Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: engraversoflight on April 16, 2010, 08:58:10 PM
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Ok, well maybe this wouldn't be a major conversion for some, but this is pushing my limits and knowledge. I have used EZ Router CNCs for about 5 years now which are 3 axis machines using Gecko drives and of course Mach3. Now I have a Shop Sabre that has WinCNC. I was under the impression that I could just use Mach3 on this machine, but after looking into the control box, it is not setup at all like my EZ Routers. There is no breakout board. I need to convert my Shop Sabre over to Mach3, so I'm thinking I need to buy a new breakout board, but I don't know what to buy. I will also need to add a Z zero plate, and currently the router must be turned on manually (my EZ Routers turn on automatically, and I want this feature on my Shop Sabre). Will I need to buy new Geckos? Oh man, for as much as I've learned, I have a long way to go!
What do I need to do? Please help!
Bill Sines
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Does the Shop Sabre connect to the computer via Parallel Port or does the computer have a PCI/ISA card that the cable comes from?
Hood
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Hi Bill,
The pinouts for the 25 way and 37 way connectors are more or less identified in the WinCNC manuals which you can download from here http://www.wincnc.net/webfiles/CNC%20Windows/Manuals/
Once you have identified the step and direction pins it should not be too difficult to connect a breakout board for the LPT parallel cable to the appropriate places to be able to use Mach with the existing controllers.
You could, of course strip out all the existing electronics and fit Gecko's etc but I don't think this would really be necessary, also sounds like a lot of extra work.
Tweakie.
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Attached are some pics of the control box. I'll reveal some of my naivete:
I'm not really sure what a breakout board does versus what the drives do. As I look at the box, it looks like it has drives but no breakout board. So I'm trying to figure out what kind of breakout board I need to get off ebay. Some of them are $25 and some are $125. Which one?!
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Attached are some pics of the control box. I'll reveal some of my naivete:
I'm not really sure what a breakout board does versus what the drives do. As I look at the box, it looks like it has drives but no breakout board. So I'm trying to figure out what kind of breakout board I need to get off ebay. Some of them are $25 and some are $125. Which one?!
The drives actually move the motors. The BOB or breakout board "breaks out" the signals from the pport in such a way as to be easily accesable. Along the way a good breakout board will either buffer or optically isolate the signals. Buffering makes them more"stable" for lack of a better term and optioisolation completely disconnects the pport power from the drive and any other down stream equipment power. This prevent high voltage from getting from the equipment back into the computer. It is possible to use a plain jane BOB that does nothing other than breakout the wires but since you are a noob I would consider something better. Others can give recommendations.
From the pics it looks to be pretty straight forward to add a BOB and connect to Mach3. If you have or can get a wiring diagram it would be much easier to do.
Those drives in the pics look like gecko's without the covers or at the very least gecko knock offs. IMHO.
Mike
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Thanks...where could I obtain a wiring diagram, short of trying to copy the actual wiring in one of my other machines?!
Bill
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Hi Bill,
Personally I would go for the fully buffered BOB but there are still many to choose from.
Just one tip - Do not electrically connect the metal part of the 25 way connector on the new BOB to the frame of your control box (like the existing 37 way connector is fitted), it will be connected to earth at your PC end and connecting it at the control box will create an earth loop which could lead to other problems.
Tweakie
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Thanks...where could I obtain a wiring diagram, short of trying to copy the actual wiring in one of my other machines?!
Bill
Glad to help.
If it where my machine I would go to the gecko web site and find the page on how to identify there drives without the covers.
If I could find a definite match I would use the gecko wiring diagram to wire this thing up. Of course if it blows something up I have more drives on hand and I like to learn.
Your mileage may vary.
I guess a call to wincnc might get them to tell you the wiring inside the box .
Mike
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Ok guys,
I got my new shop sabre up and running today...i was able to use my ez router toolpaths on it. All I had to do was remove some of the header that had multiple gcode commands and i was in business. Thing is, it runs the same exact toolpath in twice as much time. So what takes me 10 mins to run on my ez router takes 20 minutes to run on the shop sabre. Here's what I think it is, if I'm thinking right:
Since the shop sabre does not have a breakout board, it's getting all its signals in succession, one at a time (which also results in less fluid movements), whereas the ez router is getting all its signals more quickly and almost simultaneously, resulting in a faster run with smoother motion. This is why I need a BOB. Am I guessing this right???
I really need to cut this time in half to make $$$. ;)
Bill
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A breakout is not going to make anything better unless you are missing steps due to a low voltage parallel port and you would soon know if that was the case as your parts would not be correct.
It is very likely your acceleration settings that are the problem, too slow an acceleration may not allow the axis to get up to the commanded speed for the move. You may or may not be able to increase the acceleration, it all depends how close you are to the limits of the hardware at this point in time.
Another thing is you can not really compare the motion of two machines unless they have similar specs, do both machines you are comparing have the same type of motors? same type of drives? similar axis weight/size?
Hood
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Reading your post again I am wondering if you are also running in Exact Stop mode, have a look in the code and see if there is a G61, if there is you will be running Exact Stop. If there is remove it and replace with G64, if there isnt still put the G64 in the code, this will make sure the code runs in Constant Velocity and will make things faster and smoother if previously it was running Exact Stop. It may introduce corner rounding issues depending on the machines setup but that is a bridge to be crossed at a later stage if you have issues.
Hood
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Thanks Hood I will try it tomorrow at work. I'm assuming I'll just put G64 on one line at the top of the code and I'll see how that goes. The ez routers have gear racks and ride on angle iron (probably more of a hobby set up but I'm pleased with them)..the shop sabre rides on hiwin guides and has ball screw set up...is a ball screw setup traditionally a slower machine?
Maybe an idea would be to change motors???
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Wait and see how you get on with the G64, also try tuning the motors a bit to see how good you can get it. Often you will get better performance from a machine by dropping the rapids and increasing the acceleration. Lots of people think that the fast rapids are the best thing but if its at the expense of acceleration then you will end up with a slower machine, acceleration in my opinion is king :)
Hood
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Also, one machine being rack & pinion and the other one being screws ,the steps per unit are most likely drastically different.
The rack setups axis velocity:RPM ratio can be dramatically different than the screw machine. Depends on the gearing/reductions of course.
The stepper torque might be inadequate at the higher speed required for the screw axis's.
R&P machines/mechanisms are of the fastest .. but there are compromises.
Help me if I'm wrong.
Thanks,
Russ
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No luck with G64. Also, I'm playing with acceleration and rapids, so I'll see how it goes.
I did do some cutout stuff with it today. Cutout movement is good, but Vee engraving movement is slow and not as smooth as I would like.
All in all a good machine...at least it keeps some orders off my other machines. ;D
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What I would tend to do is work out what kind of speeds you would normally cut at and set that or slightly more as your Velocity in Motor Tuning. Then gradually increase the accell until you start to miss steps then back off a bit. You can then try and increase the Velocity until you start missing steps again then back off, that way you will have your max accel and the max Velocity for that accel setting.
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Hood