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PM932 CNC Build

jbolt

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#91
Jay,

After extending the Y axis notch and removing the bellows how much total travel did you end up with?

Tom S
Y-axis now has 9.8" of travel (without any way cover). I could have gone a little more but I am limited by the enclosure and chip tray. The mount for the rubber way cover takes away an inch so I have 8.8" of usable travel.

Jay
 

TomS

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#92
Y-axis now has 9.8" of travel (without any way cover). I could have gone a little more but I am limited by the enclosure and chip tray. The mount for the rubber way cover takes away an inch so I have 8.8" of usable travel.

Jay
Thanks for the info. I did the slot extension mod also and got about 10 inches but with the way cover installed. Heard/read where someone got about 12 inches of Y travel. Not sure if the way cover was still used and how much overhang on the saddle but 12" seems excessive.

Tom S
 

jbolt

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#93
View media item 94569
Thanks for the info. I did the slot extension mod also and got about 10 inches but with the way cover installed. Heard/read where someone got about 12 inches of Y travel. Not sure if the way cover was still used and how much overhang on the saddle but 12" seems excessive.

Tom S
12" of travel without any way covers would have more than half the saddle hanging off the base, about 5". I would not go over 1/3 overhang.
 

TomS

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#94
The thread I was referring to is written by GT40 and is on this forum. He did a few things differently that what I've done and was able to get a shade over 11" with the bellows installed.

And I agree with you on saddle overhang. My max out travel puts me at 3-3/16" overhang which is 1/3 of the saddle front to back measurement.

Tom S
 

jbolt

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#95
Finally got started on the VSD conversion. I milled the motor mount parts before tearing the head apart. The new electronics ran great with no drama. It's always nerve wracking to run new programs after making modifications. I'm always afraid I missed something. The motor is a 2hp 3ph inverter duty. It was gifted to me by a friend and also came with a Haunyang 3hp VFD. He bought it for a project but decided to upgrade before using it. I'm not super thrilled about having to setup the Chinese VFD as my first VFD but the price was right. Hopefully someone here can walk me through it. The manual is a nightmare to read.

pm932_VSD_mount_01.gif pm932_VSD_mount_02.gif

Tore down the gear head and removed the spindle. I had taken the cover off about 3 months after getting the mill to install the pneumatic drawbar and at that time the gear oil looked good so I left it alone. A year later the oil is almost black and smells burnt. After draining the oil and cleaning out the head with solvent I found lots of casting grit in the bottom. The splined shaft that drives the spindle has score marks where it rubs against the seal. I think this is where the oil was leaking from. It is hard to tell in the photos but the polished areas are about 0.006" deep

pm932_splined_shaft.gif

Another item of concern I found was the condition of the spindle bearings.

Upper bearing race.
pm932_upper_spindle_bearing.gif

Lower bearing race.
pm932_lower_spindle_bearing.gif

and lastly, the quill pinion was not orientated well with the rack gear on the back of the quill body causing wear marks on the pinion gear. The quill has hardly been used.

pm932_quill_pinion.gif

My original plan was to maintain the quill travel but after getting more comfortable with the CNC machining I see no reason to keep that on so I now plan on fixing the quill in place. I'm curious how others have done this? I'm not sure I would trust the quill lock alone???

Next step is to get the bearing races out of the spindle housing and install the AC bearings. The upper should'nt be too bad but I'm not sure how I'm going to get the lower bearing out as the is very little room to catch and edge for pressing and the center bore is smaller than the bearing race so access is limited. I'm open for suggestions on what others have done?

Jay
 

jbolt

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#96
After searching several belt drive conversions of these types of mills the consensus is to use the existing splined shaft that couples the gears to the spindle. The gear is turned off the shaft and the end opposite the snap ring groove is threaded to accept a nut. One on my goals with this build is to not make any permanent modification that would prohibit the machine from being returned to it's original configuration as a manual mill. So to do this mode I needed another splined shaft. I like the people at Precision Mathews but they are still a growing company and not knowing how long it would take to get parts I dug around on the net and found the Grizzly G0755 to be the exact same mill. Ordering from Grizzly is easy so I ordered a splined shaft and had it in two days.

As expected the shafts are identical.
pm932_G0755_slpined_shaft_01.gif pm932_G0755_slpined_shaft_03.gif

The original shaft from my machine has score marks on it from casting grit in the gear oil rubbing in the seal so I will use that one for the modification and keep the new part as is.

The Grizzly part number is P0754057 http://www.grizzly.com/parts/P0755057

Before modifying the splined shaft I made some modifications to the spindle and turned a clamping nut for the power drawbar system. I have been using an impact wrench type system for a power drawbar but I have really come to dislike these systems. They are noisy, put a lot of stress on the bearings and tooling from the hammering and do not provide adequate torque for the TTS tooling system. On the CNCZone There is a thread about an electric drawbar using a stepper motor and a planetary gearbox. I'm really intrigued by this idea but unfortunately electronics are not my strong pint so I will be using a multi-stage air cylinder and bellville spring washer system for now. I plan on exploring the electric design in the future.

Spindle threaded to accept the clamping nut.
vsd_clamping_nut_01.gif

Clamping nut turned from 3-1/4" A36 steel.
vsd_clamping_nut_02.gif vsd_clamping_nut_03.gif vsd_clamping_nut_04.gif vsd_clamping_nut_05.gif vsd_clamping_nut_06.gif
 

jbolt

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#97
Made some good progress on the belt drive conversion this week. The spindle bearings have been changed to angular contact bearings. The bearings are a press fit so I had to heat / cool components to get the bearings to drop in. That all went well except I forgot to preload the bearings when I put the spindle in the quill body. After the parts had cooled and or warmed up the locknut on the spindle would not move the bearing. I ended up using a piece of pipe, with the ends turned true, over the splined end and made a shim the thickness of the up-down play in the bearings and used those to press the bearing into the proper position. Keeping my fingers crossed I got enough preload on the bearings .

The pulleys are for poly-J belts. This has been used in a lot of other belt drive conversions so I went with it. The only downside is the vee-grooves are 40 deg. Carbide inserts for these are very expensive and seem to only come in 5 or 10 packs so the solution is to grind a cutter from HSS. I went with the typical 1:2, 2:1 pulley ratios. One thing to note is the splined sleeve has a pocket for a 6mm shaft key. I have a set of standard keyway broaches so I cut a 3/16" keyway in the pulley and made a 6mm to 3/16" adapter key out of 1/4" keyway stock.

The spindle, head cap with spline drive, pulleys and motor are installed and I was able to manually run the motor for the first time tonight. Everything ran great up to full speed (about 7K rpm at 120hz). My biggest issue is the noise and some vibration from the splined sleeve/shaft area. I'm not sure if others have run into this same issue. It is a lot noisier than I expected but not nearly as noisy as the gear head. I will try and post a video of the noise problem later in the week.

spline drive pulley.gif spline drive parts.gif pulley swarf.gif belt drive 02.gif
 

dracozny

Active User
Active Member
#98
....

My original plan was to maintain the quill travel but after getting more comfortable with the CNC machining I see no reason to keep that on so I now plan on fixing the quill in place. I'm curious how others have done this? I'm not sure I would trust the quill lock alone???
....
Jay
I use the quill lock by itself, it provides plenty of pressure to keep the quill from moving when in use, it also slips just barely to save me when I screw up. IE pressing the wrong button to cause the head to plunge into my part or into my tool height set gauge....... the gauge survived, the end mill did not. had the quill not slip under that pressure I would have lost both.
 

jbolt

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These are my VFD and Mach3 Spindle settings. Maybe it will be of some help to others.

On first setup I had trouble with the 0-10v PWM scaling between the VFD and Mach3. Any speed setting in Mach3 over 45% would send the motor full speed. Hours of searching and some help from PMDX support traced down the problem to VFD parameter PD072. This value needed to match PD005, the Max Operating Frequency. It was factory set to 400hz. I believe it took so long to find is that most of these Chinese drives are used with high speed spindles that operate at 400hz where as I am running a 60hz motor up to 105hz.

The PMDX-107 motor control has a great built-in calibration feature. Pressing the test button on the board for one second will start the motor at full speed for 30 seconds, a second press reduces the speed to 30%. This is great for isolating whether there is a problem with the VFD settings or in Mach3. To calibrate you set a trim pot at full CCW, press the test button and measure the spindle speed. The trim pot is used to adjust the spindle speed to match the expected full speed based on the motor/vfd/pulley settings.

My settings for PWM motor control with Mach3:

PMDX-126 BOB, PMDX-107 Motor Control, ESS Motion Controller.

MOTOR, 220v, 2hp, 3ph, 1725rpm, inverter duty, class F

VFD = Huanyang HY02D223B 3hp VFD Settings
pd001 = 1, run command = external terminals
pd002 = 1, operating frequency source = external terminals
pd003 = 60.00, main frequency
pdoo4 = 60.00, base frequency
pd005 = 105.00, max frequency (could be 120.00 with a better motor)
pd008 = 220, max voltage
pd014 = 5.0, acceleration time (user adjustable preference)
pd015 = 5.0, deceleration time (user adjustable preference)
pd070 = 0, analog input = 0-10v
pd072 = 105.00, Higher Analog Frequency
pd141 = 220, rated motor voltage
pd142 = 8.0, rated motor current (check your motor specs)
pd143 = 4, motor pole number (check your motor specs)
pd144 = 1725, rated motor revolution (check your motor specs)
pd176 = 60.00, inverter frequency standard


Ethernet Smooth Stepper Settings
SPINDLE
PWM, base hz 25


Mach3 Settings
RELAY CONTROL, disabled

MOTOR CONTROL
Use Spindle Motor Output
PWM Control
PWM Base Freq = 25
Minimum PWM 1% to 5%

SPINDLE MOTOR TUNING
Steps per = 1000
Velocity = 60
Acceleration = 5000

PULLEY SELECTION
Pulley 1, Min Speed = 0, Max Speed = 6000, Ratio = 2 (4" motor pulley, 2" spindle pulley)
Pulley 2, Min Speed = 0, Max Speed = 1500, Ratio = 0.5 (2" motor pulley, 4" spindle pulley)

Minimum speed needs to be zero or Mach3 will screw up the PWM scaling. If there needs to be a minimum motor rpm threshold it should be set in the VFD.
 

jbolt

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The VFD upgrade is done and working well. It will take a while to get used to machining at three times the speed I was before. I machined the the new power drawbar mounts and I was a bit tense watching new programs run at the higher machining speeds.

VFD01.gif VFD02.gif

The new power drawbar system is finished. A 4" 3-stack multi-stage air cylinder pushing a stack of 2700 lb bellville washers at a 100 psi. I have the tension set on the bellvilles to where the TTS tool holder will just release. I'm hoping this will solve or at least improve some of the pullout issues I was having. I purchased a foot switch to use on the floor but decided I didn;t like all the extra air line so I mounted the foot switch to the side of the head. I will make a better hand lever later and remove the foot pedal.

PDB01.gif PDB02.gif PDB03.gif

Also finished is the DIY fogbuster. Now I have both flood and mist.

Mist01.gif Mist02.gif
 

jbolt

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A little video of the spindle mods in action. I have been trying different machining strategies to see how far I can push the machine. The cutter is a 3/8" 2-flute carbide at 6000 RPM. The first outer contour cut is full depth at 0.5", 17 in/min, and the second circle cut is the same speed and feed but stepped 0.09". No signs of tool pullout on the TTS.

 

GaryL

Active Member
Active Member
The mill is once again operational.

The Y-axis motor and drive have been replaced. The head was knocked out of tram by 0.080" which surprised me.

I was able to reconfigure my control box that houses the drives , BOB and controller so all the components can be individually removed without having to disassemble half the box.

I installed a new PMDX-126 BOB, PMDX-107 spinde control card and an Eithernet Smooth Stepper (ESS) in place of the old generic BOB and UC100 controller. This was much more complicated to setup. The PMDX suffers in places from too much information in the manual and a little too cut up for my liking but I managed to fiddle my way through it. The ESS suffers from too little documentation. Hurray for online forums and Google! Anyway I really like how the ESS nests on top of the PMDX-126 as a daughter board. Very tidy setup. I am having an odd issue where if a limit switch is triggered the keyboard jog function no longer works unless the system is power cycled. Additionally, if I plugin the xbox controller the keyboard jog and fly-out jog become inactive? Fortunately the xbox controller works fine which is what I normally use for jogging anyway.

I installed the new coolant shields. The shield around the table is really slick and does a great job of directing coolant off the table without it getting into everything. The rubber way cover is also working out nicely. One end connects to the cross slide and the other end to the Z dovetail. To keep the rubber sheet from bunching behind the table I added an intermediate support that is suspended from the column. It's a little Rube Goldberg-ish but so far it is working well.

Next is to machine the motor mount for the belt drive conversion.

View attachment 97448 View attachment 97449 View attachment 97450
Hello Jay, I am in the middle of converting my PM 45M cnc mill from the Chinese board to a PMDX-126, PMDX-107, and an ESS. I was wondering if you might have some words of wisdom that might save me some time setting it up.
 

jbolt

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Hi Gary,

Cool, I really like this setup!

Are you using a VFD for motor/spindle control? That was my biggest hurdle.

If you have any specific questions on the wiring I'll do my best. I found the manual confusing since I didn't understand a lot of the terminology he uses and the examples assume you have a clue.

Jay
 
Last edited:

GaryL

Active Member
Active Member
I'm glad that this combination worked out well for you. Their is a lot to learn about properly connecting these components to the mill and then setting up mach3 to work with the hardware. My mill came with a VFD and it was already setup, it seems at least so far that the connections to the 107 are not too difficult, but I still have to set up Mach3 and test it. I am currently in the process of connecting the home and limit switches to the BOB. If I get too bogged down I will be happy to ask for help. Prior to this undertaking, my only mill project was to change the X and Y home and limit switches and there some good videos for it.
 

jbolt

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Is your mill one of the CNC versions from PM? Did it have just a basic BOB? I've never seen the inner workings of their controller. Did you post any photos?
 

jbolt

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Used the CNC router to make some new cover panels for the mill head and control box. The black is not my first choice of color but it is what I had on hand for another project.

20160410_115823.png 20160410_115840.png 20160410_115901.png
 

Oc Customs

Iron
Registered Member
Im doing a similar build i have a new enco 405-0593 mill. My question to you is where did you buy the pulleys and belt from for the vfd. Im going to try and use a 3kw water cooled spindle for driving my pulley and gearing it down to 8k rpm from 24k. This should also up my power from 4hp(advertised rating to 12hp) theoretically. i prefer some decent size pulleys for maximum contact area.
 

jbolt

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Im doing a similar build i have a new enco 405-0593 mill. My question to you is where did you buy the pulleys and belt from for the vfd. Im going to try and use a 3kw water cooled spindle for driving my pulley and gearing it down to 8k rpm from 24k. This should also up my power from 4hp(advertised rating to 12hp) theoretically. i prefer some decent size pulleys for maximum contact area.
I made the pulleys and purchased the Poly-v belt from McMaster Carr. The poly-v has a 40 deg groove so I ground a single point cutting tool from HSS.

How will the drive pulley attach to the spindle?

Be sure to start a build thread and post pictures.
 

Oc Customs

Iron
Registered Member
I am going to a the pulley on a separate .5in shaft and bearing holder block and then use the .5 collet and tighten it down as much as i can. They are er20 collet so hopefully they will have a decent bite on the shaft. this way The belt tension wont be directly on the vfd spindle bearings. atleast that is my thoughts.

Once i get some progress i will post a thread and pics on it.
Im going to convert it to cnc first then build the vfd and pulleys.

Did you use the 2005 ballscrew for x ans y axis too?

Anything i missing or concerns that you see. i called about the spindle bearings in these machines and they are rated at 75oo rpm and burst to 12k for the lower, the upper bearings are 12k rpm.
 

jbolt

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I used 2005 on all axis. The X axis was the closest fit. I would pull the table and measure to confirm how much room you have. It seems all the RF45 clones vary a bit.

I'm assuming you are going to remove the gears from the head when you do the vfd conversion. If the machine spindle bearings are AC bearings you should be good. If they are taper roller bearings I would be surprised at that rating.
 

Oc Customs

Iron
Registered Member
The lower is roller taper based off the grizzly model you said, Part #56 in the go755, Part number 30206-p5 this is the lower 75oo rpm rating one. I used that number and called a bearing company to get the specs, it can go to 12k but not continuously. The 2 upper bearings that you replaced , part number #29 of the manual is P6007zz. Bearing company said 12k rpm .

Now i haven't taken mine apart. Im just assuming its gonna be the same. Cause in my manual for my machine it only gives enco part number not the actual bearing part number like grizzly does. And yes all gears will be removed for vfd conversion.

Did you do double nut ballscrews?
 

jbolt

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There are two taper roller bearings on the spindle. On the Grizzly machine they are the 30206 & 30207. The two P6007zz bearings support the spindle drive sleeve that allows the quill to move up and down.

After I did the CNC conversion but before I did the VFD conversion I ran the mill a lot at the max 1970 RPM. CNC runs would go for several hours at a time. The taper roller bearings were worn when I removed them so I would be reluctant to run them at 6k for an extended time.

I used two single ball nuts on each screw and set the preload using Bellville washers on the mounting screws. It takes some trial and error to get them set. Tom S. started with a single ball nut and just recently switched to double ball nuts which are working well for him. I would probably go this route if I were to do it again.
 

Oc Customs

Iron
Registered Member
well the bearings i can replace tapered ones are rated at 7500 continuously. maybe add a big oil cooler to help with the heat and changing the oil to a synthetic and frequently changing it. I personally only will make aluminum parts. And even then its not like im going to run for all day.

For the aluminum i need high rpm or it will take a long time to machine something. I also think i can get a better finish with pushing the tool faster. The tools for aluminum want the high rpm range so i would like to keep it in their happy zone. lol

I plan on doing it the same way you did and not make anything permanent. So if something happens i can still revert back to stock setup.
 

jbolt

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How long of a run time are you doing at 6k? And is the head getting hot?
I have run 3D parts in aluminum that have taken over 12 hours to complete. I use a high performance AC bearing grease. The spindle never gets more than 5 or 10 deg above ambient.
 

Oc Customs

Iron
Registered Member
If i gave a cad file could you make me my pulleys i want? Im looking somewhere around 7.5 and 3.75 diameter ones. How much would i be looking at roughly. Im going to use the same belt style like you did. Probably just a wider rib belt like an 8 rib.
 

jbolt

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I could but I'm still waiting on my new lathe so it would be mid September before I have it up and running.

Send me a drawing and I can give you an idea.
 

ncf250sd

Iron
Registered Member
Jbolt,
Hey all!

I have a pm940M for several months now and do plan on a cnc conversion in the near future. I want to start by converting the z axis first and would love to get a copy of your dimensional drawings if you don't mind sharing them.
 

jbolt

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Jbolt,
Hey all!

I have a pm940M for several months now and do plan on a cnc conversion in the near future. I want to start by converting the z axis first and would love to get a copy of your dimensional drawings if you don't mind sharing them.
Excellent! I will be envious of your extra Y travel!

I'm happy to share but you will have to confirm they will work for your mill. PM me your email and I will send what I have.

What type of motors will you be using? My Z is driven by a 42 size stepper with a 2005 ball screw and nut so parts were made accordingly.