Requsting your opinions on this CNC mill

[Leav]

Hello,

My long term goal of acquiring a more serious CNC mill for my team is inching closer to completion.

We currently own and operate the Degem TP-MI (http://62.0.20.5/es/Product.asp?pid=87), which is a basic CNC mill mostly suitable for milling plastics.

We are looking of moving upwards towards a more serious mill, and have been offered a very nice table top mill, similar to this model (http://www.intertool.co.il/index.php?show=85820&popup=1), with a DRO, with all the tooling required for a total of about $3750.

However this is a manual mill and I'm pretty sure I would like to have a CNC mill.

So I sniffed around online, and came across www.microproto.com, which sell two models of CNC mills:
The MicroMill 2000 (http://www.microproto.com/micromill2000.htm)
The MicroMill DSLS 3000 (http://www.microproto.com/MMDSLS.htm)

both have the following in their product page:
A full desktop machining system with capabilities to produce most anything from very simple to very complex geometric forms in wood, plastic, aluminum or steel.

This will not come with the tooling, so I looked at this thread (http://www.chiefdelphi.com/forums/showthread.php?t=85568&highlight=table+top+mill) and i'll use the ball park estimate of $350 for tooling.

Since we are on a budget, and sneaking a CNC mill under the noses of the budget people is hard enough as it is, I was leaning towards the cheaper of the two above links, i.e. the "MicroMill 2000" (it seems to be no less powerful than it's big brother), and which costs $2295.

so that's a total of about $2650, not including the shipping (To Israel), and the taxes we might have to pay for it (taxes can be 25%-50% so that's about another $1000).

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So after that long winded introduction into the situation, here are some questions i'd like help with:


Am I making a blatant error in dismissing the manual mill? stories about people never using CNC mills to their full potential?
will the "MicroMill"s really be able to machine aluminum efficiently? what about steel? (they claim to be able to, but perhaps the claims are exaggerated?)
Do you know of any other similar CNC mills?
Any other thoughts about all this? stuff to look out for?


I really appreciate your help in this matter, the ChiefDelphi community is my main consultant in these matters. :)

Thanks!
-Leav

[joek]

look expensive, though, you probably have more sponsors than us

[JamesCH95]

I've used mills of that size in manual form and they can handle aluminum reasonably, but do not count on removing a lot of material quickly.

Also note that you'll need CAM software with either one to generate tool paths unless you plan on doing that manually.

You may want to consider buying a manual machine that can be upgraded to CNC later if you discover that you really want CNC control, just a thought. I've found the manual machines work for many things an FRC team would want to do.

[DonRotolo]

The issues with the smaller mills come down to stability and capacity.

Stability is how rigid the whole thing is. As you can imagine, vibration can affect the quality of the work. Even the largest machines have vibration, but rigid/heavy/strong enough means the effects are small.

Capacity is how fast it can remove material. A big machine might be able to remove a cubic inch of aluminum in a second, while a micro mill might take a minute or two. This is only a question of time, not quality, so if you have time but not money, a micro mill's lack of capacity won't be an issue.

That being said, the micro mill seems to be at a premium because of the CNC control. Note that anyone who can build an FRC robot can absolutely retrofit a manual mill for CNC operation. The 'problem' is not one of software or electronics, but merely attaching a motor to each hand control Stepper motors are commonly used).

For a full-size mill, you'll need 3 or 4 axes of control, with relatively large stepper motors. Such a system is under US$500 before shipping (Link (http://www.xylotex.com/Econo4AxSpecial.htm)). Then you need software (Mach 3, under $200) and a computer (maybe free, Pentium 4 is more than enough). Add maybe $300 for brackets, cog belts and cogs, limit switches, etc. I would imagine that all of this is available locally, it is not all that high-tech.

That doesn't include design software, but I don't see that as an issue.

If you really don't need 3-dimensional machining - essentially, you only cut out shapes from flat sheets - consider a CNC router.

[Dick Linn]

That ZX45 mill you posted appears to be one of the many Rong Fu RF-45 square-column mill clones. Here's a brief intro: http://www.fignoggle.com/machines/rf45-dovetail-square-column-mill/index.htm

Many folks do good work with these (assuming this is the 700+ lb. machine) and also retrofit them for CNC. Look/ask around here: http://www.cnczone.com/

I'm of the opinion that one needs to learn the basics of milling before venturing into CNC. A DRO is a definite plus.

[Cory]

That ZX45 mill you posted appears to be one of the many Rong Fu RF-45 square-column mill clones. Here's a brief intro: http://www.fignoggle.com/machines/rf45-dovetail-square-column-mill/index.htm

Many folks do good work with these (assuming this is the 700+ lb. machine) and also retrofit them for CNC. Look/ask around here: http://www.cnczone.com/

I'm of the opinion that one needs to learn the basics of milling before venturing into CNC. A DRO is a definite plus.

I agree. That RF-45 is a nice mill for what it is. It's a real piece of machinery that you can do real work on. It's going to be far more rigid than the other choices.

Those two CNC mills are hobbyist toys. You're going to have a very limited work envelope and it's going to take a very long time to cut aluminum. It will do it if you ask it to, just be prepared to sit there for a very long time.

Do you really need CNC? If you don't need to make radii/splines/etc you really don't NEED it. If you want to put holes in a plate for a gearbox you can easily do that with the manual model you linked. It might take 10 minutes longer than the CNC mill, but it'll work just fine. If you're looking at anything requiring serious material removal the manual mill is going to beat the pants off the CNC one, even accounting for the added time of manually doing it.

[Leav]

Thank you all for your help, the Xylotex conversion kit seems to fix all my problems!

I'm glad the machine got your "ok" stamp, just one question: is it a big deal that it has a trapezoid profiled screw, instead of a ball screw?
will precision suffer greatly? will the backlash increase over time?

Do you really need CNC? If you don't need to make radii/splines/etc you really don't NEED it.
well, I was thinking more along the lines of: "if we have a CNC mill, we can make radii/splines/etc..."
but with a conversion kit I agree that learning the basics of milling comes first, and CNC second.
Thanks!
-Leav

[Dick Linn]

Here's a typical thread from CNCZONE discussing a CNC conversion of an RF-45 clone:

http://www.cnczone.com/forums/benchtop_machines/104146-rf-45_cnc_advice_needed.html

There are no doubt others in this forum area: http://www.cnczone.com/forums/benchtop_machines/index2.html

You'll find recommendations on ball screws to replace the regular lead screws.