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  #1  
Old Sat 06 December 2008, 14:40
Cutter99
Just call me: Richard
 
On
Canada
Shopbot VS Mach 3

Can anyone give me an informed, objective opinion on the pros and cons?

Also please tell me which you would go with...

Thanks,

Cutter99
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  #2  
Old Sat 06 December 2008, 17:37
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Both programs will do almost anything that you need a CNC router to do. I have used Shopbot's SB3 program since July 2004 and Mach 3 (test bench only) for more than three years.

First, I doubt that you would want to hand program either SB3 or Mach3. I use PartWizard and Vectric to transform my AutoCAD LT DXF drawings into tool paths. PartWizard, furnished by Shopbot, only produces tool paths for SB3. Vectric produces tool paths for a number of different machines, including Shopbot and Mach3.

G-Code is the industry standard, but in my opinion, is not as extensible as SB3; however, SB3 lacks a few commands that might be necessary in your work. For instance, in Mach3, I can choose any two axes when I want to cut an arc. Shopbot limits you to using only the X and Y axes. That means that you'll have to either write your own code to do a simple arc using the Y and Z axes or the X and Z axes (or buy some full feature tool pathing program).

What I really like about Shopbot SB3 is its ease of use. It is more like a very limited traditional programming language (similar to BASIC). It gives you GOTOs, GOSUBS, labels, variables, the ability to call a program from another program, PAUSES, prompts, eight inputs and eight outputs.

That comes at a cost. You have to buy at least a V201 card from Shopbot. The V201 card is bundled with the software. I don't know the price, since Ted Hall gave me a couple of cards to play with about a year ago. If you're comfortable building a circuit board to interface to that card, you can do almost anything imaginable. On the other hand, if you mostly need a plug-and-play controller, be prepared to spend upwards of $6,000 for an Alpha model Shopbot controller (including motors).

Mach3 is also extensible, but you'll need to have some programming experience to add features. It is also limited to only a few I/O lines (unless you use more than one break-out-board). I have the Gecko G100 and Gecko G101/G102 modules that were supposed to be the ultimate in pulse generators, but Gecko announced about a year ago that they were discontinuing the G100 due to lack of demand and unsatisfactory integration with Mach3. Those modules had plenty of I/O and they worked very well will very few glitches after the G100 plug-in was released by Mach3, but they're obsolete. I haven't purchased a SmoothStepper module, so I don't know whether it's ready for use yet or not.

Personally, I'm satisfied with SB3. The main reason may simply be one of familiarity. It does what I need it to do. But, to be completely fair, if I had to use Mach3 exclusively, I would not be disappointed. It might be, that at my age, I've grown tired to the extensive learning curve that new software (any new software) requires.
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  #3  
Old Sat 06 December 2008, 18:59
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
For most people, the fact whether one is using SB, Mach or EMC, etc. should be "invisible". They are actually machine languages . . . . . most times only receiving a coded file and making the motors move. That coded file being a product of your CAM program.

Having moved from SB to Mach over 2 years ago (SB has obviously been upgraded since), the things we miss are:
- Hitting "pause/stop" on SB was nearly instantaneous, Mach takes a while before it stops
- the trajectory planning in SB seemed to be better. SB could figure that a lot of short lines actually made a long line and keep a consistent speed going.

The things we do not miss are:
- SB was obviously written for the inch environment and we found that running it in millimeters caused too many problems.
- Some CAM programs would not generate SB-code. Everybody else used G-code.
- SB could only run on SB hardware. There were too many reports of that hardware being glitchy, particularly in the area of communication breakdowns on the USB line. (Because of the inch/millimeter issue we were obliged to use an older version, before the USB port was used)
- SB stops running every 100 000 lines or so, to load another batch of data, leaving a cutter burn mark.
- SB could only interpolate circles in the XY plane. Vertical circles needed lots of straight segments.
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  #4  
Old Sun 07 December 2008, 06:10
isladelobos
Just call me: Ros
 
Canary Islands
Spain
Send a message via MSN to isladelobos Send a message via Yahoo to isladelobos
who axis supports each program? sb and mach.

Is possible use this in a 6 axis table or more?

Thanks.
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  #5  
Old Sat 13 December 2008, 20:48
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Another difference between Mach and SB . . . .

In Mach we set the acceleration during motor tuning and then forget about it. In SB, they don't have the concept of "acceleration" - they advocate the changing of "ramps" for each job. link

Ros, sorry, I did not understand your question??
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  #6  
Old Sat 13 December 2008, 22:33
jhiggins7
Just call me: John #26
 
Hebron, Ohio
United States of America
Gerald and Ros,

I think Ros' question is:

How many axes does each Program ( Mach3 and ShopBot) support?

I believe the answer for Mach3 is 6 axes, X,Y,Z,A,B and C.
Mach3 can also control the spindle (On, Off, Speed). Of course to control 6 axes, you must have the right Break-Out-Board (BOB) configuration.

I don't know anything about the ShopBot software other than what I've read on this Forum.

Regards,
John
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  #7  
Old Sat 13 December 2008, 23:27
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Shopbot software only runs on shopbot hardware. So, the axes question is related to the capability of the V201 control card from ShopBot - the last time I looked, there wasn't much published about the V201.
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  #8  
Old Sun 14 December 2008, 05:42
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
The V201 board has provision for 5-axes, X, Y, Z, A, B. (Shopbot's SB3 software only handles 5-axes.)

The V201 board has a male DB37 connector that handles all of the stepper driver signals as well as all INPUT signals. The +5V input voltage to the board and the OUTPUT signals are handled by a separate 16-pin IDE-type connector (two rows of eight-pins each, 0.10" spacing).

The V201 connects to the computer via a USB connector.

With the V201 board, the X-axis only has one step/direction signal. The is no provision for a "slave" axis. So, the X-axis slave motor would either be driven directly from the V201 in parallel with the X-axis master motor, or by buffering the signals through a TTL gate (7404 to invert one set of signals, or 74245 (or similar) to simply amplify the signals. Remember that the SLAVE motor runs backwards when compared to the MASTER motor, but you can easily reverse the direction of a motor by interchanging ONE set of connections between the stepper driver and the motor, i.e., Black/Yellow to the A-coil on the SLAVE motor would be wired Yellow/Black.)

The step/direction signals are the correct polarity to work directly with the Gecko G203v stepper driver.

The OUTPUT signals are reverse polarity (compared to most TTL signals). When OFF, the OUTPUT sends a 0V signal. When ON, the OUTPUT sends a +5V signal. In other words, the OUTPUT port SOURCES the signal. Most TTL devices SINK the signal where ON = 0v and OFF = +5v. (I know that is confusing to many people, but most early TTL devices could interface to 10 other devices when they SINK current, but they could only interface to 1 other device when they SOURCE current. Because of that, 0v became the accept voltage level for ON and +5v became the accepted voltage level for OFF.)

Last edited by Richards; Sun 14 December 2008 at 05:55..
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  #9  
Old Mon 15 December 2008, 04:42
Cutter99
Just call me: Richard
 
On
Canada
What about the problems with cuts and gaggies etc? I have read some posts that show Shopbot to have lesser quality cutting than Mach 3...

Are these reports fixed or still better with Mach 3?

C99
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  #10  
Old Mon 15 December 2008, 05:16
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
In terms of cut quality, there should be no difference between Mach and and SB running on their V201 controller. Both will be doing the same level of micro-stepping of the motors. Mach has always done 1/10th micro-stepping, older SB was something like 1/2 or 1/4 stepping.
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  #11  
Old Thu 18 December 2008, 08:48
Cutter99
Just call me: Richard
 
On
Canada
"- SB could only interpolate circles in the XY plane. Vertical circles needed lots of straight segments."

Is this true and if so is it fixed or still a problem? How does it affect the quality?


C99

Last edited by Cutter99; Thu 18 December 2008 at 08:51..
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  #12  
Old Thu 18 December 2008, 09:06
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
As far as I know, it is still true. It is not a problem if you divide the vertical arc into enough straight segments. A good CAM program will take care of this for you.
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  #13  
Old Fri 16 January 2009, 09:34
Cutter99
Just call me: Richard
 
On
Canada
If I upgrade to the new Shopbot Stepper Controller Box, will I be able to run Mach and or Quantum on it as well?

Thanks,

C99
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  #14  
Old Fri 16 January 2009, 09:43
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
All the ShopBot controller boxes that I know of will only run their software.
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  #15  
Old Fri 16 January 2009, 10:08
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
The latest several versions of the Shopbot SB3 software include a G-code converter so that native G-code files can be fun. When I tried it a few months ago, many of the G-code instructions had not been totally defined (especially arcs). The latest word is that SB3 handles all G-code files produced by Vectric (V-carve). I have not tried generating and running a G-code file with my copy of V-Carve Pro.
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  #16  
Old Fri 16 January 2009, 10:27
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Yes, the boxes will run the linked limited G-Code but it will be under SB's software. They will not run Mach, EMC or Mach's Quantum like our generic boxes.
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  #17  
Old Fri 16 January 2009, 22:07
Cutter99
Just call me: Richard
 
On
Canada
Quantum sounds like the perfect thing to smooth out my old machine.

Any suggestions, info, anything about the shopbot vs Mach Quantum / mach 3?

Should I get the SB controller then upgrade to a mach controller? What are the downsides of going outside of SB?


Thanks,

C99
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  #18  
Old Fri 16 January 2009, 22:34
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Richard C99, let's start at the beginning . . . . . what ShopBot do you have? What are the model numbers on the motors? What does the controller look like?

ShopBot changed their configurations and options quite often. Some of them can be improved a lot with a new controller, some can't.
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  #19  
Old Fri 16 January 2009, 23:01
Cutter99
Just call me: Richard
 
On
Canada
Thanks for all the help.

I built an older Shopbot with the older control box many years ago,
sold it and just got it back. It has a cut area of about 5.5' x 12'. I am a graphics guy with 20+ years experience in sign mfg.

Here are the motors:
Vextor PK296A1A-SG 3.6 / 5 degree Step / 2 Phase DC 1.5A 2.2Ohms
The Z motor is a PK268-02A 2A 2.25 Ohms
I was told they could be powered to 2.3A

I have an older Shopbot but it would benefit from the new controller I am told. My Z really sucks, plus I have 2 of them. It is the old ball screw type. I was hoping there was some way to fix it up without too much rework?

Actually everything sucks but the heavy duty table I built!
The rails are the old steel strut rails with BWC bearings but not the track.
But it did work, except for the jaggies, and the Z would loose it's height and it was slow etc etc...

I have heard Quantum might help out with the smoothing and racking?

Any advice weather I should go Shopbot, or Quantum?
Is their any quality differences? In functioning? In cutting? In expandability?

I have read many many threads, but they go back so far that it is hard to tell what is current information.

Then what about the CNC Brain? Bob Campbell is another very interesting option. What boards are the newest and the best technology for the money?

Does Shopbot have a limit of 5 drivers? Is there any limit to the drivers with Mach? (Anyone ever use 2 motors on one Z?)

Thanks for the interest and help. Anything you can think of that might help please share. There is another guy who emailed me in the same position as well.

Thanks,

Richard

Last edited by Cutter99; Fri 16 January 2009 at 23:11..
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  #20  
Old Sat 17 January 2009, 00:05
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Are all your ShopBot components from before the year 2000? Is it rack & pinion drive or cable drive?
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  #21  
Old Sat 17 January 2009, 04:35
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
The PK296A1A motors have high inductance when wired series. The Gecko G203v controller was not designed for motors with an inductance rating of more than 20mH; however, if you wired the motors half-coil, they would work very well with the G203v.

The PK268-02AA motors are excellent LITTLE motors. Just yesterday, I mounted two of those motors onto Oriental PAL2P motor mounts for an upcoming project. All together, I have fourteen of them that I've stripped out of old process control computers that I once built; however, they are SMALL motors. The PK29x size (34 frame size) motors are much better suited for use with a CNC router.

Although reusing old parts is sometimes possible, the electronics used in older model Shopbots are not nearly as good as the electronics that Gerald uses on his machines. The PK296A2A-SG7.2 motors that several MechMate builders have selected are excellent. The Gecko stepper controllers are all excellent, with my preference being the G203v. The PMDX-122 breakout board is excellent. A home-built toroidal power supply is perfectly adequate and the the reports of the AnTek supplied power supply seems to show that AnTek would be an excellent choice.

The non-industrial enclosures of earlier Shopbots also lack many of the features that Gerald has included in the controllers that he (and others) have built for the MechMate.

In other words, sometimes you need to just junk the old car and buy a new one. Chances are that by the time you tweaked the old electronics to give you the performance that you would want, that you would have spent more money and time upgrading the old than you would have to spend installing new.
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  #22  
Old Sat 17 January 2009, 06:15
Cutter99
Just call me: Richard
 
On
Canada
Excellent information. Thank you. I also read Mike's post over here about SB motors... http://www.talkshopbot.com/forum/mes...tml?1225829441

I am on as budget so my time vs new machine won't come into play. I need to get this machine running and producing before I get a new machine. I will have to scrape the barrel to come up with the $1500 for the new controller. Also because of the Canadian dollar I need to add almost 25% to any of the pricing for the exchange rate.

I also was wanting to do this in stages. The new controller will give me much more power and resolution than I have now. My current controller only gives me 1/4 or 1/2 micro-stepping, but the new one will give me 1/10 micro-stepping, greatly increasing the resolution. The power supply also goes from 24V to 68V.

SB will charge me $1474-$250 for my old box. This will also come with some help. That part is attractive... But Bob Campbell will charge me much the same for a better box probably.

I think once I get moving though I won't need SB so much.

I feel my next weakness is the ball screw Z, motors, then the rails.

What about the smooth stepper? Quantum and smoothing? The CNC Brain?

So from an upgrade point of view, what would you do?

I think just a new controller for now would smarten the machine up enough for me to produce product. Currently it has too many jaggies, is slow, racks, and sometimes the Z depth goes out, and is underpowered. So what controller? What circuits are the most current and best bang for the buck?

SB mentioned I would need a capacitor changed...so the box will have to be able to upgrade with the motors...

I could always sell the old SB controller and motors as well? Or get the new controller and sell the old at a later date?

Or???


RB

Last edited by Cutter99; Sat 17 January 2009 at 06:41..
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  #23  
Old Sat 17 January 2009, 07:03
servant74
Just call me: Jack
 
Nashville (Tennessee)
United States of America
ShopBot is a nice option, and their newer models are more 'industrial' that the older ones. The software upgrades over time have gotten away from many of the jaggies problems. They come with some great software (partworks, etc). They also sell a new Z axis in case you want to bite a BIG bullet, but it looks fantastic (I saw it in October in Austin, they gave one away at a conference). I have not found what dialect of G-Code that shopbot works with, but I know they say it does.

EMC2 and Mach are both great g-code interpreters and can work with lots of different controllers. But SB being proprietary, I don't think they can run on it easily (spelled: without lots of software hacking they don't stand a ghost of a chance to run on the SB controller hardware ... starting at their gecko's on, everything should be OK).

IMHO, if you have a shopbot and want to keep resale value, stay with shopbot components. Otherwise, you can just set aside the shopbot controller you have and build a new one for use with Mach or EMC2. If you like the shopbot software, like partworks, go to Vectric and see if you can buy an 'upgrade' to their current version from Vectric or to Aspire (With Aspire and Cut3D it appears you can do everything all the other Vectric software will do and in a more unified fashion, but it will cost some real $$, more than my play money budget.)

If I was buying a low to middle end CNC for a shop and had business where this machine is needed quickly, I would probably go ShopBot just to have the 'professional hand holding' available. If I had a longer time horizon, MechMate is the way, but you loose the opportunity of the possible business in the interim. Never an easy choice.

I know others will have different opinions, but your decision is the right one for you.
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  #24  
Old Sat 17 January 2009, 07:41
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Repeated question: Are all your ShopBot components from before the year 2000? Is it rack & pinion drive or cable drive?
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  #25  
Old Sat 17 January 2009, 08:13
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Jack has made some very valid points. The cost of upgrading vs the cost of lost business because the machine can't do the work is always a hard decision.

The first requirement is to thoroughly check your machine. Every mechanical machine needs maintenance. Go through the machine and replace or repair everything that is worn or out of adjustment. Add bracing, if possible, to stiffen the gantry. (80/20 aluminum is my favorite "erector set" material for one-of-a-kind projects. It is amazing how easy it is to modify an existing machine with some of their products. It's a little pricey, but all that is required is a chop saw and a few hand tools to tighten the screws. Steel is probably much better than 80/20 aluminum, but I'm lazy and I'm mechanically handicapped, so I go for the "easy" over the "best" when I'm prototyping.) Remember that adding electronics won't correct maintenance problems.

Once the machine is working properly, with every axis moving smoothly without snagging or binding, then it's time to look at the electrical.

Normally, I don't recommend things that I haven't tested, or at least seen; however, I have enough confidence in Gecko to recommend the G540 to those on a tight budget. That one device takes the place of four G203v drivers and a break-out-board (although at lower voltage and at lower current). The PK296A2A-SG7.2 motors pull 3A and require about 35VDC (32 X SQRT(1.5) = 39 Volts maximum), so those motors fall within the parameters of the G540.

A G540 costs $300. The PK296A2A-SG7.2 motors cost $257 each. An 11A AnTek PS-4N35 costs $94. Add in the price of a license for Mach 3 and you've got the basic electrical parts needed. Granted, you'll need to add switches, fuses, sensors, etc., but chances are, you don't have most of those parts on your Shopbot, so do yourself a favor and just build a cheap MDF or particle board case, add a fuse and a On/Off switch and begin cutting. After you've started cutting, use some of your profits to buy the other "elegant" parts and pieces as funds permit.

Every machine has its limitations. There are many things that I don't like about my Shopbot PRT-Alpha (too flexible, too much chatter, too hard to load from the side), but I've learned to work around the problem areas. When the machine finally breaks, and if I'm still able to do hard labor, I'll replace it with a MechMate; but, the old saying about a bird in the hand vs two in the bush is a good saying to remember. If you've already got something, make it work until you can get what you really want.

Edit: Gerald, you posted while I was typing. You've made a good point. The old cable-drive machine is probably not worth messing with, unless your needs closely match it's capabilities.
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  #26  
Old Sat 17 January 2009, 09:47
Cutter99
Just call me: Richard
 
On
Canada
Thanks again for the great info.

Yes my machine is rack and pinion. Maybe one of the first, because they flew up twice at their expense to work on it, back in 1996-98 approx. But it has the old style BWC bearings but no track. The bearings ride on angles on the lengths of steel strut.

I also lost a very large contract back then because of the jaggies, and Shopbot did not get rid of them. I kept trying everything they said but the client finally gave up on my quality. I now know it was because the 1/2 micro step then to the 1/10 micro step now. Other problems and bugs that I was suffering from I see now from the forums were Shopbot Tools bugs, but I was told other things.

All I need to do now is replace the controller.

That controller should allow for a wide range of upgrade options, as I don't know what the path will be yet.

Motors: Keep the ones I have now, but I must have the ability to upgrade to really big motors later.

I don't know the advantages / disadvantages to different controllers, and driver software, and code etc. I think that with Shopbot I won't have the quality or the flexability I would get with a Mach system.

As far as the Shopbot Z, in my opinion, it is not strong enough or substantially engineered for me to part with $1600 Canadian plus $500 more for a new motor x 2 for the 2nd Z. They don't have the "machinists" feel or rigidity to them I suspect. There are also posts about it flexing and chattering and how one should learn to live with it. Especially the 12" slide. I could be wrong here, but I bet the Mechmate Z is stronger. For the money they are asking would I not be better with a K2 or other professionally engineered Z slide?

I think I can get my ball screw Z (I have 2 of them) to work better just with the extra power and resolution from the new controller. Next I would resquare them and weld the bolted strut together. I could also put a new, bigger motor on them. Finally, replace them with a proper Z slide. I have been thinking about 2 motors for the Z. If one looses a step the other might not? Plus twice the power...

RB

Last edited by Cutter99; Sat 17 January 2009 at 10:04..
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  #27  
Old Sat 17 January 2009, 11:06
Cutter99
Just call me: Richard
 
On
Canada
What steppers do good machines like Gerber or AXYZ Automation use?

How do you know how heavy the entire gantry can be before the motors can't handle the weight?

RB
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  #28  
Old Sat 17 January 2009, 12:36
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Richard, is this what your ShopBot looks like?:


I have no experience of that machine other than the stories I have read about it. Apparently the screw on the Z was prone to getting dirty and binding up - a new control box is not going to improve that. A bigger motor on the screw will allow it to get dirtier before it binds. Twin motors could make it worse because they might fight each other and cause each other to loose steps. So, if you keep the screw, the only improvement will come from a bigger motor. (A new controller might get more power out of your current motors, but I don't know enough about what the old controller is doing now)

The gantry is a flimsy structure and obviously prone to racking out of square. But the flimsiness also causes jaggies when the whole thing starts rattling. Quantum supposedly makes an improvement with its reduced jerk on take-off. But Quantum is un-supported experimental software - it is going nowhere fast.

Your X & Y motors are good, IF they can be wired half-coil - some ShopBot motors had only 4 wires coming out the case (black, green, red, blue) and that is a problem. Check if you have yellow and white wires accessible.

If you are not in the mood to build your own control box (under about $1000), then you will have to buy. Your cut quality with all boxes (DIY, Campbell, or ShopBot) will be very much the same and a heck of a lot better than you have now. Quantum might give an even better quality, but I don't have experience of it. DIY and Campbell boxes give you a chance to try Quantum, an SB box won't give you that chance.
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  #29  
Old Sat 17 January 2009, 21:26
Cutter99
Just call me: Richard
 
On
Canada
Yes that is the machine...

I have beefed it up so it will get me by with the just the controller for now.

RB
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  #30  
Old Sun 18 January 2009, 12:36
Cutter99
Just call me: Richard
 
On
Canada
and some motors probably...

RB
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