Step/ direction signals

[Mike Windsor]

I have a Prt control box and would like to experiment with some third party drivers and more voltage . I really want to stay with the shopbot software since it is second nature to me now . Ted Hall mentioned in the forum when the PRT first came out that the prt board supports drivers that use step/direction signals . I looked at the board and see the solder points labeled step dir for each axis , but there are too many choices . Should I use the points labeled #1 ? # 2 ,3,4, 0r 5 ---Or does it matter ? My hunch is to use Point #1 , but I thought that I'd ask here first . Also does anybody know what the maximum step rate would be with a PRT board running say a 1800 Mhz computer ? ---Would the step rate be higher if I used an Alpha board for the step signals instead ? Thanks Mike
411

[richards]

Mike,
I don't have a schmatic, but I would guess that 'Channel' refers to the various motors. For instance, channel 1 might be one x-axis motor, channel 2 might be the other x-axis motor and so on. So, if I'm guessing right, you would use channel 1 step and direction for one motor, channel 2 step and direction for another motor, etc.

[gerald_d]

see this blog (http://cncshare.blogspot.com/)

[dirk]

Mike is right. Channels 1 through 5 are X,Y,Z,A,B.
There is a place for a 16 pin ribbon connector to be soldered to the board. That would be the easiest place to pull the signals. To find it look directly under the white power connector located at the corner and right beside the jumper to adjust step rate. Simply solder in a connector and add a ribbon cable .

Dirk

[ted]

Hi Mike,

The info here is correct. The PRT board uses Step and Direction signalling, and these signals are available on the board. Your picture shows one location (the signals are on the topmost pins) but you can follow the traces back to the header pad that Dirk suggests, which may be a more convenient attachment location. The "Channels" are what we refer to as physical output channels. They are then software assigned in the [VI] command to any axis -- X,Y,Z,A,B. Usually, we set them up with X on Channel 1, etc.

That said, BE AWARE, that these are the TTL logic signals straight from the microcontroller. They can only sink a small amount of current, and can source even less. You can usually get them to directly work a drive like a Gecko, but it takes a little fussing and is not good practice. And, you aren't likely to get two drives to run on one channel (e.g. two X's on Channel 1). What you really want to do is to interpose some sort of buffer/driver IC that will insure adequate signaling to the drivers you are using. This is not expensive at all, but does take a little know how. The details will depend on nature of the signal that you want to end up with for your particular drivers.

So now, let me expand somewhat on this topic. While it is certainly possible to play with other drivers using the PRT board as a starting point, and it will be potentially informative, the communication speed and thus the ultimate step rates you will be able to achieve with the PRT board are limited. This means that even if your new drivers are capable of more resolution and speed, you will have to trade one for the other. (The step rate on this board, depending on computer and serial card, will probably top out between 4 to 6 kHz.) I'm guessing, this will probably not get you where you want to be.

This brings us to the PRTalpha controller. Straight out of the box, this controller is 4X faster. It will run even faster with a higher performance USB bridge (or hi-speed serial port), and we are probably not far from a new controller chip that is even faster. Yes, you do need a good, clean XP computer to optimize speed, but the ordinary standard XP box certainly provides the 4X higher speeds. This puts you where you want to be for both higher resolution stepping, and faster speeds. The PRTalpha board is also fitted with current source drivers for each Step and Direction channel. That means it is ready to directly hook to a driver [ground-common, positive-pulse signal; e.g. Gecko 212].

To ramble just a bit more: In retrospect, when we were developing the PRTalpha almost 3 years ago now, I don't think we fully appreciated what the upgrade interests of PRT owners was going to be. Frankly, we were so blown away with speed and performance of the alpha system that we just assumed if we could get the upgrade price to something at all reasonable, it would take care of everyone's needs. [And in retrospect, we were probably also a little too fixated on SPEED as opposed to resolution ...]. We are beginning to appreciate more fully that there was also room for more modest performance improvements to the PRT that might be less constly, and did not require replacing the whole drive system. A number of ShopBotters have been puttering with solutions of this type, lately. It has been quite instructive for us and stimulated some thought about how we could contribute constructively to the process.

The problem with just providing people with the PRTalpha board, is that about 2/3d of the components and complexity of this board are related to the safety-interlock and spindle-control features of the PRTalpha system. In fact, about $1500 of the PRTalpha pricing is tied up in the sealed industrial control box that includes full industrially compliant safety interlocks and spindle power controls (we're in the process of getting the system rated and certified at the moment). This stuff is not needed for someone who just wants to update their PRT to a new type of driver to get a little performance enhancement.

SO, what we can and will do, though, is to provide a reduced-component version of the PRTalpha board -- let's call it a PRTupdate-A board. This board will have the same controller and communications as the PRTalpha board, and will have the current drives and optical isolation of outputs. You'll connect to the board and run your tool using standard SB3 Control System software (PRTalpha version).

Providing such a board should make it easier for people who want to try out new drivers, but allow them to use their existing motors and not require any significant changes to the tool. For those who already own a PRT and thus have a software license, I'm thinking we can get the price of this board under $200. I'm hoping that for those who are interested in this type of project, we will have the PRTupdate-A board available by about June 15th. As well, I will shortly shortly post a "Developer/OEM" page in the Product section of the website that will describe in detail the modular logic of ShopBot Controls, Controller Cards, Interface Boards, and CNC Boards. This should make it easier for developers and tinkerers to pick out the chunks of ShopBot that they want to integrate into their systems.

-Ted

[Brady Watson]

Sweet!!!

So...this means that you can use an Alpha board with Gecko 212s (or any other neg(-) common Step&Dir drive) by just PLUGGING them in!!!

-Brady

[Mike Windsor]

Thanks Dirk for your insight about the header by the power plug . Ted Thanks for clearing up the step rate question . I think that I'll wait till the 15th and go the Alpha board route . I'm assuming that the inputs for the limit switches and Zero plate will still be enabled on the new board ?

[robtown]

I'm a bit slow here, maybe it's ADD again, but will this board offer greater resolution with existing PRT steppers? I have no use for more speed in my work, but better resolution would put a little spring in my step...

[watswood]

Thanks Ted. You can count me in.

[richards]

Resolution is mechanical, not electrical. IF you use Gecko G212 drivers, and IF you use the standard 2,000 steps per revolution, then your resolution with your current stepper motors will be the distance traveled by one revolution of the shaft divided by 2,000. IF you also have a gear box or reduction unit, you will have to multiply 2,000 by the gearbox ratio. For instance, a 3.6 ration gear box would require 2,000 x 3.6 steps, or 7,200 steps, to rotate the spur gear one revolution.

It's important to realize that a 'standard' stepper motor using 'full' steps moves 1.8-degrees per step, or 200 steps per revolution. There are many other 'modes' commonly used, such as half-steps (400 steps per revolution) and many variations of micro-stepping. So, saying that a Gecko driver will automatically give you ten times more resolution would be entirely false, unless your current stepper/driver used full-steps with 200 steps per revolution. If your current stepper driver uses fewer than 2,000 steps per revolution, you will get better resolution; HOWEVER, if your current stepper driver uses more than 2,000 steps per revolution, you would get worse resolution. I know that this can be confusing, particularly if you aren't sure of the configuration of your stepper motors and their drivers.


If you search Unit Values (use the AND term instead of the default OR term) you will find this post by Ted Hall, Dec. 14, 1999 6:53 a.m.

Quoting:

"Gearing-------------------------------------------
Unit Values for GearHead Motors:
Gear Type...18 tooth pinion...20 tooth pinion...22 tooth pinion
Std 3.6 Ratio....127.3240.....114.5916.....104.1742
HiRes 7.2 Ratio....254.6479.....229.1831.....208.3483

Unit Values for Thrust Box Motors (with Belt drives):
Large Pulley...18 tooth pinion..20 tooth pinion..22 tooth pinion
Yel 60t 3.33:1.........117.8926.........106.1033.........9 6.4575
Blk 72t 4:1...........141.4711..........127.3240.........1 15.7491
-------------------------------------------------

Here's how to derive the Unit Values FYI. The Unit Value for X & Y ([VU]) = #steps-per-unit(e.g.inch) * 0.25

To make your computation, the basic thing you need to know is that there are exactly 400 steps per revolution of the motor.

This all means, for example, that for a Unit Value of 120 there are 480 steps per inch ... if you are running in inches."

I know that this can all be a little confusing but, bottom line, it looks like the 'standard' steps per revolution used by Shopbot pre-alpha was 400. A Gecko gives you 2,000 steps per revolution, meaning that your resolution would be five times better. The down side to this is that your step pulse train would also have to be five times faster to give you the same speed as you're getting now. There is always a trade-off.

[robtown]

read it through two or three times and becomes clear as mud...

This is all very interesting. I'm hoping to get into robotics with my son this year, he needs a hobby REAL bad... and he loves to take things apart.

Anyway, what you are saying is that it is a function of the gearing coupled with the fact that the Gecko is capable of 2000 steps per revolution. As I type and think about this, it is becoming clear, I think.... Do I take from this that the PRT's steppers are maxed out? Or is it a limitation of the current control board?

[mikejohn]

Is it possible, in a "Dummy's Guide to upgrading the PRT", for someone to say in very simple terms, what can be expected in terms of maximum speed and improved resolution by going any of these upgrade routes?
Like Rob above, I find it confusing, but I am a dinosaur (as Gerald likes to point out
)

............Mike

[richards]

Rob,
There are a lot of things at play with stepper motors. The driver (Gecko) plays a big role here as does the voltage going to the motor and the method that the motor is connected to the driver (series, unipolor, parallel, etc.). Until recently, the Gecko G212 was not available, so other drivers, such as the one the Shopbot used for the PRT, were installed. What Shopbot used was an excellent compromise. That driver gave reliability, moderate cost, and reasonable speed.

As to your question of whether the PRT's stepper motors are maxed out, I don't think so. The motors that I have on my test bench pretty well cover the range of motors that Oriental Motor sells to Shopbot. I have motors ranging from the PH299-01 to the PK299-F4.5B. Every motor, with a Gecko drive performs at Alpha speeds and at Alpha torque. (To be completely fair, the PH299-01, which is the old round design, has a LOT of harmonics - meaning that it shakes and groans at certain speeds. The PK299-02AA and the PK299-F4.5B both run very smoothly at all speeds.)

I don't have a PRT control board, but others have said that the PRT control board is limited by the number of step pulses it can produce per second - speed. The alpha control board, which I have on my Alpha 120-60 can produce pulses fast enough to jog my Alpha at 30-inches per second. So, in my opinion, the PRTupdate-A board that Ted described, will be a significant product that will certainly enhance the PRT's speed and resolution. HOWEVER, from what I've read, the PRTupdate-A board will be made available to those who are willing to the Gecko thing themselves.

Mike,
You posted while I was composing. I would imagine that, since I believe this to be a do-it-yourself project, that you will need to spend the necessary time and money to test and verify that the parts will do what you expect them to do. If it's any comfort, my tests show that you will be pleased with the speed gain. The resolution gain will be completely dependent on your gearing/spur gears, etc.

[gerald_d]

Mike, don't hold your breath waiting for an electronic/software "magic bullet" to cure the chatters. We now have two machines, theoretically very different in terms of electronics and software, and there isn't a heck of a lot of difference between them.

I want to suggest again that a practical "shoot-out" be conducted on one PRT standard ShopBot table, using the same table frame, gantry, hold-downs, motors, rails (+grease), pinions, springs, spindle/router, cutting bits, cut files, raw material, etc.......

- Let SB staff run a demo with PC and software version of their choice,

- Then let anybody else who want to sell "upgrades" have a chance to plug their equipment into the same machine, on the same day, and run the same demo's.

My take on this is that an "upgrade" will produce spectacular results on a sick ShopBot ie., where the PC is poor, ramps are badly set, motherboard is faulty, etc., but that there will little improvement on a well running machine.

(I am basing my observations on the PRT driver board with the IMS chips - the larger group of PRT standards have Allegro chips)

[richards]

I think we're all tip-toeing around the fact that the "Gecko Solution" is a project for the do-it-yourselfers, much like turning the family sedan into a hot-rod, is a do-it-yourself project. GM, Ford, or the company of your choice, would never support hot-rod activities, although individual members of those companies might very well be hot-rod enthusiasts.

I DO NOT SPEAK FOR SHOPBOT. My opinions are just that; my opinions. I have nothing but respect for Ted Hall and those who work with him. In my opinion, the PRT and the PRT-Alpha are excellent machines that should satisfy anyone who carefully checked the specifications before buying a Shopbot. I've found the specs to be conservative. My Alpha gives better results than advertised.

That being said, I think that making a controller board available to the "hot-rod" enthusiasts among us is great. But, as Gerald has clearly pointed out and as Mike John has enumerated, there are many factors involved - most of which are beyond Shopbot's control. I certainly would not expect Shopbot to do our homework for us.

As someone who enjoys making stepper motors do more than they were expected to do, I am looking forward to the PRTupgrade-A board. However, I am also looking forward to spending many, many hours tuning a "hot-rod" system until it does what I expect it to do. It may cost hundreds or even thousands of dollars to get it to peak performance, but that is, by definition, what "hot-rodding" is all about.

If someone packages all of the components into a plug-and-play package, I would expect that package to be priced just as high as any other custom package, after all, as Shopbotters, we don't give away our CNC services, nor should we expect someone to customize our machines for us.

With that being said, if there is anyone who wants to email me at miker@xmission.com (mailto:miker@xmission.com) with questions about my tests with Gecko drives, stepper motors, power supplies, breakout boards, etc., I would be happy to respond. But, be aware that the teacher part of me will expect you to do your homework.

[dirk]

Hi all

[garyb]

This is an interesting turn of events from the May 9th posting of Mark John under "I want to share this with you". There now seems to be a mad scrable to catch up to the prt/pr upgrade box the "Ascension 1000" by Custom-CNC.
As most readers of the forum know Doug Strickland and myself have been testing this box which has been commericially available through Custom-cnc for some time.
The tests have now been completed on Doug's Pr and my Prt, results are being compiled and should be available within a few days at which time we will post a notice of how to obtain this report for those interested parties.
Due to the fact that this report is lengthy and still being written it will be supplied by requested email or a supplied download link.

[richards]

I hate to be the one to throw cold water on the Gecko conversion, since I'm surely one of the most vocal advocates promoting Gecko products, but has anyone taken the time to read Gerald's post today? If you haven't, please take the time to read it. There is a huge difference between what can be done at a test bench and what can be expected from a working machine.

I have the feeling, from reading a ton of emails today, that many of you are expecting the impossible. Stepper motors, stepper drivers, and controller boards are just one part of a CNC router. You might say that they are the very heart of the router, but still, they are only part of the router.

Some of you haven't considered that your router, not spindle, but router can't plow through oak at 8-ips. Some of you haven't considered that your Fein vacuum (just like the two that I use), isn't strong enough to hold cabinet panel sized parts when you're cutting with one pass. Some of you haven't stopped to think that when you're working out of a garage, like I am, that you're not going to have room to stack pieces cut from 50 or more sheets of material every day.

What I'm trying to say is that before you rip into a perfectly good machine, ask yourself if everything else in your 'system' would make the upgrade practical.

I've read and re-read some of Eric Lamoray's posts. If I recall correctly, one of his machines is an Alpha with a 5-hp spindle and a huge vacuum. He also has a large shop with helpers. He has carefully studied cutters and tested them until he knows what works and what doesn't work. In short, he has a system that he works within. He knows the limitations of his system. He knows what he can do and what he can't do. When I read his posts, I trust what he says.

Gerald D. has built a large machine based on his PRT, improving some of the weak points of the PRT; but, he's clearly stated that there is little difference between a well tuned PRT and a Gecko equipted CNC router. I respect Gerald and his ability to design mechanical things. He and I have exchanged many emails about Gecko drives over the past few months. When he writes something about Gecko drives and stepper motors, I read it very carefully. I trust him.

Ted Hall has built a series of excellent machines that don't need to be modified to be useful. It's very clear that he has carefully studied the Shopbot community and tried to address our needs by offering machines that are affordable and reliable. I trust him, those who work for and with him, and his products.

Last of all, I admire and trust Mariss, the man behind the Gecko products. He is truely brilliant. His drives are the best that I've ever used for driving common, ordinary stepper motors. As I've written before, if I had a machine that needed repair, I would most certainly look at a Gecko upgrade as being a perfectly reasonable solution; BUT, I would not cut up a perfectly good machine in the hope that the 'Gecko solution' was the one single magical cure for a problem that has many causes.

Even though I own an Alpha, much of the time I run the machine at 3-ips or even less. Many cuts are best made at those slower speeds. Having a machine that can cut three times faster than that is not always worthwhile. Don't misunderstand me, I wouldn't want a lesser machine, but I've learned somewhere along the way that plowing through material at the fastest possible speed isn't always the wisest thing to do.

[dirk]

Mike

I think Gerald’s observations are valid for his machine. The PRT came out with 1/8 step micro stepping with direct drive, and I believe this is what Gerald has. Moving from 1/8 to 1/10 stepping would not make that much difference. SB went away from direct drive to geared motors. I don’t know the exact reason for the switch but the PRTs with geared motors are no longer micro stepping. They are ½ and ¼ stepping. The Controller is incapable of putting out the required step rate with a geared motor. I feel that physical gearing is a lot better than a direct drive geared only electronically. By being able to get a high step rate and using a good driver one should get 3.6 times more resolution than Gerald’s machine with Geckos. This is because the standard reducer on PRTs is 3.6 to 1. Will this end chatter? If the cause is step resolution I think it will certainly help.

Dirk

[robtown]

I've always been a tinkerer, don't know squat about electronics, but a super fast learner. This interests me in that sort of way.

On the practical side, as I previously stated, I don't have any need for a faster machine, I get paid for quality not quantity. I recently cut some dimensional letters out of 1/2" Lexan (or eq), after futzing around a bit (and building a vacuum jig, first one for me), I got the straight cuts to turn out very smooth, no chatter, good quality edge comparable to what I've seen come off a KOMO Mach 510, the curves and angled cuts however were not so smooth.

This is an area I'd like to address with the afforementioned tinkering, and so far all indications are that this is the area were items addressed in this thread will have the greatest impact.

[stevem]

What, exactly, do you guys mean by smooth cuts? Cuts without any tool marks at all? Edges that require little sanding (assuming wood)?

[robtown]

Steve, I have no issues with edges on wood, my PRT does a fine job on plywoods, hardwoods, and MDF.

It's when I cut aluminum, acrylic, polycarbonate, etc... that I need better "resolution".

Here's what I think is going on. In .dxf files arcs and circles are broken down into short line segments, the higher the curve's "resolution" is the shorter each of those line segments becomes until you basically have a series points that as a whole constitute that curve or circle. So at lower "resolutions" the curve or circle is essentially a x number of line segments and more like the shape of an octogon or a *gon (insert arbitrary number for *).

This appears to translate over to "resolution" in terms of steps or microsteps. Each "step" constitutes a partial turn of the shaft and has a direct correlation to the distance the gantry moves. Thus when talking in terms of moving in curves or angles, the "resolution" of your resulting shape is affected by how many, or how few, steps it takes to move the gantry. So if my thinking is correct, then being able to achieve more steps per revolution, should result in smoother curves, just like using more line segments results in a smoother arc...

[bleeth]

I think Mike's Hot Rod analogy is a good one. Not being a tech-head and frankly having a bit of trouble dedicating the time to fully research all of the specific if/thens associated with the various upgrades I, for one, need the "How do I best improve my PRT in both speed and resolution without breaking the bank" question answered in fairly basic terms. Now, apparently, Ted has graciously developed and decided to offer an appropriate method for doing so economically. For this I am grateful as my inverstment in my PRT came verrrry shortly before the Alpha was announced and plowing that much more for the upgrade at that time was out of the question. As a result I have been watching many large shapely panels over the last couple of years seem to take forever to cut and have way more chatter then I like.
That being said, it is also clear from all of the "improve your shopbot" discussions on this forum that given either the Ascension system or the soon to be released PRT upgrade-A the accompanying upgrades to the frame, gantry, and car to handle the increased speed and torque are still required.
Although there is never a universal answer to the question of what is best, here is my two cents worth:

I am used to SB code and SB controller software and so would prefer to stay there and I would dearly love to improve the two basic weakneses of my PRT (speed and res). That means that Dick's and Ted's new board will probably work for me.

The designs for a "one piece" y car such as Geralds, and a beefed up gantry such as Steve's are a great help in making the decision for "taking the plunge". I'll be sitting with my welder explaining the need for "perfect squareness" soon.

It seems that this discussion, which has been going on for many threads and months is finally reaching some conclusions that result in a practical solution for the "user" of a bot, as opposed to a "bot-builder" and I would like to express my appreciation to all of you who have stubbornly pushed forth with and shared your ideas and results here. As a result, I look forward to soon having my PRT doing what I thought it would do when I bought it.

Dave

[dirk]

Rob
Chatter marks could be caused by a multitude of problems. The cause has been discussed and argued many times on this forum. If the chatter is a resolution issue think of silhouette bit map image. The vertical and horizontal lines are very straight. When you zoom in and look at the angled and curved lines you will see little blocks and not a smooth curved / angled line. The higher the resolution of the image the smaller the blocks are. The same is true on the machines. The more step instructions we can send for a distance moved, the smoother the transition between points will be.
Dirk

[robtown]

Exactly, I left out the fact that resolution and chatter become the sum of a number of factors.

Dirk your analogy is more along the lines of pixels and screen resolution, where the picture is made up of blocks, and smooth lines and arcs are portrayed via antialiasing, but your last sentence basically and consisely sums up what I was getting at. You just articulated it better... ;)

[dirk]

Hey Rob
I don't like to be misunderstood, and at times it takes me a while to post a response. When it’s in writing it’s hard to take it back. I posted before I read your next message.
Dirk

[richards]

Whew, the flow of emails has slowed somewhat from yesterday. Somehow a lot of you took my statement that the 2,000 step per revolution would give 5X the resolution of a 400 step per revolution motor and then read Ted's statement about the PRTupgrade board being 4X faster than the original PRT board and then jumped to the conclusion that you would get 5X the resolution at 4X the speed. That would require a 20X faster step rate! (Which is probably not going to happen.)

Those of you who actually have machines running Gecko drives (Dirk, Gerald, Alan, Gary, Doug and others) have all had high praise for some particular aspect that was improved by the modification - and please remember that sometimes that improvement was attributed to other software.

I would hate to think that I've convinced any of you that you will magically turn your Shopbot into a Komo (or whatever other machine that you consider to be the 'ultamate' CNC router) by spending $1,000 for a new controller board and Gecko drivers. I'm sure that you will get some improvement and perhaps a great deal of improvement - but certainly not 5X the resolution at 4X the speed.

Please - dream on, but be realistic.

[Mike Windsor]

One other option that this opens up is the use of the Gecko 320's and a servo conversion . Then the resolution would be dependant on the encoder resolution ---Anybody running a bot on servos ?

[dirk]

Mike
The 320 still relies on Step/ direction signals from the controller. The encoder is just sensing motor position and is giving feedback to the 320.
Dirk

[benchmark]

Hi Ted

Thanks for the update, is this new PRTupdate-A board purely for the Hot Rodder that whats to connect Gecko's etc or can I use this to update my PRT to an Alpha board with 8 inputs and 8 outputs, unlike the 4 and 4 on the old board.

I am more the happy with the speed of my PRT for the work that we produce, our main requirements is the ability to control more accessories such as air drills.

If this new board would suit our requirements could you please put one in your suitcase for the Eurocamp....LOL

Regards


Paul

[dirk]

Paul
I'm pretty sure you can get the additional inputs and outputs off the PRT board. It would require a little soldering, but there are empty pads you could connect to. Email me if you want to try.




dirk

[richards]

Just as Dirk said, brushed servo motors running from a G3xx board use the same step and direction signals that a stepper uses. There is absolutly no reason that you couldn't mix and match steppers and servos if you really wanted to be exotic.

Part of my Gecko test setup includes a G340 driver and an ID30004 servo motor with a 500 pulse encoder (which translates to 2,000 steps per revolution - I know funny numbers make life confusing). Although the motor is size 34, which means that it uses the same bolt holes as the stepper motors used on the Shopbot, it is ten inches long, weighs about 8 pounds and REQUIRES substantial gearing to be of any practical use.

Servos, in general, have much LESS torque than steppers, at least when comparing motors of similar size. Even the monster that I have only produces 1/3 the torque of the steppers that I use. Servos also run much faster than steppers. The lower torque and the faster speed make gearing necessary. When properly geared, they really work well. But, if you gear the motor down substantially, and have the encoder attached directly to the motor, then you have to have an extremely high pulse rate. After a while, it seems that changing one thing requires changes on everything else, kind of like a dog chasing its tail.

If I spend enough time fiddling with servos, I could probably come up with a design that had Alpha speeds with at least 3X the resolution of the Alpha, but would it make any practical difference in the cut? If anyone wants to pay for the experimentation, and has access to a CNC vertical mill and CNC lathe to make the parts, I would be willing to colaborate - but I really think that it would take a lot of money and a lot of testing and a lot of frustration to come up with something better than Ted offers right now.

[harold_weber]

I sure would like to see a VISUAL comparison of the cut smoothness when using the PRT control box to that which is obtained from this new Ascension box.

Can't this be done by simply unplugging the PRT control box from a given router table, and plugging in the Ascension box?

Lets see a side-by side comparison of circles of the same diameter (in the range of 5 to 9 inches) cut from the same hardwood board using the same router rpm, move speeds, and the same router bit. We can eliminate the effect of ramps by doing lead-ins and lead-outs to/from the part perimeter.

All of the above parameters should be reported along with the photos, including the exact make and model of the router spindle and router bit.

Especially of interest is a photo of the two pieces showing the cut quality at 4 locations around the circumference: 45, 135, 225, and 315 degrees. (On the clock face, thats 1:30, 4:30, 7:30, and 10:30.)

Any other rules we should specify to make this test more useful to folks?