TM 2 Vibrating

[bigbaz]

Just did a job in 5" aluminium round bar were i machined around the outer side of bar in a clockwise direction climb milling then the inside of bar working in an anti clockwise direction climb milling. Noticed bad vibration at 12 o clock position on one opp and 6 o clock position on the other , I am thinking it could be thrust bearings that need adjusting any thoughts.

[tobyaxis]

I worked with a TM3 that squeaked at certain positions in the "Y" Axis. This machine was new. I would say Thrust Bearings could be the cause. When was the last Maintenance on the machine? Better yet how old is the machine?

[SORCHEROR]

i dont think its a machine problem,what cutter did u use and speeds and feeds?
is your tm-2 older?

[tobyaxis]

Originally Posted by bigbaz Just did a job in 5" aluminium round bar were i machined around the outer side of bar in a clockwise direction climb milling then the inside of bar working in an anti clockwise direction climb milling. Noticed bad vibration at 12 o clock position on one opp and 6 o clock position on the other , I am thinking it could be thrust bearings that need adjusting any thoughts.

There is also the possibility of Wear on the Linear Ways.

Did you program 360 degree interpolations, 180 degree, or quadrants? If 180 degree or quadrants it could be Feeds and Speeds as mentioned in the above post.

[Geof]

I have had a similar thing happen on a TM2, on a MiniMill and on a Super MiniMill and I am certain it is not due to loose thrust bearings or worn guides.

My diagnosis is that it is just a resonance effect; non of these machines are really massive and rigid and it seems the vibration occurs when the cutting action of the tool is tending to rock the table around the Y axis, 12 o'clock and 6 o'clock.

I have found the amount of vibration depends on how much weight is on the table and it is different on the Super MiniMill depending on whether I have my HRT210 mounted on the right hand end of the table or not.

Try tweaking speeds and feeds and if it really worries you try using a vari-flute cutter to reduce the resonant excitation.

[bigbaz]

The machine is a late 2005 that had very little use and the cutter is a 10mm two flute solid carbide slot drill 45 degree for aluminium running at 4000 rpm 1000 mm/min 10mm z depth and 3mm radial, programed in cad to do 360 degree then step over 3mm and go again.

[Geof]

Have you tried tweaking the speed and feed using the overrides? This is a good first approach when chatter/vibration is encountered on any machine.

[bigbaz]

Adjusted feed up and down 10% at a time with little affect and i think speed and feed are spot on for this type of machine, the bad vibration only peeks at 6 and 12 o clock depending on clockwise or anti clockwise movement the rest is not so bad thats what made me think a little play in the thrust bearings is being found by the pulling action of the cutter.

[bad bearings]

I'm not familiar with the "TM2" but if this is a pretty lightweight machine, it is possible you've hit some natural frequency in it's structure. I had a similar vibration problem with an old Bridgeport "H" head which has a lightweight aluminum casting suspending the motor. Some plumber's putty applied to the inside of the casting cured the feedback and chatter problem. Perhaps you might try a similar approach if your machine is not stout enough to transmit the energy to the floor. Plumber's putty is relatively safe and great for sound absorption. If you can find some large surface area to apply the putty to it will absorb the energy and reduce the feedback. It won't look pretty but you may be surprised at the results.

[Geof]

Originally Posted by bigbaz .....thats what made me think a little play in the thrust bearings is being found by the pulling action of the cutter.

Interpolate a hole very slow with a small cut so there is no vibration, also interpolate an O.D.

If any thrust bearing have a lot of slop you will be able to see steps or flat spots at 12, 3, 6 and 9 depending on which axis is sloppy.

Then do the same thing at faster and faster feeds but keep the cuts very small.

If the thrust bearings have only a little slop which shows up only when there is a strong acceleration loading you will see steps or flat spots develop at higher feed rates.

I think it is very unlikely you will find anything.

[Matt@RFR]

Originally Posted by bigbaz (snip) programed in cad to do 360 degree then step over 3mm and go again.

I assume you mean that it was programmed using a CAM program. Post the code. It may be possible, depending on the quality of your model/geometry, that your CAM spit out lots of tiny moves at those points on the circle.

[JohnJW]

Originally Posted by Geof My diagnosis is that it is just a resonance effect; non of these machines are really massive and rigid and it seems the vibration occurs when the cutting action of the tool is tending to rock the table around the Y axis, 12 o'clock and 6 o'clock. I have found the amount of vibration depends on how much weight is on the table and it is different on the Super MiniMill depending on whether I have my HRT210 mounted on the right hand end of the table or not.

It it better to put more weight on table or less?

Thanks,