[Spectyr]

No pictures yet, but stats are as follows:

FEATURES:

* Power head elevation
* Digital head tilt angle display
* Head and table travel on dovetailed ways
* Includes 5/8" drill chuck
* Dovetail column
* Digital spindle scale reads metric or inches, zero set, on/off, graduated in 0.0005"
* Head tilts 90š left, 45° right
* Digital speed display
* Reversing buttons on the spindle handles for tapping
* Coolant trough
* Front mounted fine feed knob
* Front mounted E-stop button
* See-through chip guard

SPECIFICATIONS:

* Motor:2 HP, 230V, single-phase
* Universal Spindle taper:R8
* Spindle travel:3-5/16"
* Swing:22-3/4"
* Max. distance spindle to table:16-5/8"
* T-Slots:4 @ 21/8" centers, 3/8" studs
* Table size:9-7/16" x 32-1/4"
* Table travel (longitudinal):16-1/8"
* Table travel (cross):9-5/8" Headstock travel:13-1/8"
* Headstock tilt:90° L, 45° R Drilling capacity:1-1/8"
* Quill diameter::2.56"
* Variable speed:100-1600
* Approximate shipping weight:641 lbs.


G0720R Heavy-Duty Bench Top Milling Machine

[thewoodnerd]

Just curious, how did you decide to purchase this? Grizzly's site has no photos, no manual, and the link for the spec sheet is broken.

And yes, please post some photos. After a few days with the G0602 lathe, I'm getting nervous about my backordered G0704 or anything else at the low end of their product range.

[Turbo442]

So the only difference is that the G0720 has an MT4 spindle and the G0720R has an R8 spindle?

It seems that the specs between the G0484 and the G0720 vary quite a bit. Is the G0720 considered an RF45 clone?

[thewoodnerd]

Hmm, I didn't catch the fact that the G0720R seems to be the G0720+R8. I had looked very hard at the G0720 but didn't like the MT4. I'm going to seriously consider cancelling my G0704 and go with a G0720R instead.

[thewoodnerd]

Interesting ... both the downloadable manual and spec sheet for the G0720 say it has an R8 spindle and a max spindle speed of 3600. I'm pretty sure the 3600 rpm is a typo, it says 1600 everywhere else in the manual.

Hey Spectyr, how fast is your spindle spinning?

[thewoodnerd]

Is the G0720 considered an RF45 clone?

I had read somewhere that it's an SX4 clone. I think RF45 clones are all gear-head mills?

[doorknob]

I thought that the G0720 actually was a Sieg SX4 and not an "SX4 clone".

But I have no direct knowledge about it...

[Spectyr]

Certainly looks to be the SX4 in Grizzly wrapping...

[photomankc]

So kind of an RF-45ish machine? Why copy the low spindle speed though I wonder.

[thewoodnerd]

Ah, I see now. The spindle motor speed is 0-3200 rpm, but actual spindle itself is only spinning a max of 1600.

[Velocirex]

Not sure if you sorted this out yet but I have a G0720 ordered before the "r" model came on the scene. Mine is definitely an R8 machine. It is the Sieg sx4.

[Poseidon]

I, too, have the "old" G0720 and when I placed my order I was told at the time that the MT4 spindle spec is a typo, it actually is a R8 spindle.

Btw, my mill is still sitting on it's pallet. Made the mistake of ordering before the space for it was ready. Does anyone have a good suggestion for a stand? Thought of using the G0705 stand but have not confirmed with Grizzly if it is compatible.

[Velocirex]

I wonder about their voltage specs. If you looked at the way they listed the old G0720 in one place they said 110V, in another 220V. I'm reasonably certain the spindle motor is a dc motor anyway so I don't know where the 220 comes from. Sounds like they changed something. I wonder why?

Anyhoo, I had a similar dilemma with the stand. Purists will cringe but I looked around at metal stands and decided for the money, I could do better in wood and accomodate my never ending need for storage. Check this out...

Milling Machine Stand

Much of the strength is in the top...

I'm already tired of cranking those handwheels so have started my cnc conversion.

[Poseidon]

Nice job with the stand unfortunately I am one of those @$$hole purists. I do need a heavy metal stand because this machine will be converted to CNC just as soon as funds allow. I have used heavily constructed wood stands before to support X3 sized CNC mills and while the wood stand did serve to dampen the vibrations it did start to wobble after six months of use. With a manual machine I do not see it becoming a problem since the amount of acceleration should be far less than that generated by a CNC.

That is a very nice vise you have on that mill, wish I could afford one. Had to settle for a Shars 660U. I hope Shars can match the vise I currently have when it comes time to get a second unit.

Btw, how badly out of square is the column to the bed? How many shims and how thick?

[thewoodnerd]

Purists will cringe but I looked around at metal stands and decided for the money, I could do better in wood

How are you doing at staying in tram? Any problems with wood movement twisting the base?

[Velocirex]

The Kurt vise really wasn't all that much more than a Shars or Glacern vise.. I got it over the summer at Enco when they had them on sale and I had another 20% off code.

As far as stability of a wooden bench, I guess I'll see how that goes once I get the CNC conversion completed. I built it about as solidly as I could without resorting to extremes. Between the glued and screwed lap joints and the ply sheathing I think it should hold up pretty well.

As far as column alignment, I was pleasantly surprised with this mill. I used my coaxial dial indicator and the variation was about half a division around an 8-9" circumference so I have not bothered to shim at all at this point. It has maintained that pretty well although I really haven't pushed it very hard at all. If you look at one of those photos, you can see that they did some sort of work on the column and base where they come together. It looks like a coarse scraping job but somebody did some work to get it set up properly.

I am pretty sure of the stability of the wooden base because of the use of the four 3/4" ply slabs glued and screwed together. It is extremely stiff and is well supported by the base directly under the machine pads so there is really no moment being applied to the top if you follow my meaning.

[DrWiggly]

I just lugged a new G0720R mill into my shop and checked it out. The biggest problem I see in its alignment is that the column is not perpendicular to the table. It tilts forward by about 0.003" over the 3.5" travel of the spindle. The sideways tilt is a bit smaller, and at the moment I have compensated it by tilting the head.

Does anyone have any tips to offer about placing shims where the column bolts to the base or any other fixes?

[Velocirex]

I'm not sure I can advance the state of the art on shimming... there are as many ways as operators. Some folks just shim at the ends with shim stock... others build more elaborate tapered shims to support along the entire length of the side. If you haven't seen it, there is some good related discussion here:

Tramming a Mill

[SCzEngrgGroup]

I just lugged a new G0720R mill into my shop and checked it out. The biggest problem I see in its alignment is that the column is not perpendicular to the table. It tilts forward by about 0.003" over the 3.5" travel of the spindle.

The way you've worded that makes me suspect you may not be measuring what you thing you're measuring.... If you were moving the quill while taking your measurement, you have no idea whether the column is tilted or not. It could just as well be that the quill is not parallel to the column. What you really need is a large machinists square, 4-5-6 block, or other reliable perpendicular reference. Leave the quill fixed, put an indicator in the spindle, and indicate on the reference as you move the head up and down. Alternatively, you can put a precision rod in a good collet in the spindle, mount the indicator to the table, and indicate on the rod, again, as you move the entire head up and down (here, though, your accuracy is subject to error due to runout in the spindle and collet - and there is ALWAYS runout). In either case, you must NOT move X or Y, or rotate the spindle while measuring. Moving the quill will give you an accurate reading ONLY if the quill is perfectly parallel to the Z ways (which they almost never are....).

Regards,
Ray L.

[DrWiggly]

Velocirex, thanks for the link.

SCzEngrgGroup wrote:

"The way you've worded that makes me suspect you may not be measuring what you thing you're measuring.... "

Oops. Yes, the way I wrote it was unclear. I measured the tilt of the column with an indicator mounted on the head by moving the head up and down the column while indicating against a square block clamped to the table. Later I made the same measurement to set the tilt of the head by running the quill up and down. Sorry to mislead you, and thanks for the tips. I had not thought of putting a rod in a collet.

WW