CF 7x10 vibration

V

Vanillag66

Registered
Registered
Joined
Jan 20, 2020
Messages
5
Hey guys, new here. I have a cheapo CF 7x10 lathe someone gave me. I replaced the drive belt because that was the only issue it supposedly had. I've used it a couple times here and there briefly. I was going to face something the other day and had a ton of vibration. If I engage the carriage feed the vibration stops. I've been machining for 14 years but I have very little maintenance/mechanical experience working on machines... any ideas or help is greatly appreciated
 
Forgot to add the vibration happens regardless if you're actually cutting or not but stops immediately when feed is engaged
 
i would be suspect of the spindle bearings
the import 7x's use radial bearings instead of tapered roller bearings, to reduce cost

i can't explain why the vibration stops when the feed is engaged

you could mount a substantial rod in the spindle and perform a deflection test
mount a dial indicator to indicate the chuck or spindle, and measure the deflection when you lift or depress the rod mounted in the chuck
you should have less than .002" of deflection of the spindle, if you have .002" or more, time for bearings :oops:
 
I was thinking that but was confused that the vibration stopped when I had it in feed. Weird stuff.. this is my first rodeo with these little cheap lathes. I know the original owner only turned a couple things (literally) He wanted to learn how to be a machinist and bought that lathe from HF. Not saying the bearings aren't bad but with very minimal use I wouldnt see that being the likely issue. I'm offshore right now and won't be back home for another 9 days but I'll definitely check deflection.
 
give a check of the drive gears too

i owned a Harbor Freight 7x10 for a minute.
it had a change gear that was drilled off center and made some funny noises when the carriage feed was used
 
Welcome to the forum!

As part of the troubleshooting procedure, try disengaging the drive to the lead screw. That will check out the gear train between the spindle and lead screw. If the vibration doesn't go away when the drive is disengaged the problem could very well be the spindle bearings, although the drag on the carriage (when driven) will load up the entire drive chain from the motor on. But you gotta start somewhere, right?

Based on its light use, it doesn't sound like the spindle bearings are worn (though one could just be plain defective). If the problem is a loose spindle, the spindle bearings on these need a pre-load, achieved by properly tightening the spindle nut on the change-gear side of the lathe. If you don't already have one you may need to make or buy a spanner wrench for that. The ad-hoc way to adjust it is to tighten down the nuts and run the motor awhile, then check to see how warm the headstock gets. You want that "Goldilocks" pre-load where the temperature rise isn't too much or too little.

I wish I could tell you more but even 10+ years into owning one I haven't needed to adjust the pre-load on my mini lathe, and no vibration unless I'm turning an unbalanced piece. FYI, Arceurotrade has a PDF on replacing spindle bearings you can consult for guidance.

Good Luck! And let us know what you find. I for one am curious.
 
There's a ton of videos out there - this one is the most entertaining.
I repaired one for an acquaintance once, motor mount holes were bad, gears were bad as Doc mentions, the belt was shot, and the gib was mangled.

 
Thanks for the info guy. It truly was weird; I used it roughly 10 times on random small projects with no issues out of it. Then 1 day i chucked up a nut to face off, flipped the switch, came up to speed, and had crazy amount of vibration. Looked around to see loose nut or something. I turned the handle to move the carriage and noticed the vibration completely stopped. Hit the feed and it would quit vibrating. Very strange that it would run fine as long as the carriage was moving.
 
Have you checked all the change gears for play? They can be a little fussy to get adjusted and in line with each other. As has often been noted these Chinese lathes should be seen as kits as there is often some tweaking that needs to be done.

It has been an adventure with my 9x20 but I believe it was worth it as it's mostly been elbow grease. To date I've replaced the split nut(it was adjusted wrong when I got it and it got mangled after a couple of years) and the spindle bearings. The spindle bearings were not bad I just had to take the spindle apart because I couldn't adjust pre load because the spindle wasn't machined right from the factory. So I replaced them while I was in there.
 
Gear mesh seems to be good from what I can tell. Theres some play side to side though. But that wouldn't be an issue being vibration stops when the change gears are engaged... or at least I would think that wouldnt have any effect
 
You must log in or register to reply here.
Back
Top