GME's New 80/20 CNC Build - My Design

[GME]

Re: The spectrograph. The RHS is the dB of the noise. The colour defines the dB level. dB is air pressure which correlates to volume. The LHS is frequency from 0 at the bottom to 22kHz at the top. The bottom is time so 0-0.4 maybe 0.4min? So to interpret, you have heaps of very load high freq noise. Not sure where that comes from. There is a 10kHz band at 40-50dB (yellow) but down where we want it we don't have much definition. This could be because the microphone can't register <200htz. Look at your mic spec? is it a phone camera? Look at the SPEK and see if you can filter the bandwidth. You maybe able to tell it to only listen to sub 1Khtz??

I looked up phone mics and they generally are 20htz to 20khz. But some have 2 or 3 mics and run noise cancelling software which maybe would get rid of loud low noises?? I don't think we have to dig into this much unless your interested. We know the motors fundamental vibration is 170htz....Peter

5.09*2000/60= 170htz rpm*usteps/min/sec = usteps/sec = htz fundamental which agrees with the first vib mode of the gantry section at its clamped spacing
1st harmonic 2*170=340htz
2nd harmonic = 510htz

Peter, I used the mic in my Canon PowerShot SX200 IS snapshop+ camera. I looked at the manual and online. Not much on auto specs, except that it's 16 bit mono with a 44.100 kHz sampling rate. I'm not particularly surprised - it's a camera after all. I have no way of filtering out the bandwidth.

I'm happy to go with your suggestion that we not continuing into this aspect. Today, I'm working on motor isolation, filling threaded holes and finishing my spoilboard. After performing those tasks, we should have a better idea of where things are.

I just returned from the place where I buy my fasteners. They have a very broad range of fastener type products, which their business name suggests: Tacoma Screw.

More to follow.

Thank you for working the issue with me.

Gary

[GME]

Here's a quick update.

I got the base layer bolted down and ran at 5 ipm. The least about of vibration I've observed. I had all sorts of small parts on the spoilboard, 6mm button head cap screws, a variety of washers, some hex wrenches and the like. Nothing moved. Nevertheless, as expected, there was still some vibration.

Marcus at Gecko asked me to remove, bench test at 5 ipm and video record so he could see/hear the stepper. An interesting exercise, but no surprises. The stepper vibrated. Standing on end (the shaft vertical) I got one level of noise. Laying on it's side, I got a higher level. Here is a link to the video: https://drive.google.com/open?id=1hA...yeruPUGu4YPBKn

I ran this latest video through Spek. Here is the result:



You will note that there are 4 distinct area. The first and third reflect the sound produced while the stepper was on end. The second and fourth are when the stepper was on its side. It looks like the lower end of the frequency range moved up quite a bit. The upper end is the same. The sound produced is probably influenced to some degree by my bench top. It's a 36" x 72" x 3" piece of phenolic. I'm thinking it is probably introducing some damping effect.

Peter, you asked about the pivot shaft. From the best I can tell without disassembling the drive, there is a generic ball bearing something like this:

.

I also removed the shaft (a shoulder bolt) from the pinion gear. It also has the same sort of ball bearing. The bearing is pressed in.

Peter, I believe you also mentioned that you doubted the folks at Gecko would be able to help. While I agree, I had already engaged with Gecko and felt I owed it to myself to see what, if anything, they might have to offer. I'm not expecting much, but who knows?

Next up: using the nylon washers I bought this morning to try to isolate some of the vibration.

Gary

[peteeng]

Morning Gary - I read the Spek stuff and it can be filtered so have a look at the controls. You maybe able to filter out above 1000htz say. Thanks for the bearing info. These are deep groove ball bearings. If it only uses one per shaft then the arm can wobble sideways? If it uses 2 per shaft then if fitted correctly the arm should not be able to move transverse to its thickness. I've been thinking about the vibration direction. From your test it seems greater in the radial direction not the shaft direction. Not sure what that means yet. You could also record its sound while holding it say tied with a string. This will remove the influence of its contact with things.

Davida1234 - Gary has disconnected the pinion and when the motor is stationary it still vibrated, this means the bearing is out of the picture. A cranky bearing would complain over all speeds I think? I'm 99% sure the motor is the driving resonator as its fundamental freq at 5ipm (170htz) agrees with the gantries calculated fundamental freq (170htz) . See prior calcs <#336. Peter

[GME]

Morning Gary - I read the Spek stuff and it can be filtered so have a look at the controls. You maybe able to filter out above 1000htz say. Thanks for the bearing info. These are deep groove ball bearings. If it only uses one per shaft then the arm can wobble sideways? If it uses 2 per shaft then if fitted correctly the arm should not be able to move transverse to its thickness. I've been thinking about the vibration direction. From your test it seems greater in the radial direction not the shaft direction. Not sure what that means yet. You could also record its sound while holding it say tied with a string. This will remove the influence of its contact with things.

Good morning (your time), Peter. I looked at the Spek controls in the manual (such as it is). Not much there. You can change the db range, but the frequency scale on the left remains static. So, as far as I can tell, one cannot filter out frequencies.

There appear to be two bearings. The second one is an eccentric with a cap/set screw arrangement. It looks something like this:



When the cap is rotated and tightened, I don't feel any wobble. It's not adjusted in the conventional way. According to the Avid instructions, "While pushing in on the Eccentric Collar Bearing, rotate it in the clockwise direction until it starts rotating inside the R&P Plate." Then, "[t]ighten the set screw on the side of the Eccentric Collar Bearing." In the usual case with eccentrics, one rotates the cap until tight, then insert a punch in the indent, tighten further with a hammer, and then tighten the set screw. Still, I don't get a wobble.

I still have the other Y stepper to work on. I'll see if I can scare up some string and record it.

Gary

[GME]

Peter, maybe this Spek analysis will tell you something, but I don't get a thing from it. I ran the stepper suspended from a string.



It looks like everything is pretty quiet. Starting around the 11 sec. mark, there seems to be an increase. The motor was so quiet, I moved in within a few inches to give the mic a better chance of picking up something. Where it returns to about the pre-11 sec range, I moved back out. I put it on the bench and still got the vibration. In retrospect, I suppose I shouldn't have expected more. We are measuring noise in the audio. Hanging from a string, there was nothing to vibrate against to produce noise.

Gary

[GME]

Well, it looks like the nylon washers under between the motor & R&P drive, and between the R&P drive an interface plate did the trick. The noise coming from the area of the motors changed substantially, and the frame stopped vibrating. Who would have thought something as simple as adding a few nylon washer would have such a dramatic effect? Silly question. Peter knew it would help, even if he didn't know the full extent of the improvement with absolute certainty.

My hat's off to you Peter. You're the best! Cheers!

Now I have to remove the left motor once again to move the motor pulley outward. My belt tracking off. One edge is riding just a little off the gear pulley. Not unexpected, given that nylon washers changed the previously established pulley relationship. I thought I give it a tumble without making the change. I don't much like loosening and tightening small set screw. They cam out too easily. I had a 50/50 shot, which paid off on the right. The tracking is fine.

Gary

[GME]

Okay, I got the belt on my left stepper tracking properly again. This problem I believe it was something to do with the belt itself. Interestingly, the belt tracked fine put to the point where I removed it. I have never had a belt tracking issue.

I removed the pinion pulley again, looking for something that might have caused the pulley and pinion gears to install catawampus. Nope, nothing there Maybe something with the washer that bears on the ball bearing pressed into the pulley? No, it was fine. The shaft wasn't bent, as far as I could tell. I didn't drop the shaft.

Before I took the stepper drive off this last time, and for no particular reason, it popped into my mind that maybe I didn't put the belt on the same way I took it off. There was a 50/50 chance I hadn't. So when I took it down again, I paid attention how I took it off and ensured it went on the other way. Bingo! Problem solved! Go figure. It shouldn't matter which way it goes on. It didn't when I set the drives up the first time. I'm guessing there has been some odd stretch over time. I could replace the belts, but they show no signs of wear. I'm going to leave well enough alone.

Now, I can get on with the business of finishing my spoilboard.

Gary

[Sterob]

Well done Gentlemen.
Seems like a great result.
It was like reading a exciting novel with those posts....lol

[GME]

Well done Gentlemen.
Seems like a great result.
It was like reading a exciting novel with those posts....lol

Thank you, Sterob. It's been an adventure.

All the credit goes to Peter, who devoted an extraordinary about of time and effort to finding a fix. I can say with absolute certainty that I would not found the solution without him. As I've made clear throughout the process, I have dealing with an issue that is far outside my knowledge and experience.

I've never seen any mention on the zone about using something as simple as nylon washers for vibration isolation. That leads me to believe that I'm not alone in my ignorance on the subject. Hopefully this thread will help others find a solution to similar issues. Stepper vibrate - just the nature of the beast. I suspect there are a number of folks who have experienced the same or similar issues, but ended up just living with it. Now, there is a pathway for them. IMO, Peter has done a great service to not only me, but to others in our CNC router community. Thank you again, Peter.

Gary

[mactec54]

Thank you, Sterob. It's been an adventure.

All the credit goes to Peter, who devoted an extraordinary about of time and effort to finding a fix. I can say with absolute certainty that I would not found the solution without him. As I've made clear throughout the process, I have dealing with an issue that is far outside my knowledge and experience.

I've never seen any mention on the zone about using something as simple as nylon washers for vibration isolation. That leads me to believe that I'm not alone in my ignorance on the subject. Hopefully this thread will help others find a solution to similar issues. Stepper vibrate - just the nature of the beast. I suspect there are a number of folks who have experienced the same or similar issues, but ended up just living with it. Now, there is a pathway for them. IMO, Peter has done a great service to not only me, but to others in our CNC router community. Thank you again, Peter.

Gary

Glad you found a fix, this is standard practice in the industry to use plastic or urethane bushings / washers when you want to isolate something like this, it would even be better if you changed the bearings also to a AF Delrin bushing, which you would have to custom make, having Bearings in something like this is a bad design

[GME]

Glad you found a fix, this is standard practice in the industry to use plastic or urethane bushings / washers when you want to isolate something like this, it would even be better if you changed the bearings also to a AF Delrin bushing, which you would have to custom make, having Bearings in something like this is a bad design

Thanks, mactec. Delrin AF bushings sound like a good idea, especially given what I've learned lately about plastics. Without tearing down R&P drive, I can only guess at the OD of the eccentric bearing. I'm guessing it would take a fairly large diameter rod, and Delrin AF is very pricey, even for a short piece.

I won't quarrel with you about the design aspect, except to say that these R&P drives were designed for use in a kit for the DIY market - and at a price point. It may be a poor design, but it works well enough for its target market.

FWIW, it looks like Avid CNC dropped the ball bearing in the drive pulley/pinion and moved to a Super Oilite bushing. I wonder if replacing this bushing with Delrin AF would also be a good idea?

If only I had a lathe . . . . Maybe next year! A lathe is on my wish list. Cutting some custom bushings would make a good project and skill builder, and would improve my machine.

Gary

[mactec54]

Thanks, mactec. Delrin AF bushings sound like a good idea, especially given what I've learned lately about plastics. Without tearing down R&P drive, I can only guess at the OD of the eccentric bearing. I'm guessing it would take a fairly large diameter rod, and Delrin AF is very pricey, even for a short piece.

I won't quarrel with you about the design aspect, except to say that these R&P drives were designed for use in a kit for the DIY market - and at a price point. It may be a poor design, but it works well enough for its target market.

FWIW, it looks like Avid CNC dropped the ball bearing in the drive pulley/pinion and moved to a Super Oilite bushing. I wonder if replacing this bushing with Delrin AF would also be a good idea?

If only I had a lathe . . . . Maybe next year! A lathe is on my wish list. Cutting some custom bushings would make a good project and skill builder, and would improve my machine.

Gary

If you were to modify it at anytime you would fit a aluminum bushing and then this would cut down the diameter of the AF Delrin Bushing size to be made, the pinion end is where a good bearing setup should be, it's a rolling element the fixed end is basically static, which is not a good place to have a Ball Bearing

You would make 2 Delrin Bushings with a flange, this would give you the washer on both sides for total isolation, so you would make 2 Bushes with a flange

[GME]

If you were to modify it at anytime you would fit a aluminum bushing and then this would cut down the diameter of the AF Delrin Bushing size to be made, the pinion end is where a good bearing setup should be, it's a rolling element the fixed end is basically static, which is not a good place to have a Ball Bearing

You would make 2 Delrin Bushings with a flange, this would give you the washer on both sides for total isolation, so you would make 2 Bushes with a flange

Thank you for the design tip. It would be much less expensive starting with aluminum for the bulk of it, and then machine the Delrin in a smaller size. Now I have a basic model to work from. I appreciate the additional information.

Gary

[peteeng]

Morning Gary - Happy to be of help. Been interesting wading through the issue so far away. I use a lot of delrin in place of aluminium in mining equipment. You could make the arm in delrin (would need to be a bit thicker) and then it would be an excellent isolator. Then you can integrate the bearing into it. Plus this is a mill job Happy Making. Peter

I've just launched my website! Tetra Motion - TETRA MOTION

- - - Updated - - -

[GME]

Morning Gary - Happy to be of help. Been interesting wading through the issue so far away. I use a lot of delrin in place of aluminium in mining equipment. You could make the arm in delrin (would need to be a bit thicker) and then it would be an excellent isolator. Then you can integrate the bearing into it. Plus this is a mill job Happy Making. Peter

I've just launched my website! Tetra Motion - TETRA MOTION

- - - Updated - - -

Making a new R & P drive in delrin. Now, that's an interesting idea. I'll have to give that some thought. I have a mill and CNC router, after all.

I like your new website, Peter. I didn't realize you were designing Maxiumus in anticipation of starting a business venture. I'm sure it's going to be a big hit in Australia. Depending upon the costs to ship parts to the U.S., you may have a hit here as well. The best of luck!

Gary

[peteeng]

Hi Gary - Any new squeaks to solve? I've been working on Tetra Motion for about 2 years as a back burner project. But it's time has come, so launch I have? (as Yoda would say) Peter

[GME]

Hi Gary - Any new squeaks to solve? I've been working on Tetra Motion for about 2 years as a back burner project. But it's time has come, so launch I have? (as Yoda would say) Peter

Hello, Peter,

No new issues. The machine works great. I'm finishing up my spoilboard and will then get on to the gussets.

I did a search for Tetra Motion and found nothing to link it to your website address, https://cncrouterkits.com.au/. Then, I used the search terms (Google), "CNC Router Kits.," which I believe is reasonable for someone interested in a kit machine. I gave up looking for your site on page 10 of the results. Your site wasn't listed. That's a bad deal. People won't find you. Also, I'd be reluctant to put your company name, Tetra Motion, out there without providing a link to your website. No better luck searching for Tetra motion. If you just point to Tetra Motion, no one will find you.

I wish I had some sage advice on how to improve your online presence, but my internet talents are limited to being a reasonably competent consumer. I know nothing about establishing and growing an internet presence, except that you have to have a presence people can find. Unfortunately, at this point, you don't.

Gary

[peteeng]

Hi Gary - It's only been up a week so the robots and algorithms haven't done their work yet. Takes about 6 months before these things work through the system in my experience. So be patient and eventually you will be able to type those words in and get the site. But as you know it's Tetra Motion - TETRA MOTION
... simples. I do test searches weekly and I'm setting up site metrics to figure out where and when people are looking at the site. Takes time to gather info, understand what's happening or not happening then redesign or adjust the site and links to suit. Just as much work as designing a router

I just put in Tetra Motion CNC and got this. I got the CNC Forum announcement, my facebook page and two pages from cncrouterkits, so Googlebots are chewing their way through the site. 1.11 billion results!! staggering

[wmgeorge]

It will take longer than a few weeks, more likely maybe up to a year with mine. I have discontinued my website as its time to really retire as I am 76. I will keep my FLA CNC Router for now and do interesting jobs and stuff for my Church but no more timelines. If your using Your computer and ISP to judge its not a true statement of what your going to get.

Try from another computer not on your ISP or even your city and google will log that Search.

Gary, I am glad your making progress, getting done just in time for Christmas gift giving!!

[Arjay]

For website analytics, check out Google Analytics or Microsoft Application Insights. With both you add a small amount of code to your website and it tracks page hit statistics and other info. They both give you a portal where you can view the statistics. Both are free but not sure if MS insights requires hosting the website on Azure. Read up on SEO (search engine optimization) to find out how to add tags to get more page hits.