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compfranon
27-03-2010, 11:06 PM
Well, i've spent a lot of time deliberating and pestering certain folk, so now it's time to get started.

I've decided on the following:

Main framework will be 8020 type extrusion
Belt drive for X & Y axes, and a ballscrew drive for the Z axis.
Nema 23 steppers, PM 752 drivers and an optoport BOB.
Home brew power supply
Canibalised hand router for spindle.

The assembly steps will be dependant on what materials I have managed to procure, and will take a wee while to complete.

I welcome comments and criticisms (constructive only), it's my first but I doubt my last build, there would appear to be a little niche market here in N.I. either that or nobody local wants to be friends :cry:

Be patient, it's a saga not a short story .....

compfranon
27-03-2010, 11:32 PM
Here is a pic of the build that I am basing my build on, it was the best example that I could find to meet my requirements.

Relatively straightforward construction (we'll see)
Material availability
adaptability
size
cost

HiltonSteve
28-03-2010, 12:30 PM
What size bed are you thinking of and how do you see the belt drive working on the x and y?

compfranon
28-03-2010, 12:40 PM
Bed size will be 34" x 24", this is the max size I can accommodate where it will be located.

X axis will have a stepper driven shaft running the width of the bed with a pulley at each end, a similar configuration will be at the other end of the bed using stub shafts perhaps. The two belts will be fixed to the lower section of the moving gantry.

Y axis will have the stepper and a couple of pulleys mounted on top of the gantry, belt will be attached in the area of the linear carriage.

These are my ideas at the moment, when I get the construction started then I will be able to appreciate the configuration better.

Ross77
28-03-2010, 02:26 PM
Good choice on the stepper drives. Ive got the 542's and their really good.

I take it thats not the actual drawing of your machine but just in case, Don't mount the main y beam like that cus it will move all over the place. Extend the side supports up and fix the beam top and bottom. if your using the plate and skate bearings then also extend the plate to the side support. that will make it much more rigid.

Theres quite a few other bits that could do with changing but I dont want to be to negative :tongue:

compfranon
28-03-2010, 07:14 PM
Good choice on the stepper drives. Ive got the 542's and their really good.

I take it thats not the actual drawing of your machine but just in case, Don't mount the main y beam like that cus it will move all over the place. Extend the side supports up and fix the beam top and bottom. if your using the plate and skate bearings then also extend the plate to the side support. that will make it much more rigid.

Theres quite a few other bits that could do with changing but I dont want to be to negative :tongue:

I spent the morning wiring up a test rig to see if I can get the stepper to turn, then the missus arrived home from work and we went out, so maybe later.

The drawing is a machine i'm modelling my build on, I plan on resting the Y axis gantry as per the drawing but using some plate material on the end face and down the side of the gantry support for strength, and yes I plan to extend the carriage plate across the full width. This decision is based on how I think I can physically secure the extrusions together.

I generally tend to over engineer things, so we'll see how this goes. I'm held on the main framework waiting on some more extrusion, i'm getting it buck shee, so willing to wait, well so far ....

Comment away about your ideas for change, all welcome, this is all new to me so I like to weigh up the options.

Ross77
28-03-2010, 11:22 PM
I spent the morning wiring up a test rig to see if I can get the stepper to turn


Been there:smile:, worked fine indoors as a trial but when i set it up on the machine nothing...... 1/2 hour of head scratching and I realised I hadnt done the driver test for mach to take over windows, as usual operator error....lol

Anyway back to your machine. Over engineering is fine but there are a lot of redundant parts in that design, before I stick my oar in I need to know a few more details

Are you using the skatebearing arrangement, what are you cutting, what is the power of your motors and what are the sizes of the 8020?

compfranon
28-03-2010, 11:33 PM
>1/2 hour of head scratching and I realised I hadnt done the driver test for mach to take over windows, as usual operator error - tell me more

yes i'm using the carriages with bearings etc
plan to cut acrylic, various woods, aluminium alloy if I can

Motors are from Zapp SY60STH88-3008BF wired bipolar parallel

8020 (or equiv) sizes for base frame tba
8020 (or equiv) for gantry is 90 x 90 sq section, supported on 2 x 45x45 sq sections

compfranon
28-03-2010, 11:40 PM
Managed to get doing a wee bit today.....

I wired up the unregulated power supply, outputs 58Vdc

I also wired up the optoboard, M752 driver and one of the steppers, unfortunately I couldn't get the motor to turn YET !!! made the relevant settings in Mach3, but no joy. Is it a null modem cable - think so, it's an old laplink cable. Tested using a laptop, the parallel port appeared as ECP port. Opto and driver boards show power leds fine, on power on the stepper "clamps"

Enjoy the pics.

Ross77
29-03-2010, 12:39 AM
Have you got the manual? page 2-5. Look for "driver test.exe" in the folder that you installed Mach to. save a short cut to desk top and run before you open mach3. Using a laptop could be your main problem tho. big no no. some people have got them to work but i understand its a nighmare. I've found with any new process or eqipment its best to start very basic and work up. so have you got a desktop PC that you can use to get it up and running?
That way you would know the drivers and motors worked and it was purely a windows thing.

I'll have a look at your design tommorow

Good luck

compfranon
29-03-2010, 12:50 AM
Have you got the manual? page 2-5. Look for "driver test.exe" in the folder that you installed Mach to. save a short cut to desk top and run before you open mach3. Using a laptop could be your main problem tho. big no no. some people have got them to work but i understand its a nighmare. I've found with any new process or eqipment its best to start very basic and work up. so have you got a desktop PC that you can use to get it up and running?
That way you would know the drivers and motors worked and it was purely a windows thing.

I'll have a look at your design tommorow

Good luck

i'll print out the manual, i dont generally rtfm

I foud out that laptops are not preferred, but I thought I would have got away with it for the purposes of a test. Desktop pc is now on my list.

Ross77
29-03-2010, 01:10 AM
IMHO you need to RTFM :rofl:

I'm pretty good at just using programs to find out how they work but not this one, You only have to have one tick box unchecked and you get didly squat........

compfranon
29-03-2010, 01:13 AM
IMHO you need to RTFM :rofl:

I'm pretty good at just using programs to find out how they work but not this one, You only have to have one tick box unchecked and you get didly squat........

Just wish I knew which box needed ticked to get my stepper moving :rolleyes:

Ross77
29-03-2010, 01:25 AM
Have you done the driver test ? ( trust me it wont work untill you have done that, at least mine dosnt) and configured the ports ect

I used PMINMO site, http://pminmo.com/mach3-setup that was enough to get the motor turning.

mel_earp
29-03-2010, 10:44 AM
Is it a null modem cable - think so, it's an old laplink cable.

I hope you have made some progress but thought that a couple of things might help. First off, I guess that your comment about "null modem" is a red herring, or at least I hope so. A null modem cable only ever refers to a serial comms cable. All this is very old hat now and you rarely see them. It was all about whether the transmit and receive lines were straight or twisted (one only of each) The vast majority of laplink cables were serial, so if it really is one of those then you have the wrong cable - but then you would have had to hammer it quite hard to get it to fit a breakout board!

Even genuine parallel cables can be insufficient. Some were produced for restricted use, typically old printers, and don't have all the conductors. For cnc use you need them all. It is worth checking the continuity of all the conductors in the cable.

On a more constructive note, this thread on the build your own CNC forums describes one guys attempts to overcome a similar issue and has helpful lists of his parallel port settings.
http://www.buildyourtools.com/forum/post/1049298

mel_earp
29-03-2010, 12:47 PM
And just in case it really is the less common parallel laplink cable (introduced later for speed) then this site might help http://www.indiacam.net/pinout/ It shows the differences on the cable wiring. If this is where you are, then it could still work for you, but you would have to treat all the BOB connections differently - nightmare.

compfranon
29-03-2010, 07:53 PM
Ok, state of play now is that I am currently installing XP on a desktop pc, then mach, do the configuration, run the driver test, try the "cable" I have . then !!!!! we'll just have to wait and see ...
tick
tock
tick
tock

OK, pc built, software installed, config entered, drivertest run, said successful, under control of mach3, exited drivertest
ran mach 3
tried to move the stepper - nowt

Reckon it is down to the cable, each end has a db9 and a db25, fits the parallel port on the pc and the optoboard (no hammer required lol) but I reckon it is a serial cable because I had to use a gender changer at one end.

ah well...... now to hoke out a cable.

tick
tock
tick
tock

Found a cable, wee bit short, but hey it works :cool:

1 stepper down 2 to go. That will be a while now, as i'm held for extrusion. But in the meantime i'll box up the power supply and control boards, fit some nice 4 pin plugs and sockets etc.

Happy camper tonight, another hurdle overcome, thanks for the helpful advice and info links guys.

mel_earp
29-03-2010, 11:53 PM
If the original cable has a DB9 at both ends (as well as DB25) then it is serial. It is a general purpose cable. Originally serial cables were DB25 at both ends for modem signalling, but for a pure data cable only three cores are absolutely necessary and the DB9 got introduced with data and some restricted signalling lines. For CNC to work you must have a 25 core cable with straight through connection on all pins and 25 pin connections at both ends.
OK 25 not strictly necessary as several are earths which can be common for some applications .

Ross77
30-03-2010, 01:33 AM
Glads it working, Now you have a benchmark can you get it working on the Laptop???

I bypassed all the cable issuses buy cutting the plug off one end, quick pin check and wired it direct to the driver (built in optos). not pretty or a long term solution but good for initial testing :naughty:

mel_earp
30-03-2010, 09:00 AM
can you get it working on the Laptop???
It has been well documented in lots of places that using a Laptop for CNC control is not a great idea. There is no reason why it shouldn't work superficially, but it is risky if you want consistent decent results [bet someone is successful though]. The main reason is that both the operating system (specifically Windows) and the BIOS of laptops have deeply rooted features for extending the battery life. You can, and should, turm off all the features that suspend or even slow the processor down after periods of inactivity or elapsed time, but there is still the nagging doubt that somewhere deep down in the software, interrupts and latency are being disturbed. The symptoms would be disruption of the real time nature of Mach with missed steps or false readings or worse still, crashes and lock ups.

The situation with EMC and Ubuntu is a little different as this installation has a real time add on to the operating system. This makes it better than the Windows situation but still does not eliminate whatever the manufacturer of the laptop chose for the BIOS.

compfranon
30-03-2010, 06:06 PM
Glads it working, Now you have a benchmark can you get it working on the Laptop???

I bypassed all the cable issuses buy cutting the plug off one end, quick pin check and wired it direct to the driver (built in optos). not pretty or a long term solution but good for initial testing :naughty:

I had no intention of using the laptop for "production", it was merely for testing and satisfying my impatience while I was waiting for the desktop. Understand 100% mel, as you say laptops are designed to work but save power when idle, and in order to do so tend to cause issues.

Ok, I would need a sowester and hat to reach my shed tonight due to the adverse (perhaps not unusual) weather conditions, so it's a night of for the build. Perhaps i'll read the mach manual instead :eek: