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Message |
    
Gerald_D
Registered
Username: Gerald_d
Post Number: 97
Registered: 11-2005
| | Posted on Tuesday, May 30, 2006 - 08:58 pm: | 
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Bob Campbell of www.campbelldesigns.com has been working on a ShopBot project for a long time. Below are some extracts of his posts to the public Mach user group. I don't know what the status of his project is today. However, I believe that the Ascension is largely based on his work......
March 31, 2004:
By Bob Campbell:
I have offered some assistance to a couple of Shopbot plasma users. I would like to work with them and convert them to Mach2 and our breakout boards plus our THC boards. It would be a great match.
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Feb 19, 2005
By Bob Campbell:
Has anybody connected a stepper motor with a pinion gear direct to a rack without a belt or gear box?
I am in the process of helping a customer convert a ShopBot CNC router to Mach2 and Gecko drives.
We have got the X and Y axis converted, but we are only getting a little over 500 steps per inch.
I would like to get some feedback. We may opt to add a gear box.
The original equipment uses a 1 amp motor and a 3:1 gearbox. The motor was run in 1/4 step and the customer was never satisfied with the quality of cut and speed.
One other problem is that the original motor has some type of spline on the end of the stepper motor shaft. That connect to the inside of the gearbox.
Any help or ideas would be appreciated.
By Art Fenerty:
I know of several systems hooked by stepper/rack mount. Makes it a bit coarse in resolution and some higher levels of rounding errors on corners at too low a res. I'd try the gearbox if you can...
(Dont know what the heck to do about the spline...)
By Bob Campbell:
Thanks very much. That was the answer that I was looking for.
For your information, there are several thousand ShopBot users thinking about upgrading to Mach2 and Gecko drives. Jim and I along with one of our customers are working on a good solution. We have Mach2 installed on the low cost PC that I mentioned before. I have built a nice control box about the size of a PC case with our breakout board on the top shelf along with a solid-state relay to control power once mach2 has control. The power supply is on the bottom shelf. I have a heat sink with the Gecko drives mounted below the top shelf. This arrangement keeps all the wires as short as possible.
By Art Fenerty:
Excellent. Let me know if I can help with any special features you may need
By Bob Campbell:
Thanks, there may be some features like special screens. The main thing that we are working on is better resolution. The customers ShopBot uses small 1 amp motors, a 3:1 gearbox and I believe 1/4 step drives. The quality of cut is poor. If his machine is rigid enough we can solve all the other problems with Mach2 and Gecko drives.
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Mar 13, 2005
By Bob Campbell:
I just did an experiment on a ShopBot machine where I am trying to get a better quality of cut. I connected a 640 oz/in stepper motor direct. The speed was very fast, but the resolution was only about 500 pulses per inch.
We are now in the process of building a belt reduction gear box to increase the resolution.
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May 25, 2005
By Bob Campbell:
Jim Cullins and I have had some recent experience on upgrading a ShopBot CNC router to Mach2.
We started with one of my 640 oz/in stepper motors. We put a pinion gear on the shaft of the stepper motor. The speed was terrific, but the resolution was not good for Mach2. We were getting about 500 pulses per inch. Mach2 wanted a lot more.
The next step was to build three 3.2:1 belt reduction drives.
This time Mach2 was happy with about 1600 pulses per inch. The ShopBot table performed very well. The comment from the customer was that it ran very smoothly and quiet.
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July 18, 2005
By Bob Campbell:
I just built a control box for a ShopBot CNC router upgrade.
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Sep 8, 2005:
By Bob Campbell:
I will need it for our ShopBot Mach3 upgrade. My intensions are to bundle the wizards along with Mach3 and our new control box.
I want to offer a complete package.
By Gerald_D:
Bob, don't overestimate the importance of the ShopBot "wizards". Most of us don't even seem to know where or what they are. (You can download all the SB stuff to try and find it all yourself).
A snag for your endeavour may be that there is a large crowd of SB'ers who have only used the bundled PartWizard software for their design & toolpathing. I don't think that PartsWizard will output G-code and thus these guys cannot consider a Mach/Gecko setup.
By Bob Campbell:
Thanks for the insight. They just don't know what they are missing.
One of the main things that we are working on is a better quality of cut. I have seen some of the parts machined that were designed in ArtCam. The poor quality of cut made them worthless.
We will be putting together the router wizards and anything that we can bundle together to help the ShopBot community.
I will look at the Part Wizard. I know one person who may have written some of it. There is always a way to make a conversion to G code.
Working on the ShopBot project has been very beneficial. I will now have a complete control box with Gecko 202 drives for sale that will help other Mach3 builders.
By Gerald_D
Bob, don't bargain on many SB'ers wanting to "upgrade" because of poor quality of cut. My guess is that more than 80 - 90 % of SB'ers are quite happy with the cut quality. We are basically happy, and so are our customers who come back for repeat orders. The reason that I am looking at Gecko/Mach is that I'm building a second router. If I wanted to spend some money on "upgrading" a ShopBot's cut quality, I would look at its mechanical structure (mainly gantry) first.
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Sep 14, 2005:
By Bob Campbell:
Just a quick note of thanks. Jim Cullins and I upgraded a second ShopBot CNC
router.
This time we used the original 1 amp motors and their gear box. Before we did the conversion to Mach2 and Gecko G202 drives we watched the machine run. It was very noisy and seem to jerk a lot.
After the conversion we could hardly here the machine run. It was very quiet and very smooth. We were getting rapids of over 400 IPM.
Thanks to Mach2 the customer is very pleased with the conversion of both
machines.
Next will be the conversion to Mach3.
I am in the process of having a very nice control box built. I have most of the design done. I am working with a local sheet metal shop. The control box will have the power supply, a couple of our boards, Gecko 202 drives . All the connector holes will be pre-punched and ready for assembly.
The ShopBot machines could still use work on making them more rigid. There is an opportunity for someone to come up with a mechanical modification kit.
By Chris:
I wonder if you could answer a question for me. You mention that you are using the 1 amp motors and I am assuming you are also using the original spur gear/rack drive system.
Can you tell me how much cutting force you have on that machine? By cutting force, I mean if you move the X or Y axis against something solid, how many pounds of force (using a bathroom scale or similar) do you get?
Also, do you have the rest of the specs for that motor?
By Bob Campbell:
We have not done any testing on cutting force.
The ShopBot is a good machine for many of their customers.
I do not have the specs on the 1 amp motors.
Yes we used the original 1 amp motors and the original spur gear/rack drive system. Which includes the gearbox.
Basically all we did was to use Mach2 and I built a new control box which included Gecko G202 drives.
We just unplugged the ShopBot control box and then connected the stepper motor wires to the box that I built. I was able to find the matching connectors.
My box was driven by Mach2.
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Nov 24, 2005:
By Bob Campbell:
When we release our ShopBot upgrade package around the first of the year it will only be with Mach3.
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Feb 23, 2006
By Bob Campbell:
To start, look at what ShopBot has done www.shopbottools.com. Then look at ez-router www.ez-router.com . Both use Bishop Wisecarver V wheels and rack and pinion.
For the rack and pinion you will need to look at a belt reduction drive . About six months ago I built a set of drives for a Shopbot customer. Recently I helped another customer build a set of belt reduction drives. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 309
Registered: 11-2005
| | Posted on Monday, October 16, 2006 - 06:20 pm: |
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There has been some news at Campbell Designs. Have another look at the website and this page.
It is a practical option to use the "Campbell Box" for the MechMate. The dust-proofing, for industrial CNC router application, will be a bit problematic since it "breathes" shop air. If the box does get dusty inside, the front & back covers need to come off for cleaning. This need for access from both sides will prevent permanent wall-mounting. |
Robert Masson
Registered
Username: Robert_m
Post Number: 1
Registered: 04-2007
| | Posted on Thursday, April 26, 2007 - 04:58 am: |
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Hi Gerald, All !
As you know Gerald I’m getting back in the saddle after “swimming around” for too long with other DIY design.
In order to prep my self to make my own MechMate, I’m too been on the reading spree to find out all updates on component breakdown to make my list of components to buy / needed.
Wile on this controller subject, I’m wondering why is it I’ve yet to read some suggestion ( if any ?) on using the Campbell Breakout Boards. I did read Gerald recommending, with some reserve on some dust concern, Campbell complete controller box on this thread.
But how about your opinion on Campbell Breakout Board VS PMDX your using / recommending ?
How about CNC4PC breakout boards wile were at it ??
Thanks to clarify this for me and surly for some others too !!??
Later,
Robert |
Mike Richards
Registered
Username: Richards
Post Number: 109
Registered: 05-2006
| | Posted on Thursday, April 26, 2007 - 05:25 am: |
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Robert,
Make sure that you check with Bob Campbell to see if his new design is on the market, the one that works with the Gecko G203. As you know, the G203 uses a common GROUND connection rather than a common 5VDC connection. That requires that the signals also be inverted. On the CNCZone forum, some users were not able to use his breakout board with the G203. Bob announced that he had a new board in the works.
The PMDX-122 works with the G202, G203 and G320 drivers that I have. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1295
Registered: 11-2005
| | Posted on Thursday, April 26, 2007 - 12:42 pm: |
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Robert, I know that Geckodrives only recommend:
- PMDX
- Campbell
- CNC4PC
and I am sure they are all good. But they are not all the same - there are differences on power supply, "charge pumps", onboard relays, indicators, options, etc., etc. I recommend the PMDX simply because I know it, the designer is helpful, and I can give a little support on it.
The Campbell boards were designed by Jim Cullins who has now teamed up with Tom Caudle and they call themselves www.candcnc.com. I am sure that Geckodrives will add a fourth recommendation to their list soon. |
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70. Control Systems