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Benchtop CNC Milling Machine (on hold)
02-02-2013, 07:12 AM, (This post was last modified: 09-11-2013, 10:48 PM by Brian_H.)
#1
Brick  Benchtop CNC Milling Machine (on hold)
The potentiality of a Spokane hackerspace has motivated me to continue my long lost benchtop cnc milling machine project.

The base mill is to be a Grizzly G0463 Benchtop Milling Machine:

[Image: g0463.jpg]

[Image: g0463_det1.jpg]

The machine is fairly rigid for a benchtop mill and among the cheaper mills on the market. It weighs 400 lbs. The key to using small mills like this, whether manually or with cnc, is to know how to work within their limitations. This means using smaller diameter cutters and shallower depths of cut in harder materials. I expect It should be able to cut mild steel at typical feeds and speeds with a 1/4" end mill. In aluminum it will probably be ok with a 3/8" end mill and good removal rates. A friend of mine had this mill in stock configuration in his garage and we used to use 3/4" end mills in aluminum without it bogging down too much but this was pushing the limits.

Unfortunately the mill is four or five hundred dollars more expensive than it was in '08, however back then I was washing dishes part time while going to college for machining, so it is now more affordable to me.

The parts I already have are 3 gecko drivers and three stepper motors:

[Image: driversandsteppers.jpg]

The X and Y steppers are 425 oz-in, and the Z axis stepper is 780 oz-in. These steppers should be plenty powerful for this machine, I believe. To complete the electronics portion of the project I will need to pick up a power supply and build an enclosure for the drivers.

There is a company called CNC Fusion who makes a complete CNC conversion kit with ballscrews for this mill. It is a bit expensive at a grand but will really simplify the complexity of this project. This is their deluxe ballscrew kit:

[Image: img1102ao.jpg]

So the total cost of the essential remaining components will be somewhere around $2600. Non essentials like a flood or mist coolant system will add some cost. Also a 4" vise will be necessary which Grizzly sells for $130. I will need to build a heavy duty bench. Overall this conversion should run considerably cheaper than comparative ready made cnc benchtop mills, which typically sticker at about $5000.
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03-11-2013, 10:19 AM,
#2
RE: Benchtop CNC Milling Machine
This looks interesting as well: http://diylilcnc.org/
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03-15-2013, 06:53 PM,
#3
RE: Benchtop CNC Milling Machine
It looks like a pretty neat project, Brian.

I just joined the hackerspace forum and have not yet attended my first meeting.

However, I like the idea of what you are doing. Small scale CNC is impressive stuff!

John Pollack and I are members of the veteran's garage (a new group) and our group put together a CNC router this year. We are in the process of building simple furniture and signs on our router and hope to soon work our way up to molds, forms, etc -- so that we can do some real production.

I hope to see you at a future meeting.

Incidentally, the router is housed nearby on Sprague Avenue.
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04-16-2014, 08:14 PM,
#4
RE: Benchtop CNC Milling Machine (on hold)
Brian,

It was good to see you tonight. When you are ready to resurrect this project, let me know if you would like a hand. This is a great idea, and I have a HF Mini Mill and similar plans for it.
-N8

"I built it because I didn't know I couldn't"
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04-17-2014, 10:46 PM, (This post was last modified: 04-19-2014, 11:23 PM by Brian_H.)
#5
RE: Benchtop CNC Milling Machine (on hold)
Likewise, when you decide to to move ahead with converting your HF MM let me know. I can mill out the underside of the table for your ballscrew clearance, tap holes, and also make any necessary brackets.

I had a similarly sized cnc benchtop mill years back, a Taig. It's major downsides are that it has acme screws rather than ballscrews, rigid couplings from the steppers to the leadscrews rather than flexible ones so it is prone to binding and stalling during travel, the spindle motor is very heavy and offset to one side so the Z axis tends to bind up, and also the V belt would constant flip around backwards on the pulleys... Taig sent me a new pulley and that fixed that problem though. The construction is pretty simple; the frame is simply welded 2" square steel tubing with some machined blocks attached as ways. I always thought that if it were 4"x4"x.25" wall pipe instead of 2" it would be quite a rigid frame. Fill the tube up with solid epoxy for dampening. Can you tell I've considered making one from scratch?

[Image: crmill1.JPG]

Xylotex used to be the cheapest source for new steppers. They are still $45 each for the 269 oz in. as well as the 425 oz in. They sell some controller and stepper combo kits for about $300. 4 axis drive with 4 steppers for $350. It was circa 2006 when I bought their kit for my Taig, so there are probably better kit options, or of course go with Gecko drivers or the like and built your own controller box.

Sherline's products are mostly too darn tiny, but they have a pretty compelling 4th axis unit (rotary table) for $320. They claim it's quite accurate, but the unit cannot be used with flood coolant.

[Image: 3700cncpicm.jpg]

For windows based controller software, which controls the mill via computer, I'd go with flashcutCNC or mach3, although Mach4 should be out sometime soon. Hopefully it's much improved over mach 3. I already have a Mach3 license; it used to only be $60 but now it's $175. I don't know how much FlashCutCNC software costs but I know you need a hardware decoder so it probably is quite a bit more costly than Mach. EMC2 is another controller option which runs on Linux.
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04-21-2014, 08:46 AM,
#6
RE: Benchtop CNC Milling Machine (on hold)
(04-17-2014, 10:46 PM)Brian_H Wrote: I had a similarly sized cnc benchtop mill years back, a Taig.

Hey that's what I have! Smile

I use a gecko G540 4 axis controller with Kelling 282/oz steppers
and I also run EMC2 (re-branded linuxcnc now).
I have been very impressed with the quality of it it. I set it up to jog back and forth and can reliably hit .001, these are the second set of steppers because the first set were just not powerful enough and would stall as Brian mentioned. but I haven't had any problems now that I have the more powerful steppers and a good quality power supply.
-Dan

"If you didn't build it, you will never own it." - Barton Dring
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04-22-2014, 08:27 PM,
#7
RE: Benchtop CNC Milling Machine (on hold)
A lot of really good info there. Thanks Brian. I will take you up on the offer when I get back to this...hopefully soon.
-N8

"I built it because I didn't know I couldn't"
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