I have someone offering me a slightly used one of these
http://www.cncmasters.com/CNC%20Jr%20Mill.htm
with all the bells and whistles.

The price is $5000 and it comes with lots of endmills, vises, etc.

What do you think?

Personally - I don't think that's all that great. I will bet you could just about duplicate that for less than $3500.

If you have an immediate need, then look around. If you have the ability or willingness to learn, buy a basic machine and build your own controller - it's not all that hard and you have a tremendous resource for information right here.

Scott

A round column CNC machine with Z-axis on the quill is not normally a good idea unless you know the class of work you will perform will be OK with the limited Z-axis travel. At USD 5,700 new or USD 5,000 slightly used its a bad idea. Half price might be OK if you can live with the Z-axis travel limitation.

Look at:
Tormach, Smithy CNC and also IH.

Phil

I have someone offering me a slightly used one of these
http://www.cncmasters.com/CNC%20Jr%20Mill.htm
with all the bells and whistles.

The price is $5000 and it comes with lots of endmills, vises, etc.

What do you think?

Do you have any SPECIFIC suggestions for a better deal? I'd like a bigger table than on my Taig 2019 which has 12"x6" travel. I need at least twice that for the parts I need to make. I need roughly 36" of x-axis travel.

The Taig also has a 1/4 HP motor. It's just not strong enough.

gs

$5000.00 for that? No way! You can build it for less than $3000.00. The mill head looks like a Harbor feight Mill that sells for 1,800 and just add step motors

I need roughly 36" of x-axis travel. gs

There is a thread on this site from a guy who built a machine with a very long X axis. If time permits, I will scare up a link.

For this kind of travel, you are looking at either a home-built special or a VMC. The home-build could be done for your price range, but the VMC is out of the question.

Scott

It's not clear why you asking about the cncmasters machine, which has only 19" of travel on the x-axis.

I need at least twice that for the parts I need to make. I need roughly 36" of x-axis travel.

I was also comparing CNC Masters, IH, Tormach, or rolling my own from an X3 etc. I was aware of the round mill issues, but I did not need much Z travel, so the 5" would've been fine.

I was offered a used CNC masters mill for about half the new price, but I held out because I was unsure at the time, then came across someone local to me selling a pre-converted HF geared-head mill/drill, and let's just say I got a great deal on it :cool:

Being a running system, I found it easy start using the mill and upgrading where I see necessary, but I've still spent waaaayy less than the used CNC masters unit would've cost me, or had I converted one myself.

However, I've now realized that the 5" Z travel decreases to only 2" or so if I have to change between endmills and drill chucks in the same operation due to the drill chuck being very long. If I raise the head on the column to compensate, I have to re-align the mill since it's a round column. Not a problem, but just time consuming. Now, I'm looking for a low-profile drill chuck, longer end-mill holders, or some other solution to closer equalize the heights of the different tool bits I use for a single part.

I'm still fascinated with what I can do for what I spent, but I know I would not have been happy if I had picked up that used CNC Masters unit for that price. Also, if I decided to roll my own, I would be sitting on a pile of parts still and scratching my head. :)

BTW, you say you need 36", but that CNC masters mill only does half of that.

Cheers,
-Neil.

$5000.00 for that? No way! You can build it for less than $3000.00. The mill head looks like a Harbor feight Mill that sells for 1,800 and just add step motors

IIRC, that mill is a Rong Fu RF-31, such as this... http://www.use-enco.com/CGI/INSRIT?PMAKA=105-1110&PMPXNO=953999&PARTPG=INLMK3

Yeah, I know the CNC Masters is only 18" or so on the x-axis. But even that much would be a BIG upgrade from my 12" Taig. And I'm not sure how tight my Taig will hold over 12" anyway. The CNC Masters machine looks a lot more rigid.

On the suggestions here alone, I'll probably avoid the one offered to me. But the questions still remains, what else should I do? I don't absolutely have to get 36" of x-axis travel but it certainly would make things easier. I suppose I could figure out a jig of some kind and cut my parts in two passes. I could do one end, flip the piece horizontally and do the other end. But that seems prone in inaccuracy.

If I went with a Rong Fu machine, how much of it am I going to remove if I do a CNC conversion? I'm pretty confident that I could machine any parts I need for the conversion. And $2500 to $3000 would make my checkbook much happier than $5k. But I don't want to buy another machine that will sit around for 2 years before it gets used. I have plenty of orders right now that I could be filling. And I could probably pay for the machine within a year if I start cutting now. It seems there's a never ending supply of machine work.

Will I need to buy BALLSCREWS for one of these Rong Fu machines (or clones) or can I just hook up some steppers and connect them to a driver and my software and start cutting?

Would someone who knows about converting one of these machine (maybe has done it before) mind calling me or PM your phone number to me so I can have a one-on-one discussion about this project?

Actually, if you have no problem making the parts to convert one, then that would be the way to go. And in that case, I absolutely recommend going with a square-column mill. One other thing to look at is the conversion kits that some companies offer (including CNC masters, Microkinetics, etc). Not to use their parts, but it would help you see how they converted theirs and you'd see how to convert one.

Cheers,
-Neil.

Could this be converted to CNC easily?
http://www.lathemaster.com/HEAVYDUTYMILLINGMACHINE%207045FG.htm

Am I right about needing to replace the lead screws or could I leave them as they are and just hook up my motors?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290185359932&ssPageName=ADME:X:RTQ:US:1123
This one is only a couple of hours away from me. It's older and has a round column, but what about converting it to CNC? I don't expect the auction to end very high. Probably under $1000.

Converting a round column you already own to cnc is one thing. Going out and buying a round column in order to convert is another. Don't do it is my advice.

Phil

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290185359932&ssPageName=ADME:X:RTQ:US:1123
This one is only a couple of hours away from me. It's older and has a round column, but what about converting it to CNC? I don't expect the auction to end very high. Probably under $1000.

I think you need to focus.

You want 36" of travel. you hope to get by with USD 2,000 to 3,000 and you have paid work waiting.

Which is it to be: big, cheap or now. You can't have all three, not unless you are lucky on the scale of "I just won the jackpot on the lottery ".

Regards
Phil

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290185359932&ssPageName=ADME:X:RTQ:US:1123
This one is only a couple of hours away from me. It's older and has a round column, but what about converting it to CNC? I don't expect the auction to end very high. Probably under $1000.

Could this be converted to CNC easily?
http://www.lathemaster.com/HEAVYDUTYMILLINGMACHINE%207045FG.htm

Am I right about needing to replace the lead screws or could I leave them as they are and just hook up my motors?

That machine looks like a good one to convert, because of the square column. However, you should also look at Industrial Hobbies as their mills have larger beds/travels IIRC. So you can start with a better (for your needs) base machine and convert that.

Also, not to confuse the issue, but how about converting a knee-type mill, just for the larger travels?

One advantage of converting your own is that you can CNC with standard lead screws and later convert to ballscrews. This way you can start running jobs for customers sooner.

So if I go with the LatheMaster mill, I can just create motor mounts, mount the motors, and connect them to my driver, right? No other hardware needed?

There's a guy on eBay selling 640oz steppers for $79 each and 906oz steppers for a little under $100 each. How big do I need to go on the motors? The 640oz motors are 4-wire like the ones on my Taig and they're 6 amp. Some of his bigger motors have 8 wires and I'm not familiar with that layout.

Hey, I just looked at that Industrial Hobbies mill. Holly cow that thing is big. Looks exactly what I'm looking for. Looks like it would cost about $2500 to get it here. Then probably another $700 or so to get it converted. I wonder if anyone here has converted this one.

So if I go with the LatheMaster mill, I can just create motor mounts, mount the motors, and connect them to my driver, right? No other hardware needed?

There's a guy on eBay selling 640oz steppers for $79 each and 906oz steppers for a little under $100 each. How big do I need to go on the motors? The 640oz motors are 4-wire like the ones on my Taig and they're 6 amp. Some of his bigger motors have 8 wires and I'm not familiar with that layout.

8 wire motors have two pairs of windings. They can be wired series for more speed or parallel for more torque (or even unipolar).

Alan

So which one is the one to get? What size would I need for a larger mill?

Go here for everything you need to know about CNCing IH mills.

http://www.cnczone.com/forums/forumdisplay.php?f=284

There are many other things you need besides drivers and steppers. you are not going to CNC an IH mill for USD 700. You need to do much more reading before spashing out with the cash.

Regards
Phil


Hey, I just looked at that Industrial Hobbies mill. Holly cow that thing is big. Looks exactly what I'm looking for. Looks like it would cost about $2500 to get it here. Then probably another $700 or so to get it converted. I wonder if anyone here has converted this one.

Philbur, what else am I going to need? I've been reading those other posts but there not a lot of detailed info there. At least I haven't found it yet. What will I need besides steppers and drivers? I can make my own mounting brackets and shaft connectors. Wire is cheap. Where's the extra cost going to come from?

I'm not an expert at this, but I was doing a lot of research into converting my own (but then I came across an already-converted machine so I stopped). But here's the basics I can think of -- mill, motor mounts/brackets, couplers or pulleys/belts (depending on which drive method you use), motors (steppers or servos), connectors & wire for the motors, drivers (stepper or servo as appropriate), power supply for the motor drive, power supply for the driver electronics, some electricals such as limit switches, e-stop switch, additional wires/connectors for these, breakout board, and a PC. Later, you can convert to ballscrews, and there are a few really good writeups on this, which I can dig up for you later if you wish.

To me, the biggest hassle was figuring out what size steppers I would need (as a lot else would be based upon that), and the only real answer is to see what others were using for similar sized mills, and with similar drivers and power supply. But having purchased an already-converted mill, I had the advantage of having a baseline from which I upgrade as necessary.

My mill came with 276 oz-in steppers, with a 1:10 belt drive reduction to get more torque. It also came with a small 24V power supply, which I replaced with a 70V linear supply and now I can do 40IPM rapids (but I keep it at 30IPM to be safe). The drivers I have are really nice (IMS805's), so I intend to replace the motors with larger 500 oz-in units. I also built a PC directly in the case that came with it (nice large, machined aluminum case). And finally I'll switch to ballscrews. Oh wait, not finally, since I do intend to swap to a 3-phase motor with a VFD, so I can get more spindle speed, and PC-controllable speed.

Disclaimer: I am not an expert, and there are a lot more experienced people on these forums from whom you should get better advice.

Cheers,
-Neil.

See cnczoner's post.

However I think he may have forgotten to list the machine control board, control software and a cabinet to put the resulting bird's nest in.

Regards
Phil

Philbur, what else am I going to need? I've been reading those other posts but there not a lot of detailed info there. At least I haven't found it yet. What will I need besides steppers and drivers? I can make my own mounting brackets and shaft connectors. Wire is cheap. Where's the extra cost going to come from?

See cnczoner's post.

However I think he may have forgotten to list the machine control board, control software and a cabinet to put the resulting bird's nest in.

Regards
Phil

Phil,
What are you referring to as the machine control board? Are you referring to a USB-type control board for example? My machine uses a parallel port breakout board which goes directly to the driver, so AFAIK they not necessary unless higher speeds are required.
-Neil.

Then we are talking about the same thing, machine control board may be a bit more descriptive.

Phil

Phil,
What are you referring to as the machine control board? Are you referring to a USB-type control board for example? My machine uses a parallel port breakout board which goes directly to the driver, so AFAIK they not necessary unless higher speeds are required.
-Neil.

mill - I'm buying it
motor mounts/brackets - I'll make them
couplers - I'll make them
motors (steppers or servos), $300 on eBay
connectors & wire for the motors I already have it
drivers (stepper or servo as appropriate), Not sure $400?
power supply for the motor drive $50?
power supply for the driver electronics, $50?
some electricals such as limit switches - not required - add it later,
e-stop switch - also not required - add it later
additional wires/connectors for these - later
breakout board - huh?
and a PC - I have several

So unless I'm missing something - under $1000 should be enough for the conversion shouldn't it?


Later, you can convert to ballscrews, and there are a few really good writeups on this, which I can dig up for you later if you wish.

control software
cabinet
breakout board (machine controller)
Direct drive or belt
tooling

Leave out the e-stop and limit switches at your peril.

good luck and go for it, make sure you have a contingency fund.

Phil

PS: If you are not fully confident then buying a complete kit can workout much less expensive than buying individual components at rock bottom prices off ebay only to find (after many many hours of fiddling) that they are not compatible with each other.


mill - I'm buying it
motor mounts/brackets - I'll make them
couplers - I'll make them
motors (steppers or servos), $300 on eBay
connectors & wire for the motors I already have it
drivers (stepper or servo as appropriate), Not sure $400?
power supply for the motor drive $50?
power supply for the driver electronics, $50?
some electricals such as limit switches - not required - add it later,
e-stop switch - also not required - add it later
additional wires/connectors for these - later
breakout board - huh?
and a PC - I have several

So unless I'm missing something - under $1000 should be enough for the conversion shouldn't it?


Later, you can convert to ballscrews, and there are a few really good writeups on this, which I can dig up for you later if you wish.

First of all if you need 36" X axis travel then buy 36"
Otherwise you will kick yourself later
And you had better do some more work on the costs involved
I have been thinking bout putting a CNC conversion on my
round column Jet benchtop which also has a short table
but I'm beginning to think that this is not wise
and I figure it to cost about $1500
Here's why:

Motors:
Larger tables take more torque to drive obviously
Steppers loose torque the higher the RPM
So you probably need bigger motors than you think
You can go with 1/2-1/4-1/8 steps and it helps but it slows
down the motor and makes it run smoother
For my little mill I calculated a minimum of the NEMA 34 @ 900+ in/oz
Bout $130 each

Servos are a good way to go with encoder feedback, but these cost more
However the torque is better on the top end
Bout $200 ea w/encoder

Power supply:
I see alot of cheap power supplies out there for sale
Better check the volt/amp output for these units as most of these
are only capable of handling smaller motor sizes
So you have a motor than runs @ 48 volts and 7 amps input
A cheap $50 power supply only puts out about 2-3 amps
What do you think is gonna happen?
(Who let the magic smoke out?)

Linear power supply:
These work but are quit inefficient
Lets say you put in 120VAC
Thru a bridge rectifier transformer diode system you get back
say 75VDC at 10 amps What happens to the extra power you just
put in? (It is lost in space)
Now the 7 amp motor you put in is going to draw probably 10+ amps
at startup (they always do)
How many motors do you need to run?
Standard 110-120 VAC wall outlets have 14 ga wire rated at 15 amps
as an output, 12 ga wire is rated at 20 amps
Are you figuring on driving all your motors from a standard outlet
With a single small power supply? Me thinks not
How many small power supplies do you need?
See where I'm going with this?

Switching power supply:
Much nicer as these units switch the power on and off to the motor
causing lower running temps and peak power to be available when
the motor starts up
These you can run on a 100-120 VAC outlet for all your motors
as it runs much more efficiently
And they help the torque for the top end
But they cost more
I would look at one with at least 20 amps output
Probably in the $250-300 range

Controller cards:
I see alot of cheap controller cards in the marketplace
But most of these can't handle the larger motors either
A Gecko drive runs bout 100-$130 per motor depending on
steppers or servos
and can handle the job quite nicely

Software:
You might have the computer at hand
But what is going to control the output for the motors
A software package like Mach 3 is bout $160
Looks pretty good to me so far as I have been checking
out the free demo version for awhile

What are we up to so far in the money aspect of this project so far?

And you still havent considered the ball screws that are a must
to be able to help hold accuracy
I know people say you can use the old ACME screws and have
backlash compensation and this works for making circles
that are pretty round at the 3-6-9-12 O-clock positions
But what happens to the 1:30-4:30-7:30-10:30 positions
Also the screw is still loose inside the nut
Are you just hoping that this is not a problem?
I guess you will find out when the table jumps .010"+ the second
you change directions from X to Y
This is probably not a problem with smaller tools
But I'll bet it rears it's ugly head on a 3/8"-1/2" end mill

I'm figuring bout $250-300 to get new screws made up if I do the work

Still need pulleys and belts
Mounting brackets you can make yourself

I think a cheap tower computer case might make a nice enclosure

It keeps getting to costing more than I was prepared for

Still figuring bout $1500 though to do a decent job

Check out Keling Inc, Stepper world, and maybe some vendors on E-Bay
etc before you get too far into it
Ask around some more first as this costs you nothing

Hope it helps
Widgits

Yep. I've done more research, talked to Gene at IH, read more posts, etc. Looks like I need to just stay with my little Taig for now and buy the IH machine with the CNC kit when I have the funds. Hopefully, within a year I'll be able to do that. Maybe I won't have to pay any unexpected doctor bills, buy a new car to replace one I crash, or something like that this year.

Oh well!

mill - I'm buying it
Check.

motor mounts/brackets - I'll make them
Check, but remember that it costs money for the aluminum, bolts, etc.

couplers - I'll make them
Hmmm... not sure about making couplers. I like the belt drive system as it has the ability to change ratios. But the pullies/belts will cost you more money.

motors (steppers or servos), $300 on eBay
Also look at http://kelinginc.net/StepperMotor.html . I recommend going with a larger motor frame size (eg: Nema 34 vs. Nema 23) so that you have upgrade options if necessary later. And the larger your mill, the larger the motors you'll need.

connectors & wire for the motors I already have it
Check.

drivers (stepper or servo as appropriate), Not sure $400?
Check.

power supply for the motor drive $50?
More like $100 to $200 for a good linear supply (with an enclosure, switch, etc.).

power supply for the driver electronics, $50?
More like $10-$20 for a regulated wall-wart supply.

some electricals such as limit switches - not required - add it later,
Sure, you can add it later, but I absolutely think it's necessary before you do any milling that you won't have your eyes peeled to.

e-stop switch - also not required - add it later
Same as above, and probably more important.

additional wires/connectors for these - later
Check.

breakout board - huh?
Something like this (http://www.cnc4pc.com/Store/osc/product_info.php?cPath=33&products_id=47) or for higher performance, perhaps something like this (http://www.geckodrive.com/product.cfm?pid=19) that philbur mentioned.

and a PC - I have several
Check. Make sure you have a parallel port or USB as appropriate to your interface card, and that the PC specs are what Mach 3 recommends.

So unless I'm missing something - under $1000 should be enough for the conversion shouldn't it?

I'd say closer to $1300-$1500 with the limit switches etc.