End of mill rigidity issues.?

[Naiveambition]

I've been studying all the ins and outs of milling machines for a while now, and have come across this new to me, milling machine.

The general consensus for bench mills is that they lack rigidness, unless they weigh a ton or more.
I have had my heart set on a g0704 from grizzly for roughly 1300$. Which seems to be a good entry into machines that can do a variety of jobs but still seem to suffer chatter etc...

Then I ran across this one just looking around and discover for bout 3-400 $ more I could get this one. So here the ?'s .


What if I decide to upgrade to cnc, ball screws etc.. Are these friendly machines to upgrade?

I know this is a relatively large unit for a benchtop, but am hoping that with this machine I could open possibilities that would be out of reach for the g0704 , like stainless, cast iron, and maybe some type of small production work later on.
The ultimate plan would be cnc with manual controls kept if possible, and maybe 4 th axis option. This is way off but I would like to start the plan in the right place, which is why I'm here asking you fine people

These machines as I understand it have about the same travel and movement which makes it a viable option, I think.
Will this not solve the column issues and flex issues associated with bench mills? And will I be able to pull off good knee mill results, if that makes sense, or say results comparable to a Bridgeport being that they are both knee mills and have the same design.

 

[Wizard69]

I've been studying all the ins and outs of milling machines for a while now, and have come across this new to me, milling machine.

The general consensus for bench mills is that they lack rigidness, unless they weigh a ton or more.
I have had my heart set on a g0704 from grizzly for roughly 1300$. Which seems to be a good entry into machines that can do a variety of jobs but still seem to suffer chatter etc...

Sadly it really looks like the quality of the G0704 has gone down hill. At least from some of the posts I've seen on other sites buying one is a gamble, so that brings into question the wisdom of going the G0704 route in the first place.

Then I ran across this one just looking around and discover for bout 3-400 $ more I could get this one. So here the ?'s .

Have you looked in Grizzles catalog for similar machines? Most of these machines are not really bench machines.

What if I decide to upgrade to cnc, ball screws etc.. Are these friendly machines to upgrade?

If I was about to upgrade a mill to CNC I'd hope that it was a bed mill of some sort. CNCing a knee mill isn't impossible but you would be on your own to a greater extent.

I know this is a relatively large unit for a benchtop, but am hoping that with this machine I could open possibilities that would be out of reach for the g0704 , like stainless, cast iron, and maybe some type of small production work later on.

A G0704 is fully capable of machining those materials, you just can't drive the machine like it has a 20 HP spindle.

The ultimate plan would be cnc with manual controls kept if possible, and maybe 4 th axis option. This is way off but I would like to start the plan in the right place, which is why I'm here asking you fine people

If that is your intention you may be better off with this machine as it is flexible like a Mini Bridgeport. The flexibility for manual work should not be underestimated.

These machines as I understand it have about the same travel and movement which makes it a viable option, I think.

There is no thinking about it, refer to the manuals or catalog data for travels and clearances.

Will this not solve the column issues and flex issues associated with bench mills? And will I be able to pull off good knee mill results, if that makes sense, or say results comparable to a Bridgeport being that they are both knee mills and have the same design.

That all depends upon the specifics of the machines mechanical structure. It might be better than a bed mill or maybe not, however it is foolish to compare a Mini Mill to a full size Bridgeport. In the end the result you will get depend upon how you setup the machine and your skills as a machinist. Don't forget guys are known to do exceptional work on Sherline type machines. That isn't to say a machine doesn't put limits on what you can do with it. What it does say is that the operator is a key part of getting good results.

 

[Naiveambition]

By bed mill you mean one that has the bed stationary and the head used for travel on z axis versus the knee mill style, which raises and lowers the bed?

I'm trying to follow others that have posted to buy the biggest mill u can afford,and space constraints, which brought me here.

Yes I understand these aren't really comparable, but at the same time a lot of similarities are their. The table size, and movements are pretty much the same, so the only real thing I am gaining would be heavier weight, and stiffening up of column, which is a usual upgrade done to other bench mills. Why not start here if I am going to upgrade anyways.
Or is their problems I am not aware of with this style?

I suppose in the end I want the beefiest benchtop machine,( really strong bench), I can buy new, for under 2000$ while getting accuracy and dependability

 

[jwcnc1911]

A friend of mine had one of those... at least it was green. I gave him some 3/4in emdmills and later he told me he was cranking down on them at 3/8in depth. So that's definitely decent for a mill of this size. Chatter in my opinion is more feed related any way. If you don't feed it fast enough you got chatter. We got 80,000lb Hellers that chatter until you dial in on a good feed and speed. Every tool is different.

 

[rodw]

I suppose in the end I want the beefiest benchtop machine,( really strong bench), I can buy new, for under 2000$ while getting accuracy and dependability

Have you considered the Seig Super X3 which Grizzly call the G0619
http://www.grizzly.com/products/6-x-21-Mill-Drill/G0619

I have one of these and I am very happy with it so far. it has a strong following as a CNC machine if you want to go that way with it. I have found the quality to be a step well above my Chinese built lathe. I personally don't think column rigidity is an issue on this one.

 

[Naiveambition]

Thanx for all your fast replies.

Yes I have considered the x3. It seems a nice machine but have some horror stories. Of course they all do.

So far the worst on the harbor freight version,seems to Be limited y movement at six inches. If the grizzlys are the same, I don't understand why this would not automatically be a more precise machine hence the weight and design. Most people recommend a Bridgeport as the pinnacle mill to have. I don't have this option , mainly size and electrical requirements.

I really like the idea of being able to hog some metal. I like to machine things , but I do get bored if a part takes too long. I like to get somewhere in a reasonable amount of time, can the x3 or the g0704 make these cuts and still live for another day? HF's mill can do all the head angles the others can but seems a extra strong which I'm sure helps in some way.

So far I have read really great reviews on these machines, with production and hobby work being the norm.
The weight on HF version is roughly 750 pounds versus the x3 at 380pounds and the g0704 at 290 pound.
Precision Mathews offers a upgraded version of the g0704 style machine, known as the PM30. This one weighs in at about 750 also give or take but comes with a 1850$ price, g0704 is $1300', X3 rings in at 1900 but on a 20% coupon I can get the HF version for $1600 but sells for 2000 normally.

So as an uneducated machinist an going from what I have read over the last couple years, it seems weight is a sure winner. HF +1 . Table size goes to g0704 +1 ease of cnc seems to be the X3 ,. Is it better to have head movement or table movement.?

If the knee mill takes a little extra to get cnc added, this will be fine as long as the machine is up the task of cast iron, stainless, blah, blah, blah,. I may never machine these metals but at the same time who knows what can happen. I like as many options as possible.

Please keep the comments rolling as every post is taken into consideration to help my decision. Thanx again

 

[aarggh]

The only thing I'd be concerned with this unit, is how rigid is the knee, and will any deviation or "slop" be able to the adjusted out without having to tram or square everything up every time you move it? When I was looking at buying my mill, a lot of the Cheaper Chinese knee mills had a lot of slop that wasn't uniformly able to be adjusted out, move it a bit higher, one end lifted or dropped, moved it a bit more, the other end or back, or side, was now out of adjustment. That's what I'd watch out for.

cheers, Ian

 

[rodw]

Thanx for all your fast replies.

Yes I have considered the x3. It seems a nice machine but have some horror stories. Of course they all do.

I am only a noob so I don't have anything to compare it against. A neighbour in my street has one set up for CNC and he throws some very aggressive roughing cuts at it and he reckons it screams but does the job. I jammed the spindle once doing something silly and blew an internal fuse but a spare was provided so I guess that says it will live to run another day.

It really impressed me as being a precision instrument from the moment I unpacked it. The Y axis is good to 170mm which is almost 7". Anyway, I still have not used it enough to find its limits or even know what these might be, but I like it a lot. So much so, I sold the drill press I moved out of my shed to make room for it this week as I don't miss it at all.

 

[hanermo]

Let us know how you get on.
I scratch built an (industrial) cnc mill, so I got a lot of experience when building it ...

Cheers, Hannu from the land of the flamenco
(In Barcelona)

 

[blighty]

my vote would be the RF45 type of mill. i converted mine to cnc a few years back and i'm very happy with the results.

i friend of mine cnc'ed a mill like the first one suggested. over in the UK there called a 262. the mill its self is a very good bit of kit. but tend to have a down side when cnc'ing.

the problem is the Z axis. you can put a stepper on the quill ( like me mate did) that gave him a limit of 70mm of day light. plus, minus your safety margin 10mm top and bottom. now your down to 50mm. also the quill its self is not the tightest of fits. he was getting about 0.30mm of float when the quill was at the bottom of its travel. that could just be his mill......

you could cnc the knee, some have done this.

with the RF45 mills..... loads of people have converted them..... lots of help and info out there about how to do it

 

[RonGinger]

The red mill above is the Chinese version of the Clausing 8500 series, and they are well regarded for hobby use. I own an 8513 and like it a lot.

I did not CNC the Clausing, rather a Jet knee mill, which looks almost the same as this one, but about 50% larger. I did CNC the knee, and left the quill free. I find that a great combination

My big gripe on the Rf45 is the gear head. For model work we rarely do big hogging jobs for which the very low spindle speed would be needed. If the FR45 offered one with a belt drive and about 3x the speed it would be a real winner.

 

[blighty]

The red mill above is the Chinese version of the Clausing 8500 series, and they are well regarded for hobby use. I own an 8513 and like it a lot.

I did not CNC the Clausing, rather a Jet knee mill, which looks almost the same as this one, but about 50% larger. I did CNC the knee, and left the quill free. I find that a great combination

My big gripe on the Rf45 is the gear head. For model work we rarely do big hogging jobs for which the very low spindle speed would be needed. If the FR45 offered one with a belt drive and about 3x the speed it would be a real winner.

with you on the geared head. bit on the slow side for fine stuff. high speed on them is 1600rpm, but when measured it's more like 1720 rpm.

one of my many projects waiting to happen is the the belt mod. got the motor, VFD, belt and have machined up all but the last pulley. can't wait. it should give me 5200 rpm (ish) on the head and no more 110db gear noise

 

[Wizard69]

By bed mill you mean one that has the bed stationary and the head used for travel on z axis versus the knee mill style, which raises and lowers the bed?

Yep that more or less is it. In a knee mill most of the time you raise or lower the knee.

I'm trying to follow others that have posted to buy the biggest mill u can afford,and space constraints, which brought me here.

For a home shop it isn't that easy. You need a mill that is big enough for your current interests and possibly some growth in those interests. I like wise caution people not to buy too little but that doesn't mean buying the biggest you can afford makes sense either.

Yes I understand these aren't really comparable, but at the same time a lot of similarities are their. The table size, and movements are pretty much the same, so the only real thing I am gaining would be heavier weight, and stiffening up of column, which is a usual upgrade done to other bench mills.

I'm not sure what you are referring to here. There are some mills people have purchased that time has proven are not really that good design wise. There is really no sense in purchasing a machine that has a column that is known to flex, so cross such mills off your list. Considering the extra expense of reinforcing a poorly designed mill it buying a better mill is a smart move. Especially these days when we have several machine manufactures to choose from and a few designs.

Why not start here if I am going to upgrade anyways.

It is a waste of time buying a new mill that immediately needs column reinforcement when you have rational alternatives.

Or is their problems I am not aware of with this style?

I'm assuming you are talking X2 style mills. If you where to buy new I would see them as a poor choice. It isn't just column flex but the effort required to keep the machine aligned.

I suppose in the end I want the beefiest benchtop machine,( really strong bench), I can buy new, for under 2000$ while getting accuracy and dependability

You want a machine that can handle what you project to be doing. There are many good benchtop machines out there but honestly past a certain point you might as well get a dedicated stand for the machine. Especially if CNC is in the cards because along with that comes lots of chips and the need for coolant.