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Messages - Perfo

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General Mach Discussion / Re: "Holding" vs "Running" torque
« on: July 24, 2008, 11:51:33 PM »
In the flavour of this thread is there also a rule of thumb for maximum RPM expected out of motor or even maximum RPM where torque is still 90% of the 70% if you know what I mean :)

I've got myself some fine 86BYG450B-011 from motion control products 4 phase 4 amp per phase 305 oz/in (2.16 Nm holding torque. I've only got two at the moment but need to find a third as they no longer do these in MCP but have got similar In my simplistic mind I thought I'd try the two I've got and if they work fine then get another but if it struggles on one axis then I'll get a bigger one for that axis.
To with them I've got three MSD542 Microstepping Driver (4.2A Peak)  from the same company.
I must admit though I'm not sure holding torque is directly related to driving torque.

okay cokay then that's how I'll set it up. I do like to know the inns and outs of things but will always opt for the proven tried and tested methods suggested by fellows such as yourself then fiddle and break them later once I know it's all working. :)

Thanks for the response. Playing with stuff is a natural pastime of mine so I'm sure I'll be playing with this as soon as I get my system up and running. An absorbent mat underneath the object may be good as well as the correct wavelength filter. The resultant of the scan goes in to some sort of matrix file. Can it then be turned back in to G code? Similarly with the hardware probing experiments which one is producing the best results?  The good thing for this facility is the price of small lasers and web cams have dropped fantastically over the last few years almost to the point where people give them away. A real good source of powerful lasers is the LED type used in disk players.  I’ve fiddled with them before and using the DVD burner types you can actually etch wood with it. Wearing all the necessary protective gear of course as they will burn out your retinas just as quick given a chance and are infra red so you can’t see them coming to get you.[/b][/u] They also come with a small lens already matched to the laser giving you a small but very accurate dot at a give focal length.

Your bridgeport seems a bit bigger than my 626/vmc which I'm glad about as my steppers are only rated at 305 Oz-in of holding torque (is this the same thing?) so they have a third of your stepper power.
No probs with the book thing whenever you feel like it when you have a minute is good enough for me. I'm still waiting for the base to be released from a fellows locker which I may get back next week. Then I've probably got another week on top of that to wait for my smoothstepper. At least when i get my Base back I can start machining the plates etc for mounting the steppers on.

hmmm Yep I wasn't counting on micro stepping I thought 800 steps per rev would be good enough as your 20Khz on 2000 steps is correct then div it all by 2.5 gives you 800 steps per rev at 8Khz. I think my calcs and yours are the same except I didn't factor on micro stepping. Does this seem likely?
This is where I come unstuck I'm quite at home with software or electronics etc or even mechanical systems that I've got a bit of experience with (which I haven't at all with a mach3 setup on a proper mill).
As concerns how many steps to use I simply thought what's my target accuracy. I guessed 0.01mm would be a good starting place but not sure if it's realistic. I then thought if 0.01mm is my target then the electronics must have at least this level of resolution so I guessed I'd need at least 100 steps per rev. With my motor and drive combo I think the minimum I can get is 400 steps per rev so I doubled it to 800 steps per rev thinking this gives me a resolution of 0.00125mm I then multiplied or divided this with my mechanical gearing to actually arrive at a final resolution figure which in my case as I have a 3mm pitch lead screw and a 3:1 gearing on the motor I end up with 0.00125 mm travel per step. I’ve got this sneaking feeling I am missing something fundamental here so please don’t give up me just yet. Are there any advantages of micro stepping except a smaller degree of rotation per step? And thus do I need more than 800 steps ?

G-Code, CAD, and CAM discussions / Re: Lathe Gcode
« on: July 23, 2008, 03:15:43 PM »

being a newbie I'm allowed to ask stupid questions (aren't I). What actually do you do with this function ? I can see you need a laser source and web cam  but can mach 3 do everything else ? do I plug the webcam in to the PC and set up a target area and tell Mach to go scanning ? I know I've over simplified but in general is this the idea? Could I also make a request to the moderators that there is a sticky post at the top of each section very very briefly explaining what that section is all about? Only a few lines but it will help the newbie tremendously in trying to find the right area to help solve their problems or read up on what they should be doing. In general though this forum is pretty splendid with a very broad knowledge base. Thanks to all who contribute especially to Art and the Team for still being as involved and as enthusiastic as ever.

Wow 50mm wide that’s a chunky belt. I suppose it is the main drive so has to be good for a few horses. Some motor bikes use timing belts as the drive and by eye these are probably only a bit larger than 50 mm and are good for I dunno 60 Hp.
I've found a company called HPC gears on the net and gave them a phone. You give them the ratios, shaft sizes and power of the motors etc and they'll work everything out for you. The fellow got me thinking though he asked what the shaft speed of the Motors was.  I did a quick calc back from 600 mm per minute and came up with 600 RPM as there is a ratio of 3:1 and the lead screw is 3 mm per rev. This started me thinking at 800 pulses per rev this is only 8000 Hz’s. Is this a normal frequency to run these motors at i.e. are there torque problems trying to run them any faster. At 800 steps per mm of travel I have a resolution of 0.00125 mm per step so plenty fine enough for my set up. Should they run faster? Or am I missing something fundamental here?
WantCNC what is the restriction to 600 mm per minute I’m guessing it’s the torque curve and even though 600mm is fine for me I still like to know these things.
Thanks for looking Hood.

I've had a look on the RS site to. They don't appear to be that overpriced the cheapest I could find was a company called HPC I'll have to give them a ring tomorrow as again whilst their site is a bit easier to navigate than most I'm still not sure what type of pulley and belt I need. WantCNC if you get a few minutes can you remember or have you got to hand which pulleys and belts you used in RS?

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