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HF Drill/Mill to CNC ?

18K views 152 replies 10 participants last post by  Coils 
#1 · (Edited)
This thread is mostly BS and me asking how to do the conversion, I will do another thread on the actual conversion to cut out the useless info

I have an older model HF drill/mill like this one and I'm thinking about looking into CNC'ing it.
Anyone know where to look for info for doing the conversion? I tried to look around on the cnczone forum but only seen the square column models, and I didn't want to join another forum unless I had to.
I only seen one video for this model on YouTube and a couple companies selling complete kits but I think they're over priced.

I know this model isn't the best to convert but I know it can be done and I don't want to buy another machine
 

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#4 ·
Thanks Moleman, I thought someone on here did one but I couldn't remember who


VZ here's a dark pic of mine, the main difference on the older model is the Z scale is to the left of the head. I see you sent a PM, going to check it when I'm done here.
 
#5 · (Edited)
Since Coils is far from the first to ask and I am on my back from surgery and have time, I will try to detail my CNC conversion. This will be a work in progress and I will add to it/ change pics out as I get better ones.

My conversion is not the only way I am sure but it WORKS and works well.


CNC stands for Computer Numeric Control. Basically you give the machine a series of numbers or "G" codes (more on this later) and the machine moves in one through 4 axis (yes there are more axis but for us this is it)


A basic explanation is this:

A g code is written or converted from CAD (Computer Aided Drawing)
by means of a thumb drive or CD this is put into the desktop computer.

You open your CAM (Computer Aided Machining) program and it checks the code automatically for basic errors (i.e. is the code in the right format)



You locate your zeros on your part (basically where the coordinates are x0,y0,z0,a0

Zero your program or enter the coordinates it is to start machining from.

Make sure your material is well clamped.

Hit start.

The CAM sends signals to the stepper controller which is powered by the power supply

The Stepper controller sends signals through the shielded cables to the steppers telling it how fast and how far it needs to turn. My controller can do all 4 axis at once.

The steppers either rotate the ballscrews or cogged pulleys attached to the ballscrews to move the table and head.

The steppers are also your measuring device, each rotation has hundreds of "steps" and each step is calibrated to a linear distance of the bed, you can use some scales to interface also if you have DRO (Digital Read Out) but the steppers work very well themselves UNLESS THEY SKIP.

Your part is machined.



You will need:
A mill drill, mini mill or knee mill.

A desktop computer running XP(for some reason beyond me many laptops are "clocked" different and?or lack the type of graphics card you need) ADD LINK HERE I use an old dell I bought from the local computer repair shop for $50

A power source for the stepper motors


CAM program


A stepper driver


Shielded cable (ADD TECHNICAL NAME HERE) ADD LINK TO ebay

Cable connectors

Stepper motors (YOU MUST SOLDER IN A RESISTER AS SPECIFIED OR BURN OUT YOUR SYSTEM)

Ball screws

Ball nuts or zero back lash ball nuts

Bearings (MUST SUPPORT AXIAL AND THRUST LOADS)

brackets (you make)

OPTIONAL PARTS

pulleys (to increase the power and holding ability of the steppers) McMaster-Carr

belts McMaster-Carr



My set up:

My CNC uses a X Axis stepper directly driving a ball screw

This is a direct drive coupler used to correct any misalignment.


It is hidden in here:


one end goes on the stepper shaft and the other goes on the ball screw




The stepper is
NEMA 23 Stepper Motor: KL23H2100-35-4B (1/4” Dual shaft with a flat) 381 oz-in
Specification Price: $49 (Inductance 2.8 mH) Can be used for G540, G251, G250 or any other driver
381 oz In. Hybrid Motor
1.8° /200 Steps Per Rev.
3.5 Amps Current Per Phase
4-wire Bi-polar, NEMA 23 Frame
Found here:
Stepper Motor
Buy a stronger stepper for the mill drill, it should be fine for a smaller mill

The ball screw is
5/8 X .200 Right Hand Recirculating Lead Screws & Nuts for Power Transmission - Roton Products, Inc. $11.24 a foot

The ball screw nuts are (need 2)
5/8 X .200 Right Hand Recirculating Lead Screws & Nuts for Power Transmission - Roton Products, Inc.
Part Number: 19193 $26.23 each

Belleville washers (unknown number, maybe 6-8)
McMaster-Carr
0.630" 1.250" 0.040" 0.082" 0.021" 230 330 qty12 9712K82 $5.11
now I think these are right, I will measure some. They are 1.250" OD and the mount for zero backlash is only 1.00" wide. You will have to mill out room for them.

Heres a pic of the outside




My y axis was skipping (caused by not enough torque and resulting in a lost "zero") so it is geared down for power by using cogged xl pulleys, belt and idler bearing)

I designed a better bearing retainer here, look at the button head screw that over lapps the bearing.




The stepper is
NEMA 23 Stepper Motor: KL23H2100-35-4B (1/4” Dual shaft with a flat) 381 oz-in
Specification Price: $49 (Inductance 2.8 mH) Can be used for G540, G251, G250 or any other driver
381 oz In. Hybrid Motor
1.8° /200 Steps Per Rev.
3.5 Amps Current Per Phase
4-wire Bi-polar, NEMA 23 Frame
Found here:
Stepper Motor
I would go with a stronger stepper here, but for a smaller mill it should be fine


The ball screw is
5/8 X .200 Right Hand Recirculating Lead Screws & Nuts for Power Transmission - Roton Products, Inc. $11.24 a foot

The ball screw nuts are (need 2)
5/8 X .200 Right Hand Recirculating Lead Screws & Nuts for Power Transmission - Roton Products, Inc.
Part Number: 19193 $26.23 each

Belleville washers (unknown number, maybe 6-8)
McMaster-Carr
0.630" 1.250" 0.040" 0.082" 0.021" 230 330 qty12 9712K82 $5.11
now I think these are right, I will measure some. They are 1.250" OD and the mount for zero backlash is only 1.00" wide. You will have to mill out room for them.

The Z axis seems to have a million solutions, this is mine. a XL belt, cogged pulleys and idler bearing. It drives the head up and down.


Video of z axis operating. Dont get dizzy ;>


The stepper is
NEMA 23 Stepper Motor: KL23H2100-35-4B (1/4” Dual shaft with a flat) 381 oz-in
Specification Price: $49 (Inductance 2.8 mH) Can be used for G540, G251, G250 or any other driver
381 oz In. Hybrid Motor
1.8° /200 Steps Per Rev.
3.5 Amps Current Per Phase
4-wire Bi-polar, NEMA 23 Frame
Found here:
Stepper Motor
It is just right for my use
The ball screw is
5/8 X .200 Right Hand Recirculating Lead Screws & Nuts for Power Transmission - Roton Products, Inc. $11.24 a foot

The ball screw nuts are (need 2)
5/8 X .200 Right Hand Recirculating Lead Screws & Nuts for Power Transmission - Roton Products, Inc.
Part Number: 19193 $26.23 each

Belleville washers (unknown number, maybe 6-8)
McMaster-Carr
0.630" 1.250" 0.040" 0.082" 0.021" 230 330 qty12 9712K82 $5.11
now I think these are right, I will measure some. there is plenty of room here so no need to cut mount



The top of the assembly





The middle




The attachment point to the head. Please note the red wires go to a ton of LEDs glued in to light the work surface evenly




I added this spring to put constant tension on the head. It makes machining much easier to not have to loosen and tighten repeatedly.

I believe this is the spring
McMaster-Carr
9434K163 1 Pack Music Wire Precision Compression Spring, Zinc-plated, .750" Length, .12" Od, .016" Wire $4.65



my A axis (or 4axis or rotational axis) is run off a cogged set of XL pulleys and an XL belt, run to a dividing head.


The stepper is
NEMA 23 Stepper Motor: KL23H2100-35-4B (1/4” Dual shaft with a flat) 381 oz-in
Specification Price: $49 (Inductance 2.8 mH) Can be used for G540, G251, G250 or any other driver
381 oz In. Hybrid Motor
1.8° /200 Steps Per Rev.
3.5 Amps Current Per Phase
4-wire Bi-polar, NEMA 23 Frame
Found here:
Stepper Motor
It is just right for my use or even too big




I did not buy ultra expensive zero backlash ball nuts, I made them.



homemade zero backlash nuts
The belleville washers are under significant pressure. The right nut is secured in the mount. The springs push against the left nut which is prevented from rotating but he sides and bottom of the mount but it is allowed to slide in the mount for wear adjustment. The springs MUST BE STRONG or the table will shudder and grab as the end mill cuts.


power supply
KL-350-48 48V/7.3A
110V/230V $49.95
Switching Power Supply

Stepper driver (Gecko)
GeckoDriver G540 4 Axis driver Current New Version with a
complete Motor Connector Set of four 9 pin modules,
Special $239.95,
Page Title

CNC CAM (Mach III)
$149
Mach3 - 45000Hz 6-Axis Controller for
Windows XP and 2000 $175
MACH 3 FEATURES
Converts a standard PC to a fully featured
CNC controller.
Up to 6 axis cnc control
Allows direct import of DXF BMP JPG and
HPGL.
Visual G-Code display
Generates G-code
CNC Software
Axial/thrust bearings
McMaster-Carr

Ballscrews are EXTREMELY hard be sure to anneal before turning and threading.





PRICE

$66 ballscrews
$170 ball nuts
$49 POWER SUPPLY
$50 DESK TOP COMPUTER
$239 Gecko driver
$149 CAM mach III
$200 bearings pulleys couples etc

TOTAL
under $1000 easy
 
#6 ·
Sorry to hear about the surgery :(

And thank you for all the info so far, I'm not in a hurry and can wait, so take your time I'll check out what you put up so far.
 
#9 ·
Smartbomb I did see that, but it looks like he only does them for the mini-mills.

Zoom, wait and see how well this thread goes, it is a good subject to be sticky.
 
#10 ·
VZ, wow that's a lot of info in one post. Don't know where to start asking questions? :D


Let's start with the lead screws & nuts since these seem like they will take the most work to get mounted up.
The link shows the lead screw is sold by the foot, let's just say I need 6 feet (I'm guessing). Should I just place an order for a 6' piece (which seems costly for shipping or could get damaged), get two 3' pieces or ask to have them cut at 3', 2' & 1'?
-The factory X acme screw on mine is right at 3' (don't know if I should go a few inches over this or not).
-The Y looks to be about 18-20", so 2' should work here. If I remember right the rear of the stock acme screw isn't supported at the rear, would the ball screw one need to be supported at the back, or can it basically be setup like the original?
-And I don't know what I'd need for the Z? I was thinking 8-10" but I might be wrong on this. I'm having trouble understanding how you did yours, the top & middle makes some sense but I don't understand how the lower part works and is hooked up to the rest of the setup?

For the ball nuts, are you using two on each lead screw?
I understand the spring washer thing, that's a good idea.
 
#11 ·
i can measure the ball screws for you. Have them shipped in convenient lengths, ball screws are HARD to cut, turn and thread.

The x axis ball screw is captive on the right side, it has a radial and thrust bearing captive to the table and screw. the left side should have a RADIAL bearing and the ball screw MUST slip in it. As the temperature changes the the screw lengthens and the left side of the screw should be allowed to slip in and out as needed.

The y axis far end is free with no bearing as it is so short.

Z axis has a bearing on the top and bottom

Pics, drawings and video are coming for the z axis

ALL ball screws use 2 ball nuts
 
#12 ·
LOL on the dizzy thing. But thank you for adding the video and drawing or the Z, that makes sense now.
If you want to get a rough measurement of a ball screw, can you measure the one on your Z? I should be able to figure out the others.

Would it be better to have all the motors on a belt drive setup?

I was wondering what that cap screw was for, that's a good idea for a bearing retainer.
 
#13 ·
If I was to do it again I would go with larger x y steppers and direct drive them. I am running a 3:1 ratio on my belts. Look for stronger steppers and possibly a larger required power supply. Or you could belt drive the y axis and go with a larger direct drive x.
 
#14 ·
Do you think the 495 oz motor would be enough for direct drive?
What about the Z, think that would work with a direct drive? Assuming it could be mounted that way.
 
#15 ·
I think that will be enough, becaise of the shape of the table, the x needs a drirect drive. They y can do either.. the z needs belt drive to keep it compact. I would go with larger steppers on x y z just to be on the safe side. Remember of it skips you lose zero...
 
#17 ·
Since you keep saying about going with large stepper I'll plan on those 500+ oz ones since they're just five bucks more.
Thanks for the measurements, I think I'll get two three foot pieces so I'll have extra for the Z in case I need it.

The only reason I was thinking of doing all axis with belt drives is because other then yours I've seen four other machines like ours and they had all three axis belt drive, guess I'll have to rethink what I was thinking of doing. :D
I tried to join that CNCZone forum to try and see what others have done on theirs, but I haven't gotten the confirmation email yet
 
#19 ·
Mostly I got a few pics I saved, I'll most likely have to put them in a couple posts, and a few videos I found on YouTube.
Remember I was just looking for mounting ideas.

Here's some links to videos.
This was the first one I found, it looks like it just hooks up to a stock machine.
[video=youtube;kibbg1tjTOc]http://www.youtube.com/watch?v=kibbg1tjTOc]Vulcan - Harbor Freight milling machine retrofit. Testings - YouTube[/video]
This guy did servo motors and a variable speed DC drive motor
[video=youtube;cJRAGhC3KWw]http://www.youtube.com/watch?v=cJRAGhC3KWw]CNC CONVERTED RONG FU DRILL MILL (DC SERVOS + MACH) - YouTube[/video]
This one mostly shows it cutting
[video=youtube;ADmjSwr_O9Y]http://www.youtube.com/watch?v=ADmjSwr_O9Y]RF30 RongFu milldrill converted to cnc - servos-MACH-GECKO - YouTube[/video]

[video=youtube;E4mq7wnjmmY]http://www.youtube.com/watch?v=E4mq7wnjmmY]First Cut with my CNC Converted Mill - YouTube[/video]

[video=youtube;KbeuQ55yY10]http://www.youtube.com/watch?v=KbeuQ55yY10]CNC home shop mill retrofit - YouTube[/video]
 
#20 ·
Now the pics

I like how this guy set his up. He kept the X mount thin so it will clear the base if the table moves far enough, but it does stick above the table a little.

His Z is a really nice setup but it's complicated looking with little margin for error.
 

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#24 ·
That sucks
If the hard drive in your new pc isn't too big or expensive, you might want to add another one the same size just as a backup unit.


And a friend is delaying me a few weeks in buying the ball screws & nuts that I was going to order this weekend, he's thinning out some of his gun stuff and I can't pass this one up, he's selling a litely used Hornady Lock-N-Load AP press with some extras well below the cheapest price I can find on the net. At this price I can't pass it up.
So I'll most likely have to wait until next month to order those parts.


OK now a program question, which anyone can answer.
What's a good but easy to use CAD program or whatever is needed to design stuff, by easy I mean for "a complete idiot" style one, free would be best but a trial version that you have to buy is ok too.
And it has to work with Mach3, this seems like the standard for the home user.
I want to start messing with the programs a while, I think it will take me some time to figure them out, so I might as well get a head start on them :D
 
#25 ·
Here's the X axis double ball-nut setup, stack of spring washers between ball nuts to keep tension between them:


Same thing on the Y:


I built my own controller one part at a time and stuffed it all in an old computer case. I added a 4th axis after this photo was taken, luckily I left room for another gecko drive:


I started out trying to position the Z axis like this, but it didn't work well enough because of the slop in the geartrain:



And ended up going this route:
 
#26 ·
I made the 4th axis from a stepper driven rotary stage I found on Ebay and adapted a little 3 jaw chuck to it. It's been very handy for making replacement gears:







My uncle gave me the mill so I had nothing in it. I already had a Bridgeport and didn't see a need for two manual mills. I started out with an idea that I should be able to make the conversion toCNC for about $800 since I made a lot of the mechanical parts myself, I think I ended up with about $1100 in it when it was all done. Whatch what you buy on Ebay with regards to controller boards, I learned the hard way (but this was many years ago).
 
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