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Thoughts on this Machine
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Author:  Anthony Z [ Tue Aug 28, 2007 11:00 pm ]
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My brother and I have been toying with purchasing an entry level CNC machine. Recently I came across this one sold by a company in Toronto called MotionTek

It sells for about USD$6,000 and is manufactured in China and uses a Taiwanese manufactured variable speed spindle.

Any thoughts or questions I should ask when I go to see it demonstrated on Friday would be greatly appreciated.
Author:  Bob Garrish [ Wed Aug 29, 2007 1:30 am ]
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The price is right, but it's hard to judge a machine without being there. The accuracy numbers router manufacturers give out are pretty much always malarky. Talk to a bunch of former customers, that's the best tip I can give you.

If you had a few hours alone with the machine, then you could run some good tests on it. Cutting a circular hole in something or using a known circular hole and then seeing how fast you can cut a circle on the machine and have it still come out round is a good one.
Author:  Parser [ Wed Aug 29, 2007 2:16 am ]
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Man, I wouldn't touch it. I'd rather pay a few bucks and 1) have more confidence in what I was getting and 2) be able to get support in my native language.

I went thru the same decision making process before getting mine...and that was my final conclusion.

It may be a good deal and it might be a maintenance nightmare. K2's are right in the same price range and have a more proven track record.

Author:  Rick Turner [ Wed Aug 29, 2007 2:23 am ]
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I got a Techno, and aside from horrible documentation and instructions, the machine itself is doing fine.
Author:  Anthony Z [ Wed Aug 29, 2007 6:24 am ]
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Gents thanks for the words of wisdom and taking the time to respond.

Bob - I hear you -- tough for you to judge a machine w/o seeing it yourself. Though I will see if they can run a circle test on it. Good thought on asking for referrals. If they have confidence in their machine they shouldn't have a problem providing contacts.

Parser -- I've looked at the K2 CNC that I think you have 3925 and yes it looks attractive but it means ordering, shipping and service from California. Something in my home town is what attracted me to investigate this machine further.

Rick -- Yup -- if cost weren't a consideration I suspect I would be looking at a Techno-Isel. Nelson Palen has shown me some archtop plates that he has done on his -- they sure looked good.

The residual question I have and should have led with is, should I be concerned with having a Z axis of 4"? I would use this machine for making Archtop guitars and possibly some flattops (i.e. the neck).

Thanks again folks!
Author:  Parser [ Wed Aug 29, 2007 7:14 am ]
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I would definitely want more Z capacity. 4" is not much...especially when you consider how you are planning on jigging everything up. I have 8" and that is more than adequate. The minimum is somewhere in the middle, depending on how large the parts are that you want to cut.

Keep in mind also, that you may want the additional capacity to cut things besides guitar parts...such as jigs. I made a 12 degree "ramp" jig for cutting perfect scarf joints...that's probably right around 4" high.

Author:  Bob Garrish [ Thu Aug 30, 2007 11:00 am ]
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3.5" guitar neck at heel + 4" of cutter protruding to cut it 'til the ball is side-on...

There's a company called GorillaCNC near Toronto. I've done some contract programming work for them. I can't specifically recommend their machines, as I haven't used one myself, but they'll be able to provide references near your area and also service and support close to you. As well, Larken CNC is in Ontario somewhere, I believe. There's also Precix in BC.

If you're looking for an inexpensive, hobby-grade machine then I think all three of them have something in your range. The Techno prices would also be OK if the Canadian distributor wasn't so greedy. You should get a quote from them and then an American reseller, just for interest's sake...
Author:  Anthony Z [ Thu Aug 30, 2007 9:43 pm ]
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[QUOTE=Bob Garrish] 3.5" guitar neck at heel + 4" of cutter protruding to cut it 'til the ball is side-on...
[/QUOTE]

Bob, are you saying that a 4" Z-axis is cutting it too close? (pardon the pun)

I really appreciate you providing the GorillaCNC and Larken names. Larken I had never heard of before. Now that you mention it, I spoke to the GorillaCNC people at the Toronto woodworking show this past winter. The GorillaCNC machine I saw looked really robust. I will check these vendors out --

I am going to see the MotionTek machine demonstrated this afternoon. They are only 15 mins from my office.

I didn't realize Techno had a Canadian distributor.

Parser - I had another look at the K2CNC 3925 and I can see why you purchased one.
Author:  Rick Turner [ Fri Aug 31, 2007 1:24 am ]
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The other consideration on "Z" height is that your holding fixtures gobble up some of that, too. We primarily use vacuum fixtures made out of MDF (for first generation tooling), and the fixtures are either 3/4" or 1 1/2" thick.   We have 11" of "Z" available, and it's great.
Author:  Bob Garrish [ Fri Aug 31, 2007 1:38 am ]
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I forgot about that one, as well. For the back carve of a neck, on my machine, the Z height requirement would be:
1" vacuum fixture plate
3.5" height of part
4.25" of tool protruding (because I don't want to chance the collet rubbing the part)

8.75"

You can get by with about 6.625" of Z height and carve a neck if you're cutting it on it's side with a 1/2" ball.
Author:  Anthony Z [ Fri Aug 31, 2007 2:05 am ]
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Bob, I spoke with Larken this morning. Their machines look very robust and their sales people are really helpful. They don't use any aluminum extrusion parts --its all heavier guage aluminum machined right in their shop. Larken will build a machine up to a 12" Z axis height. I am in the process of getting a quote from them for a 24" x 36" x 8" machine equipped with Steppers (Servo's are an addition $1200). It's going to be more expensive than an equivalent sized K2CNC but I suspect a much more solid machine.

Rick I hear you about Z height. When you go above a 5" Z height the cost of the machine goes up considerably as a good chunk of the machine needs to be beefed up for the additional stress. You and I are in entirely a different snack bracket in terms of machine requirements and use

Guys your responses in this thread have been really helpful!!
Author:  Don Williams [ Fri Aug 31, 2007 2:22 am ]
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[QUOTE=Anthony Z]They don't use any aluminum extrusion parts --its all heavier guage aluminum machined right in their shop.[/QUOTE]

You say that like it's a bad thing!

The 8020 aluminum extrusions, specifically the 15 series are very robust. Believe me, when you handle the stuff, you don't get the impression that there's any lack of strength at all. It's far stronger by weight than steel to begin with, and with engineered cross-sections, the stuff can surprise you.

BTW, I'll have almost 8.5" of Z travel. That should be enough to do anything I want. If not, I'll replace the actuator.

Author:  Anthony Z [ Fri Aug 31, 2007 4:18 am ]
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Don -- you didn't read my message as intended. Many of the smaller CNC machines both manufactured and homebrew ones as you know use extruded aluminum...nothing wrong with that at all. If I were building one I would do same. My point was these guys machine solid aluminum whereas they could have readily used extruded like most others.
Author:  Brock Poling [ Fri Aug 31, 2007 12:00 pm ]
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I talked with Chris @ luthier tool the other day and it sounds like he is going to be coming out with a turn key CNC package for luthiers that includes the machine and "everything you need to get going". It sounds like it will be in the $4k - $5k range.

What I like about these turn key systems (Sylvan will b be selling one soon as well) is that they will also be selling programs to cut common stuff (necks, bridges, etc.) as well as provide custom programming.

I think that is a nice option for CNC neophytes like me. It allows you to enter into CNC for a decent price point and have support, not only for the machine, but from someone who understands what you are trying to do with it.

I am starting to learn Rhino now, but I can see that CNC will have an enormous learning curve.

I mostly want it to build custom tooling and do inlay work.
Author:  Don Williams [ Fri Aug 31, 2007 12:22 pm ]
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[QUOTE=Brock Poling] I am starting to learn Rhino now, but I can see that CNC will have an enormous learning curve.[/QUOTE]

You can say that again...

Brock, did he give you any indication as to what kind/size of motors and what electronics would be involved? Also, what size cutting area?

Thanks...


Author:  Jim Watts [ Fri Aug 31, 2007 2:42 pm ]
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I have a cheap nc machine which I have posted a little about in the past. I had to rebuild part of it just to get into what I consider acceptable limits. I can pretty much guarantee you that there is no way this will cut at 160 ipm. I believe it will move that fast, but 30 ipm is more realistic looking at the construction, my opinion here.
That's not really a big deal though.
I realize I'm a little late on a post here, I've off on travel, but if you get a chance to cut on it, cut not only a circle but also a diamond and square. A bunch of em if you can and look for repeatability.
I'm sure you could do a lot with this however and it might very well be a good first machine. I like the fact that it has ball screws and you can get a spindle with it.
Have fun and let us know what you decided.
Author:  Brock Poling [ Fri Aug 31, 2007 4:15 pm ]
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[QUOTE=Don Williams] [QUOTE=Brock Poling] I am starting to learn Rhino now, but I can see that CNC will have an enormous learning curve.[/QUOTE]

You can say that again...

Brock, did he give you any indication as to what kind/size of motors and what electronics would be involved? Also, what size cutting area?

Thanks...


[/QUOTE]

Not really, we talked about it in general terms. But I asked specifically if it will be big enough to cut necks and he said it would. (But again, most of my facination with CNC is about cutting custom tooling and inlay.)

Every tool I have seen from Chris has been top shelf in terms of quality. I suspect this machine may have its limitations (speed etc.), but I bet it will be well made and a great value.

From where I set I would almost rather spend $4,500 on a machine that might not be the be all end all... but let me get my legs under me with CNC in a way that I can make it productive while I am learning. I am going to have to learn a lot of new skills so having someone in the wings who can help out is a big draw.

Author:  Don Williams [ Fri Aug 31, 2007 10:53 pm ]
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I agree Brock. Having someone there to advise and give service is a great idea. When I calculate how much I have into mine, I realize I probably could have bought an inexpensive product like that, but I was into building one.
To date, I (will) have into this roughly (sans laptop computer):

$250 for the Z-axis actuator
$400 for the linear rails
$180 for my PC router
$1000 in aluminum extrusions, and I need more
$450 into my Gecko drives
$400 into the Gecko G100
$200 in hardware
$50 for the power supply
$460 for the motors
$1050 for the ballscrews and bearings
$160 for Mach 3
$300 for Rhino (student)
$25 for the arcade joystick and buttons

so I'm almost up to $4900 and there may be more to get.
BUT I'll have the capacity to do a lot of stuff with a roughly 34 x 52 cutting area. And It will have some serious oomph to it with the 600 oz/in steppers and the Gecko stuff. I should easily be able to see cutting speeds up into the 200 ipm range, but of course inlay work etc must be done a lot slower than that.

To get a spindle would require an additional commitment of around $3000 which I'm not about to spend for this. Maybe someday if I'm making money with this machine, but not yet. And since I don't intend to sell services or products with it, a router should be all I really need.

I'm not second-guessing my decision to build one though.   I think the learning experience has been good for me as far as forcing me to understand motors, torque, etc. Not that I fully understand it all, but I'm learning, and that will give me a leg-up when I decide to build another one someday.
Author:  Anthony Z [ Sat Sep 01, 2007 8:02 am ]
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Jim thanks for your thoughts -- keep them coming as I am still in the hunt.

I saw the MotionTek machine demonstrated yesterday. Quite impressive in many respect, though in the end not the machine for me.

The machine was well build and sturdy and made from solid machined aluminum (no extrusion and no slight Don). It also has T-slot aluminum table which is an extra on most machines and uses 220 oz steppers. It comes complete with a 2.25 hp spindle that is run with a 8" x 8" control pad that you load your G-Code onto, i.e. it isn't run off your PC -- though it could. That is a really neat feature as when running a program if you don't like what you see you can shut down the spindle quickly. The machine also uses ball screws and comes with CAD/CAM software. In the future they will offer the machine with BobCad for the same price.

The spindle however will not accept end mills of 1/4" or 1/2" rather it is metric and uses roughly 0.375" end mills. It could be outfitted with a different spindle but for significantly more $'s. The "Z" axis could be upgraded for 8" clearance and 8" of travel though for a one off cost of about $3,000. That would entail using more robust rails and beefing up the gantry. Now the machine would be in striking range of more commonly known CNC machines as well as some of the Canadian manufactured ones that Bob Garrish mentioned.

The vendor was great to talk to and indicated that if he were to go back and make the modifications to the design, his Chinese manufacturer in time would be able to offer the machine with a spindle that met our needs with the 8" Z axis clearance and 8" Z axis travel desired for around $8,000. Which would be one hell of a deal. But it will be sometime before such a machine could be made widely available.

So the hunt continues!!
Author:  Marty M. [ Sat Sep 01, 2007 11:38 am ]
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I am thinking of upgrading to a commercially made CNC machine soon. One thing that I will definitely consider besides the price, is who has a good chance of being in business in 5 years. If you were looking at hobbiest CNC machines a few years back, there were a number of players. Many of them are gone now. Somebody that has been in business for 10-20 years probably has a good shot of being there when you need replacement parts.
    I know that there are no guarantees, but having bought a thickness sander from a new company and having them go out of business the next year gets you thinking about things like that.
Author:  Bob Garrish [ Sat Sep 01, 2007 5:52 pm ]
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If you can find me a company making hobbiest CNCs for 20 years, I can find you a liar.
Author:  Don Williams [ Sat Sep 01, 2007 10:18 pm ]
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Bob, I think that was Marty's point. He's seen a number of them go out of business.

I'm just having a hard time with stuff made in China these days. The quality tends to have major issues and we suffer for it. Tainted wheat gluten, lead paint on children's toys, what's next? A spindle that flies apart and kills a luthier? Not me! So many US companies are making their stuff in China that we have no control over what we're buying. It doesn't help our unemployment numbers either. What I like about a number of companies is that they make most of their stuff in good ol' North America. I would trust stuff made in Europe, or Australia, or just about anywhere but China. Unfortunately, we've come to rely on them for most everything. Heck, even my nice new Mac laptop is made in China...
Author:  Don Williams [ Sat Sep 01, 2007 10:28 pm ]
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[QUOTE=Anthony Z] The machine was well build and sturdy and made from solid machined aluminum (no extrusion and no slight Don).[/QUOTE]

None offense taken. I didn't mean to sound offended when I defended aluminum extrusions...I wasn't. Some aluminum has to be machined on these things. Even plate sometimes has to be machined. If it's extruded plate, it will often warp just like wood and will need machining to be flat. A number of CNC manufacturers make their machines without using extrusions. Some folks have the ability to machine plate good and flat, and that can be less expensive than quality extrusions. It makes economic sense to do so.
Aluminum extrusions are more expensive than plate, and because they are engineered, they are also stronger by weight than plate for some applications.
Author:  John Watkins [ Sat Sep 01, 2007 11:42 pm ]
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A couple of thoughts;

I wouldn't worry too much about the height clearance as long as you have enough Z travel. I made a riser kit for my main machine. It took about a half hour and hasn't had any effect on speed or cut quality. I simply bolted in four aluminum blocks (2"x4") between the Y bearing assemblies and the existing gantry uprights.

The neck clearance math: Bob said 3.5" for neck height, which I assume he arrived at by considering a 3.75" deep body with the heel of the neck extending to just meet the 1/4" binding of the back. But, since not everybody does that, and some bodies are deeper, you really need to get a healthy 4" above that fixture, which is an inch tall with a 5" cutter that sticks 1" into the collet. You also need to be able to get your collet down onto the table (or very close to it) when there's nothing in it. So you need 9" of travel, and 4.25" of clearance. Remember that your Z axis is just bolted on to X. It can be moved to suit your needs on any gantry machine.

I have three recommendations for your machine Anthony (and everybody):

1. Get Servos
2. Get Servos
3. Get Servos

Steppers are fine for short jobs that are cut out of sheet goods, where as long as all the parts are within the boundaries of the sheet, you're fine. If you ever want to use a fixture with any sort of indexing methods where you have to run a program a number of times in the same exact location, you need servos. An example would be cutting neck block mortises on one side of a number of pieces and neck bolt holes on the other. The stepper is going to lose position over time. Mariss will disagree with this, but he will also readily admit that he has never been in the same room with a CNC machine. He's going on theoretical math, which is his job, so I just respectfully disagree.

Servos aren't that expensive either in the retrofit market. I think I paid $2,000 total on my last machine. It's not chump change, but we're talking about the single most important componenet of a near-5 figure investment. Hell, I paid more than that on the Techno just to upgrade from Servos to Bigger Servos. Worth every dime, by the way (1200 ipm).   

Hope this helps. Hope I haven't offended anyone.
Author:  Marty M. [ Sun Sep 02, 2007 2:38 am ]
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Somebody that has been in business for 10-20 years probably has a good shot of being there when you need replacement parts.

I was referring to commercial grade machines, not hobby machines, and magically picked those numbers(10-20) out of the air :-).
mm
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