G704

[Whizbang]

Hey guys I have a few questions I was hoping to get some expertise on.
I am looking at getting a G704 as starter mill and then later get a mtw md001 and upgrade the md001 to cnc with the G704 here a few questions I have.

1) Is the work envelope of the g704 big enough to do this upgrade?( note I may buy the hoss2006 dvd and cnc the G704 first for practice).

2) On grizzly.com the g704 table size in the y direction is 7.125" and the cross travel is 6.875 so is the biggest part I can fit on the y the cross travel or table size or neither. I am looking to machine some plates that are about 9"x9".

3) On most g704's I see the use of stepper motors being used, however on most rf45 conversions I see servos being used with encoder feedback, why is this so common? (pros and cons?)

4) I have seen quite a few bridgeport cnc's most have servos for cnc operation but they still have the handles for manual milling is this a viable option to have both cnc and manual on one machine. what is the reason I dont see this done more?

Thanks in advance for any feed back you can provide.

[photomankc]

3.) Mostly because a servo system is more expensive and these machines are doing fine with 570oz steppers. As the machine grows so does the cuts it can take and the forces involved and past a certain point it gets hard to find steppers that match. Still Tormach is a successful platform based on steppers in the size range of the RF's so servos are not a requirement.

4.) Handles seem a little odd to me now. With ball screws it is entirely possible to push the table and back drive the handle. That's not so good. It means the tool can push the work around and if you aren't holding against it breaks or ruins stuff.

There is also the issue of an unbalanced mass rotating at a rapid clip, all it can do is add vibration which isn't desirable not to mention getting thwacked by that at speed is not going to feel good, especially where the Y motor sits on the 0704.

Finally you have to remember that a motor is a generator in reverse. If I grab the handle and really give a fast cranking to it you will find a substantial voltage being produced on the leads. That's not great either when the drivers are powered down. You are forcing voltage back at it from the wrong direction. I also notice a lot of BP's kept the handles but I can't say why its so common there.

[hoss2006]

Hey Whizbang,
1. Sure, the mods are generally milling room on the saddles for ballnut clearance, etc.
The 0704 can be modded to give 9.5 inches y travel.
2. See above, but you'll run into situations inevitably no matter how big a mill you get
where the part exceeds the travels but that just means you need to make it in 2 (or more) setups.
That's part of machining, making what you have at hand get the job done.
Hoss

[LUCKY13]

Just forget the manual handles, they are not needed because you can still do manual machining with the electronics of the CNC. This is why you dont see it.. Plus like one other already meantioned the handles become a danger to the user when it is operating on CNC. Plus using the CNC in a manual mode ( by the electronics) is even better than using handwheeels.


The only difference is with handwheels you get that feel/feedback kinda thing. Doing it weith electronics its just a different thing and you use sound of the cutter, sound of the machine both spindle and drives, the way the chips look and the heat they hold and many other things that you will learn after using the CNC. Its the same thing as using a handwheel, only you just push a button.


All though some my dissagree, servo's are a bit better system. And of course it cost more. Most times people buuilding a small machine are working with a tight budget so steppers are the choice. Use to it was hard to find steppers strong enough to run a bigger machine and it was kinda like up to this size you can get away with stepper but as the machine got bigger you needed servos. Both stepper and servo system have got better and servo's are easier to setup ( was always harder than steppers) and steppers have got stronger. You can use either one as long as you pick the right size motors and drivers. But a servo system can go the extra mile on the sccuracy. A servo system knows where it wasnts to be and with the encoder feed back it can make onthe fly ajustments to keep the machine there. A stepper gets told go here and if something doesnt work right it doesnt know it screwed up. But still steppers have got so much better that when sized right you can expect it not to have trouble. It might also could be said that a servo system might be smoother also. Either way a worthy system can be made with the servo being a bit better with the added cost. Normally not worth it unless you have the bigger machine. WIth the new A/C servos that are out servos are getting much easier to setup though, and there performance is very good.


The G704 is a very good little machine, and a great size for a simple stepper setup. It should do what you need and then some. And probably one of the best buys and machines foer the size/money.


The MD0001 is one heck of a machine. Will make a very good setup with a servo system, but it can be done with stepper if you want simple and cost effective system. My self I would go with the DMM A/C servos on this machine. There simple and have great performance, with a price that is pretty good, although more than a stepper system. Quite, lots of power, very smooth, very reliable. When running a machine day in and day out this becomes important.


Jess

[Whizbang]

As to not take up valuable new post names on the thread page. I was hoping to continue here with some more questions.
I am planning to buy the G704 because it seems to be the best buy per price/size. It will be used to make small parts and reinforce to my fiance that this is a hobby I will enjoy so that I can convince here to allow me the space for a rf45.
I plan on doing a hoss conversion starting early july.
as for tooling what all should I purchase. obviously the G704.

But along with it does grizzly offer any good vises or would you recommend another company.( I have 3 Bridgeport vises stacked in my basement but they are huge.)

Other things I think I may need:
grizzly r8 collets.
grizzly tslot clamps.
rotary table or perhaps swivel vice.
I have endmills from my router cnc.
I have dial indicators.
I have calipers.
I have seen this dual dial indicator advertised here for tramming in the head should i get one of these?

[paulsv]

But along with it does grizzly offer any good vises or would you recommend another company.( I have 3 Bridgeport vises stacked in my basement but they are huge.)

Other things I think I may need:
grizzly r8 collets.
grizzly tslot clamps.
rotary table or perhaps swivel vice.
I have endmills from my router cnc.
I have dial indicators.
I have calipers.
I have seen this dual dial indicator advertised here for tramming in the head should i get one of these?

Vise: You use the vise constantly. Get the best you can afford. Kurt is the standard, but their 4" is spendy, and the 6" is too big for the 704. Check out Glacern, or, since you are CNC'ing, Little Machine Shop's 4" or Tormach's 5" CNC vises.

R-8 collets: definitely. Grizzly's are fine
T-slot clamps. Get the clamping kit from Grizzly. It is cheap, and very handy to have.
Rotary Table or swivel vise: Everybody buys a swivel vise when they start, and the swivel attachment sits on the shelf gathering dust. Never used mine. Grizzly sells a 6" import rotary table kit that comes with dividing plates and tailstock for a reasonable price.

H7527 6" Rotary Table w/ Div. Plates

You need to think about a chuck or collet chuck for the RT to hold parts. Most flexible is a 4 jaw chuck with an adapter for the RT, but of you are only going to hold small parts, perhaps a collet chuck. A 5C collet chuck would be nice because you can buy square and hex collets, as well as round.

The head tramming tool is nice, but you can tram just as well without it or make your own. Hoss has plans on his website (G0704.com). That money is better spent elsewhere.

Get yourself a good edgefinder. A 45 degree face mill is nice to have. Glacern makes a great one. The 2.5" is about the right size for the G0704.

A boring head is pretty important for manual work, but not so much for CNC.

Don't let the GF know what all of this costs!

[Whizbang]

ok so far here is what i have.
from grizzly
g704: G0704 Drill/Mill with Stand 1,194.00
clamp kit: G1075 52 pc. Clamping Kit - 3/8" Bolt Size 42.95
12 pc. Precision R-8 Collet Set:
G1646 12 pc. Precision R-8 Collet Set 73.95
G9815 Parallel Sets - Thin 10 Pairs:
G9815 Parallel Sets - Thin 10 Pairs 28.75
possibly to save money:
G7154 Premium Milling Vise - 5"
G7154 Premium Milling Vise - 5" 164.95
compare to glacern below
If money is saved then:
possibly a boring bar. recommendations?
glacern 2.5 45 degree face mill. its 99 but is that just the head whats the best inserts. does the head come with a shank? i think i have the right set up below.
is this the 5c you were talking about. how is it held in the machine?
H2715 5-C Precision 3 Jaw Chuck - 4"

Glacern:
R8-DC500 Drill Chuck, R8 Taper $119.99 1 $119.99
GSV-440 4 Inch Standard Vise $249.00 1 $249.00 (how does this compare to grizzly above)

R8-FM100 Facemill Holder - 1.00 Arbor $69.99
FM45-250 FM45 Facemill - 2.5in (63mm) $99.99
cheap inserts anyone? 169.00 is insane

[paulsv]

ok so far here is what i have.
from grizzly
g704: G0704 Drill/Mill with Stand 1,194.00
clamp kit: G1075 52 pc. Clamping Kit - 3/8" Bolt Size 42.95
12 pc. Precision R-8 Collet Set:
G1646 12 pc. Precision R-8 Collet Set 73.95
G9815 Parallel Sets - Thin 10 Pairs:
G9815 Parallel Sets - Thin 10 Pairs 28.75
possibly to save money:
G7154 Premium Milling Vise - 5"
G7154 Premium Milling Vise - 5" 164.95
compare to glacern below
If money is saved then:
possibly a boring bar. recommendations?
glacern 2.5 45 degree face mill. its 99 but is that just the head whats the best inserts. does the head come with a shank? i think i have the right set up below.
is this the 5c you were talking about. how is it held in the machine?
H2715 5-C Precision 3 Jaw Chuck - 4"

Glacern:
R8-DC500 Drill Chuck, R8 Taper $119.99 1 $119.99
GSV-440 4 Inch Standard Vise $249.00 1 $249.00 (how does this compare to grizzly above)

R8-FM100 Facemill Holder - 1.00 Arbor $69.99
FM45-250 FM45 Facemill - 2.5in (63mm) $99.99
cheap inserts anyone? 169.00 is insane

That all looks pretty good to me. Glacern sells a shank for that face mill, but they get a lot of money for it. Lots of guys get a cheaper shank from Shars. For that matter, you can get a cheaper 45 degree face mill from shars, too, but its a pretty precision tool, to get all the inserts at the right height, and I trust Glacern to do that more than Shars' chinese supplier. Plus the Glacern is prettier. As for inserts, get the number off of the Glacern website, and check out Enco and MSC's prices.

For $85 extra bucks, I'd definitely go with the Glacern vise. I bought a cheaper one, and now I cuss myself every time I struggle to square up stock in the vise. even tho it is an "angle lock" type vise, I can never get the part to seat on both parallels. I'm on the lookout for a used Kurt 4", and if I don't find one soon, I'll buy the Glacern. I took my cheaper one apart and looked it over pretty closely, and I may try to salvage it. Wish I had a surface grinder.

5C chuck:
LittleMachineShop.com - Collet Chuck for 5C Collets

That would be for easy holding of stock in the RT, not in the machine. You would need to machine a back plate for attaching it to the RT. You might want to hold off on that until you actually have the RT and play with it a bit, to see how you want to use it.

Boring head:

LittleMachineShop.com - Boring Head Set, R8 Shank

Again, once you cnc your machine, you won't have much use for the boring head. so you might want to get an inexpensive set like this.

You do get an R-8 drill chuck with the 704. Im sure it is a real cheap one, but mine works very well. Maybe I got lucky.

[mrcodewiz]

Hmmm... I picked up a boring head not too long ago. My reasoning was that it should cut more precise holes (like bearing pockets) since I have a little backlash in the nuts.

[Connor9220]

Again, once you cnc your machine, you won't have much use for the boring head. so you might want to get an inexpensive set like this.

I wouldn't say you won't have much use for a boring head. They're very nice to have, CNC or not.

[photomankc]

I wouldn't say you won't have much use for a boring head. They're very nice to have, CNC or not.

Agree, though the statement is partly true. You don't need it for every hole you drill that's beyond the largest drill/endmill you have. I interpolate any hole that I can to save the tool change.

[Mad Welder]

.........2) On grizzly.com the g704 table size in the y direction is 7.125" and the cross travel is 6.875 so is the biggest part I can fit on the y the cross travel or table size or neither. I am looking to machine some plates that are about 9"x9"..................

Hi there Whizbang welcome..! regarding one of your first querries of the Y axis travel and as Hoss said you can add a little mod to increase your Y axis travel when doing your CNC conversion...have a look at the pic here where like many other CNC builds I added an extra 2" towards the front of the Y axis....


check out other build threads too that will be similar to the G0704 like the PM25, BF20 and other similar clones.......

hope this is of some help