Rong Fu 31 Questions

[Jaylab]

I wonder if there are any sites that might discuss adjustments and modifications, I'd like to reduce the backlash on the axial movements but don't know where to begin.
X and Y have about .010 and .015 and I suspect there must be some way to tame this.

A few times I have tackled a prohect that would have been a lot easier with a right angle spindle drive. Is there one suitable for this bench top R8 mill.

Thanks, -Jay-

 

[mickri]

Some of the RF models have an adjustment screw on the table nuts for backlash adjustment. Even with the adjustment screw you can't eliminate all of the backlash. Tightening the gibs sometimes helps with backlash.

 

[pontiac428]

Backlash of .010-.015 isn't too bad of a starting point, but the RF can be adjusted to .005 with a little effort. The awful photocopy of the HF RF manual floating around the web shows how to access the trapezoid nuts. Gibs are important too, adjust those by feel but leave enough resistance to hold the table while milling.

I got good results from replacing the head fixing bolts (search here for rong fu head bolt fix). I got my quill backlash down to zero by loosening the quill gear housing and realigning it to close the gap on the gear teeth. Use the play built into the machine to make your adjustments, there is a lot of improvement to be had. Adding an extra wind to the clock spring in the quill will help take play out of quill extension as the tool pushes away from the work.

Any adjustment that can be done can also be undone, so get comfortable playing with it. Every machine needs a little tuning periodically.

 

[Jaylab]

Thanks very much!
The gibs seem good, and I have a diagram somewhere. I think there may be an adjustment around the table nuts, thanks for mentioning that.

I'll have to look for the trapazoidal buts, I probably have never seen those!
I'm grateful for your help.
-Jay-

 

[Makintrax73]

What I discovered on mine (copy?) is the nuts were not adjustable. I installed a Touch DRO - BIG project, but incredible increase in utility for several reasons including working around backlash. I also discovered that while the gibs felt ok an indicator said different- the adjustment screws were actually bottomed out. They were shimmed (watch the HW Machine Repair video on YouTube- easy to do) and it made a big, big difference in performance.

 

[pontiac428]

I no longer have a Rong Fu, but I found a thread here with lots of pics of the trapezoid nuts (lead screw backlash adjustment) from a member who replaced the originals for a CNC conversion.

Custom table nuts for my King PDM 30 (RF 31 type) round column bench mill

When I purchased this mill in 2008 I did a full teardown to clean everything up, refurb what was needed, and paint it. One thing I noticed right away was that the backlash in the table nuts was excessive, .080" on the Y and about .030" on the X. Part of the Y problem was a loose mounting bolt...

www.hobby-machinist.com

Here is the manual in .pdf also.

 

[Jaylab]

I have thought about a DRO and it would be far more convenient than the old fashioned dial indicators I have mounted on magnets. I restored (un-bent is more accurate) a 2-in stroke with a 2-inch dial and it has made a world of difference in setting the Z axis.

I have been using a Grizzley G0705_PL.pdf for an exploded diagram, but sure appreciate the rong-fu30-31 manual and the link to Canuck's page!

-Jay-

 

[AlexPeel159]

Second the DRO. In process of installing mine (TouchDro) and just having the X axis available while building parts for the Y axis was a world of difference. Its a very significant increase in the capabilities and ease of using the machine. Way beyond just dealing with backlash. Highly recommend.

 

[Parlo]

The gibs have nothing to do with backlash.
Investigate the free play in the bearings on the ends of the leadscrews first. This is often where most play is found.