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Acceptable spindle runout

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Forum topic by JoshNZ posted 02-23-2018 02:32 AM 1665 views 0 times favorited 13 replies Add to Favorites Watch
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JoshNZ

105 posts in 1091 days


02-23-2018 02:32 AM

just wondering what you would consider an acceptable runout. I had a shaft machined for my union graduate to a thread more compatible with today’s equipment. I got it back together and appears the whole thread and base are not running true. The machining must have been off center as the flange and tapered hole are still dead on.

The video shows a 3mm flathead next to it, no dial indicator.

Really gutted as this was the one I was pouring money into so I wouldn’t have to buy another lathe again!

https://youtu.be/jk2glHpb4TI


13 replies so far

View cj5's profile

cj5

32 posts in 1217 days


#1 posted 02-23-2018 02:54 PM

if the morse taper is on center and the shoulder is centered you may be ok. Check it with spur drive and faceplate.

View Lazyman's profile

Lazyman

2038 posts in 1409 days


#2 posted 02-23-2018 03:10 PM

When I watch the threads against the background it looks like they are moving slightly too but the unthreaded part at the end doesn’t seem to. Could just be an allusion but if it isn’t, I think this is going to be annoying. You can still turn things round but if you remove a blank you have roughed round, when you flip it around for example, it will probably be slightly off center and you will have to re-round it in the new position. Sometimes you do that anyway but not if you have finished the outside of a bowl for example and then turn it around. Checking with a faceplate or chuck mounted may be the only way to be sure.

Not familiar with your lathe. What thread was it before? Was there not an an adapter available?

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Wildwood

2322 posts in 2157 days


#3 posted 02-23-2018 08:37 PM

Couple different approaches to measuring run out. Not a big fan of using a screw driver, if okay with a SWAG (scientific wild ass guess) looks like your doing just fine.

If shop around can find an inexpensive dial indicator & mag base combo good enough wood working machines besides just your lathe. Little more if buy a digital model.

http://www.grizzly.com/products/Magnetic-Base-Dial-Indicator-Combo/G9849

https://www.youtube.com/watch?v=16xBV3PggQI
https://www.youtube.com/watch?v=GKdj23J6c2U

-- Bill

View JollyGreen67's profile

JollyGreen67

1676 posts in 2785 days


#4 posted 02-23-2018 10:12 PM

I had the spindle inspected for run out and concentricity due bearing failures on my DVR XP. Inspection was accomplished by an aerospace industry machine shop.

Findings: “The bearing journals tilt into each other .0003. This would possibly not cause bearing failure, except it was coupled with a concentricity of .007, as the bearing journal on the short end of the shaft is shifted in X axis .003 and Y axis on the long shaft .002. These two issues coupled together would cause higher than normal heat buildup in the bearings, and a balance that will cause premature bearing failure. The higher the RPM the shaft rotates the quicker the bearing failure”.

I would think Teknatool Nova owes me a new spindle?

-- When I was a kid I wanted to be older . . . . . this CRAP is not what I expected !

View johnstoneb's profile

johnstoneb

2932 posts in 2195 days


#5 posted 02-23-2018 11:20 PM

In an aircraft engine yes. In a wood lathe no. Wood lathe isn’t turning long enough or fast enough for those tolerances to cause a failure. The heat required to cause a failure would discolor the paint and you should smell something burning or at least very hot. The headstock would be hot enough during bearing failure to burn any flesh that might touch it.

-- Bruce, Boise, ID

View Richard Lee's profile

Richard Lee

123 posts in 797 days


#6 posted 02-23-2018 11:20 PM

That much runout is scrap in my machining world.

View JollyGreen67's profile

JollyGreen67

1676 posts in 2785 days


#7 posted 02-24-2018 12:18 AM

johnstoneb – Then the question is: Why have two sets of SKF bearings burned out ? I usually turn 1800RPM. I would think that an inspection at a premier machine shop would find what they did find – burned bearings.

-- When I was a kid I wanted to be older . . . . . this CRAP is not what I expected !

View JoshNZ's profile

JoshNZ

105 posts in 1091 days


#8 posted 02-24-2018 12:22 AM


That much runout is scrap in my machining world.

- Richard Lee

I agree Richard…

Outboard thread was LH (useless) inboard was 1.5”x6tpi. Useless in NZ also. Single adapter didn’t cost much less than just machining threads to something common and never worrying about it again. Outboard has an awesome high bed and tool stand so wanted to use it in reverse with vfd+3phase. I didn’t want to buy another lathe again so didn’t want nuisances.

I know it’s a wild ass guess but it’s bad enough to the naked eye that it’s bad. The taper and the flange run dead true to my eye, which the cutter never touched. So does the shaft inside the headstock. The thread and shoulder, and face plate when fitted, and chuck when fitted, all exhibit the same wobble. Obvious to even the partially blind. It mustn’t have been chucked right.
Absolutely gutted =/

View Wildwood's profile

Wildwood

2322 posts in 2157 days


#9 posted 02-24-2018 08:56 PM

My big problem with using holding a screw driver in one hand and rotating lathe spindle with the other hand and normal breathing and trying to check spindle run out just not a SWAG but crap shoot too.

With a dial indicator attached to a solid base mo better because gives you geeral idea of what you have. You could spend a fortune on expensive extremely accurate indicator reading down to .000001ā€™sā€ for really better indication but not sure worth the money for a wood lathe.

Lathe bearings with .0005 or less run out rated acceptable by most manufacturers. If much more than that suspect a bent spindle too. So if wood lathe is reading anything .0005 or less at the spindle also acceptable by manufacturers. Lathes from the same manufacturer can have different run out.

As Johnny CNC tells us in the video run out can and might change inserting components into or screwing one onto lathe spindle threads; (talking about chucks, drive centers, and faceplates). Not much of a problem with drive centers, and alluminum & steel faceplates. Not so sure about chucks, other than fooling around with threaded insert if possible.

-- Bill

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MrRon

4793 posts in 3265 days


#10 posted 02-24-2018 09:00 PM

A good machinist would not make an arbor as you show. I would reject it. Looks like it was made by an amateur machinist, not a professional. I hope you didn’t have to pay for it.

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JoshNZ

105 posts in 1091 days


#11 posted 02-25-2018 08:48 AM

The lathe is running at its slowest speed and the video is 240fps slowed down, screw driver is supported against the headstock. I appreciate what you’re saying, but I don’t need a dial indicator to see it’s untrue, I can see the chuck wobbling when fitted with my naked eye.

I’m buying too many other one-time otherwise useless tools right now to take care of other failing projects to worry about buying a dial indicator to prove it’s untrue haha.

I think I’m just going to cut my losses and replace the whole spindle.

Thanks for the input!

View Richard Lee's profile

Richard Lee

123 posts in 797 days


#12 posted 02-25-2018 03:29 PM

The only way to identify the problem is to remove the spindle and either put between centers and check or dial up on a lathe and check it.

View Woodknack's profile

Woodknack

11763 posts in 2402 days


#13 posted 02-27-2018 07:17 AM

I wouldn’t accept it.

-- Rick M, http://thewoodknack.blogspot.com/

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