Mini mill vibrates a lot

A

Alberto-sp

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Apr 8, 2021
Messages
138
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
 
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
 
Last edited:
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?
 
Is your quill locked when you are milling?
 
quill.jpg


This lever? Yes. I tight all the levers except the ones I need to move the table
 
Yes that's the one I was thinking of.
 
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.
 
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.
 
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
 
Last edited:
You must log in or register to reply here.
Back
Top