Kurt D50 Vise Bearing Question.

[Rata222]

Hi All.
I purchased an old D50 ? Kurt vise. When I disassembled it, I seen thatit was missing the thrust needle roller bearing in the rear. The flange on the main screw was just bearing on the back casting. There was nothing in the counterbore where the bearing would usually be. I ordered the rebuild kit from Kurt.
The OD of the bearing kit received is too large. The bearings and washers received are 1-7/16” OD and 7/8 ID. The counterbore in the vise body is 1-1/4 OD x 3/8 Dp.
I called Kurt Mfg. The young man that helped went out of his way to dig into this and find the correct setup. He called me back and told me that after digging around he was told that the older vises with the main casting marked “A50” did not utilize a bearing. ( Note that all the other castings of the vise are marked” D50”.) It was suggested suggested that somebody may have added the counterbore. That seems unlikely to me since I could not find a 7/8 ID needle thrust bearing with that small of an OD.

I machined up a brass bushing – fitting the counterbore to utilize as a thrust bearing and it all seems to work just fine.
I had been thinking about and was curious if anyone knows what the “original” configuration would have been? If just a solid thrust bearing was used originally I would not think they would have made a counterbore so deep – nor the flange on the shaft bigger than the counterbore - if the flange were to fit inside the counterbore it would help keep the chips out.

Thanks Jim

 

[benmychree]

There is really nothing wrong with steel bearing on cast iron as a bearing surface, providing it gets some lubrication.
, most vises do not have antifriction thrust bearings. The bearings on Kurt and like vises just allow more clamping force with less effort on the part of the operator. The deep counterbore would help keep crud out of the bearing area. Did the vise screw have excessive end play without the bearing that you inserted?

 

[Rata222]

"The deep counterbore would help keep crud out of the bearing area. Did the vise screw have excessive end play without the bearing that you inserted? "

My thoughts exactly. If there was no bearing intended to be in the counterbore - then the OD of the flange should have been smaller to allow it to recess into the hole. The OD of the screw flange was only 3/16 larger than the counterbore - so the outer edges of the flange were bearing on just the the perifery of the counterbore. I thing some type of bearing was intended to fill that gap. .

All play in the screw could be taken up by the back theaded collar. The new models have a snap ring.

I could open up the counterbore - but it is working well and I will most likely leave it as is. I was just curios what the intended design was - the answer from Kurt did not seem logical.
Thanks for the info. I did not know that steel to cast would not cause wear.

 

[benmychree]

Yes, cast iron on steel is a good bearing, as long as it has lubrication; on a lot of old machines the bearings were cast iron, in fact some models of South Bend lathes had cast iron headstock bearings that were part of the headstock itself.