Enough HP for mini-lathe?

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The_Apprentice
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Re: Enough HP for mini-lathe?

Post by The_Apprentice » Sat Jun 24, 2017 11:30 pm

Well, so far I'm not too thrilled with it. Haven't made a test cut yet, partly because the gear connected to the spindle is so wobbly... I fear the spindle is bent far out of shape. Unless something else is going on there. Here is a video I took showing it.

https://www.youtube.com/watch?v=9L5JAecVHyE



This isn't normal for a Chinese lathe, is it? Maybe I am expecting a little too much?

John Evans
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Re: Enough HP for mini-lathe?

Post by John Evans » Sun Jun 25, 2017 12:27 am

That is no way correct. Return that POS forthwith. Hard to tell what is the cause gear-spindle ?? Send the vendor your link and demand a full refund.
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spro
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Re: Enough HP for mini-lathe?

Post by spro » Sun Jun 25, 2017 12:34 am

I watched the short video and there is definitely something wrong there. I wouldn't engage the gear. If the spindle was actually bent, the outer threaded end would wobble too. All I see is the gear and some collar going crazy. There must be too much slop in the bores or bores misaligned. By this time, you may have removed them for inspection. This appears to be an example of defective parts and since you bought it new, they should replace them.
Another video come up around there; A guy comparing a Grizzly G0765 against a similar HF 7X12 or 14. He prefers the Griz and runs it in different speed. You can see the exact same spindle end running slow and it doesn't wobble.
The link to your vid is; http://www.youtube.com/watch?v=9L5JAecVHyE

RSG
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Re: Enough HP for mini-lathe?

Post by RSG » Sun Jun 25, 2017 8:12 am

The spindle looks ok, at least from the threaded end. It appears as though the gear is either not on correctly or machined incorrectly. King isn't known for sending out defective components so this surprises me. Might want to take the gear off and inspect it. Then make a call to the vendor to have it rectified.
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SteveHGraham
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Re: Enough HP for mini-lathe?

Post by SteveHGraham » Sun Jun 25, 2017 9:53 am

I got dizzy watching that. Time for an exchange.
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The_Apprentice
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Re: Enough HP for mini-lathe?

Post by The_Apprentice » Sun Jun 25, 2017 4:55 pm

Thanks for the confirmation. I currently have a few tools on arrival, to help take off the spindle lock-nuts. Yes, I know there are other ways to take them off (such as two plumber's wrenches). I am hoping that it's not as bad an issue as I first thought... will investigate deeper soon to see what is really going on there. I'm hoping it's just a crappy gear & wonky plastic spacer making things look worse than it is.

While I wait for that, I will take a closer inspection of sections for the rest of the lathe.

spro
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Re: Enough HP for mini-lathe?

Post by spro » Sun Jun 25, 2017 6:34 pm

I agree, this to be the best avenue. In fact, King may Want you to just do that- Only those particular parts. If your inspections show something else grossly wrong / you decide this isn't the right size, they may take it in return for another one. Perhaps a 7X14 in perfect condition. Bad reviews are poison so give them a chance.

ccfl
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Re: Enough HP for mini-lathe?

Post by ccfl » Wed Jul 05, 2017 12:26 pm

That wobble is because there's a plastic(!) spacer between that gear and the rear spindle bearing. Just make a new one... you have a lathe now and that's what they're for. Aluminum is more than good enough, it's just applying the bearing preload which isn't much since the bearings are plain radials.

When you reassemble with the new-made spacer, crank the snot out of the bearing preload. Tighten the nuts until after ~10 minutes runtime the top of the headstock feels noticeably warm, but not hot. From factory the bearings are way too loose. As-is you'll get lots of chatter, especially on facing cuts. That mostly goes away after adding preload.
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earlgo
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Re: Enough HP for mini-lathe?

Post by earlgo » Sun Jul 09, 2017 10:29 am

ccfl wrote: When you reassemble with the new-made spacer, crank the snot out of the bearing preload. Tighten the nuts until after ~10 minutes runtime the top of the headstock feels noticeably warm, but not hot. From factory the bearings are way too loose. As-is you'll get lots of chatter, especially on facing cuts. That mostly goes away after adding preload.
On my ATLAS 12" I have applied the preload as instructed in the manual that came with the lathe, and it still chatters occasionally. After reading your comment, perhaps I should try to snug the preload nut a bit more. The head-stock has never run even warm, so your suggestion may help. Thanks.
--earlgo

ccfl
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Re: Enough HP for mini-lathe?

Post by ccfl » Sun Jul 09, 2017 2:55 pm

If you have tapered rollers it likely won't improve anything. The 7x's use plain dumb radial ball bearings and benefit greatly from as much preload as they will stand.
"Never trust a man who puts a witty quote in his sig line." -Mark Twain

pete
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Re: Enough HP for mini-lathe?

Post by pete » Sat Jul 15, 2017 2:54 pm

I've been around and watched some very large and expensive bearings get fitted and the guys who seem to really know what there doing use both measurements on the radial and end play along with a well educated sense of touch about how warm the bearing gets under operating conditions Earl. That chatter once in awhile is a tough one to pin down on machine tools since so much can contibute to the cause of it. For a lathe everything seems to matter. Any slack from the lathes carriage fit to the tool tip including the feed per revolution and depth of cut harmonics, unsupported tool extension, cutting tool material, shape, condition etc can fool you into thinking it's probably the spindle bearings or there adjustment. It might well be, but when I knew a lot less than I do now it also cost me a set of un-needed spindle bearings for me to learn there's lots of other causes. Using the machines carriage and slide locks when you start getting chatter can quickly help to diagnose what isn't part of the problem though. That and adjusting the depth and feed are the first things I now start with. It's not a 100% rule for every single situation, but I've seen it mentioned more than a few times in old machinist books about upping the feed and/or lowering the rpm is the first thing to try. At a guess if your bearings are running that cool then it sounds like they could be adjusted a bit tighter.

earlgo
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Re: Enough HP for mini-lathe?

Post by earlgo » Sun Jul 16, 2017 4:46 pm

The_apprentice: sorry that this OP got hijacked.
Pete, I am answering in the thread "Rebuilding(?) a worn out lathe"

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