# Mini mill vibrates a lot



## Alberto-sp (Apr 21, 2022)

Hello.

I have a minimill. Is a chinese weiss 18vm. Its configuration is very similar to a precision matthews, but smaller, it weights 133 LBS while the precision matthews weights 340 lbs.

The question is it vibrates a lot. Sometime ago in other forum I asked about that because I was using a face mill (2 inches) and that could be so big for that machine, but now I´m using a HSS TiN coated 10mm  2 flute end mill in aluminium and it is the same.  I tried at 1.000, 1500 and 1.900 rpm and it vibrates a lot. The deep of cut is 3 mm and no matter the feed rate. Even at 0,3mm per second feed rate.

I lock all the slides, I tight every scree I can, except of course ones I need to move the table. The mill is firmly bolted to the  table and I have put a thick layer of dense rubber between the  milling machine an the table to try to avoid vibration.

I leave you a video.  




Is that normal? I know is a 1.300 USD chinese machine, but I don´t know if  it is normal  so much vibration

Thank you

best regards


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## markba633csi (Apr 21, 2022)

Seems normal to me, how is the finish?  Are you using good, sharp tools?
Have you measured for runout on the smooth portion of the endmill shank?  Are you using a spindle adapter/collet chuck with excessive stickout?
The spindle bearings on those cheap machines are often of marginal quality, even when new
Have you any experience of operating larger, heavier machines? Light machines lack rigidity and are prone to chatter
Try some slower speeds in the range of 400 to 600 rpm
Lock the head firmly. Use some type of cutting fluid
-Mark
ps Check for looseness in the fit of the quill to the head- it should not rattle (if machine has a quill)
pss 3mm deep cut is nearly 1/8" which believe it or not is a fairly heavy cut for a small machine, try 1mm
psss also try 3 or 4 flute endmills. 2 flute cutters clear chips better but vibrate more and leave a rougher finish


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## Alberto-sp (Apr 21, 2022)

Thanks for your answer.

I´m new in machining, so I haven´t used other machines and no idea if that is normal. I see videos in youtube of home machinist with machines like mine and I feel theirs vibrate less, but of course, this is not very acurate, is only my perception.

The tools are new and sharp. Not the best ones, but not the worst

About measuring the runout on the smooth portion of the endmill shank, I have no idea about what is that.

I have just tried lower speeds and the vibration is less. Also reduced the deep of cut and improve again, but changing to a 4 flute end mill has improved a lot.  I tried with 1.900 because I calculated that RPM. And yes I lock the quil fimly and use cutting oil.

How can I Check for looseness in the fit of the quill to the head?


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## DavidR8 (Apr 21, 2022)

Is your quill locked when you are milling?


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## Alberto-sp (Apr 21, 2022)

This lever? Yes. I tight all the levers except the ones I need to move the table


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## DavidR8 (Apr 21, 2022)

Yes that's the one I was thinking of.


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## epanzella (Apr 21, 2022)

Have you checked tram on your machine? A 2 flute end mill on an out of tram table suddenly becomes a one flute. 3mm DOC on that machine is too much. Try half that.


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## Ken from ontario (Apr 21, 2022)

I would loosen and re-adjust all the gibs (head, table), it is possible the he head for example, is still slightly loose even though you clamp it,  same goes for the table, I also recommend  you try a different collet , clamp it tight and see if you notice a difference.


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## Alberto-sp (Apr 21, 2022)

Thank you so much for your answers and help.

Yes I have checked the tram. I have ajusted it as much I cant.  I put a square in the table and a micrometer atached to que quill and I don´t remember now, but I think the desviation from the vertical part of the sqare is maybe 0,0005" per 4 inched of the square.

I was triyin 3 mm because I have read you should use up to the half of the end mill OD, but now reading you I now I was wrong. This calculations must be for bigger and more quality machines.

And yes, I removed, cleaned and oiled all the gibs.


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## markba633csi (Apr 21, 2022)

I think you are doing fine Alberto, making small improvements you will arrive.
Measuring runout as I mentioned requires a dial indicator or test indicator, mounted on the table and making contact with the
rotating part in question, in this case the endmill shank, or a piece of precise steel (silver steel or drill rod) mounted in the spindle
then turning the spindle slowly by hand
I do not believe you have excessive runout however
-M
You are correct, speed calculations are often for large, heavy, powerful machines rather than small hobby ones
in order to obtain maximum material removal and lowest cost production- not as important for us hobby nerds


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## Ken from ontario (Apr 21, 2022)

Alberto-sp said:


> Thank you so much for your answers and help.
> 
> 
> 
> ...


It takes a while to find what works best with these small mini mills, to figure out   feed , speed, and depth of cut with these machines is something you need to also feel and hear, I am still learning everyday especially with new tools or different materials.


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## Eyerelief (Apr 21, 2022)

I started out many years back with a small mill like that.  I had much better success with four flute cutters, even in aluminum.  Carbide for steel, HSS for everything else.


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## homebrewed (Apr 22, 2022)

I have an SX2 mini mill and my typical depth of cut is around .01" for steel.  More than that and the vibration gets pretty bad.  DOCs can be greater for softer materials.  I have a few 2-flute end mills and they are much more vibration-prone than the 4-flute ones.  I have a 1/2" roughing mill that allows me to go to somewhat greater DOCs but it's not a huge improvement, maybe 2-3X is all.

These small DOCs can make some jobs take awhile so when I have have to remove a large amount of material I look for alternate ways to remove the bulk of it.  As part of that I graduated from hack saw to portable bandsaw and eneded up with a 4x6 bandsaw.  Just going from a hack saw to the portable bandsaw was a significant time saver.  Not to mention arm saver    Sometimes I end up with small but usable pieces for something else.  The HF portable I use is pretty noisy so I wear ear protection when I use it.

I also got a few slitting saws and an R8 arbor for them, pretty much for the same reason.  I also have to cut pretty slow with them but, again, they can release a larger chunk that would otherwise be turned into swarf (lots of swarf = lots of tme spent).  And they leave a pretty nice surface behind.


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## Shotgun (Apr 22, 2022)

Have you tried packing the column and base?  I have an RF-30, a bit larger than yours, but still had a lot of vibration.  I packed the column and base with a portland cement and granite gravel mixture. Didn't turn it into a Bridgeport, but did improve the vibration quite a bit.


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## Alberto-sp (Apr 22, 2022)

Thank you so much again for all your help.

Ok first idea, I overstimated my machine. Second, 2 flutes sucks haha.

Well this is about the journey, not the destination and I have to learn that I´m going to make some mistakes and trow away some money. But now I feel comfortable knowing that the machine is not broken. I almost buy another model, a little more expensive but it wheights double, but size and weight is a concern in my house. I have the shop in the rooftop over the bedroom (This is why I can´t pack with concrete the mill)

 So it´s OK, need to be patient and less RPM and DOC.

Nevertheless, next week I have some free time and with a dial indicator I´ll check all the measurementes you told me.

Thank you


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## Road_Clam (Apr 23, 2022)

Couple setup questions. First is how is your mill bolted to your table , and what material is the table made of ? With a mini mill wood is your friend. Wood offers a robust table surface, AND helps to deaden harmonic vibrations.  Second is how are you holding your endmill ? You always want to keep unncecssary protrusion length to an absolute minimum. Looks like you have your mill sticking out pretty long. This festers vibration. Lastly is rpm's in certain circumstances you want to slow down your rpm's and increase your feedrate.


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## Alberto-sp (Apr 26, 2022)

Hello. I have been taking measures and trying to align the mill. At the beginning I thought tath I got it but not.

I have been taking the measurements in this way







Clamping the square firmly (It suposed to be a good square, chinese but not cheap) in diferent positions. But the measurementss change in each place of the table. For examenple, in the left side, in 150mm of path, the deviation is only 0,01mm, but in the right side is 0,3mm.

Even in the same place, if I flip the square, like in those pictures, I have diferents measurements. In the right one is almost perfect. 0,01mm in 130mm, but in the left one 0,12mm in the same path.






Every time I clamp the square I clean the base of the square and the table very well, and there is no visible dents. And I put it in the exact same position but flipped. How can it be possible? Y used only one clamp in these pictures but I use 2, the results are the same.

If I can´t trust the square, aling that milling machine is going to be complicated.

Nevertheless, what tolerances are OK for tath machine? How many 0,01mm per 100mm are tolerable? Because, I can try to get better align, but the more acurate I want to be, the bigger dificult it is, so I´d like to know how much I need to archieve


Road_Clam​The table is made of steel, and there is 20mm hard rubber betwenn the table and the mill. And yes, I use to golde the end mill the shortest posibble, but I forgot about that in the video.


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## Shotgun (Apr 26, 2022)

Attach your indicator to the quill and drop it to the table.  Run the table back and forth underneath it, writing the measurement down every few inches (cm for you . I bet your table is wavy.  My RF-30 table (much larger) was.

And I have serious doubts that having the indicator out on the end of that flat bar is doing you any favors.  It's going to introduce all sorts of inconsistencies. Again, attach the indicator to the quill.


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## Alberto-sp (Apr 27, 2022)

Thanks for your answer. Ok, I have attached the indicator to the quill, and the arm is very tight. I have repeated all the measurements to check that they are consistent. 

In the first test I have attached the indicator to the quill and in each "way" , using the left side as reference "0" i have move the table until the indicator probe reach the other side, not really side to side, but 300mm. The + mean the table goes up.







In the second test, I have attached the indicator to the quill and took the lower way as reference 0. Move the table until the indicator probe reach the upper way.

The red numbers indicate that in each test I have moved the indicator, while the black numbers indicate that I have to move the indicator and the table








What do you think about that results?

Thank you


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## Shotgun (Apr 27, 2022)

For my reference 0,04mm is about 0.0015"

So the table is off by a couple thou at most, but I'm bothered by the "moved the indicator".  I don't know how you're going to get a repeatable measurement if you move the indicator.  I'd lock the indicator to the quill, move the quill down to engage the indicator, then lock the quill. The only thing that moves is the table.  Use a ruler to lift the probe when crossing from one way to the next. Drag the probe down every way.  Write the measurement directly on the table with a sharpie (alcohol or any other solvent will take it off later).  Measure at both the front and back of the ways.  For extra credit, connect similar measurements with a line to get a topographical map of the table.

You'll find that the table has dips and rises that are impossible to see.  When you clamp your square to the table, did you clamp a corner that was sitting in a valley?  Maybe one side was on an incline?  Measuring accurately at this level is a whole new world that I know barely enough about to speak to.  But, I mounted a cup style grinding wheel in a collet, and was able to grind off the high spots from my table.  My RF-30 had peaks as high at 0.006" (0,15mm)


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## Eyerelief (Apr 27, 2022)

Alberto, if your goal was to measure the flatness of your table, you now have some good information.  If your goal is to tram the spindle to the table, ie make sure the spindle is square to the table, you are not there yet.  I apologize for not clearly understanding what you are trying to achieve.  
If you have been traversing the table across its X axis and Y axis travel limits, you have measured any variations in the table surface relative to the mechanical motion of your indicator.  Assuming your setup is rigid, in the first picture with the red numbers, you have discovered that your table is higher on the left side (of the image) of the x axis, and is your table is higher to the rear of the table on the y axis.  These numbers seem acceptable to me relative to the distances you are reading across.

To tram the table, you will need to measure differently.


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## Alberto-sp (Apr 27, 2022)

Thanks for your answers.​​Shotgun​No no, For example, in the central mark, I fix the indicator. Dial to 0 and later I star movving thee table until I reach the upper way.







So in "A" I dont move the indicator, I only move the table to get the 0, -0,02 and -0,04. Later I move the indicator to B and later C. Since the blacc numbers are so far, I need to move the table and the indicator, but once fixed, I don´t touch it until I get the 4 measurements.

Eyerelief​Yes, I´m triying to get the mill square. What I have to do? I was triying to doit ataching a square to he table.





In A, I have checked the inclination of the colum along the X axis, in B the same but in Y axis and in C I have checked the inclination of the head, because in my mill is adjustable. In C i measured that the distance from the quill to the ends of the table are the same

Of course, for those measurements I attach the square properly, that setup is only to take the pictures to show you how I measure


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## brino (Apr 27, 2022)

okay,  wait....... do you really mean +1mm here?





1mm ~= 0.040" ......that would be a huge lump in the table!

If this is real, then you should be able to place your square there and actually feel it rock over the high spot.

Hopefully that's a typo and it's actually "+0.01 mm"

Brian


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## Alberto-sp (Apr 27, 2022)

brino said:


> okay,  wait....... do you really mean +1mm here?
> View attachment 405300
> 
> 
> ...


Ooops no no, i forgot about tte 0,0  sorry. Is 0,01

I have edited the post. Thank you for warn me

by the way, I use metric because I see tin the forum there are some nationalities. But if the language of the forum is imperial I´ll star to speak in imperial.


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## Eyerelief (Apr 27, 2022)

Alberto,  There are many options and tools for this procedure.  The description is more difficult than the process. 

Fundamentally, you need an indicator that can be attached off center to the spindle.  As you turn the spindle around, you wilI take readings from the indicator (s).  In theory when the spindle is square to the table, no matter where the indicator sits on the table, the readings will be the same when table variances are considered.

One of the most straight forward tools is a spindle square or tramming tool.  Here is a picture.




Here is a basic set up video. Notice the use of the magnet? This insures that you are setting both indicators to zero from the exact same place. 




_A spindle square is not required_, many people use an indicol or some other device which allows the indicator (s) to be offset from the spindle. Being rigid and square to the spindle when mounting your indicator is required. It would be difficult to achieve this with the bar stock mounted indicator you showed in one of your previous photos, but you were on the right track.


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## Alberto-sp (Apr 27, 2022)

Thank you. Ok ok, but since I have spent a lot in tools I´ll try with the square but avoidiing to attach the base of the indicator to the bar.

And one last question. How much tolerance are aceptable for a hobby machinist? Because you know, the finest settings will be the most dificult


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## Eyerelief (Apr 27, 2022)

My goal is .0005" (.0127mm) across 5" (127mm).  Others may disagree.


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## Alberto-sp (Apr 27, 2022)

Yes, of course is your point of view, but for me is a valuable starting point, Thank you very much for the data!

To be sure 
	

		
			
		

		
	






If A = 5" B could be up 0,005 thou, right?


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## Eyerelief (Apr 27, 2022)

I apologize, I am being confusing.  When I say "square to the spindle", I am not implying that you should use your square against your spindle.  I don't think that gives you enough information to make an adjustment.  I am trying to describe an indicator positioned approximately 63mm from spindle center that is at a perfect 90 degrees to the spindle.  When the spindle is rotated 180 degrees, the indicator will be 126mm (5 inches) from its original position.  Here is a picture of a shop made spindle square (not one I made) which if properly built would get you close.  The round bar needs to be at 90 degrees when fastened to the flat bar, and the indicator should also be at 90 degrees when fastened to the flat bar.




	

		
			
		

		
	
 Fearing deflection or flex, I would not have that much round bar sticking out of a collet if I was to make one unless the round bar was greater than .500 (12.7mm) or greater in diameter.


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## Alberto-sp (Apr 27, 2022)

Ah ok ok, I understand. Thank you!


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