Small Milling Table CNC Conversion a Worthy Endeavor..?

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JAndrew

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HMEM,

I used this small milling table from Grizzly for quite a while to do light milling on my drill press:

Now that I have a mill I was batting around the idea of re-purposing this table for use as a CNC engraver or for light milling. I'm looking for input as to why this would or wouldn't be worth the time and money.

The table has a travel window of 5.5"x9.5" and it's leadscrews (I believe) are 1/2"-10tpi. I was envisioning some type of gantry above it to hold either a dremel for engraving or some kind of small spindle.

Is this at all feasible...? I have no CNC experience so any help would be appreciated!

Thanks,
-J.Andrew
 

aonemarine

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you could cnc it and mount it on your mill table for some 2 axis milling. But honestly for the cost you might as well do a 3 axis cnc.
Townlabs.com sells a servo controller and servos for $525.00, then you need software and ball screws and ??
 

RonGinger

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What mill do you have? why not CNC it?

These XY tables are less than the most accurate devices. I suspect the leadscrews will have a lot of backlash and thats a killer on CNC (yes, I know software corrects for backlash, but it doesnt really work)

It will probably take as long and cost as much to do this table as to do a small mill, and in the end it will be a much less capable machine.

On the other hand, I heartily encourage building CNC machines- it has become my hobby in place of model engineering. So go for it- there is lots to learn and its very satisfying to watch a machine you built do real work. And you can always re-use the motors and drivers on another machine when you decide this was not such a good idea.
 

vederstein

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A few years ago I CNC'd my mini-mill. With the ball screws, it cost about $750. More than what I paid for the mill ($500).

I used the Hoss plans:

http://www.hossmachine.info/

...Ved.
 

JAndrew

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All,

Thank you for the replies. I must apologize for my delay in reply. I had a bit of a drainage issue to deal with in my backyard. A couple hundred pounds of gravel and sand later....

Now that I see the price tag on Steve Hucks's similar CNC table I think that Ron Ginger is right. I really should look more at someday converting my mill instead of messing with this table.

My mill is a Diamond M22 horizontal mill that I'm currently putting an R8 vertical milling adapter on. The work area is 19"x9"(I believe). What concerns me though is would I still be able to use the Diamond mill as a manual mill after the conversion? The programming side of CNC seems daunting to me and I'm curious how it is you do things on a CNC machine like touch-offs? Seems like touch-offs would require manual operation or am I missing something...?

Thanks for all the links. Tin, always helpful info!

-J.Andrew
 

aonemarine

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Tin Falcon

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Dave: seriously look long and hard at the gecko web page. Top shelf components made in USA.
A little more money but a lot more product support.

Motors are $64 each 280 oz for the G 540 $300 and this is virtually plug and play unit. 50 v and 3,5 A . and another $50 or so for the power supply. this has 4 axis built in.


if you want to go with a 400 in/oz motor the motor is the same price but expect to pay about $150 per axis for the controllers. And you need a breakout board. but you can run up to 80v and 7 amps.

Geckos tend to be conservatively rated and well built. The import stuff has a reputation of being over rated. And may not take the volts or amps the manual says it will.

the mill you are looking at probably has about an 80 -100 Lb table a bigger machine than the x-2. IMHO the g 540 is a great driver for a small bench lath but may not be enough for the Grizzly 704

Tin
 

cfellows

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I have to agree with Tin. In the end, I bought the Gecko G540 for $260 from an Ebay dealer and am very pleased with it. I also bought the Nema 23, ~390 oz in steppers off Ebay. They are rated at 3.0 amps and I'm driving them with a 24v power supply. I have them geared down 3 to 1 so I'm getting close to 1200 oz in on each axis. I'm using Mach3 on a used HP desktop I picked up on Craigs list for $70, including a keyboard and a monitor. I'm running Windows XP on it.

My conversion was done on an Enco version of the Ronfu RF30 Mill Drill. I did a build thread here:

http://www.homemodelenginemachinist.com/f38/enco-rong-fu-rf30-mill-drill-conversion-22159/

Chuck
 

vederstein

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If you don't want to wire up cables, boards, etc and would prefer a ready made blackbox, look at Probotix. They're whole business is geared to the CNC hobbiest. They have entire 2, 3, and 4 axis stepper motor kits available. For a little extra money, they'll wire up the electronics in an enclosure.

When I CNC'd my mill, I purchased the 3 axis kit in a box and had no issues with it.

...ved.
 

picks27t

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I would agree with the last post i have had very good results with them and they can be CALLED and they worked wit me till the unit was ready to go


Sent from my iPhone using Model Engines
 

Tin Falcon

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It appears Keiling is now automation technologies. They have been around and have a good rep they offer several kits based on the G 540. they have cables and other needed bits to build a cnc
http://www.automationtechnologiesinc.com/products-page/g540-stepper-motor-kits
I purchased my PS from keiling.



If you decide to buy a' la cart TRC electronics in Montgomeryville PA has a large selection of Meanwell brand Import power supplies a 48v 7A unit will run you about $80 http://www.trcelectronics.com/View/Mean-Well/HRP-300-48.shtml

Tin
 

aonemarine

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The only downside to the g540 is that if I blew a driver or something im kinda screwed and would have to replace the whole thing. Having individual componets make it easy to swap them around for testing, replacement, and trouble shooting. Going with the 570 oz steppers lets me direct drive the Z axis instead of having to go to a 2:1 belt drive or steppng up to a nema 34 on the Z.
I Think the g540 is too underpowered for the g0704 mill as well....
 

Tin Falcon

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The only downside to the g540 is that if I blew a driver or something im kinda screwed and would have to replace the whole thing.
On the contrary G -540 is modular.
The G540 is a complete 4-axis system which plugs directly into your computer via the parallel port and to your motors through DB9 connectors. It contains four of our G250 drives, our own breakout board and a hard anodized aluminum case. (Quoted from the Gecko site)
And unless you are using 4 axis on a regular basis it comes with a spare driver.
so you blow a driver you swap the bad one for a spare. One of the reasons I selected the g 540.
And i expect if you wanted to you could just reassign pins and tell the computer to use the A axis for your x,y or z and keep going in a jamb without physically swapping the drive card. I expect Marris will gladly send you
A replacement breakout board in the unlikely event it failed. or it could be repaired.
You can purchase G250x separately as well. the G251 is the same card you can have more access to in a bigger box and has screw terminals. So you can choose a breakout board.

I Think the g540 is too underpowered for the g0704 mill as well....
This point you may be right on it depends on how fast you want your rapid feeds to move.
Chuck has the same machine and likes his setup with the g 540. admittedly it is not likely a screamer when it comes to performance as he is running 24 volts. But you can run 48 volts safely on a g540.

Gecko drive gives all the math and info you need to calculate what you need based on your machine and desired performance.
A Volkswagen and a Ferrari will both get you from point A to point B the question is how much horsepower and acceleration do you feel you need or want and what are you willing to spend for it.

Like I said gecko make many more choices in stepper and servo drives as well. the G-540 is not the only horse in the stable.
Tin
 

aonemarine

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The G540 is a complete 4-axis system which plugs directly into your computer via the parallel port and to your motors through DB9 connectors. It contains four of our G250 drives, our own breakout board and a hard anodized aluminum case. (Quoted from the Gecko site)

Did not know this....more research is required LOL...
 

Tin Falcon

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It also has built in vfd/pwm spindle controller.
And while it is a complete controller you need to add a power supply to run the motors 15 to 50 volts I think most people use 24,36, or 48 volt PS.
On the subject of max rapid feed. On a small x-2 acceleration and high rapid rates are mute . Now if I was building a router to handle a 4 x 8 sheet of plywood then rapid rates may mean something.
If you are only traveling a few blocks and not miles then a bicycle may be all one needs.
Tin
 

aonemarine

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Tin I keep trying to find a picture of the inside of the g540. Yes i know it says it has 4 of the g250 drives in it, but it does not appear (from what I can tell) to be individual cards. I get the feeling they are all on one board??
 
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