[GreenLead]

The BrickArms guy (Will Chapman) uses a Taig 2018, CNC ready. He added his own Gecko drives and 267 oz-in 200steps/rev steppers from automationdirect.com. Specs should be available on the Taig site.

I suppose now the issue is more about whether the X2 is good for the molds or not...so are you guys saying that the Taig will help machine finer quality molds than the X2?

That GL45/RF45 - it's an Enco mill drill, right?:

http://www.emachinetool.com/new/cata...?ProductID=697

doing a CNC retrofit on one of those seems really daunting, considering I don't know of any drop-in retrofit kits for those

I suppose the only reason I suggested the Siegs in the first place was because CNC Fusion kits for them seemed to be foolproof from what I heard...

I'll try contacting Taig sometime this week, but I'm not putting much hope on it. It would be my ideal mill, but...blasted shipping and exchange rates

By the way, since it's custom Lego accessories, the highest resolution needed is 0.01mm, since a Lego person (commonly called a minifigure) has hands with an internal diameter of 3.14mm, so any accessories that is to be held by a minifig hand must be just right. Will has managed to get 1/10000" resolution out of his setup, although I'm not sure if this means anything...

[Stepper Monkey]

For bigger, heavier material removal the X2 would be the way to go. However for using the extremely tiny tools required to make molds for lego parts you want to stick with something with a spindle that goes over 10k RPM, has the more accurate er16 collets, and as light a headstock as possible.
The Taig fits those three needs right off the bat, but an X2 with a secondary spindle attached could do the job too. Not exactly optimal, as it would be slightly more hassle - you'd be breaking a lot more tooling and probably sometimes need to make multiple attempts per mold cut - but it isn't impossible if that's what you have at hand to work with either.

I have a new Taig I haven't even assembled yet - so later tonight I'll see if they can even be broken down into < 20 Lb sections or not. I'll let you know how that goes, it may be possible but it will be very close if it is! Now I'm curious..

[Jason3]

By the way, since it's custom Lego accessories, the highest resolution needed is 0.01mm, since a Lego person (commonly called a minifigure) has hands with an internal diameter of 3.14mm, so any accessories that is to be held by a minifig hand must be just right. Will has managed to get 1/10000" resolution out of his setup, although I'm not sure if this means anything...

How does 1/100,000" resolution (0.00025 mm) sound? I have one little mill clogging up my entryway that would do you nicely.

Yep, the GL45 is the same. Maybe even the same manufacturer? I did gather together servos & drives and some 25 mm ball screws to retrofit it before the project was canned. There would be a few parts to make, but hey - you would have a mill to make them. Seriously though, it would certainly be a lot more involved than a retrofit kit, and I don't think it would be the best machine for your purpose.

I think the Taig would be a better machine for your use than the X2.

Or, if you have a little time and the price is getting too high I would build you one. Then you can pick the colour

Best regards,

Jason

Ps - could this be related to your studies? Call it "course related costs", and put it on your student loan!

[cyclestart]

Will has managed to get 1/10000" resolution out of his setup, although I'm not sure if this means anything...

Using my definition of resolution that figure really doesn't mean much.

200 steps/rev x 8 pulses/step x 5 revs/inch = 8000 pulses/inch

8 pulses/step refers to 8x micro-stepping. That's the way my drives are currently setup.
My ballscrews are 5 threads/inch.

So the resolution in inches is 1/8000. 1/10000 if you want a round figure. The working tolerance of the machine is no where near that figure.

2x micro-stepping with a 20 tpi acme screw is also 1/8000. If the machine is not direct drive, well.....there's all kinds of possibilities.

That explanation might be clear as mud but it is a possible explanation of the number you were given.

Ballscrews will give you a faster machine and less time spent on adjustments. For your needs and budget I really don't see a practical advantage in using them. The really good ballscrews cost big money. A well adjusted acme screw will outperform a mediocre ballscrew for this fussy work..

[GreenLead]

Just asked Will - he says he uses his Gecko drives at 10 microsteps...

20TPI * 200steps/rev * 10microsteps = 40,000steps/inch

He told me my maths was correct, and that he uses direct drive...okay, that number seems a bit ridiculous now...

So in short, what do you guys think of the Taig 2018, CNC ready? I'm starting to think that, since investing in a mill only for the little molds isn't exactly a cost-effective idea, how well does it do larger jobs?

[awerby]

The 2018 CR gives you an X-travel of 10 inches, so any part it makes will have to fit in that envelope. The 2019 CR gives you 12" of travel, and that extra space can really come in handy at times. I believe I was the Taig dealer who sold your friend Will his 2018, but he must have shipped it to New Zealand himself. It would cost about $560 to send one there by air freight, insured - expensive, but not impossible. If the part fits inside the working envelope, the Taig will cut it, but obviously it won't take the "hogging" cuts that a bigger machine can. However, if you mostly want to do fine work with small cutters, the Taig's higher spindle speed will make that go a lot better. For larger cutters, just slow down the spindle, take multiple light cuts, and it should work fine.

The Gecko G540 would probably be a good driver for it; I bought one recently but haven't got it hooked up yet for testing. It certainly offers a lot of functionality for its price - pretty much all you'd need to add is a case, stepper motors, cables, and a power supply. EMC should be able to drive it, if you get along well with Linux, otherwise you might want to try Mach3, which many people here in the Zone are using.


Andrew Werby
www.computersculpture.com

[GreenLead]

Thanks Andrew - althought Will's actually based in Redmond, WA. So yes, shipping is quite dear.

Other than that, really appreciate the notes on the mill, the G540 andthe choice of control software. I'm using EMC2 mainly because it's free, although I'd have to look for an additional program to get it to work with Pro/Desktop...

[acondit]

Just asked Will - he says he uses his Gecko drives at 10 microsteps...

20TPI * 200steps/rev * 10microsteps = 40,000steps/inch

He told me my maths was correct, and that he uses direct drive...okay, that number seems a bit ridiculous now...

So in short, what do you guys think of the Taig 2018, CNC ready? I'm starting to think that, since investing in a mill only for the little molds isn't exactly a cost-effective idea, how well does it do larger jobs?

My understanding of the microstepping is that you really ought not count on the microstepping as determining your resolution. The microstep just smooths out the movement but doesn't really increase your resolution. I believe that I read that the angle of movement per microstep is not necessarily even and that is why you should only rely on the full step travel for determining your resolution. However, you still have to use the microsteps in setting up your machine because it still takes all those little microsteps to get you there.

Still, 4000 full steps per inch gives your 0.00025" per full step which is pretty amazing.

Alan

[Crevice Reamer]

Your 20TPI lead screws will guarantee good resolution. The G540 is ONLY set up for 10 microsteps. There is no full step option. However, it will morph to full step performance after about 300 RPM. Clever little drive, and excellent for a Taig.

I wonder if you could use something like a Proxxon:

http://www.emachinetool.com/new/cata...?ProductID=719

You could convert it to CNC:

http://video.aol.com/video-detail/my...id=VIDURVHOV08

Or even buy it already converted:

http://www.kdntool.com/userfiles/mf70_pkg.pdf

CR.

[Stepper Monkey]

Each individual step is usually around +/- 5% non-repeating error and is fixed, and unique to that particular step. This is therefore usually in the millionths and shouldn't be worried about. It is true that a stepper is only in known perfect alignment once every full 360 degrees.
Imagine a gear with slightly different spacing between each tooth. One tooth to the next can be slightly varying in distance, but it is always a fixed distance betwee those two particular teeth, and the gear is still always in the same place after each full rotation anyway.
Worrying about it on a benctop mill is like worrying about how much a bug splat on your cars windshield is affecting your fuel economy. Theoretically, yes, it adds weight and disrupts your aerodynamics and burn more fuel. In practice it's irrelevant.

BTW, the Proxxon is a neat little device, but remember it weighs less than 15 pounds. Less than a third of that is the frame - of cast zinc. The whole mill - spindle, motors and all - under 15 pounds.
Neat, but probably not for metal mold cutting!

[acondit]

Your 20TPI lead screws will guarantee good resolution. The G540 is ONLY set up for 10 microsteps. There is no full step option. However, it will morph to full step performance after about 300 RPM. Clever little drive, and excellent for a Taig.

CR.

I was only talking about the calculation of resolution based on "full steps" (i.e., issuing ten microsteps), that is to say calculate your resolution as though you were using full steps.

Alan

[cyclestart]

Sorry guys. I was only trying to explain where numbers like 1/10000" might originate. Didn't intend to throw this thread off course.

Other than that, really appreciate the notes on the mill, the G540 andthe choice of control software. I'm using EMC2 mainly because it's free, although I'd have to look for an additional program to get it to work with Pro/Desktop...

These lower end gecko drives became something more (better) than than gecko originally intended. If it wasn't for a minor disagreement over shipping details I'd already own the G540. I'm surrendering to the terms and buying. It will be running with emc2.

Mach3 is only around $150USD or something like that. Considering the amount of time and money many of us sink into this cnc stuff, $150 is minor in relative terms. Look at both. I like emc2, you may prefer Mach3. There is a helpful community for both. The Mach community is considerably larger.

CAM software that runs in linux is very limited. No big deal but adds a bit of file transfer nuisance. As a student you should be eligible for some software deals? Maybe even a CAM related course?

edit/ "although I'd have to look for an additional program [b] "
Won't you need an additional program in either case? Mach3 has the advantage of running on the same operating system as the most popular CAM products. You will still need CAM software to generate toolpaths (g code).