[Bob La Londe]

I bought this old used machine with the intention of NOT converting it to CNC. I do use it quite a bit manually, but often its just grunt work. Today I used it for surfacing one side of a plate before transfering it to one of the mini CNCs on the work bench while the CNC was surfacing the plate the first one was going to rest on. While I was standing there cranking it back and forth I was thinking a power feed would be nice, or better yet to convert it to CNC and keep a bunch of "stock" programs handy like surfacing different standard size plates I use all the time.

The table looks pretty straight forward with lots of room to work, but the Z-axis is kinda odd IMO.

My thought was to remove the depth clamp and all the internal up down hardware on the Z and go with my own home made clamp with a couple external guide rods and an external ball screw. I'm sure there must be a reason why that's a stupid idea, but it seems to be a simple brute force answer to having accurate Z height positioning.

So tell me why this idea proves I'm an idiot.

[Bubba]

Bob,
Idiot, NO and as a matter of fact, I have seen a couple of good installations like that and a couple that I think are less desirable.
1. BUILD LOG: King Midas mill conversion is one way to do this type of mill in a manner that you suggest.
2. I thought I had another site bookmarked and the author was Jeff ?? and he was selling plans and parts also. As I remember, it was Home Shop or something like that. He gutted the existing system and put a rotating ball nut and servo up in the cavity of the head. Very neat installation.
3. I did mine by tightening up the clearances on the pinion and the worm wheel of the fine downfeed and get minimal backlash.

I have seen some others, but from an engineering point think they move the ball screw out to far and use to flimsy a bracket. This increased leverage looks to me to provide flexibility and poor accuracy.

Whatever you do, you can make this into a very capable machine if you live within the limits of rigidity.

[Bubba]

As a followup, got to looking through my TB of stuff and found more info on "Jeff"

He is Jeff Davis and his site is:
HomeCNC Technologies Introduction

Hope this helps.

[109jb]

If you are an idiot then so am I. I am right now in the process of converting a round column mill to CNC. I think it willwork just fine. I have the X and Y axis working now and have the quill feed (Z axis) designed. I am putting together a list of parts to order for that part of it now. My plan is to have a ball screw vertical in the front of the head as close to the head as possible. Then there will be a plate that clamps on the lower part of the outer quill that extends forward to where the screw is. There will have to be a tube from that plate extending upward for the ball nut to mount to. This is so the screw doesn't project below the quill nose. This will be driven by a stepper/ belt drive system.

[arizonavideo]

Here is a rather useful RF-31

[ame=http://www.youtube.com/watch?v=Qv-0Cjj0S-o&feature=plcp]"Automatic Tool Changer" - YouTube[/ame]

Making parts

[ame=http://www.youtube.com/watch?v=l2PWuqgviS8&feature=channel&list=UL]" Automatic Tool Changer" - YouTube[/ame]

Tools are to be use.. well.

[Bob La Londe]

Here is a rather useful RF-31

"Automatic Tool Changer" - YouTube

Making parts

" Automatic Tool Changer" - YouTube

Tools are to be use.. well.

That's an RF-31? Who set it up like that. I am impressed.

Hey, did you ever sell that 0704 you had listed?

I loved that last bit, "Ouch! Its Hot!"

[SCzEngrgGroup]

That's NOT an RF-31. It's a completely custom-built machine. The guy is Dave deCaussin, one of the founders of Fadal. He is hand-building those machines himself.

Regards,
Ray L.

[hoss2006]

That's NOT an RF-31. It's a completely custom-built machine. The guy is Dave deCaussin, one of the founders of Fadal. He is hand-building those machines himself.

His UMC10 is a custom made machine, the VMC8's shown ARE built on the Grizzly 1006 round column mill
commonly referred to as rf30/31 mills.
Hoss

[109jb]

Some of those are scratch built machines using linear rails, but he has at least made a few based on a Grizzly round column mill. This video is the one you want to watch. Obviously a round column mill was used as the starting point.

" Automatic Tool Changer" - YouTube

[arizonavideo]

Lots of good parts have been made with the RF-31. I would guess that their is still more of them around than the RF-45.

You just have to work within their limits.

That being said the Weiss-30 or MP-30 are much better machine to use and more ridged. Many people who wish to CNC step up to the square column mills for many reasons, mainly the Z.

But they all will cost more to buy that a used RF-30/31.

With the price of the G0704 being so low it is getting hard to justify not getting one if the price is anywhere close to the same.


Yes, I sold the extra 704 the same week. I threw in a few motor mounts and a X and Y ball screw with nuts. If you look in the background of this picture you can see the G0704 mounts.

[Torsten]

Just some food for thought, the machine you got makes for a great 2-Axes Cnc conversion that is the best bang for the buck in cutting performance, work envelope and cost.
Easy conversion with few simple Parts and fast to accomlish.
There are even some programs availabe that will convert standard cnc programs written for 3-axes machines by inserting a stop command before any z-axes command to allow you to manually reposition this axes.

Now about converting the Z-Axes allso to cnc be aware that this will require much more skill, time and money to do right.
Even when done perfectly it will never be better in cutting performance then the 2 axes version.
The reason is the more axeses are driven the less ridgid a machine becomes, while a manual axes is usually locked when cutting with the other axeses the cnc'd axeses are allways open and rely on the motor to hold them in position.

I have converted a similar machine to 3 Axes and belive the results have been exellent. The z was the most difficult to convert and required many Parts to the drive mechanism that where not initally obvious.
I consider the convertion a hobby and did not mind the huge amount of time spend on this, for someone looking for a quiker turnaround I would not recommend this.

Good Luck, wichever way you go with this.

[arizonavideo]

A cheep and simple way to CNC the quill is to reverse the quill return spring to remove all the backlash. Most cutters pull down so by having the slop already taken out in the down direction a cutter can't pull into the work. You direct drive the quill fine feed with a stepper.

Only one mount needs to be made for the complete Z setup.

Simple.

[Bob La Londe]

A cheep and simple way to CNC the quill is to reverse the quill return spring to remove all the backlash. Most cutters pull down so by having the slop already taken out in the down direction a cutter can't pull into the work. You direct drive the quill fine feed with a stepper.

Only one mount needs to be made for the complete Z setup.

Simple.

I had not thought that. Makes sense though.

[109jb]

I had not thought that. Makes sense though.

I had not considered this either. Now I'm changing my plans for my round column mill. I had planned on a ballscrew arrangement, but this just makes too much sense. Last night I took the spring apart on my quill. I have to make a simple tool to re-wind it in the other direction to put it back in, but I'm excited to get the Z-axis into CNC mode quicker. Sometimes the obvious isn't obvious.

One thing that I will do though is I will remove the plastic knob that engages the fine feed and replace it with a bolt for safety. That way the spindle can't come crashing down uless I get a wrench out.

[arizonavideo]

Not my Idea, I saw one done on the net. Worked well.

A ballscrew setup might be better but for most work I would think it will be fine.

Or is that fine feed?