Make AC Servo Motor Mounts For CNC Mill Spindle (DMM DYN4) 

Thank you, glad the information was helpful. One of the best improvements that I've made to this mill.

Thank you Alan. Temporary parts just have to last long enough. You've probably seen people using printed parts as soft jaws; that's pretty wild :)

That's great to hear Mike! Thank you for letting me know the models helped. I've installed a 1kW DMM too, replacing the 750W that had the brake. I've not done too much yet with it because the spindle bearings are near the end of their life.

Awesome; that's a massive servo motor! I'm delayed a couple of weeks finishing up. Electrical and timing pulleys need additional work. No big deal, just unexpected. Murphy! A Happy Thanksgiving to you as well, thank you :)

Thank you Jody, it's great to hear from you!

Always room for improvement :) Thank you

Hi David. Didn't like trying to mill with drill bits? :) Have a great weekend!

Hi Dan, that's great to hear! I've had problems with interfacing the encoder feedback due to noise on the ground line from the encoder output. The only thing that helped was to add optocouplers, which requires a new circuit board. So, next video is delayed two weeks! That's how it goes :) If in the US, have a wonderful Thanksgiving!

@@kentvandervelden I made my own encoder and power cables to fix the noise issue.

Happy Thanksgiving to you!

@@LtDan1 I'm really glad it was easier for you; I spent a lot of time on the noise problem 😐 What board do you have the encoder attached to? I'm using a Pico Systems USC. The moment the DYN4 received power, and disabled, the signal grounds had noise that was as high as ~10Vpp, and with shared grounds, messed up singled ended input and differential inputs. Enabling the drive and turning the motor created no noticeable increase in noise.

Hi Gus, great to hear from you. That's an impressive design and I hope you'll post some videos of the build. If you'd like some ideas on electrical, @corvetteguy50 may be a good channel to check out too. Have a great weekend! ru-vid.com

@@kentvandervelden Thank you, I have looked up corvetteguy50 and its exactly what I needed. My electronics skills and knowledge are my weakest point. I have a science degree but my experience with it is low. Your videos really help fill that whole. Thank you. If I do my own videos on the build would you be up for a skype session and be part of one of them?

@@gusbisbal9803 Hi Gus, I'd be glad to help regardless if you document the build. If nothing else, maybe I can help avoid the mistakes that I made. Skype works. Glad to help a fellow science grad. Shoot me an email.

Hi Barry, please check if the f3z and step files at the following address will help you. If not, send me an email and I'll send you the entire mill head model. github.com/kentavv/kvvcreates/tree/master/pm25mv%20cnc%20mill

Thank you Ray! Here are the parts numbers. You'll need cables as well. DYN4-H01A2-00 - DYN4 AC Servo Drive - H01 Frame 0.75~1.0kW servo motor pair 86M-DHT-A6MKB - 86mm Frame, 0.75kW, medium inertia with +24VDC holding brake I estimate the inertia ratio between this servo and the spindle to be ~2.44x, so well within the recommended range. I thought the brake might be usable for tool changes (nope) and broaching (probably), but not sure it's worth the extra control logic, electronics, irritation of not being able to turn the spindle when the power is off, and possibly noise.

Thank you! I once experimented with a DIY oil mister. That was a huge mistake. I'm sensitive to unclean air, e.g., saw dust, grinding, welding fumes, smoke, and such, but misting oil for just a few minutes really beat me down. I'm been thinking about a parasitic pump for better coolant regulation, but realistically, the best solution, for milling at least, is high pressure flooding. In mister, high pressure air is used to clear chips, but as you said, that atomizes the coolant.

@@kentvandervelden @Kent VanderVelden Thx - often we don't realise that we are taking an industrial process into our homes when we enjoy using machinery for creative purposes. I have contact dermititis caused by over exposure to machine tool oils, and it takes only the slightest oil contact to set it off(painfully, broken and itchy skin). I appreciate a face mask(RPE) would be a nuisance, but a simple FFP2 or 3 mask would suffice. I've often thought that we now have the opportunity to utilise remote cameras with audio to allow us to monitor machinery at a much higher degree and in a much safer way - perhaps you could do an interesting setup this way re: cheap endoscope camera integrated onto the machine tool head - it would be interesting and of value to peeps, and perhaps lucrative(supply of kits, fixtures, etc) too?! :)

@@craigywaigy4703 These are excellent ideas! Thank you for taking the time to write them. I'll immediately implement the mask recommendation. I know that's right, and there's only upside. I've have some experience with cameras as measurement tools... a consumer product is pretty involved, but an interest and I like the way you are thinking. Thank you :)

@@kentvandervelden I've found that dilute koolmist 77 in a fogbuster-style system is pretty good. Works nicely on aluminum and steel (but not for drilling/tapping). High-pressure anything really sucks if you don't have an enclosure, but you can make do with mist/air and some shower curtains.

Thank you. While a bit out of date, I have some information that resembles at bill of materials and some thoughts about the selection of the parts at following link. Check out the mill design breakdown document. The tool holders that I use come from Tormach. Hope this is helpful github.com/kentavv/kvvcreates/tree/master/pm25mv%20cnc%20mill

You may be able to do more with the powerful servo than the machine's rigidity allows. There are online calculators for power requirements for a tool, feed, and material. Running less than rated speed, you're in constant torque range of the servo, so look at the operation's expected torque. Should work well. Thank you

@@kentvandervelden Thank You so much for your input much appreciated. I started epoxy granite filling my machine🙏 and the weight and rigidity chance is amazing.

The belt is a Gates GT3 (390-5MGT-15) equivalent from Misumi. Here are links to the belt and pulleys. us.misumi-ec.com/vona2/detail/110303273750/?HissuCode=GBN390MR3-150 us.misumi-ec.com/vona2/detail/110303274020/?HissuCode=GPA60MR3150-A-P35-NFC us.misumi-ec.com/vona2/detail/110303274020/?HissuCode=GPA60MR3150-A-N14

Hi Michael, I started with the 750w servo to be able to compare to the stock 750w bldc and to have higher speeds. (The larger servos from DMM have lower rated speeds.) This was easily a great upgrade. DMM has since started offering a 1kw that's an identical size and speed to the 750w. The part number is 86H-DHT-A6MK1 Double check, but the required drive appears to be DYN4-H01A2-00 Best of success to you!

Suggestion heard :) Other people have also mentioned YG1. I'll check them out. I have a good collection of Lakeshore at the moment.

Short answer: Use whichever interface is simplest and works for you. Long answer: I'm glad I switches the motor. Unless you need position control (e.g., for clocking tools or using a ATC), 0-10V control may be enough. If I could have used the 0-10V interface, I probably would have. It was the first interface I tried but for some reason, despite all DMM's help, the 0-10V interface on my drive never produced reasonable power at the spindle. However, the Step-Dir or A/B-phase interface worked well and had the advantage of position control (which I don't really need.) 0-10V not working is probably unique to my setup and possibly my drive was damaged. I'm sure that DMM said there's no speed/torque advantage of 0-10V vs. Step-Dir. There might be a small improvement in responsiveness with Step-Dir over 0-10V but nothing that we'd notice with our eyes. I would not rely on the Step-Dir interfaces for synchronized movements, and would only use an external encoder for synchronized movements. The DYN4 signals are fine for speed monitoring. A/B-phase has the advantage of better bandwidth, so roughly 2x greater pulse speed is achievable over Step-Dir. Let me know if any other question comes up.

Thanks! I’ll play with both. As usual you knew what I was talking about even though I didn’t. I really appreciate the information.

I didn't change the bearings for the higher speeds, but I should change them because of their runout. Here is a CNCZone post where Starleper1 included specs on the bearings and they seems OK for 5500RPM. www.cnczone.com/forums/benchtop-machines/101231-pm25mv-bf-series-9.html#post859477

Thanks Kent.

I prefer milling steel over aluminum. This motor works well for me. Using carbide tooling, the cutter rotation speed can be increased to be in zone of highest continuous power. I use 1/2" end mills regularly, control depth and width of cut and all is good. Will need to to step drill, but the servo is nicer than the BLDC. The difficulty comes from the rigidity of the mill shown, including play in the bearings which only degrade. Consider replacing the bearings and increasing preload. Still, the will be limited by overall rigidity, but may be enough.

They are NEMA23 Leadshine Easy Servo stepper motors. These have encoders and a current control feedback loop. They work pretty well. I use them on my lathe too, where they are very much overkill. If you want to take a look, I talked a bit about them in an old video. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KuX1QdGcGJ0.html

Thank you! Orientation and holding is pretty easy, if needed. But what most people like is that servos have a high power:size ratio and constant torque up to rated speed, and beyond that speed they have constant power. DMM has a 1kW servo, which easily outperforms the stock BLDC on this mill. An induction motor would be better than the BLDC too but they are bulkier than a servo with similar power.

An analog +/-10 control for direction and speed initially, then changed to step-dir, and finally to A/B phase. The pulses of the later two come from a step generator inside a PID control loop. With each change the maximum and variance of velocity improved. 240v was just installed, and 4700RPM is currently the maximum velocity before phase of lost. This may all be unique to my setup though.

The 750W servo delivers less maximum power than the stock BLDC, but speed does not sag and the BLDC, which has less protection, may be overdriven. I prioritized higher speed, but wish I could have gotten higher speed and power. I'm sure you made the right choice for your use case.

I actually have been thinking about a 1.5kw ac motor and inverter too

The servo drive may be roughly a drop-in replacement for your VFD used in velocity mode with 0-10v speed control and may a few extra wires for direction, start, stop, etc. To get fancier, the DYN4 servo drive (and most others, just double check) can also accept step-dir pulses and be controlled like a stepper motor. If your breakout board can generate pulses quickly enough, then the servo could be run at full speed as a spindle motor and have easy positioning. The drives are pretty fancy, have many interfacing options, generally we use a small fraction while having options for the future. Pretty amazing engineering. Hope this helps.

Sure, would glad to help. You're welcome to the Fusion360 files or any file F360 can export, e.g. STEP. Drop me an email with your preference.

@@kentvandervelden Sharing via Fusion360 would be great. I have never done that through Fusion360, just let me know you need from me.

Please try importing kvvcreates.com/kvvpm25_v29.zip. This contains the DMM related parts and a few others.

Please see the part items below. The servo motor is from Dynamic Motor Motion and the belts and pulleys are from Misumi. Servo motor: 86M-DHT-A6MKB (with brake) or 86M-DHT-A6MK1 (without brake) Timing belt: GBN390MR3-150 Timing pulley attached to servo: GPA60MR3150-A-N14 Timing pulley attached to spindle: GPA60MR3150-A-P35-NFC (will need to be bored and broached)

@@kentvandervelden thank you sir. That help me a lot

@@kabadaluk You're welcome to have the 3d models of the mounts too, if they would help you.

A/B Phase

@@kentvandervelden Thanks, I have never heard of that. The Dyn4 manual has 3 references to A/B Phase. None talk about using it to drive the servo. The first is under position servo. How is it wired from the breakout board to the Dyn4, and how do I set the drive to use it? Thanks for your time!

@@barebooger The reason to use A/B-phase is better use of the two-wire bandwidth (i.e., higher frequencies and noise tolerance.) I used it because of problems I had with step-dir on the particular drive I had and you will hopefully not have problems. If you want to use A/B-phase, use DYN's software to configure the drive. [The software is useful for other work as well. If you're using the servo for a spindle (not for positioning) there are other settings to looks at. (Sorry, I don't have the details in front of me.) But, the servo will work without those changes.] Using a Mesa card, step-dir and A/B-phase are wired the same. There is a small change in the linuxcnc configuration needed to switch the Mesa to A/B-phase. I think it's the step_type parameter on the stepgen module.

@@kentvandervelden Thanks. I have a Dyn4 with a 86H-DHT-A6MK1 (1KW) servo motor and the intent is to use it on a Taig Turn lathe spindle with 1:1 belt drive and use the encoder out from the drive for threading. I may use a Mesa card, but I am toying with a EC500 and Remora firmware. I have to get the card flashed successfully before I am ready to wire the spindle motor. I think step and direction control is what I will pursue.

What is the benefit of a/b-phase over step/dir? While the same number of wires are used, a/b phase encodes steps across two channels, increasing bandwidth. Said another way, the bandwidth available for dir in step/dir is mostly wasted. A breakout board not able to produce a fast enough pulse train using step/dir might be able to with a/b phase. Compared to velocity control, position control allows positioning as well as speed control, without the complication of an additional servo loop. Thank you for asking. I hope this was helpful.

Thank you Kevin! Several reasons maybe none are so important though :) I wanted to 1) show others how the same size servo and BLDC compare; 2) use the same 120V15A service; 3) have 5000RPM; 4) keep near the same size as original motor frame. Now, #2 had already gone busy because to get to 5000RPM, 240V is needed. There are some 1.8kW eBay servos that are 5000RPM. If interested in the DMM, check what options they have that are unlisted. Someone pointed recently, and DMM confirmed, they have a 5000RPM 1kW servo that uses the same DYN4 drive as the 750W and is the same 86 frame size. If I'd known of this option and known I would install 240V, I would probably have gone with the 1kW. I'll post an update once the timing belt arrives.

I'm now using a 7i76e. All my mill LinuxCNC configurations can be found at the following link. (Go back one directory for the lathe and router configurations.) github.com/kentavv/kvvcreates/tree/master/linuxcnc/configs/pm25mv_mill

@@kentvandervelden thanks! You just saved me days of trial and error

Glad to help. Do you have LinuxCNC running? You'll need to use a 2.8 version for the 7i76e. Let me know if you need help. I've meant to put something together to show the steps.

@@kentvandervelden just put 2.9 on the computer I intend to use. I have Linuxcnc running on a g540 powered router I built, but this 7i76e/dmm servos and spindle are all new to me. I'm getting my servos tomorrow and my retrofit kit in a few days. I was going to build my own kit but i had half the machine apart to get it in my basement, so I figured I'd yank it apart instead of putting it back together. Cost vs time is probably marginal at best

Good deal! The link below is to a wiring diagram that I found very helpful. Also, my configs reference a HAL component I wrote to talk by serial to the DYN4 to get torque, position, send a few commands, and do data logging. You may want to ignore that stuff. forum.linuxcnc.org/media/kunena/attachments/3278/7i76_Anschluss.pdf

You don't need a servo to perform rigid tapping, just the encoder on the spindle and a way to control it CW and CCW. Just atach a quadrature encoder to the spindle, with index signal. In your case that you already have a servo, you can just hook the drive encoder output to linuxcnc. You would need 1:1 ratio between the motor and spindle for the index signal, or use other spindle index sensor.

The Dyn4 can output an encoder signal to your motion controller. Need to have a timing belt setup though.

The encoder signals are passed through from the DMM drive to a Pico Systems USC board. This is the same as I already for rigid tapping but based on the servo's encoder instead of a spindle mounted encoder. Position would be lost if the belt slips, so I'm waiting on a timing belt and pulleys. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-gnyIOU-e9cY.html

I do rigid tapping in linuxCNC on a PM25MV with the stock BLDC driven with a Mesa 8i20 and an encoder mounted to the BLDC. Rigid tapping in Linuxcnc is a funny thing, if you plan to only use the servo's encoder, you need it's index pulse as well (LCNC needs the index for rigid tapping) and it must be 1:1 pulley ratio. I use the stock pulleys and I gave the gearchange component setup to scale the velocity feedback from the encoder, and change the PID settings for rigid tapping and I set the pulleys 2:1. I have a proximity switch mounted to read an index pulse off the spindle itself. Works rather well, but I'm thinking about picking up a DMM set because the BLDC just doesn't have the guts. Did you by any chance post CAD files for the motor mounts you made?

@@justinwhite9535 I'd be happy to. They are in Fusion currently. Would the f3d files on GitHub work for you? I'll put them up tomorrow with links to the pulleys and belt I used.

Figure about $500USD for the DMM DYN4 and 86M-DHT-A6MK1 (no brake). The brake adds quite a bit of expense so probably only valuable for a vertical axis and not a spindle. The servo is 750W. There are larger ones from DMM, maybe maxing at 1.8kW, but the top speed is lower (3000 vs 5000RPM). The pulleys and belt from Misumi were roughly $80USD. Thank you

Some servo drives have an output that controls a relay that switches the brake. If yours does not have that, you'll need to switch the relay using your controller a second before turning turning the motor and then switch the relay again a few seconds after the motor is turned off. The goal is to be sure the brake is off before turning the motor and that the motor is stopped before turning the brake on. Both could be done with timers but the latter could also be done by monitoring the RPM. How all this implemented is going to depend on your controller. Hope this helps.

While you may be able to get the motor to turn, maybe requiring a lot of tweaking, it's unlikely to have much torque. The servo is meant to run synchronously, requiring feedback, especially with varying loads. VFD can have feedback mechanisms, e.g., using motor mounted sensors or measuring back emf, but vfds are meant for induction motors. Just a hunch though.

​@@kentvandervelden ok thks , may god bless you

Sounds like a great project! I use LinuxCNC now and used Mach 3 on an Industrial Hobbies mill. LinuxCNC works well for me as a software tinkerer. Mach 3 worked well for me when I trying to just make parts. Today, starting all over, I would very closely at some of the turnkey controllers like Acron, Masso, Buildbotics, and Pumotix and the like. They might be less configurable, less powerful, etc. but have the potential to be more reliable with less cost and less headaches.

@@kentvandervelden i am also building an 8 axis 3d printer/ mill ( for making the final dimensions i have a light mill to finish the 3d prints) the mill i am building is for making parts for the printer.. i was thinking of using a ramps controller as i have 4 of them lying around.. and another option on the drive of the mill is putting a ac induction motor right on top of the spindle.. (the linear rails behind my spindle are 30mm and 4 carridge so plenty strong) and the z axis is mount on a concrete wall that's 300mm thick by 8x 10mm chemical anchor somebody done that already?? was thinking to mount on a knee to the table but that will be a giant leaver and prone to vibrations..

Sounds fantastic! Ever considered posting videos about your projects and ideas? Keep them short and simple so not to take away time from the project. See what the reaction is.

@@kentvandervelden the 8axis machine will be on RU-vid when finished,first want to have a patent onto it.. the mill yeah when i have a motor that build willbe on RU-vid!! mabee ill film the mounting off the machines cnc hardware..

If you're in the US, and need help with the patent, check out vanderveldenlawfirm.com/ I'm biased, but I know she'll do good work. Wishing you the best of success! Sounds awesome!

Speed to print and reducing warping during cooling. There are a decent number of external layers for strength. Maybe was luck? :) Thank you

@@kentvandervelden I have my X and Y mounts printed it Carbon Fiber PLA. was planning to replace them ASAP with metal, but actually they both work just fine! 100% infill tho. :)

Hi John, sorry to have missed your question. If you drop me an email with the details you have I'll try to help.

@@kentvandervelden Yes! I'll send you an email, just want to make sure that I connect properly the relay and connect in the right place the pins! Thank you!

Misumi

No problem. Please send me an email reminding me to do so.

@@kentvandervelden sent 👌👌

Electronics and LinuxCNC setup will be in the next video.

@@kentvandervelden I am really looking forward to this. I feel like my spindle motor is going to give up in some time and I am in the middle of production. I really need help setting up a servo motor as a spindle motor with linuxcnc.

Send me an email with some details and I'd be glad to help with specifics if the two setups are compatible. I tried analog, step-dir, and a/b phase signals, velocity and position control, and closed loop and open loop. Only combination I didn't try was serial speed control.

Hi Stephan, that makes a lot of sense regarding the new pulley. I'll need to do that in steps. The smaller machines are much more fun than large machines. Finding and fixing problems is a greater education than everything being perfect from the start... Of course someone looking to make parts for profit should get the bigger machine.

Yes indeed. Thank you for asking

It's not going to be a satisfying answer but... it just worked. I did see what you were seeing though and I'm sure it's related to the control method. I'll describe the wiring and LinuxCNC setup soon and hopefully you'll notice something that's different from your setup... or I could still be wrong :)

Ha, okay...I’ll wait for the next video!

Hi Kent, I’m still patiently waiting for your next video.😁 Michael from DMM sent me a wiring diagram and claims it should work properly. It’s been so long, I can’t recall if it’s how I had it wired up or if something is different. I like their product and their enthusiasm for supporting hobby projects, but until the issue is resolved, I’ll continue to be disappointed with them, at least for the special use case.

@@ScotY808 A few things slowed me down including making a PCB to cleanup the encoder signals. I'll make the new pulley this weekend. Still don't have 220v pulled, but that may need to wait. Just encountered a lot of gotchas.

Hi Kent, I’m just teasing.😁 I know you’ll get to a follow up video when you’re done. I seem to take forever to get anything done myself!😂 I didn’t have 220v in my work area and running a line was pretty much out of the question so I bought a big transformer, per Michael’s recommendation. Never did hook it up though. For me, it seemed an easier and less expensive way to supply the Dyn4 for more rpm.

Thank you. A mill enclosure is on the short list during the next couple of months. The electronics are already enclosed.

@@kentvandervelden i made mine enclosure on polycarbonate 8mm thick, much less noise and i can work without risk, i spent about 600 euros for this but value the Money, bye

This is 750W which is the largest that DMM offers normally that runs at 5000RPM. They have higher power motors but if higher speeds are important, a large motor will be needed to maintain power after the pulleys. I'm testing a 24,000RPM 2.2kW spindle now and each is optimized for different purposes.

@@kentvandervelden I am thinking changing my cnc spindle to servo too, but the problem is the low rpm. Most of the servo I found in China second hand market are 1000rpm, 1800rpm, and 2500rpm. I found second hand servo much cheaper, only 200 HKD (about 25usd i think) for a used 750w chinese servo, about 90usd for a 2.7kw servo with driver. The only problem is the rpm issue, if i adopt 3:1 accelerated pulleys, the diameter of the pully will be larger than the size of the motor :(

​@@tomtang2639 Are these the rated speed or the maximum speed? The DMM that I have is rated at ~2500 RPM, the speed at which it changes from constant torque to constant power, but continues to increase speed up to ~5500 RPM, with reducing torque, until finally the back EMF is too great and the drive faults. Higher voltages are necessary to get to the higher speeds. Regarding pulleys, here is the most genius pulley setup that I've seen: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-kW_8BJLwJL0.html Regarding high RPMs: I've added a higher speed spindle and hope to soon have a video up about it. One spindle for slow low torque and a second for high speed. It's working pretty well and less of a compromise.

@@kentvandervelden That's very helpful thanks! My servo haven't arrived yet but i checked from the internet that it could go up to ~3300 rpm! For very high rpm, i've got a 800w 24000rpm spindle. Now i just want to upgrade it to a higher torque spindle motor to cut steel.

That sounds like a winning combination! I'll try to get the video about my high speed spindle up soon. The two spindles work very well together.

Thank you Peter! I didn't know about that. Maybe that would have helped with the Anaheim Automation driver I had for the BLDC motor. That combination just never worked well.

Timing belt and pulleys will be added in next video

Roughly $200 for the motor and $200 for the drive. Approximately, $400USD total

@@kentvandervelden I was looking at Ebay but prices are on top of the hill..... 😭

@@kentvandervelden are those the Tormach tooling system tool holders?

Yes, they work well for this size of mill, very repeatable, save a lot of time changing tools. Just be sure to tighten the drawbar tight. Use a torque wrench to get a sense of how tight is tight enough. It was more than I expected. Their prices seem unfortunately higher than I remember, but I spread out the pain over time. You can find a less expensive options for servo motors on AliExpress. Pretty amazing what can be found there. I plan to try ordering one soon. Will be my first experience with AliExpress.

Great question. The spindle has a sort of encoder inside the head from the factory. It's a ring with 16 holes that pass through a photo interrupter. Can't tell direction with this but certainly can tell speed. It would be a tight fit, but could add a more sophisticated encoder. I showed in another video adding a high resolution encoder to the top of spindle. That worked well but required removal when changing the tool.