CNC Retrofit Plate burner Questions ( Airco Servograph )

[Rebar Grove]

I am brand new to the site, and I know I will get some good answers here.

...CNC RETROFIT....

I have an Airco servo graph plate burner 5 x 12 feet (Pictures attached). My unit has an electric eye, you can draw a picture and the eye will follow it. I have a gas torch and a plasma torch mounted on it. The width has a rack and pinion, and the length has a metal bar and a tension wheel runs against that.

I would guess that the Cross Assembly made of the square and rectangle tubing weighs around 200 pounds.

I don't plan on cutting real close tolerances, mainly art and some fabrication pieces. I would still like to keep the electric eye for some applications.

If I add a rack and pinion to the length will that be fine?
I see some use screws, slides, ball, belts, etc.

What kind of motor should I use?
A servo or stepper motor?
Controls?

Thanks..

[Torchhead]

I did a retro fit on a similar table over a year ago. The motors were actually tiny servos with gearbox reduction and top cutting speed was about 20 IPM. That works fine for flame cutting but is WAY to slow for palsma. Average plasma speeds are in the range of 80 to 180 IPM for 1/4 down to 10ga. on their table they did not want to cut plasma so the slow speeds were not the problem.

The machine you have is just not designed to have the speed or accuracy for plasma cutting. Keeping the tracing eye presents an even bigger challenge since it is part of the servo system. The eye generates an error signal if it deviates either side of the line and that corrects the tracking. Feeds an error amp that feeds a servo amp and runs the motors.

I bid the job for $4000 and lost my shirt. They too wanted to keep the "eye" and I spent most of my time trying to tie the two systems together. It was all custom work.

I would not recommend the exercise unless you are looking for a new hobby.

TOM CAUDLE
www.CandCNC.com

[millman52]

On the brighter side you have a lot of what you need to build a decent gantry style Full CNC machine. It will only use 1/2 the floor space.

Take a week of evenings & read the build or project logs on plasma & also router tables here on the zone. Most of your questions will already be answered somewhere here. If you have more feel free to ask.

[tinman13]

I have recently finished a refit of a Koiki 1200 optical tracer, almost identical to your machine. I wanted to keep the optical tracer for those impossible to cad draw templates! The problem is that it is such a pain to go back to the OLD way that I will spend more time getting the drawing right than it is worth, just so I can use the cnc instead of the tracer!

I set up my machine with a complete independent servo drive system, it's just a matter of engaging which ever drive you want, cnc or optical.

Tom is correct in that these tables aren't perfect for cnc plasma, mine get's a little shaky over 100 ipm. I don't consider this too much of a problem as I rarely cut under 10 ga. and then suffer the added cleanup from cutting too slow.

It's not perfect but in my case I am very pleased with the conversion. I do a lot of flame cutting also and have been pleased with the added accuracy and ease of use over the optical system, although it comes with a steep learning curve!

All things considered it was one of the best moves I have made and I don't regret it a bit!

Good luck, Steve

[Torchhead]

After I spent all of the time and effort of the conversion I did, the customer had me do the first 3 conversions of paper templates they had into a DXF file then they learned how to do it themselves, and they have never used the "eye" again. It just sit's out there on the arm as wasted space. They could have had all the tracing area space freed up if they had realized that they would never use the eye again. It's like buying your first car with automatic transmittion but wanting to keep the old manual stick shift and clutch for security(:-). For some people the conversion and challenge is the fun part. For me it's more about what you can do with the equipment (make STUFF!) after it's converted.

Then there is the whole issue of THC with plasma that needs to be addressed if more than occasional use is required.

I set their larger drawings up taped to a wall with photo lights and took higher resolution pictures, being careful to make sure the camera was square in both plains to the wall. I traced the bitmaps into vectors and made outside measurements and made the vector drawing the right size (1:1) in the drawing software.

A lot of them were simple brackets and by just measuring and drawing we could get what we wanted.

Parts used to come in on blueprints but I told them to ask for the CAD file and now we just use it and strip out all of the dimensioning and other layers and build the vector file. Then it is into SHeetCAM to build the toolpath and out to the table via a network connection. Just that alone saved them time.

TOM CAUDLE
www.CandCNC.com

[arelewis]

I had a heath shape cutter table, looked similar to yours. I researched and finally went with torchmate, using steppers with a dyna AHC. started with 4x8 rebuilt now have full 5x10 with plasma and oxy cut from 16ga up to 2". best investment so far.

[linatrol god]

That is an HL90 tracing head you have on that machine. Extremely reliable and decently accurate. A larger servo amp can easily be attached to that and still use the tracing eye. The speeds of that particular unit can be increased to 120 inches per minute and a cnc can be installed quite easily.
If you have any questions please feel free to ask, I work for the company that makes the HL90 and I have personally worked on more than 5000 of them!!! Hard to beleive they kept me that long...LOL

[Rebar Grove]

I would love to get some more info from you, and get this going. I am wondering what kind of software you use fot it all. Can you tell me how well it pierces.

neilmrogers@yahoo.com

Thanks

[linatrol god]

In order to use any software you need to have a CNC installed. The HL90 will also need a CNC interface installed in it. It is a plug and play interface. It will also need encoders in order to operate with the CNC, these are not cheap. There are 2 types, ones that bolt directly to the motor and a type that will run on the rail. I prefer the ones that bolt directly to the motor. Koike uses both.
I would be beneficial to change to rack and pinion, the friction drive is okay but not as good as R&P.
The software you need depends on what you will be doing. I am not familiar with the packages mentioned on this site. The package we sell is quite powerful and expensive. You may prefer one of the lower priced ones mentioned on this site.
The type of CNC that connects to that is called Picopath, or the Koike version is called D11, they are the same thing.
Where are you located?
I have some of these things available.

[Mike@Torchmate]

You might be looking for a retrofit kit from one of the vendors here on this board. One that includes all the electronics you will need to get your table up and running. You'll most likely have to fabricate custom motor mounts and a rack and pinion setup, but it's probably going to be alot better then trying to upgrade your current motor/driver system to CNC control.

As tinman stated a dual drive type system might be something you'd like to consider so that you can keep the use of your shape eye.

[linatrol god]

to upgrade this with a CNC is quite easy. I have done dozens myself. The HL90 is designed to connect to a Picopath. Its just a matter of spending the money. A new upgrade package will cost around 10k, that includes the Picopath, encoders and cables. Total time is around 2 hours, as long as the user knows where he wants to mount the CNC and has ordered the correct length of cables. Most the time is spent bolting the encoders to the motors. New motor mounts are totally unecessary because the correct encoders have the same bolt mounting pattern as the motors.
My company does sell this as a kit, we also offer to do it in house so it is a simple plug and play for the end user.

[Torchhead]

I submit that you could build your own separate stepper or servo based Plasma/oxy table WITH rack & pinion drives, Motors, Digital Torch Height Control, Control Software (MACH) and have a real CNC solution for less than just the electronics of the 10K retrofit suggested. If you want to keep the "eye" table then it will work like it always has. With a CNC based plasma you can take advantage of automatic lead-ins, automatic pierce cycle, preset feedrates, and cut parameters by type of material and tip. The Digital THC will give you consistant cuts and extend the life of consummables. After you get used to cutting using a computer and CNC you will throw rocks at the "eye"


You can buy ALL of the electronics and control software, including motors, cables, etc in a stepper version for about 1/4 of the 10K target leaving thousands for mechanical components.

If you want the performance of servo control then the package will cost you about $800.00 more....still a lot of room left to source the rack and pinion and other mechanical components.

You can use a wide range of CAD and CAM solutions to generate the cut files from simple brackets to complex decorative signage. Even there you can put together a very capable package for less than $300.00.

tomCAUDLE
www.CandCNC.com
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