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Jung HF50 1965 spindle rebuild

Vulcanalia

Aluminum
Joined
Jul 4, 2014
Location
The Netherlands
Dear Friends,

After fixing the guideways of my 1965 Jung HF50 i still think it can be a bit improved.
I measured the runout on the spindle nose to be 7um. New bearings and a taper regrind could probably improve the finish quite a lot.
But there is no info on the web about this spindle.
I found a drawing of a Jung F40 spindle, added to the album below.
It has a very similar design. It suspect the 2 pins that are coved by setcrews ar also cartridge locks, and the cartidge should be removed backwards. I assume from the F40 spindle drawing that the stationary coil of the motor is attached to the spindle catridge. We will see.

Here are same pictures of the progress:

It likely saw some moisture in its lifetime... and after almost 60 years most bolts needed a bit persuasion to come loose.

I took off the clamp as in the attached picture, but the cartridge seems really stuck in cast iron housing :(

Anybody experience or tips on how to remove it?
Tight fit, a little moisture, 60 years...
I dont want to slam it and pressing is difficult as i have nothing to mount on..
If anybody has a drawing of the HF50 spindle, it would be greatly appreciated :)

btw the motor has no own bearings, the rotary coil is just attched to the end of the spindle shaft.

If i get it out i will post more pictures and bearing numbers.

Posting this as reference for other Jung HF50 owners with similar plans :)

Best regards,
Paul
 

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  • IMG_8888.JPG
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Okay, thanks to Ludo from Belgium, hereby the mounting instruction of the Jung F50 spindle.
The instructions are in German, but at least there is the drawing :)
I also have the full replacements parts catalog. The second picture is from there.

According to the manual the cartridge can only be removed towards the rear, and the 2 pins on the side are indeed spindle lock pins. These have to be removed. And the "Eilgangmotor", which is the motor that drives the spindle head upwards, should be removed before the spindle is taken out.

The HF50 still looks a bit different for the motor of the F50, but it is likely a similar construction.




1708969483161.png1708969592882.png
 

Attachments

  • JUNG HF50RD Montage Anleiting Einstecksleifspindel F50.pdf
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Short update:

The spindle bearings are of size 7307. ID=35, OD=80, B=21. millimeter.
They are not normal 40 degrees, but as far as i can find and see 15 degrees. This is visible on the wearband in the races. That would make sense as the main load is radially.
The ball retainer is from polymer. They are open on both sides. In between the bearings (at least in between the front 2) is a ring between the inner race. So they are not matched but simply preloaded. I measured the balls at 13.5mm diameter.

Normal bearings are quite cheap but have a tolerance of P6. The SKF ones i found would be around 60 euro a piece. But a 35mm bore bearing at P6 tolerence has max 10um runout... I am not sure of the grinder would improve if i did that.

Source: https://nsk.com.br/upload/file/NSK_CAT_E1102m_A58-81.pdf

A P4 bearing has 4um runout, but it is a challenge to source them for a reasonable price.

NSK 7307-C-T-DUL-P4 would be the prefered option if you ask me.

C=15 degrees
T=Phenolic ring
DUL= light preload in face to face of back to back configuration
P4 = tolerance


Any advice welcome

ps here the link to the JUNG HF50 PARTS CATALOG: http://www.vulcanalia.nl/jung/Jung HF50RD Ersatzteile.pdf
:)
 
That is a good store i see, thanks.
Could find them but did not request the price as i ordered them already from Germany. Helpfull for somebody who will find this post in the future :)

I checked the shaft and yes, its bent. Measured 0.05mm runout at the end, motor side.
Not sure how to proceed and what acceptable numbers are.
The 7um runout at the flange side i want to grind out. Not sure if i should do this with the spindle in place, or to bring the spindle to a company/enthusiast with a cylindrical grinder.

I see you are also from Holland, if you have a good adress or tips let me know! I am from South Holland, Pijnacker.
 
It depends where it is bent Can you detect that??
Perhaps hardcrome it all and grind all feautures
InTilburg there is e a shop that could do that
CZL
I do not know how good they are nowadays And how costly

Peter
 
The bent i can correct with the "flame straightening method", i have a oxy acetylene set. Found it on youtube.
Spindle shaft is out now. It has 8 bearings, and, looking back, that is stated in the picture above. 8 bearings after machine number 2528...
I am measuring all the parts that come of the spindle, model it in 3D and will post the model of it when the operation is completed.
 
The bent i can correct with the "flame straightening method", i have a oxy acetylene set. Found it on youtube.
Spindle shaft is out now. It has 8 bearings, and, looking back, that is stated in the picture above. 8 bearings after machine number 2528...
I am measuring all the parts that come of the spindle, model it in 3D and will post the model of it when the operation is completed.
Flame straightening ???
I have done that on big shafts 120mm or so
But this one I would see if I get any succes on a press first
Be sure to have the right position where it is bend
I do it in V-blocks
Support it the same way it was supported in the machine
Peter
 
Spindle is now rebuild.
Here you can find the model: https://grabcad.com/library/jung-hf50-spindle-1
Not sure the dimensions are 100% but i did my best.
The flame straightening worked in my case very good. Got the runnout at the motor side to within 5um. I think this is preferable above pressing because in this way you can specify the bending point much better.
.
Please note that the 4 bearings in the back need a cutout, and dont fit without. With the wire erosion machine these were easily made.

If i am correct the small circles on the bearing indicate the direction of excentricity. I positioned the cutout in such a way that the circles were evenly distributed after installation, and the excentricity would cancel each other out as far as possible.

For future reference:
First place the 4 back bearings on the shaft, then fit them in the cartridge, turn around and put front bearings in.
This is deviating from the Jung description, but as the cutouts need alignment, this is the way to go.


IMG_9053.JPGIMG_9059.JPGIMG_9044.JPGIMG_9066.JPG
 
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