Unbalanced 4 jaw on my 12x36

[John Conroy]

While I was playing with chucks I installed my 8" Atlas chuck (which has an Accusize back plate) and ran it through the entire rpm range. I noted a small vibration that caused my DRO head to quiver at around 800 rpm. That's the same speed as the vibration on the 4 jaw was but I really could not feel it in the machine anywhere but I could see the disturbance in the DRO head. I put the chuck onto the balancer and sure enough there was a distinct heavy spot that would return to the bottom every time. I used masking tape to stick a 7 gram wheel weight to the OD of the chuck and it only took one placed directly opposite the heavy spot to bring the balance to neutral. I really did not want to mess around removing metal from the chuck or backplate so I made up some threaded plugs to fit into some of the threaded holes in the back plate and did some trial and error weight placement. I placed two 5 gram threaded plugs into the threaded holes that house the bolts that hold the chuck to the backplate, bisecting the light spot and achieved a neutral balance. I could have put a 7 gram weight into the large vacant hole in the backplate directly opposite the heavy spot but it is not threaded and it would have been a pain to make something like that. In the pics you can see the heavy spot marked with black sharpie and the 2 M10 X 8mm plugs I made to add weight to the empty part of the threaded chuck mount holes. After mounting the chuck again the small quiver in the DRO head at 800 rpm is gone, cool stuff!

 

[Tom O]

I’ve seen them using two knife edge pieces of flat iron to give lower rolling resistance than bearing supports Although it requires a wider area Depending on the circumference of the piece.

 

[PeterT]

I have a mini version of the beam style used for RC props back in the day. The only thing is the rails have to be perfectly level otherwise the item likes to roll down hill. There was kind of a mickey mouse level bubble. Another style has the axle supported with opposed magnets, supposedly frictionless but they are a pain. Only good for light items. The bearing races look easy & cheap, at least for this kind of mass. I've been watching YouTube videos on home made air bearings. I guess you would set your chuck on those & come back next Tuesday when it stops rotating haha

When I was looking for tungsten ballast for my RC (sailplane) there is quite a selection of slugs available under fishing supplies. I guess lead is bad for water so this is the norm. Its high density so works well for balancing. There is also tungsten putty but its spendy.

 

[Former Member]

There are some great apps for phones that give you direct on speed of vibration, along with some youtube tutorials.

 

[Aliva]

I also have a king 12x 36 I did mount it on hockey pucks, but the pucks were to soft and the whole machine would vibrate. I removed the pucks and went to solid steel pads. Perhaps remove the pucks and see if the vibration is reduced.

 

[Former Member]

I also have a king 12x 36 I did mount it on hockey pucks, but the pucks were to soft and the whole machine would vibrate. I removed the pucks and went to solid steel pads. Perhaps remove the pucks and see if the vibration is reduced.

I upgraded to the BB equivalent and when installing it I mounted it on pads from KBC, this are a lot softer than hockey pucks. Initially I was worried about the same issue initial as they are really soft. No vibration at all and movement running.

So I suspect you you may have a more serious issue than you initial suspected and should investigate further before investing more money. It could be manufacturing or shipping induce flaw that slipped by final quality control.