My round column RF30 mill to CNC conversion, the cheap way

[stioc]

The mechanical parts

OK, so far everything was really straight forward: simple, inexpensive and readily available. However, the mechanical parts was a bit of a challenge for me. I really didn't feel like building parts myself unless I had no other choice. Remember from post #1 of this thread:

Goals: cheap, quick and easy.

I briefly looked at Grizzly's kit and I mean...briefly- as soon as I saw the $5k price tag I closed the browser window . Then I found FlashCut, at the time I didn't know it's their kit Grizzly sells so I emailed them asking if they'll sell the mechanical parts to me. I got no response

At this point it was looking like if I wanted it cheap, it wouldn't be quick because I'd have to take the project on myself. I was coming to terms with this when I came across someone's kit by the name of PaulCNC - I saw the youtube video, then found the pricing online and thought the price was right up my alley. However, I wasn't sold on the design, it just looked too simplistic to me and I wasn't convinced it would work effectively. I'm not a mechanical engineer so when I build mechanical things I often tend to over-engineer things and make them more complex than they need to be perhaps. Anyway, I reached out to Paul via email asking for availability of the mechanical kit. As of this writing Paul sells a complete kit all put together for you to just plug in for $820. He also sell the complete DIY kit for $620 and the mechanical kit for $320 (he loves $20 I see). BTW, Paul's kit is geared towards Mach3 which doesn't matter much to me since it's the same interface as LinuxCNC just different control software.

http://paulcnc.ipower.com/site/

I asked Paul for a reference of a customer whom I can talk to about their experience and longevity of the kit. Paul sent me a contact- this gentleman happens to have a really informative website about all sorts of machining stuff. From his website I gleaned quite a bit of info already and realized he bought Paul's kit several years ago and has since made lots of things on it.
Anyway, I reached out to the contact and as suspected got a very positive feedback. OK Paul, here's my $320 via paypal...and two days later the kit was in my mailbox:



The kit allows you to use the handwheels too, this was important to me as I didn't want to lose that capability if I could help it. I could see times when I'd prefer to run a job manually (e.g. repair work on say a...cylinder head, I know mighty ambitious of an example, but hey...).

 

[stioc]

Mechanical parts fitting and a couple of oops:

So the mechanical parts in theory should be a matter of replacing the handles with these parts. That is if you're not me lol, for me it's not a project without some oddball issue cropping up or me messing things up. In this case it was both.

OOPS #1, looks like the hand me down mill was previously 'modified' in that the Y-axis shaft collar doesn't have 3 jaws like the X-axis...so Paul's collar can't mate with the jaws of the leadscrew collar.

The way the Y axis should've been (this is my x-axis):


My Y-axis leadscrew collar:


I decided to drill and tap Paul's collar and use set screws, similar to the hand-wheel that was on it. My table-top Craftsman drill-press has too much run-out for precise holes so I moved its small X/Y vise to the mill, since I'd removed the mill's handles and didn't feel like putting them on.



Done, two set-screws in place, the other is opposite to the one in the pic.



OOPS #2, (self inflicted of course) when you order the kit from Paul you have to measure a few things to get the correct kit. This is due to the fact there have been man RF30 clones sold over the past few decades and there are slight variations of the shaft size etc. Well when I measured my Z axis shaft I thought it was a 1/2" dia. but it was more like 13mm so when I put it on it was *very* snug, while not realizing the issue I gave it a few taps with a soft hammer to get it about half way onto the shaft. Then when I went to remove it by tapping it back out it wouldn't even budge Well it doesn't know who its dealing with so I break out my slide hammer :scared: a few gentle taps and I see it moving...wait, its not the collar moving but the whole shaft is coming out of the housing :lol_hitti I quickly tapped it back in hoping I didn't mess up anything inside (I didn't even know what the inside looks like as I've never messed with any internals of a mill, ever.). After some head scratching and cursing I decided to take the housing apart. Luckily nothing was visibly damaged :bowdown:



I clamped it in a vise, then used a vise-grip as a stop for the shaft sliding out of its housing but this collar was not coming off! I ran through a couple of options in my head, slice the collar to get it off and reorder it from Paul and thought this might be my last resort. Then I thought, it's aluminum on steel, I should be able to heat it up with my propane torch and that should help. Boy, did that help, let me tell you just 1min of heat and the thing slid right off! Then I put everything back together the way it was before. At least I put some synthetic grease on the gears.



Finally, I chucked up the collar on my 9x20 lathe and faced off the end and bored out the hole a few thous for a good fit.



Lesson learned: a bigger hammer is not always the best solution

 

[stioc]

Back to the electronics
I only had about 5hrs of shop time but most of the control side wiring, layout and control board is done now, yay! I didn't even have to go to Home Depot, everything I needed I found in the garage, or put another way, I used what I had lol

I got the these cables with the breakout board, I cut one end of the connector to wire up the drivers. This made for very nice and clean looking wiring.




I then added power/ground by daisy chaining it to keep the wiring as clean as possible.



Finally, decided on a layout that I liked and one that wouldn't stress the parallel port and USB cable, marked out some holes...



...and it's all done!

 

[Boswell]

Your moving right along

 

[stioc]

It's ALIVE!!!

I got all the wiring completed and the control panel mounted.





Then I dialed in the backlash using the Touch DRO...the 1.000 on the DRO screen represents the 1" jog command on LinuxCNC for each access - and they match up perfectly! In all honesty I would've been happy with a .002 error too since this is just backlash (and not the full screw mapping, which I don't know how to do yet).



My backlash settings/config, I'm still playing around with some of these settings so if anyone has any thoughts/advice I'm all ears:


...and finally its first test under CNC power...using a pencil:


OOPS #2.1:
There's a problem, of course...remember when I had to bore out the Z axis coupler? Apparently I didn't indicate the part properly so when the shaft spins the whole motor/assembly started wobbling round and round, son of a...

OK so what now? I could give Paul a call and buy another coupler which he sells separately on his website. Then I thought, dummy at least try to fix your mess and learn to do things properly...a learning opportunity you see? So I chuck up the collar in the lathe, indicate it to within .001" this time and bore it out to a bigger size 0.70". Then I take a scrap piece, bore that out to 1/2" and then turn it down to 0.685".







Then I cut out the appropriate length and pressed it into the collar, took a bit of an effort, which is what i wanted. Finally, drilled and tapped a hole. The whole thing now turns perfectly!





I now declare my conversion complete.

Total cost: $516 (btw, Paul sells his kit for only a $100 more than this and I would've gone that route had I not already bought some of the stuff before finding Paul's website. Also for $820 he sells a turn-key bolt-on kit which if you consider the amount of time involved in wiring is a fantastic deal.)
Total time: about 3 full days given a couple of issues I ran into
Difficulty factor: hard to quantify this but I'd say if you already use things like mills, welders, automotive stuff then probably a 2 out of 5 (5 being the hardest).

Not bad for a hobby machine, I couldn't be more pleased

Now Fusion 360, that's a solid 5 for me, and I'm an IT guy- I'm just not good at drawing/CAD etc. I made a design for engraving in Fusion 360 but couldn't quite get it to work right, some letters it wants to deep engrave while the others it barely touches. I think it has to do with it trying to be too smart about how wide the engraving bit is. I'm going to try the Trace function instead.

LinuxCNC also has a learning curve...I've just barely scratched the surface on it.

 

[Boswell]

I now declare my conversion complete.

Great seeing how quickly you were able to get this running!

 

[stioc]

Thanks Boswell. It was a fun and easy project and hopefully the documentation will give others a cheap way to CNC these inexpensive mills, afterall most people that buy these mills wouldn't want to spend $5k (or even $2k) on a $1500 mill. Also, the round column mills are written off but I really like mine. I used to have a mini mill and there's just no comparison, this thing weighs about 800lbs, very rigid in comparison and not much more money either.

 

[agfrvf]

I plan on doing something similar to my 2.5ton horizontal using a makerbase and some 50Nm steppers.

 

[gzoerner]

stioc,

Many thanks for your write up. You've inspired me to build a 3-axis router project. I'm just finishing my first arduino/stepper motor project for my 9x20 lathe.
Glen

 

[Paul Thompson]

$516 has to be some sort of record.

Very resourceful