Tips For Owners Of Rong Fu Rf-20, Rf-25, Rf-30, Rf-31 Mill/drills

[KenS]

Many of us hobbyists can neither afford or have space/power for a Bridgeport or even an RF-45 square column mill. Often we have to settle for one of the Rong Fu or RF clones -- RF-20, RF-25, RF-30 or Rf-31-- round column mill/driils.

I have both an HF mini-mill and and RF-31 (Taiwan made). And while the mini-mil is a nice for small parts, the RF-31 is in an entirely different league. The mill weighs well in excess of 400 pounds and you need an engine hoist or crane to move it. However, on craigslist you can often pick up a Rong Fu for just a little more cost than a mini-mill. I saw a nice RF-31 the other day for $375 including vise.

At any rate, being round columns, the Rong Fu's are notorious for losing tram whenever the head is moved up and down the round column. The R8 drawbar can also be a little annoying.

Searching for ways to improve my RF-31, I came across the following YouTube machining channel belonging to a video creator whose handle is "Cuppa Joe."

This is a link to Cuppa Joe's machining site with Rong Fu Mill/Drill information.

This ingenious machinist has developed a novel -- and relatively inexpensive -- way to fix the tram problem, and has made several other modifications to his RF-31 that have transformed it into a real workhorse.

As a joke he calls his videos about his improvements to his RF-31 either "Wrong Fu" or "Wrong Fu." This may have hurt hits to his site when those titles are bypassed by Google searches.

Just today in response to a backchannel email exchange I have been having with him, Joe released this overview video showing his many modifications.

I encourage any of you Rong Fu mill-drill owners, or prospective owners, to take a few minutes to visit Joe's YouTube site. I'm sure you'll find it worthwhile.

 

[Hawkeye]

Bookmarked it. Thanks.

 

[hman]

Back in November, 2014, CannonFodder started a thread about a device for quickly setting a vise square on a mill table.
http://www.hobby-machinist.com/threads/tool-for-quickly-setting-up-your-vice-on-the-mill.28527/
He added a steel plate to the front of his column for a reference surface.

I did something a bit different. I kludge-mounted an angle grinder in my mill vise, with a hold-down to keep it from popping out. I advanced it to just kiss the column surface, then ran the table back and forth [thank goodness for power feed!], advancing it just a bit each pass. This gave me a concave surface known to be parallel to the X axis.

I then re-mounted the grinder and cut a second groove a bit higher. The final result was a nice ridge, against which I could set the quick tram.

 

[hman]

The RF-30 and its cousins sometimes have an issue with the vertical motion handles interfering with a workpiece, vise, or other object on the table. I solved this by making a new crank handle, whose end is sized to just slip into the threaded holes of the spider. I pressed on an aluminum collar that has some 8mmx8mm magnets pressed into it. The magnets keep the arm in place even if I crank the spindle all the way down and release it to "fly" back to the top. But it's easy enough to remove and/or reposition in a different hole. Just for fun, I used a file to flatten the areas around the holes, though that may not be necessary. Those magnets hold very well!

PS - Yup. I've posted this before. But I thought it would go well in this particular thread.

 

[davidh]

vertical motion handles, sheesh, i can't count how many times i have smashed my face or head into those damm things. thats a great solution.

 

[KenS]

I solved this by making a new crank handle

Great tip! Thanks for sharing.

 

[GreatOldOne]

I've just completed several of Joe's mods on my own rf25. They've worked out really well, and with minimal setup I've got the head clocked at 0.02mm (which I believe is a little under a thou) when indicating the quill.









I've also pinched his captive drawbar mod, added an LED IKEA milling light ala Doubleboost, and cobbled together a TouchDRO system.

 

[KenS]

Thanks so much for sharing -- especially the photos. Here are a few questions:

1. What is the diameter of the shaft and radial bearing? And are the shaft and bearing Thomson? Can you give us an idea of the cost?

2. How did you attach the blue angle iron that holds the bearing support block to the rear of the mill?

3. Any chance we can get a few photos showing the back of the mill with the blue angle iron?

4. What type of scales did you use for your TouchDRO. Have you been happy with the results?

Glad you're enjoying your mods!

 

[dave_r_1]

Very unusual to mount the mill to the ceiling...I guess it makes it easier to see, with the swarf falling away from the work...

 

[GreatOldOne]

Very unusual to mount the mill to the ceiling...I guess it makes it easier to see, with the swarf falling away from the work...

What the fudge??? dunno what happened there - they look fine on my iPad / iPhone, but not in a PC browser... Must be the exif / image data. Hang on. I'm turning the gravity back on.