Sieg SC3 7x16 Mini Lathe Question...

By way of a quick update:

I have the replacement headstock bearings in hand, as well as the needed bearing puller but I will not have time to get to this before next week. I have an AGM to attend as well as sorting out a few other things this week. Annoying, but life has a habit of throwing a spanner in the works when least expected.
 
Update as at 27th Feb 2024

Replacement bearings (angular contact) fitted, spindle appears straight. Problem remains but less than previously. Bearings improved issue, but not a total solution.

One other potential contributing factor is next to be resolved. If it is indeed what I suspect, it would have saved an hour of work!

Will update when the potential secondary cause is ruled out.
 
Last edited:
CraigH said:
Drilling/grinding in the non-critical parts of the heavy side. A crude operation, but was absolutely necessary on my 4-inch 3-jaw chuck (LMS 5100). In the image I posted above, the heavy part is the upper location. Note the area of three rings there, and only two rings elsewhere. (small grinding points and small masonry drills will be needed)

Since the scroll is relatively light, I could not figure out how to check the "work". I assembled and disassembled the chuck several times to check its balance.

BTW, to test for this run the bare chuck body throughout the speed ranges and there will be no vibration.
Click to expand...
What method did you use to find the imbalance?
 
CraigH said:
The 4-inch 3-jaw scroll is out of balance.
Click to expand...

Have never once noticed an imbalance in my 3JSC, nor for that matter, in my 6JSC either on my SC3 or the 7x I am rebuilding before I stripped it completely apart.

Will look into such things as chuck balance when I have the current issue dealt with on the SC3.
 
mac1911 said:
What method did you use to find the imbalance?
Click to expand...

1. Ran the bare/stripped chuck body at all speeds - no vibration. With the odd spindle hole plugged.

2. Placed the assembled chuck on drill rod with the jaws (hence scroll) in different positions.

3. Step 2 shows the chuck placing itself in different locations of rotation on the drill rod.
 
4th March 2024 Update:

Have now replaced headstock bearings with Angular contact.
Have replaced Timing Belt
Have replaced Motor belt pulley.

Vibration is still evident. Have taken a video of the "Glass test" I carried out, which is available here (<<< Link). I unbolted the lathe so it would show the vibration to its fullest.

For those interested, skip to around 32s in to see the vibration.

Supplier looking into options as to what is going to happen next since the obvious things that could have been tried have been.
 
Last edited:
Is this a 2 speed headstock, that sounds like you have a gear mesh problem. Can you feel the high low gears binding when rolling the spindle over by hand?
 
Firstram said:
Is this a 2 speed headstock, that sounds like you have a gear mesh problem. Can you feel the high low gears binding when rolling the spindle over by hand?
Click to expand...

The SC3 is a single speed headstock with brushless motor..

And that noise? I have no idea.

Belt direct from motor to spindle and the change-gears were not even engaged!
 
Last edited:
The sound is different than mine. Your machine's "whirring" is much more of a "wRhirring" - and mine is from the motor, but less The flopping sound may be in the belt drive parts. What I most hear from mine in the idler gears.

I had wondered about my machine's various sounds - thinking bearings, and the sounds did change to become more muted with the tapered roller bearings.

But vibration was from chuck imbalance as I previously mentioned.
 
CraigH said:
The sound is different than mine. Your machine's "whirring" is much more of a "wRhirring" - and mine is from the motor, but less The flopping sound may be in the belt drive parts. What I most hear from mine in the idler gears.

I had wondered about my machine's various sounds - thinking bearings, and the sounds did change to become more muted with the tapered roller bearings.

But vibration was from chuck imbalance as I previously mentioned.
Click to expand...

No chuck fitted when I shot that video.
 
You must log in or register to reply here.
Back
Top