[Marshallj]

I recently purchased a Grizzly G0722
and I would like to do a CNC conversion to it.

I see that there is tons of info and kits available for the G0704 but almost nothing for the G0720/G0722. In fact, I was going to purchase a G0704 but Grizzly was closing and they had the G0722 for about the same price. I figured that I'd get it since it's a larger, heavier machine. It also has a more powerful spindle motor.

Being a larger machine I figured that the advice for the G0704 wouldn't apply. The motors would need to be larger and the kits would not fit. So I need some advice here.

The first question I have is: Has anyone done this conversion before? I've seen a couple of threads on here with people talking about their 720/722 conversions but I haven't seen any details posted.

Mechanical Pieces:

What ballscrews and fitment pieces would I need?
What pulleys can I swap to increase the spindle RPM above 1600 RPM?

Electronics:

Should I go with steppers or servo motors?
If steppers, will the Leadshine MX3660 driver be beefy enough, or should I go with individual drivers such as Geckodrives?
What size motors would be suitable for this conversion?
Should I keep the stock spindle control? It has a 2 HP universal motor.
Do I need a smoothstepper? Go with ethernet?


Thanks for any help you can offer.

[rs4race]

You got that for about the same price as the 0704? What a deal! I think this looks similar to the RF 45 mill so that may be a good starting place. If there aren't already kits you can make your own. The manual lists the basic screw dimensions as 20mm dia. You can get those custom cut on ebay. You could also use your stock screws at lower speeds.

My best advice is if you want to go steppers and use the mx3660, the KL34H280-45-8A Nema 34's are the best performance match I have found. The MX3660 is limited to about 48V 6A. I spent a lot of time looking at spec sheets trying to match up the best performing steppers and the 640 ozin is the best. They are really similar to what Tormach uses on their PCNC 1100, though I suspect Tormach runs higher voltage (more torque). I have to make some new mounts, but once I'm done these are replacing the 570 ozin steppers I have on my g0704 w mx3660 and 48V power supply. The 570oz are cheaper and roughly the same performance as the 640oz motors under 80IPM (with 5mm pitch screws) but above that the 640oz motors have 2-3X as much torque. This will really help out rapid movements especially when raising your z axis. I think you will stall your spindle motor before you stall the 640oz motor.

If you don't have the printer port on your computer you will need something to adapt it. The ESS does work really well for this, I haven't had a problem ever with mine.

I'm sure there will be some others that know more about your machine.

[gd.marsh]

I'm not too familiar with that mill, but by looks it appears to be in the 25 class where my experience is with the 45 class machines.

While there are kits out there for the G0704 that are very nice, there are many who still make their own parts. It's a good way to get more comfortable with machining metal .. (while you are in control of everything!)
Many make the parts on the same machine they're converting. The down-side to that is you will need to disassemble & reassemble the machine a few times. The up-side is it makes you real familiar with your machine!

I would personally lean toward direct drive steppers on that machine.
I'm no expert on steppers or servos, but I have built a cnc router using steppers & converted a 45 using servos.
Someone may correct me on this, but I think you want to look for a combo drive or individual drives with higher amp ratings & look for Motors with lower inductance ratings to achieve best torque & speed.

You can certainly start with the stock spindle & controller which I'm pretty sure can be controlled via software, but I have no experience there because I went with a 3ph motor & VFD.

Best of luck & most of all .. Enjoy the entire process!

gd.marsh

[109jb]

Nope. That is definitely a 45 size machine. You can look at RF 45 conversions and get an idea of what can be done.

[gd.marsh]

Yep, my bad .. should have looked closer & read the specs. 45 it is!

There are several threads pertaining to the 45's on the zone, of which one is mine. 'Bolton ZX45 Conversion'
I went with: Kelling 850oz Servos, Gecko Drives, ESS, PMDX Bob ..
I can say I'm 'Very Satisfied' with the results!

gd.marsh

[Hypnotoad]

It looks like this G0722 mill is a rebranded Sieg SX4. Armed with that knowledge you can google for CNC conversions for this mill. Here's one, I'm sure there are others:

https://www.youtube.com/watch?v=jppUu-EZcxY

You can also look at other mill vendors and see if someone other than Grizzly sells it and google for that model name too. The rebranding of Chinese milling machines is kind of annoying for someone searching for information.

Cool machine!

[Marshallj]

Hypnotoad, that looks like it. Thanks for that info.

[Marshallj]

I picked up the machine... having trouble getting it into the basement. It's heavy as hell.

[Hypnotoad]

I picked up the machine... having trouble getting it into the basement. It's heavy as hell.

Surprise! That thing is a beast.

[ninefinger]

Disassembly is the way to go on a RF-45 type machine. Table, saddle, motor, head, column, base and z-slide all apart. Its manageable in pieces, that's how I got my MD-001 to the basement (twice..moving is a pain).
Do be aware that the head has a vented cap for the oil, and will spill when tipped sideways (ask me how I know!)
Mike

[Hypnotoad]

Good thing you had that tree there!

[Poseidon]

Hello Marshall,

Welcome to the 0720/0722 build.

Joe

[Fastest1]

Interesting method of getting it into the basement. I work alone much of the time and can understand how the procedure got layed out. However why couldnt the mill have been slid down the stairs on a skid or the pallet? Control the descent with a rope or the winch? Too late now anyway. Glad we dont have basements in the Houston area (they would be called indoor pools very quickly).