Looking in to a G0758 mill, would like some info / opinions

[Pat of TN]

Hey folks.

I have decided to start looking for a mini mill to put in my small workshed. I started out looking at mills in the size of Sieg X2s and Little Machine Shop's 3960. I moved up just a touch, mainly after seeing LMS's insane shipping costs for machinery.

I am now looking at the Grizzly G0758 mill as my pick. Shipped, it should be under a grand for the machine, although it would be significantly more if I opt for the stand.

My needs are a fairly lightweight machine with a decent work envelope. Well, everyone wants as much as they can for as little as they can get, I suppose. If I can find a way to stiffen the floor in my small shop, I may opt for a G0704; it is only a wooden floor, with 2x4 floor joists and two layers of plywood, hence the worry over weight.

I will only be using it on the weekends for mostly small jobs, making tools to make tools, if you will. If I must, I could squeeze a larger job in at the shop I work at, besides.

My point follows. First of all, how much does the machine itself weigh? With and without the stand, I suppose. Grizzly claims a shipping weight of 176 pounds (without the stand, I assume). If there would be 30 or 40 pounds worth of crating, that would be fantastic.

Second is longevity... my shop is not heated, cooled, humidified, or dehumidified. Except when Mother Nature says so! Which, in southeast Tennessee - if it's not cold and wet or hot and dry, it's cold and dry or hot and wet - know what I mean? I was wondering how well the machine would hold up to that, electrically? I've heard some mixed things about Grizzly electronics. I'm not the handiest person around, you see.

I may come up with more questions as time goes on.

Thanks, fellers.

 

[tmarks11]

My point follows. First of all, how much does the machine itself weigh? With and without the stand, I suppose. Grizzly claims a shipping weight of 176 pounds (without the stand, I assume). If there would be 30 or 40 pounds worth of crating, that would be fantastic.

According to the spec sheet, weight of the mill is 161# (no stand).

Weight of the G0704 is 265#.

 

[brav65]

I have a PM-25MV which is almost identical to the G0704. There should be no issue with using a mill that size on the floor you describe. You could always throw down some more wood or a steel plate to distribute the load if you were concerned. Keep in mind that these Chinese Machines are more kits than complete machines. They require a great deal of tender loving care to reach their full potential. You should count on having to make some repairs.

 

[compsurge]

If you can afford to step up to the G0704 (or PM-25MV), I'd say that is the wiser choice. I think you'll run into more limitations with the X2 type mill in the future. There are also some idiosyncrasies that would drive me crazy (hand wheels on the LMS and X2 class are divided as 1/16" per rotation instead of 0.100", for instance).

There is no reason to not verify this with a professional builder or structural engineer. You could likely call a local deck design studio to see if they'd answer a loading question based on your concern (you'd have to give them the span of your floor joists and any other pertinent information). My best guess is that the mini mills won't have an issue, but if you were installing something like a PM932/PM940/RF-45, you might have some issues. I'd verify your floor geometry and cross-reference it with something like this, though. http://www.msrlumber.org/spantables.pdf and this might help.

The G0704 has a HUGE aftermarket. Most of the thanks for this mill in the CNC arena can go to "hossmachine2006" as he sells CNC conversion and belt drive upgrade plans.

Once you get familiar with the small Chinese-made machines, you'll find they are very simple machines in design (this isn't a bad thing) with terrible paint quality. I have the Weiss-made PM-30, and while mechanically I find it quite good, the paint will flake since much of the surface is bondo-filled and painted, versus a painted rough casting (I guess the castings are that ugly). It shouldn't be a deal breaker. These machines are inexpensive, all things considered, and paint is cheap. The mechanics are good and should serve many hobbyists quite well.

Grizzly has upgraded the G0704 motor and speed controllers, so any issues you've found on those subjects has likely already been addressed since the early adopters purchased that mill.

Good luck!

 

[Pat of TN]

Boy, I let this go. Ugh. Sorry, fellas.

Currently I am looking into this decision. I am in fact starting to err on the side that I could indeed handle a G0704/PM25-size machine... I will be performing a simple test one of these days, if there's hardly any deflection with two people standing back-to-back, there should be no problem, I'd wager. As you all say, a couple layers of plywood or such beneath the stand would add a touch more strength.

I suppose my quandary now is - mill now, workshop later or, workshop soon, mill later... I'd much rather have the mill now. Hum.

I'll be looking into this matter again. Thanks for the help, all.

 

[tmarks11]

I will be performing a simple test one of these days, if there's hardly any deflection with two people standing back-to-back, there should be no problem, I'd wager.

265# (G0704) is just like one heavy guy. Of course, the rules for fixed floor loading is different than for people walking around, but I doubt you are going to get OSHA and the building inspector involved, so who cares. If it works, it works.

I would personally get a 2x6 and cut it in pieces long enough to span at least three floor joists. Line up three of those pieces side by side to make a platform, and bolt the G0704 to that. Problem solved, you spread the load. Plywood isn't going to do the job.

 

[brav65]

265# (G0704) is just like one heavy guy. Of course, the rules for fixed floor loading is different than for people walking around, but I doubt you are going to get OSHA and the building inspector involved, so who cares. If it works, it works.

I would personally get a 2x6 and cut it in pieces long enough to span at least three floor joists. Line up three of those pieces side by side to make a platform, and bolt the G0704 to that. Problem solved, you spread the load. Plywood isn't going to do the job.

The span capacity of 3/4" plywood on a typical floor system with truses 24"OC is 117.33 lbs/sq. ft. That is completely ignoring the existing floor deck. Assuming a weight of 270 lbs for mill and stand and a footprint of 2.875 square feet nets 93.91 lbs per sq ft which is well below the max for 3/4" plywood. Two sheets glued and screwed together would offer plenty of margin for safety. I have built hundreds of homes and worked on structures that are over 150 years old that supported heavier loads with less structural support so you should be good to go. If in doubt give a structural engineer a call and ask him about the typical live load max for a residential floor system. Anything that is not a permanent part of the structure is considered live load meaning it can be moved.

 

[tmarks11]

Assuming a weight of 270 lbs for mill and stand and a footprint of 2.875 square feet nets 93.91 lbs per sq ft which is well below the max for 3/4" plywood. Two sheets glued and screwed together would offer plenty of margin for safety.

Since generally you try to get your machinery level within 0.005-0.010", this will be complicated by how much flex the plywood has, which will far exceed 0.010" under acceptable loading, making you chase a moving target. That was why I was suggesting solid timber.

Also, if you use adjustable feet on your mill, you will be concentrating the force in a much smaller area, but again, under normal considerations would be acceptable loading for the plywood, just not acceptable considering what the flex would do you your leveling efforts.

 

[kd4gij]

I have a g0704 on a wood floor 3/4" plywood on 2x6 joist with no problems.