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Mini lathe taper bearings problem

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Sdmf5150

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#1
I am trying to install the taper bearings on my HF headstock, but when I get the spindle installed I have about 3/16 space between the plastic spacers that go on either side of the gear, letting it slide around on the spindle. Definitely not going to work like that. Anyone else have this issue?
 

royesses

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#2
Did you make sure that at least one of the new bearings (rear one) has a sliding fit on the spindle? We have seen that before. That's about all I can think of for the loose fit of the hi/lo gear. Maybe bearing outer race not all the way pressed in?

Roy
 

MasaAMD

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#3
I'm having this exact issue. I have the Grizzly 7x12 and with the outer races fully seated and using the original spacers I have about 3/16" axial movement of the main gear on the spindle. I'm going to order some additional spacers to account for the inset of the inner race on either side. I will let you know what sizes work for me.
 

royesses

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#4
Please let us know what you find wrong. I installed tapered roller bearings in my 7x10 quite a while ago and did not have a problem. I used all the original spacers and cut down the rear spacer to get the drive gears aligned about .090". I also notched the rear spacer to make installation of the key easier. There are 3 spacers in mine one on each end of the main gear(they are the same thickness) and the long one that is between the adjusting nut and the rear inner bearing race.

Roy
 

Richard King 2

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#5
Please explain why you took it apart or does it come apart and you have to assemble it? Did you take a cell phone picture before you took it apart? Have a manual that has a drawing ?
 

MasaAMD

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#6
Please explain why you took it apart or does it come apart and you have to assemble it? Did you take a cell phone picture before you took it apart? Have a manual that has a drawing ?
This upgrade involves replacing the OEM headstock ball bearings with with opposed tapered roller bearings. Due to the construction of the bearings, the outer race sits proud of the inner race by a small amount. This extra space now allows the main gears to have noticeable axial play on the spindle. To remedy this slightly thicker spacers need to be machined. Also due to the offset of the inner and outer races the rear spacer needs ~0.1" taken off.

I just got my spindle back apart and I'll take some measurement to see how thick I need to make the new spacers. Also, I'll post some pictures to illustrate what is going on.

Edit:

Just found a great picture showing the differences in the bearings. (source: http://www.toolsandmods.com/lathe/mini-lathe-headstock)
minilathe-headstock-spindle-bearings-dimensions-3.jpg


Assuming the Nachi bearings are dimensionally the same as the SKF, this shows a 3.25mm offset
 
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markba633csi

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#7
Yep 3.25mm offset on one side, 1.25 on the other
M
 

MasaAMD

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#8
Here are some pictures:
IMG_20181102_174411.jpg

IMG_20181102_174454.jpg

IMG_20181102_174729.jpg


Looking at about 0.055" offset from the outer race to the inner race.

Original spacer:
IMG_20181102_175021.jpg


Two new spacers @ 0.346" need to be machined. This should take up the extra axial play.
 

royesses

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#9
Thanx for that information MasaAMD. I never even bothered with the extra end play on the spindle gear. I have all metal gears in mine and have had no problems with noise or anything else. I remove the spindle every six months to repack the bearings and the next time I'll make some spacers.

Roy
 
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