Grizzly G0484 Conversion Project

[chiefsr]

I would like to purchase the G0484 as a CNC conversion candidate. I am fortunate enough to have a CNC mill, so constructing the mounts shouldn't be an issue. I am a bit lost on the motor/driver selection, however. How does one decide servo vs. stepper, torque value, and driver selection? I have seen many builds that use Gecko drives, so I assume this to be the manufacturer of choice. I noticed that McMaster offers ball screws and have treated me well in the past.
I am drawn to this "RF-45-type clone" as it uses a lead screw in the column compared to some that use a rack/pinion setup. My plan is to replace the power up/down motor and lead screw with a ball screw and stepper/servo setup. The hand wheels will be removed and the x/y screws will be replaced with ball screws. I will add a way & screw oiler as well.
Mach3 will be used, so anyone that wants to slip in a breakout board recommendation, feel free.
Any help with the component selection questions above is greatly appreciated! Thanks in advance.

[pete from TN]

I dunno if you are new but if ya are welcome to the zone!! I am in the process of converting a similar machine to the Grizzly you are looking at. These are some decent machines and they do have the advantage of the square column so you can power the Z that way. I have never seen one of the Grizzly machines but to be honest with you if I were gonna spend anywhere near the $2k mark on a benchmill I would probably spend a couple hundred more and get the Industrial Hobbies Version which is a bit heavier, and a owns a bit more real estate under the spindle due to longer travels and a larger table. I have an Early Lathemaster mill which is similar to the IH mill only a little smaller. Lathemasters current machine looks pretty good and is basically the same machine as the Grizzly but several hundred dollars less. I also hear the Enco model is around the same money.

I have chosen to use some larger servo motors and Gecko G320 servo drives and have done a ballscrew conversion and a one shot oiler setup. There is also one or two others on here who are in the process of doing the same thing. One is RLberg who is doing a nice job albeit slightly different approach and Lucky 13 is also getting going on a square column mill conversion. I would recommend you visit Bob Warfields fine website in which he is chronicling the conversion of an Industrial hobbies manual mill to cnc with an Industrial hobbies conversion kit. There are tons of pictures and information concerning these machines and it seems they are getting more popular lately mostly due to the column setup. Only real drawback is the lowish spindle speeds but there are ways around that too. My personal conversion thread is entitled "Finally getting Started" I have owned my machine for nearly eight years and have run it manually for some time and I am Finally getting around to the conversion. I do not see how you can go too far wrong with Geckos as they are well represented here. Anyways, I will be glad to help you however I can altho my machine is not yet running, I am in the final stages of the mechanical conversion and now I am getting ready to start the electronics buildup. Show some pics and progress of your machine and your conversion when you get started and peace....

[chiefsr]

Thanks for the info!
I took a look a the version from Industrial Hobbies and it is a fantastic option with a much larger work envelope than the Grizzly. However, they list it for ~$2400 compared to ~$2000 without the power feeds. I assume that these will bring some cash on eBay, so I think I will take the envelope loss. I hope I don't regret this later, but the Grizzly offers a significantly larger work area than my current mill.
The Lathemaster version offers a touch more Z height and 400RPM more on the top end. This does not come with the power feeds and I am worried that the column is not driven with a lead screw, but uses the rack/pinion setup. I may give them a call today to verify. If it does, the bottom line shows a difference of $500 that lacks 2 power feeds and a stand. Harbor freight sells a stand for $150, which ends up being $200 after gas or shipping, leaving $300 for the feeds. I guess I am actually back to the Grizzly in the end as I should consider pre-mounted limit switches, etc. too.

As far as the servos you went with, what was your criteria for these? How did you decide servos vs steppers? What torque did you go with?
Your point on the RPM range from stock and ways to increase this catches my attention. I am going to look into this a bit more as I am not sure how this is done.

[pete from TN]

That is cool man whatever you feel you want to do is great. These machines are all pretty similar with the exception of the IH which you have already seen. My lathemaster mill has a leadscrew driven Z axis but I cannot vouch for the one they sell now since it is quite different from the one I currently have. To be honest I think that the one they sell now is not as rigid a machine as mine is and I will not get into why unless someone wants to know specifics. It is really not an issue whether or not the machine has a rack and pinion setup or a leadscrew since you are gonna replace it all with a ballnut and mount and ballscrew setup. It would probably be about as simple either way... As far as the power feed units go I thought I would sell mine on craigslist and had no luck for some time and wound up getting another mill, a round column one and put it on there until I sold it for a knee mill. I can tell you that I could not find anyone to buy it for half what it cost me to buy it with the machine. It would be worth a call to Bob Bertrand at Lathemaster to at least talk to him about the machine, he treated me golden and I have no complaints with him or my machine and I have owned it for a number of years now. Not trying to steer you away from Grizzly, they are a great company and import some good machines. I dunno if the stand is gonna be a great addition to a cnc conversion because most that have these machines wind up building a flood enclosure, that is my intention anyways. The spindle speed increase is no small advantage either as these machines are a bit on the slow side for aluminum to say the least as it is.

I chose to go with the Servo setup because I think it is a more robust system and I do not wish to deal with losing steps and all the tuning that steppers seem to need altho after reading many threads here on steppers it is probably only a personal choice. The mill head on these machines is quite heavy and it would require a rather large stepper to lift it which will also be slow. A large servo setup with a reduction belt drive is what Industrial hobbies chooses to install on their turnkey cnc systems so that is good enough for me.

When I bought my machine it was a little cheaper than they seem to be selling for now. If I had known about the IH machine and I had the extra money at the time I would probably have gone that route. You can modify your machine a lot and make it do things it was not designed to do but you really can never increase the travels without some major reworking of the machine. The larger machining envelope is really what you are paying for and those cubic inches of travel make a huge difference. I am sure if you have a smaller machine already that you are in touch with this fact. My lathemaster is a good machine and has some decent travels. With a slight overtravel of the Y axis I am looking at like 9.5" of Y, about 23" of X and I guess around 20" of Z travel. This has been nice to have and will be even nicer under cnc control but it is still not what the IH machine has without overtravel. Hell even my small knee mill does not have the travels that IH mill has. If you get into any kind of engraving it will make the difference between having to reposition your parts or do it in one run on large jobs.

As far as the spindle speeds go there are basically two options. You can get a 3450 rpm motor which will effectively double your speeds albeit at the loss of some low end torque. You can also get a 3 phase 3450 rpm motor and run it off a vfd for variable speed and again slightly higher top speeds. The third option is to somehow build yourself a belt drive system altho I know of only two guys that have done it. Cruiser did his IH mill with a rather elaborate and internal belt drive setup which apparently works rather well and Industrial Hobbies made a belt drive machine which they use every day and I wish I coud get my hands on some specifics or pictures of this mod since ultimately I will probably be doing something like this down the road.

So there you have it my not so humble opinions about these machines. Whichever one you get will be a pretty good machine and be able to cut steel and aluminum pretty good and is IMHO a big step up from the smaller desktops out there. I think that the IH is about as close as you can get to a knee mill without actually getting one. I am actually considering selling my small knee mill to finance a manual IH mill believe it or not.... Good luck and peace

[myiws2]

I just bought a g0484 could not get a clean cut with a carbon endmill . I noticed when push on the head not very hard my dail would move 0.003 one way and 0.006 the other way.Is anyone else having this trouble the base is very thin, and when i took off the column, the base was grounded, with a hand grinder, has anyone else have the trouble