Regrinding double V ways, jung hf 50

[Vulcanalia]

Dear friends,

I have a worn Jung HF50 surface grinder with double V ways.
All work what i make on it is convex or concave... especially in the middle..
Has anybody experience regrinding these v ways?

I asked for a quote here in the Netherlands, 2 years ago, but they asked 15.000 which felt like an excessive amount.

On youtube i found the video of Keith Rucker, restoring a planer with double v's:

This was a really big machine and that took 3 days grinding. Was wonderfull to see how they do it.

Would love to hear some reference prices, has anybody experience with this?

Best regards,
Paul

 

[Vulcanalia]

With some spare time in the christmas - new year period, i reconditioned the double V guides of the Jung on the new Okuma M560 we have got here. With a 6mm ball cutter i just followed the profile in a parallel toolpath, and got a good result.
Time spend on the reconditioning was around 3 days, with the milling took roughly 6 and 8 hours.
Roughly the same time went in alligning and measuring.

The machine as i bought it had its guideways scraped without being ground. So it looked good but was at the middle around 0.3mm low. With all reassembled and the magnet ground, the runout now is under 0.01mm on the full 500mm stroke.

First milled the top part of the moving slide flat (the surface were the magnet sits on), flipped it and then milled the male V guides. The spacing of the V's is exactly 180mm so easy to model. More challenging is the protruding cast bracket for the trapezium nut on the saddle. You cannot simply lay it down. I used 50mm spacers and shimmed it until flat.

Here is a link to the album:

Milling JUNG HF50 V guideways

www.practicalmachinist.com

I am aware it is not as perfect as grounded, but with the staightness of the Okuma copied into it, i am not worried
Would have been better to add the scraping surface and check it with bleuing but i am at the moment not equiped with those tools. Maybe as a future project.

 

[Peter from Holland]

Nice job
A liitle bit of scraping on the saddle would help significantly in lubrication
I imagen you could have milled oil pockets with the CNC
Better as nothing
Peter

 

[implmex]

Hi Vulcanalia:
How did you ensure you didn't twist or bend the casting when you clamped it down to the mill table?
Did you have to shim it?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[michiganbuck]

Nice job
A liitle bit of scraping on the saddle would help significantly in lubrication
I imagen you could have milled oil pockets with the CNC
Better as nothing
Peter

.That is very essential, dry places can cause heat and so make more error. Chuck hold downs should only be holding in from the chuck hold down flange edge, I put a .020 to .060 x 1/4 shim there to be sure I am not pressing on the edge.

Agree, *Nice job .01 mm is good coming off a grinder.
Chuck hold downs bolts should be less than 20 lbs. Tq. Too tight and this can distort the table.
I would add some flaking/scraping for lube, check the chuck hold downs. then run the machine 20 hours. If still having .0004 out of flat I would fix that.

Good way to check is to wet skim grind .0003 to ,0005 off the chuck with an open 46 K to L wheel and the check the chuck to for flat with a straight edge. Chuck should check < 0002 off. On long travel.
Check chuck top flatness with a straight edge blue if. Not running an indicator from the wheel head to the chuck.

A good method to grind a table with hold downs is to put a double bump stop in the go direction, and then little pressure on the hold downs.

When done I like to put a double thickness if mashing tape covering the parting space between the table and the saddle so spark grits can’t bounce off the column and into the works. An oil wipe keeps the tape from sticking on the lower part.

 

[cash]

Dear friends,

I have a worn Jung HF50 surface grinder with double V ways.
All work what i make on it is convex or concave... especially in the middle..
Has anybody experience regrinding these v ways?

I asked for a quote here in the Netherlands, 2 years ago, but they asked 15.000 which felt like an excessive amount.

On youtube i found the video of Keith Rucker, restoring a planer with double v's:

This was a really big machine and that took 3 days grinding. Was wonderfull to see how they do it.

Would love to hear some reference prices, has anybody experience with this?

Best regards,
Paul

Grinding the machines with a double Vee just add to the excitement, this was a fun project in working with Keith.

 

[Batavia]

Dear friends,

I have a worn Jung HF50 surface grinder with double V ways.
All work what i make on it is convex or concave... especially in the middle..
Has anybody experience regrinding these v ways?

I asked for a quote here in the Netherlands, 2 years ago, but they asked 15.000 which felt like an excessive amount.

On youtube i found the video of Keith Rucker, restoring a planer with double v's:

This was a really big machine and that took 3 days grinding. Was wonderfull to see how they do it.

Would love to hear some reference prices, has anybody experience with this?

Best regards,
Paul

By now it's probably not of any use anymore, but for jobs like that I would highly recommend going abroad. The living standard in the Netherlands is incredibly high and with that so are the salaries and thus costs of having a metalworking company doing a job for you. It doesn't help that we have a lot of medical, semiconductor, military, scientific and precision engineering companies here who metal working companies do work for (and lots of it at that), and thus know they can ask premium price quotes for any work they do. So next time my recommendation is to find a company in Belgium, or even better France, who can do it instead, they can do the same thing just as accurately but for a fraction of the price, and if it saves you many thousands of Euro's it is definitely worth the 400-1500 extra kilometers of driving to go there instead of in the Netherlands.

 

[tdmidget]

Grinding the machines with a double Vee just add to the excitement, this was a fun project in working with Keith.

Good to hear from you, Cash. Worry when a good poster is absent for a while.