Zx45

[zvika-g]

I want to buy this mill:
http://www.allproducts.com/manufactu.../product5.html

Does anyone own/familiar with the ZX45 mill?
What can you tell about its quality, accuracy etc.?

Thanks in advance,
Zvika

[tai42]

I can't say anything about that specific mill, but it looks very similar to the Industrial Hobbies mill that I have. I am very pleased with the IH mill. It is more than ridged enough for the work that I've been doing. (Mostly aluminum, some mild steel.) I routinely do work with accuracy of a thousandth of an inch or better. (I also have a DRO, which helps a little.) However, like most machines your accuracy will depend as much on you as the machine.

[zvika-g]

Thanks a lot tai42,

I have noticed the similarity between the two mills.
I know that these two mills are not the best that can be found in the market, and this is the reason for my worries.
The two things that worries me the most are accuracy and quality.
The accuracy aspect is really important to me since I'm buyimg this mill in order to manufacture really delicate parts (small engines for exanple).
In these two mills the leading screws are not "ball screws" and I can't estimate the precision that I can get.
I also don't know how accurate is the table and its movement.
Regarding the quality aspect, I don't know if the mill is made of quality steel or just simple iron.

I guess I'll be able to answer these questions just after buying the mill.

Thanks again,
Zvika

BTW, I intend to convert this mill to CNC. do you have any suggestions about it?

[tai42]

As far as the accuracy, I can tell you that when turn the handle one thousandth of an inch, the DRO and a dial indicator both register that the moves one thousandth of an inch. Beyond that it is really up to your abilities as a machinist to achieve the end result. I was routinely doing parts with better than one thousandth of an inch on my X2 before I got my IH mill. And the X2 didn't have a DRO and wasn't nearly as ridged. If you tram it right, and don't try to make it do something it can't, then you will be fine.

In the end if you want to achieve accuracy over a large distance, then you will probably want to set up a DRO with a nice glass scale attached to the table to measure its actual displacements. For "local" accuracy, then the marks on the hand wheels are usually fine. (DRO's can make the setup a lot faster though. I really like mine. )

As for quality, I have only had my IH mill a couple months but I have heard from many that these mills are built to last. (You may want to take a look at the Industrial Hobbies Forum.) Of course if you want the "best" then these mills are copies of the Rong Fu 45 (made in Taiwan I believe.) Real RF-45's are supposed to be a VERY nice manual machine, but also a lot more expensive. I've never worked on one personally, but quality wise the clone mills suit my purpose for a fraction of the cost. Still, maybe something to look into.

As for ballscrews, you won't generally find them on a manual mill. They are far too efficient at transferring motion, which means they work well BOTH ways. (Rotation to translation, and translation to rotation.) When you have a CNC mill with motors holding the screws then it's not a problem, but on a manual mill you usually want to be able to let go of one wheel and not have it move under normal machining forces. With acme screws, you have enough friction that this is possible, but not with ballscrews.

I can't give any specific advice on CNC converting a mill such as this. I went what some would say is the "backwards" route with my X2 being set up as the CNC mill, and the IH mill dedicated as a manual mill. (Or NC mill if you take into account the function of the DRO.) For me I enjoy manual machining, and the IH mill is a much more valuable manual machine to me than the X2 was. (And the X2 had the capacity for anything I must do CNC.) The IH CNC kit looks pretty nice. You can also "roll your own" kit. I would of course recommend ballscrews with preloaded nuts on all axis. In my experience, a mill this size is pushing what you would want to do with steppers, so I think servos are a probably a better choice. (I used steppers on my X2, but it's a MUCH smaller mill.) Beyond that the sky's the limit and will depend a lot on your requirements. Just my 2 cents, others will probably have their own opinions.

-Bob

[zvika-g]

Thanks a lot Bob. I really appreciate your answers and your effort.
Thanks again,
Zvika

[Climatepro]

I also have the same mill, not sure if it is a Rong Fu or a copy. I have several annoying quality problems that I am forced to "work around" in order to make good parts. My R8 spindle bore is at a slight angle relative to the spindle axis, and my dovetail column has one dovetail cut with a taper. I can work around both of these flaws, but it's annoying. I've had to replace 2 failed bearings inside the gearbox, and I was irritated at how dirty the gearbox was with manufacturing debris like casting sand and paint chips.

I kept the acme screws on the X and Y axes and made some heavily spring preloaded delrin anti-backlash nuts, and I drive those two axes directly with (large) size 34 stepper motors. I'm quite happy with the speeds and machining power I get, and rapid feed rate doesn't mean that much to me. I get around 0.001in total backlash on X and Y, some of that just due to stiffness of brackets.

The Z axis I drive the little feed shaft on the front of the gearbox with a size34 stepper, and I always program such that the (considerable) backlash isn't a factor by always approaching a depth by moving downwards. If I were doing contouring or something like that, I would have to do something different.

Overall, I suppose it's a love-hate arrangement. I've worked with high quality Bridgeport type machines, so I know how bad this mill is, but it can be moved into my heated basement workshop. I think these mills are great in concept, just hope you get a good one.