slip fit is 10 +0 - 0.018
On a steel mill or something heavy load i would use collar clamp and nut .
if i was using the 7000 series bearings i would have stayed with nut, but 5000 series you don't need nut to adjust bearing.
Click to expand...


Would it be possible to put any of what you 2 are saying into laymen's terms?? I think I understand a little of that, which probably means I'm totally confused....
 
pescadoman said:
Whether or not a belt driven 4th axis is suitable for intricate inlay work on cues.
Just exactly what a threaded connection on a ball screw really is.
Just exactly what a pressed fit ball screw connection really is.

I'd like for these to be discussed. I wondered myself why the bearings aren't really a press fit. As for the threaded connection, I simply don't know any better and would like to understand the pros and cons of George avoiding them..
Click to expand...



Randy

I'll try to explain this without pictures.

In a threaded connection for ball screw mounting, the ball screw has 3 different sections at the end of the screw.
The coupler attachment area is closest to the end and is a smooth cylinder machined to fit the coupler to be used. Usually anywhere from 1/4" up to 3/8" on our sized machine.
The next area is the attachment threads. It's larger so the nut can slip over the coupler area. It's job is to attach the screw to the double row angular contact bearing. It locks the inner race of this bearing to the ball screw so that it cannot move, thus controlling end play in the screw.
The last is a smooth alignment bore for the inner race of the bearing. It's always a slip fit and is slightly shorter than the thickness of the bearing. You don't want the nut to bottom on this part of the screw.

I'm not sure what George is calling a Press Fit. I'm familiar with his alternative to the threaded mounting so I'll describe it here.
Basically, in this mounting you don't have the middle threaded area. You have the bearing slip fit area and the coupler mounting area.
Instead of using a threaded nut to attach the bearing to the ball screw, you use the coupler. You press it by hand firmly against the bearing, pushing it back against the screw, and tighten the clamping screw on the coupler. The clamping friction is what carries the end to end loads keeping the bearing and screw together.
The X and Y screws on my machine are installed like this. I'm not as confident in this method as with a threaded nut, but it does seem to work just as well. My fear is that it may slip at some time and I will develop some end play.

As for the belt driven 4th axis, yes it can work for inlay work on cues. It's not my preferred method, but it can get the job done. They do wear and you can get slop in the belts and pulleys leading to poor positioning. With the availability of the Harmonic Drives on Ebay for around $400, I don't think I'll be opting for a belt driven 4th axis anytime soon.


I hope that helps!

Royce
 
BELT DRIVE 4th AXIS

Royce, you and I both know that all belts are not created equal - there are "no-slip positive drive belts" available - they can be had with dual stainless steel cores, as well as, Kevlar cores. So let's not throw all belts in a heap or suggest that only harmonic drive units can provide the accuracy we require.

Granted the Harmonic Drive units look great and the cost of the import stuff is certainly favorable, but there are lots of 4th axis units using worm gears and belt drives that are MORE that accurate for anything cuemakers can throw at them. Just because a unit is belt driven is not a reason to suggest that accuracy, repeatability and durability is unobtainable using belts.

Paul
 
pfd studios said:
Royce, you and I both know that all belts are not created equal - there are "no-slip positive drive belts" available - they can be had with dual stainless steel cores, as well as, Kevlar cores. So let's not throw all belts in a heap or suggest that only harmonic drive units can provide the accuracy we require.

Granted the Harmonic Drive units look great and the cost of the import stuff is certainly favorable, but there are lots of 4th axis units using worm gears and belt drives that are MORE that accurate for anything cuemakers can throw at them. Just because a unit is belt driven is not a reason to suggest that accuracy, repeatability and durability is unobtainable using belts.

Paul
Click to expand...

Paul

I don't disagree, and I said that they will work. But I choose something else.

Yes, I've used the the best belts etc, etc. But, they do wear. I recently replaced both pulleys on my belt driven indexer because the teeth had worn and would allow some movement. Don't get me wrong, it's lasted a few years and it does get quite a lot of use. We do use it for turning as it turns just fast enough, but we also index with it for our slotted rings.

Royce
 
Royce, I think that the one major determinate that should be part of any discussion on what particular equipment is being considered is the actual "use" . . . your use on a monthly basis likely exceeds most cuemakers annual use/production. So when you suggest wear on various components is factor in you decision making you are coming from a very different place than the majority of makers here.

Paul
 
pfd studios said:
Royce, I think that the one major determinate that should be part of any discussion on what particular equipment is being considered is the actual "use" . . . your use on a monthly basis likely exceeds most cuemakers annual use/production. So when you suggest wear on various components is factor in you decision making you are coming from a very different place than the majority of makers here.

Paul
Click to expand...

Paul

You are absolutely correct.

I always try to give my thoughts and explain how I use the stuff. I usually mention the volume I do, but sometimes I forget.

Anyway, my goal is to not tell anyone what's best for them, only give my thoughts and observations. I prefer to let them choose for themselves.

Thanks for pointing that out. I really need to remember to mention the volume.


Royce
 
JoeyInCali said:
Here's hoping the new lathe and mill will have Clearpath and finer/slower lead screws.
Ball screws no like dust .
Click to expand...
The ball screws require seals to be successful, and really need to be bellowed as well if it can't be enclosed from the working environment.
A lot of machines I have seen in the Ali joinery buisness, have positive air to keep the swarf etc from the front seal area.
Neil
 
pescadoman said:
Thank you Royce!! Pictures really do help a guy like me.

I wonder how the ball screws on the 5 Predators George made for a certain company were done....?
Click to expand...

Randy

Well, I don't know.

I would expect the ball screws were done the same way he normally does them. The tough part is that going into it, you just expect that they would be done the way everyone else does them, so you don't even ask. You don't find out it's done differently until you get the machine, and then it's too late to change. Well, you can, but it's another wait on new balls screws and you have to figure out the length differences and how to fit the couplers in place.

I ended up installing mine George's way because I just didn't have time to modify them. They are working fine, and may work that way forever. But, I'm not sure so I'll be checking them fairly regularly.


Royce
 
Disappointing

George decided he no longer wants to answer questions here. Since I'm directly responsible for the sale of at least 4 machines, it's pretty disappointing..

I apologize..... Hopefully any questions you have will be answered privately.

Considering these machines fit perfectly within the zone of cuemakers, I thought being part of this community was an exceptional opportunity for his business....

Apparently, I was wrong...
 
pescadoman said:
George decided he no longer wants to answer questions here. Since I'm directly responsible for the sale of at least 4 machines, it's pretty disappointing..

I apologize..... Hopefully any questions you have will be answered privately.

Considering these machines fit perfectly within the zone of cuemakers, I thought being part of this community was an exceptional opportunity for his business....

Apparently, I was wrong...
Click to expand...

https://www.facebook.com/xzerocnc.routers
Might be better there.
 
pescadoman said:
George decided he no longer wants to answer questions here. Since I'm directly responsible for the sale of at least 4 machines, it's pretty disappointing..

[...]
Click to expand...

All due respect, Randy. go back and read the thread. George wasn't really "answering questions" here anyway. I personally think - and if you read the thread you will see I am not alone in this - there are some construction decisions that George may not have thought out very thoroughly. Concerns of that nature justify asking questions and expecting reasonable and understandable answers, which he didn't seem very able to provide.

After a while, those asking the questions become a little tired of getting the run-around, and I think that's what happened in this case.

TW

 
Thomas Wayne said:


All due respect, Randy. go back and read the thread. George wasn't really "answering questions" here anyway. I personally think - and if you read the thread you will see I am not alone in this - there are some construction decisions that George may not have thought out very thoroughly. Concerns of that nature justify asking questions and expecting reasonable and understandable answers, which he didn't seem very able to provide.

After a while, those asking the questions become a little tired of getting the run-around, and I think that's what happened in this case.

TW
Click to expand...

I was summarizing his answer to my question about his presence here. I share your sentiments regarding most of his replies.

Instead of having an open mind and likely improving his product, he created an apprehension towards potential buyers IMO.

I still believe in his product, as my Predator is nearly identical to Bob's and, if I ever get enough money, I'll finish it...lol. I don't agree with his position that Clearpaths are the worst choice for theses machines...
 
Status
Not open for further replies.
Back
Top