Is this a standard taper for an internal grinding spindle? What are the other bits?

ballen · Nov 11, 2018

Can someone identify the taper for these internal grinding spindle arbors? Is this a standard, so I could tell what spindles would fit it? Dimensions are listed on the photo.

By the way, the collet chuck has no identifying marks, but it's hardened and ground on all surfaces. The collet inside is Schaublin, 5-6mm.

I'd also like to know what these arbors shown below are meant for. And what's the purpose of the black screw? Again, dimensions are on the photo.

sfriedberg · Nov 11, 2018

If I had to guess about the arbors, I would guess they are for holding cup wheels, or possibly recessed straight wheels. The black screw would clamp down on the ID rim, inside the recess. But the 24.7mm bore doesn't seem to be a standard size for the wheels I'm familiar with.

ballen · Nov 11, 2018

sfriedberg said:
If I had to guess about the arbors, I would guess they are for holding cup wheels, or possibly recessed straight wheels. The black screw would clamp down on the ID rim, inside the recess. But the 24.7mm bore doesn't seem to be a standard size for the wheels I'm familiar with.

Thank you for replying, but it doesn't make sense. Look at the end of the shaft: it's threaded for a small retaining screw to hold on a little wheel. And one of the shafts has a tiny (~6mm) grinding wheel still screwed there!

Regarding the first photograph, page 33 of this catalog:
https://www.slf-fraureuth.de/wp-content/uploads/2015/07/SpindeleinheitenKatalogDE.pdf
seems to indicate that slf-fraureuth spindles of type SSI 2.5-X/X take these tapers. But I'm not sure. Nor do I know if other spindle makers use the same dimensions or have their own proprietary standards.

SIP6A · Nov 11, 2018

They look like there for an SKF spindle.

Toms Wheels · Nov 11, 2018

Are those threads metric for sure, as 5/16 is very close, a TheMac grinder extension spindle is 5/16 x 24, 9mm x 12.0 x 32mm. Looks like what you have with the two holding flats`on the extensions.

Kees · Nov 12, 2018

The arbors in the first photo I cannot tell the manufacturer. There are many out there and they are all sort of the same with diffents in diamensions.No standarisation here.

What you see in the 2nd picture are arbors for the fischer/ SFJ UJ40 spindle.The black nut goes in the spindle . IMHO a superior design compared to the arbors in the 1 picture. More stable, less run-out.

https://shop.fischerspindle.com/Fischer/UJ-Spindle

Plusminus · Nov 12, 2018

I also think the first pic are arbors for the fraureuth spindles.

I have some myself and also some arbors i have to grind the taper.
Only the ones i have have m6 thread. My larger spindles need the m8.

Greetings,

Peter

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michiganbuck · Nov 12, 2018

Toms Wheels said:
Are those threads metric for sure, as 5/16 is very close, a TheMac grinder extension spindle is 5/16 x 24, 9mm x 12.0 x 32mm. Looks like what you have with the two holding flats`on the extensions.

Agree with Tom Wheels to be sure of the thread as the taper could be .500 x .312 and 1.250 length(1/2 x 5/16 x 1 1/4"

You might call Precision Spindle 519-672-3911 and ask if they might know that taper.

ballen · Nov 12, 2018

Kees said:
What you see in the 2nd picture are arbors for the Fischer/ SFJ UJ40 spindle.The black nut goes in the spindle . IMHO a superior design compared to the arbors in the 1 picture. More stable, less run-out.

You are right. I checked the dimensions against the catalog and they are exactly the same. Thanks for this!

https://shop.fischerspindle.com/epages/fp.sf/en_US/?ObjectPath=/Shops/fp/Products/"UJ-HJN Katalog"

ballen · Nov 12, 2018

Plusminus said:
I also think the first pic are arbors for the fraureuth spindles. I have some myself and also some arbors i have to grind the taper.
Only the ones i have have m6 thread. My larger spindles need the m8.

Peter, thanks for responding! I found the dimensions for the slf-fraureuth spindles listed in this catalog, on page 48:

https://www.slf-fraureuth.de/wp-content/uploads/2015/07/SpindeleinheitenKatalogEN.pdf

For the SSI-60 spindle series, this shows a taper length of 35mm with a larger diameter of 14mm and 1:10 taper, which makes the smaller diameter 10.5mm. So unfortunately this (10.5mm to 14mm over 35mm) does NOT match the dimensions of the arbors that I have (9mm to 12.7mm over 32mm).

It's a shame, because there are a lot of used slf-fraureuth spindles available in Germany at reasonable prices.

ballen · Nov 12, 2018

Toms Wheels said:
Are those threads metric for sure, as 5/16 is very close, a TheMac grinder extension spindle is 5/16 x 24, 9mm x 12.0 x 32mm. Looks like what you have with the two holding flats`on the extensions.

Buck, TomsWheels, this would be unusual, because these arbors came with a Swiss grinder in Germany. I am pretty sure that there are very few Themac grinders on this side of the Atlantic. But I'll check the thread carefully and get back. If it's not M8 x 1.25 thread but an imperial one, then you are probably right.

Is there any on-line source for the Themac arbor taper? I looked at Themac's on-line web pages but couldn't find that information.

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