[TurboStep]

Mike sr -
I’m hoping that the pulleys are the cause because compensating for a motor imbalance is likely to be much more difficult. A Haas isn’t an option for me and I really don’t need the performance. However, when using smaller tools it would be really nice to be able to take advantage of the 5100RPM speed while using a realistic feed rate. Some of my finishing operations currently take forever! I’m going to see what I can do with the pulleys but I’d be very interested in what you can achieve.
Step

[Steve Seebold]

I have found that I can ruff at 5000 RPM, but if I try to finish at that RPM, my parts look like I cut them with a hacksaw. If I slow down to 4,000 RPM for the finish cuts, all is well.

[mike sr1]

Mike sr -
I’m hoping that the pulleys are the cause because compensating for a motor imbalance is likely to be much more difficult. A Haas isn’t an option for me and I really don’t need the performance. However, when using smaller tools it would be really nice to be able to take advantage of the 5100RPM speed while using a realistic feed rate. Some of my finishing operations currently take forever! I’m going to see what I can do with the pulleys but I’d be very interested in what you can achieve.
Step

I ordered one of those Fenner belts from ebay friday, I will post as to how it does when I get it installed.
The motor vibration goes way down when the belt is removed, so I am hoping thats most of the problem.....

[tbaker2500]

I liked the anti-vibration properties of the Fenner belt, but I didn't like the whistling. The high-frquency noise is higher.

[rowbare]

Bob,

The drill bit I am using is carbide with slow spiral. I do not think is possible to drill in a single pass in plastic (15d). With the heat generated you will melt the plastic...

I saw one video of Titex and is impressive! Of course, you need TSC...

Ricardo

Looks like this thread has gone off on a bit of a tangent but what plastics are you cutting and what feeds and speeds are you using?

bob

[riabma]

Looks like this thread has gone off on a bit of a tangent but what plastics are you cutting and what feeds and speeds are you using?

bob

Ertalyte (PET-P). For 2 mm: 3000 rpm and 500 mmpm.

Ricardo

[twocik]

"Looks like this thread has gone off on a bit of a tangent but what plastics are you cutting and what feeds and speeds are you using?"


But aren't those the best ones to read.....


Let me know how the belt works out, maybe we should start a new thread on finishing.

[samco]

There are linuxcnc configs for both the 1100 and 770. I don't know how complete they are. As far as I know they work.

I am mentioning this because if you add a normal 3 channel encoder (ABZ) to the spindle - you could rigid tap. IIRC the tormach uses all of the pins of the printer port - so you would have to add one for the spindle encoder. Also - if you are using the printer port for counting the encoder you would want to pick one in the 100ppr range. (so the computer can count at higher rpms)

sam

[mike sr1]

I installed the Fenner belt, it is a bit quiter but most of the vibration is still there. If those motor and spindle pulleys are cast, which I suspect they are, then that could be the problem, I may at some point take them off and check the balance or if there is enough meat on them just machine all the surfaces......
Kind of one of those "roundtuit" things ha!

[riabma]

Interesting issue about the pulleys...
Yesterday I have been machining some aluminum parts and I programmed a second finish pass at 3000 rpm with the same feeds. The finish is much better. You can still seeing the 'waves' but after sandblasting with glass bead the finish is great.
Ricardo.

[Steve Seebold]

Interesting issue about the pulleys...
Yesterday I have been machining some aluminum parts and I programmed a second finish pass at 3000 rpm with the same feeds. The finish is much better. You can still seeing the 'waves' but after sandblasting with glass bead the finish is great.
Ricardo.

I do my finish cuts at 4,000 RPM with feed rate 20 so 25 IPM, then I put my parts in a vibratory tumbler with ceramic media for about an hour and they come out almost polished.

Then if I want a better finish, I put them back in the tumbler in crushed walnut shells and jewelers rouge. That polishes them. Only problem with this procedure is, it takes a couple of days.

I did a test batch of parts once. I let them run in the walnut shells for a week, and they came out with a finish I could use as a mirror to shave with.

[riabma]

Hello to everybody,

I have been thinking all this time and I decided that I am going to keep my Tormach. I am still looking for a production machine and I will use the 1100 like a second machine, prototyping, fixtures, etc...

I had my first contact in machining with the Tormach and (it can sounds very silly, hehe...) and I am very attached to the machine. I learned a lot of things and I want to keep it for a LONG time.

I appreciate all your comments and feedback all this time. They were really helpful.

Thanks!

Ricardo

[Steve Seebold]

Good choice Ricardo, but if you want a production machine, if memory serves me correctly, you were talking about a Haas Mini2. They are a nice LITTLE machine, but if you have the room, I could consider a VF1 or a VF2.

If you go with the Mini, you'll be giving up a considerable amount of Z axis capacity.

[dak1]

I have no affiliation whatsoever with this company nor have any idea of cost or whether you can utilize on your machine. I just recently learned of them as we are looking into a new HMC & asked about programmable coolant. Here is a youtube vid that might interest you for you drilling application. They have a dual nozzle system also & I'm sure there are others out there as well. Looks pretty slick.


[ame=http://www.youtube.com/watch?v=yP2z4149o1g]Original Model SpiderCool Flood Coolant Operation - YouTube[/ame]

[Spinnetti]

yah know, if drilling lots of holes is your thing, why not make up a drill head with x number of drill motors (maybe a bunch of air powered pencil drills) and drill a whole mess at once with your existing mill. More than one approach to a problem

[mike sr1]

I installed the Fenner belt, that may have helped a bit but not much.

I removed the motor and balanced the pulley as best I could(helped somewhat), the vibration is coming from the motor, and pulley combination or at least most of it.
The motor is a 1715 rpm, and at that rpm up to about 3600 rpm the balance of the rotor is good, past that it isnt so good, but it is being used out of its design balance range with the addition of the VFD.

There is no set screw to hold the pulley on the shaft, a center bolt is used to do that but it allows the key and shaft to float inside the pulley, I used locktite on mine so it wouldnt move and produce wear between the two components.

From what i see so far to get a better balance the armature, pulley assembly needs to be rebalanced up to the maximum VFD rpm. That may well prove to be expensive.
The spindle pulley I havent checked yet as most of the vibration seems to come from the motor and pulley assembly.

My machine seems to be good up to just under 4000 rpm so thats what I will use for the time being......

[TurboStep]

I originally wanted to submit a full report on my balancing work but as Mike is also working on this I decided to share the first part concerning the motor and motor pulley.
After removing the belt and just running the motor I could still detect a significant vibration. I continued by removing the motor pulley but the vibration was still present.
Looking up inside the “dome” at the top of the motor I could see something white, wobbling a little as the motor turned. Removing the dome revealed a plastic fan. I removed the fan and supported it axially on a light, horizontal tube as an initial balance test. This fan is clamped to the motor with a single screw and although it has a cutout this is presumably not intended to compensate for the weight of the screw, washers and nut. The first photograph shows an additional screw that I added (shown on the right side) as a counterweight. My original idea was to be able to first select an appropriate screw length and then adjust the position of the screw as a fine adjustment but it turned out that the fine adjustment wasn’t necessary. However, trial and error didn’t get me close enough, so inspired by the work of G. G.Kamysz (see CNC Milling Spindle @ DIESELRC.COM) I set up a small loudspeaker as a sensor and a reflective opto detector as an indexer for the position reference as shown by the second photo. The motor was removed from the mill and placed horizontally on rubber strips in order to allow it to vibrate freely.

THIS IS A DANGEROUS CONFIGURATION AND IS NOT RECOMMENDED!
The rotating pulley and fan were fully exposed while rotating at high speed . I was also very careful to switch the motor on and off only at the minimum speed setting because I was particularly concerned that fast deceleration caused by the brake could throw the motor off the table! Please don’t get hurt – either find a better, safer way to do this, or just forget it!

The third photo shows an example of what I saw on the oscilloscope. A peak in the waveform indicated the position of the excessive weight relative to the index pulse. Using this technique I was able to balance the fan end of the motor quite easily.
To balance the pulley end I drilled and tapped 3 pairs of M5 holes, 10mm deep at 120° separation in a pulley (I had ordered an additional set of pulleys because I needed an operational mill to machine the pulleys). The idea was to add grub screws as necessary in order to achieve the balance. My initial attempts with allen grub screws wasn’t very effective because these screws are essentially hollow and weren’t heavy enough. I therefore made some heavier grub screws by cutting the end off a couple of standard screws and making a small slot in one end. A combination of both types of screws was sufficient.
The end result was quite pleasing. With the motor and pulley re-mounted in the mill they now ran with very little vibration over the entire speed range.

While an oscilloscope may not be in everyone’s toolbox it might still be worth trying to balance the fan statically on a light plastic or thin walled alu tube.

In Part 2 (in a couple of days) I’ll describe what I found on the spindle end, and of course the all important results.

Step

[mike sr1]

I originally wanted to submit a full report on my balancing work but as Mike is also working on this I decided to share the first part concerning the motor and motor pulley.
After removing the belt and just running the motor I could still detect a significant vibration. I continued by removing the motor pulley but the vibration was still present.
Looking up inside the “dome” at the top of the motor I could see something white, wobbling a little as the motor turned. Removing the dome revealed a plastic fan. I removed the fan and supported it axially on a light, horizontal tube as an initial balance test. This fan is clamped to the motor with a single screw and although it has a cutout this is presumably not intended to compensate for the weight of the screw, washers and nut. The first photograph shows an additional screw that I added (shown on the right side) as a counterweight. My original idea was to be able to first select an appropriate screw length and then adjust the position of the screw as a fine adjustment but it turned out that the fine adjustment wasn’t necessary. However, trial and error didn’t get me close enough, so inspired by the work of G. G.Kamysz (see CNC Milling Spindle @ DIESELRC.COM) I set up a small loudspeaker as a sensor and a reflective opto detector as an indexer for the position reference as shown by the second photo. The motor was removed from the mill and placed horizontally on rubber strips in order to allow it to vibrate freely.

THIS IS A DANGEROUS CONFIGURATION AND IS NOT RECOMMENDED!
The rotating pulley and fan were fully exposed while rotating at high speed . I was also very careful to switch the motor on and off only at the minimum speed setting because I was particularly concerned that fast deceleration caused by the brake could throw the motor off the table! Please don’t get hurt – either find a better, safer way to do this, or just forget it!

The third photo shows an example of what I saw on the oscilloscope. A peak in the waveform indicated the position of the excessive weight relative to the index pulse. Using this technique I was able to balance the fan end of the motor quite easily.
To balance the pulley end I drilled and tapped 3 pairs of M5 holes, 10mm deep at 120° separation in a pulley (I had ordered an additional set of pulleys because I needed an operational mill to machine the pulleys). The idea was to add grub screws as necessary in order to achieve the balance. My initial attempts with allen grub screws wasn’t very effective because these screws are essentially hollow and weren’t heavy enough. I therefore made some heavier grub screws by cutting the end off a couple of standard screws and making a small slot in one end. A combination of both types of screws was sufficient.
The end result was quite pleasing. With the motor and pulley re-mounted in the mill they now ran with very little vibration over the entire speed range.

While an oscilloscope may not be in everyone’s toolbox it might still be worth trying to balance the fan statically on a light plastic or thin walled alu tube.

In Part 2 (in a couple of days) I’ll describe what I found on the spindle end, and of course the all important results.

Step

Step,
Carry on with the balanceing, I am very interested in your findings as well.
I used more crude methods on the pulley end, I located the heavy side then drilled and tapped it 1/4-28 and used grub screws to get it close, the fan end I havent had off yet, I was thinking about sending it out to a motor shop and having it done, but I dont want the machine down, so a bit of a quandry there ha!
I did loctite the motor pulley on to the shaft because unless its tight it will wear eventually and cause other problems.
Mine is good to about 4000 now, but needs to be better.
It is a 1750 motor and at the design rpm (name plate) it works fine.
I look forward to your findings..
mike sr

[Spinnetti]

I just got my machine setup, and don't know that much about how it "should" be, but noted that over 4000 it got loud.. would it be normal practice to take the motor with pulley and fan to a motor shop and have them balance? Rather have somebody with the right tools do it if possible... seems kind of odd it wouldn't be balanced for its rated speed ?

[philbur]

Machines do get louder as they go faster. No it is not normal practice to take the motor off and balance it. TurboStep is having fun but is possibly going a bit OTT.

One should take care not to develop a machine related hypochondria. Like its' medical relative, it can get very expensive for no real benefit. If you think you have an issue talk to Tormach, don't take everything you read on the Internet at face value.

Phil

I just got my machine setup, and don't know that much about how it "should" be, but noted that over 4000 it got loud.. would it be normal practice to take the motor with pulley and fan to a motor shop and have them balance? Rather have somebody with the right tools do it if possible... seems kind of odd it wouldn't be balanced for its rated speed ?