New to me Ferro mill (Taiwanese Bridgeport clone)

[GA Gyro]

Nice buy!

I bought a PM935 in Oct of 2014... probably a little brother to your new mill... IMO you will enjoy this machine.

If you want to move it and are concerned about the 'top heavy' issue with a BP J head machine... put the knee table all the way down and rotate the head over so the motor is down. This is the way they are shipped from Taiwan, they are a LOT easier to move around in this configuration...

 

[johnnyc14]

I bought a Huanyang 3KW vfd on ebay to convert my shop 240V single phase power to the 3 phase this motor takes.It has taken a couple of days to figure out all the wiring and paramater settings. I have set it up with 2 latching switches for Run and Rorward/Reverse and a momentary switch for Jog and a 10Kohm linear pot for variable frequency. Amazingly after researching and setting all the necessary parameters as per the manual it all works as I intended.

I will post some pics and more information on my settings if anyone is interested.

 

[johnnyc14]

After running the mill for a while to test my VFD settings I noticed a rattling noise from the belt drive area. Looking up through the missing belt cover hole I could see the upper bearing was loose on the bearing cover. The outer race was spinning. I removed the 3 screws holding the cover down and it just lifted off, the bearing is supposed to be a light press fit into the cover. The mill came with a box of extra parts that includes most of another head branded "Kent USA" but all the parts appear to be the same as this Ferro branded mill. There was a good upper bearing cover with that box of parts. I bought a new 6007 2RS bearing and installed it on the shaft and used the hold down bolt to pull the "new" cover down onto the bearing. The head runs much quieter now.



After running the machine at 2000rpm for 30 minutes with no load it seems like the rest of the bearings are OK as there are no more unusual noises and the spindle was nice and cool.

 

[johnnyc14]

I have completely dis-assembled the table, and knee on the mill to do a major clean-up and replace some worn parts. The Y axis lead screw and nuts are badly worn and the knee lift screw gear was full of cuttings. I am having some trouble finding replacement parts and may have to make the lead screw and nuts. Here are some pics.
Here's the bottom of the table after clean-up. It has some wear but not too bad.



This is how I removed it.



The cross slide before clean up.



I used a jack to lift the knee after removing the bevel gear assembly.





I can't believe the knee lift actually worked pretty smoothly like this.



I removed the knee with my engine lift and used engine shampoo and a pressure washer to clean it up.







I re-installed the knee with new bearings on the bevel gear shafts and put lots of high pressure grease on the bevel gears and made a shield out of a piece of plexi-glass to keep the chip out of the bevel gears











The knee is back on and the gib adjusted.

 

[johnnyc14]

You can see here how badly the Y axis lead screw is worn in the middle. The one shot oiler ports into the nuts were completely blocked. The X axis screw and nuts are in good shape. The screw is 1.25" acme screw with left hand thread. I have ordered a 3 foot length of screw and should be able to make the screw shaft with no problem on the lathe. The keyways I can cut on my PM932 mill. I am trying to find a source for the nuts.







This is a rough drawing of the nuts, if anyone has any ideas where I can get some I would be grateful.

 

[catmechanic47]

After posting the same problem with my Sharp, I took advice offered and bored and sleeved nuts. Then recut threads. Worked like a charm. See split nut repair in this forum.

 

[johnnyc14]

After posting the same problem with my Sharp, I took advice offered and bored and sleeved nuts. Then recut threads. Worked like a charm. See split nut repair in this forum.

Thanks for your input. I looked at your thread but I'm not clear on the repair you made. More detail would be appreciated. I'm leaning toward order these nuts from McMaster Carr and machining them to match the originals. Pretty pricey though.
http://www.mcmaster.com/#95090a429/=wiprd5

 

[catmechanic47]

Sorry about brievity in previous post. I first chucked up the nut halves and bored them out past thread root apx. .100". then made a sleeve with a slight interference fit on OD and pressed sleeves into nut shell with red lock tite. Then cut new threads. It has worked well to this point. I wish I had taken pictures like you. I like your idea for covering the knee drive. Mine was in a similar condition when I first exposed it. Thats a nice job your doing. Good Luck.

 

[johnnyc14]

Thanks again for you input. I didn't want to go to the trouble of machining the lefthand acme threads in the nuts. I did try to order the nuts in the link above from McMaster Carr but they would not ship them to me. The is the reply I got to my order.

Hi John,
Due to the complexity of U.S. export regulations, McMaster-Carr accepts international orders only from businesses. This decision also applies to orders shipping within the United States, because it is based on the final destination of the items. We cannot accept this order or future orders.

I'm going to have to find another source for the nuts or make my own. This is turning out to be a pain in the butt!

John

 

[johnnyc14]

Well, I called Roton industries and ordered the nuts. The sales rep said they can be shipped to Canada, no problem. We'll see I guess. These can be machined to fit and are bronze.