Newbie- Shopping for my first Mill

[TMc]

I am interested in purchasing a hobby class mill. I have been looking at the Sherline 2000, but it seems pretty small, expensive and not particularly ridged. Can someone give me a quick comparison of the various mills, and direct me to the mills I should be looking at.

I am looking for a system I can add stepper motors to. I can probably spend up to $1500, and would like as large of a working area as possible for the money.

TMc

[jalessi]

TMc,

What are you going to use it for?

How much room do you have?

Is $1,500 your total budget for the machine only or for everything?

Welcome to the Zone

Jeff...

[Teyber12]

ill say i love my x3 and you can get it at hf with the 20% off coupon for pretty cheap

[Jeff-Birt]

Hi welcome to the forum. Are you looking for a 'ready to go' machine or one to convert?

In the same size category as the Sherline you can get a 'computer ready' version of the Taig 2019 mill: http://cnczone.com/TaigMachines.aspx . It has couplers to mount NEMA 23 steppers. I'm a bit biased as Taig dealer but I think they are the best small mill for the money.

Another choice is the 'X3' manual mill. Many places sell them, they are made at the same factory in China, but I think Grizzly does a better job of quality control: http://www.grizzly.com/products/6-x-21-Mill-Drill/G0619 . There are several places that sell conversion plans, kits and parts for them. It is a heftier mill with about the same work envelope as the Taig. Some places even sell them already converted but I'm not sure about one that is just 'CNC ready'.

I guess it comes down to the type of machining you want to do and how much work you want to put into converting a manual machine yourself. The Taig and Sherline goth use 20 TPI lead screws which give enough reduction for direct mounted steppers. The lead screws used on most manual machines are not suited for a direct drive arrangement, some sort of belt reduction is required. Some folks try to get around this by using really large steppers but your better off with the belt reduction.

If you want some more info on the Taig just let me know.

[bjones]

Originally Posted by Jeff-Birt The lead screws used on most manual machines are not suited for a direct drive arrangement, some sort of belt reduction is required. Some folks try to get around this by using really large steppers but your better off with the belt reduction.

Most manual machines have screw pitches of 16 or 20 tpi like the Taig.
Direct drive is the cheapest, easiest most efficient method.
Why in the world would someone want to put a belt reduction on a stock lead screw
unless they were after godawfully slow rapid speeds like a Taig.
You think spending $40 for a belt reduction is better than spending $20 more for a bigger motor?
Bill

[Jeff-Birt]

Well, I might be inclined to answer a question if it was asked in a civilized manner. Seriously, there is no need to be nasty just because you disagree. For the benefit of others I will since it is good to ask why.

Many machines will come with a lower pitched screw and many 'upgrade' kits come with a lower pitch screw. These are not good candidates for direct drive (which was my point.)

Even is you just bolt a bigger stepper on you may not be getting any benefit throughout the entire speed range of the stepper. If you check the torque/speed graphs of stepper motors you'll notice that at a given voltage as you increase the size of the stepper the available torque drops off very quickly with speed. So after the first few RPMs you may not have any more available torque than the next smaller motor. With proper gearing you will have a motor producing the torque you need in the proper speed range.

For a small mill more then 40~60 IPM is a waste. You don't have the HP or rigidity to machine that fast and there is not enough travel to benefit from the increased speed either.

[bjones]

Originally Posted by Jeff-Birt For a small mill more then 40~60 IPM is a waste. You don't have the HP or rigidity to machine that fast and there is not enough travel to benefit from the increased speed either.

the OP can read lots of threads about people's machines that benefit from much faster speeds and rigidity the taig can only dream of.
Easy to jump over to the taig forum and read the complaints about minuscule cutting depths and gargantuan cutting times.

[Jeff-Birt]

I was trying to help answer a question from a new forum member and add to the knowledge base of the forum.

Spewing venom and vitriol helps no one.

[Hirudin]

Hmmm... well, this thread is toast. Thanks bjones.

Originally Posted by TMc ... I am looking for a system I can add stepper motors to. I can probably spend up to $1500...

Originally Posted by bjones ... much faster speeds and rigidity the taig can only dream of ...

Hi, if you have a mill that has "speeds and rigidity the Taig can only dream of" that also conforms to the OP's request I suggest you start naming some names and citing some links instead of being an *******.

[jalessi]

We have several CNC machines the smallest being a Roland PNC-300, next a Taig, a CPM 2018 Benchtop, a Bridgeport and a Hurco KMB-1

They all work well doing what they where designed for.

I cant say anything bad about any of them, for a small bench top machine you cant beat the quality of the Taig.

The right size tool for each job has merit, like a lid for every garbage can.

It would be nice if we give constructive advise instead of destructive criticism.

Welcome to the Zone,

Jeff...

[DeusExMachina]

I have a Taig, its a great little machine. But, it is little, you need to size the machine to what you want to do. If you're going to limit your parts to about 7"x3"x2" then the Taig will be fine if you don't mind waiting an hour or two once you have it CNC'd.

But, since this is your very first mill, do not worry about whether its cnc ready, or how easy it will be to convert etc. You need to learn about metal working first before jumping to CNC or you'll just end up ruining parts and cutters before you learn the ins and outs.

Since you have $1500 to spend, I'd suggest an X3, a vice, some basic tooling and some stock and start learning on it manual first. Spend a couple months making little things and learn how to use the tool.

You'll need to learn how to take the machine apart, to clean it, how to adjust the gibs, cut down on your backlash etc.

Once you've learned the machine enough that you can quote your travels, backlash on each axis/where it is, the biggest cutter you can run and at what speed/feed as well as the smallest cutter, all off the top of your head then you're probably ready to start looking in to CNC.

The X3 is probably the best starter machine if you have the money, after learning it then you can start converting it yourself. Once you're ready to convert, and if you do it yourself, you're probably looking at $600-$900 more to convert it. But, you will have a nice machine that you know inside and out and won't have any problems fixing it.

If you just want to jump straight in to CNC, then the Taig is probably the easiest as it uses true inch screws (though this probably won't matter if you're outside the U.S.) and you can purchase then CNC ready machine for ~$1200, hobby cnc board (hope you're not afraid of soldering - $90), steppers of the 270 oz-in variety (~$60-$120), 36v power supply ($50), a computer with EMC2 ($0.00 but you'll need a decent understanding of Linux and some patience to get everything working). All of this will probably put you slightly over budget after shipping.

Next up would probably be an X2 with a ballscrew conversion (here) then the same basic electronics mentioned above.

As far as how rigid the Taig is, while bjones here is being clearly inflammatory while offering no real help, I can tell you that dispite its size its a very stout machine. In fact, its only real failing is how little HPs the stock motor has. I've run some simulations on it, with ~100lbs of force acting on the spindle, the entire column/head assembly is only torqued a maximum of 0.0014" (1.4 thou), I don't believe the simulation is entirely accurate (I bet maximum deflection with that load would be closer to 8 thou), but I've noticed myself that the motor runs out of torque long before any scalloping occurs in the surface finish.

[TMc]

Originally Posted by jalessi TMc, What are you going to use it for? How much room do you have? Is $1,500 your total budget for the machine only or for everything? Welcome to the Zone Jeff...

Thank you all for your help and advice.

I think I am going to use it mostly for soft metals, Brass and Aluminum, perhaps a little steel, but not much. I am interested in building a larger CNC for woodworking and I would like to make parts on the mill for use on the larger woodworking CNC. After that it will be used for making smaller metal models, etc.

I definately want to keep this to a tabletop version. I do have a little workshop space, but I don't want to dedicate a lot of space to this. My budget is 1,500 to get things started. I assume that I will invest more if I really get into the hobby, but that is my seed money. I want to get a good working manual platform I can build on in the future. I don't want to buy a mill I will have to replace once I get serious. I did that with a shopsmith and woodworking and didn't get my money back.

Priorities:

1) Reasonable sized work envelop ( as big as possible)
2) Ability to CNC it
3) Ability to use stock accessories
4) Robust quality mill.

The Sherline looks nice, but I am a little worried that it is more of a toy than a machine. I'm also concerned that I will be required to use high priced accessories. The Taig looks interesting, but I am not sure about the differences between the AC and DC motor. Sherline seems to make a big deal about that.

The X3 looks like a good mill, and perhaps a winner, but if it isn't a quality machine it might not be a good platform to build on and I might always regret my initial decision. I'm also not sure how easy it is to SNS the device.

Thanks again for your feedback.

TMc