MechMate CNC Router Forum

Go Back   MechMate CNC Router Forum > Personal Build Histories > Construction started, but not cutting yet
Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Reply
 
Thread Tools
  #1  
Old Mon 17 September 2007, 20:30
stefanv
Just call me: stefan
 
Port-au-Prince
Haiti
Has all parts to make motors turn, also limit switches - Port-au-Prince, Haiti

Hi all!

My name is Stefan, I live in Haiti in the Caribbean where I moved in 1983 from Belgium. I graduated there as an industrial engineer electronics. Though electronics has always been a hobby of mine, it was never my main occupation. But I love to play around and design electronic boards. Iíve got the shop and the tools. All this got me going on CNC. So far I build a smaller, cheap, cnc table using one of Kleinbauers (http://www.crankorgan.com/) designs. Fun, but not a lot of power. So I started to work towards building a Mechmate.

First and foremost; thanks Gerald! Your plans are fantastic and the documentation of your build has proven inspiring to many. I hope to be honored with one of your serials numbers in few months.

In Haiti we can get nothing regarding CNC. Everything I need comes from the US. Import of goods is difficult. So my build is slow as I bring in some parts from time to time combining shipments with my factoryís goods. At this time I do have all the parts to build the controller and make the motors spin. I didnít get Vextaís yet, but I have some KL34H280-45-4A from Kelling (620 oz 4V 4.5Amp). Once I have the Mechmate up and proven, Iíll upgrade to Vextas. Anyway, in the next few weeks I hope to finish the controller. Main parts are;
- 700VA 54V 14Amp Torroidal power supply
- Bob Campbell Break out board rev 1.8
- Bob Campbell parallel relay board
- 4 Geckos G202

So far this introduction. I wanted to keep myself quiet and one day surprise you with an almost finish Mechmate. Hey, Gerald explained everything so much into great detail, that I was sure there were no intelligent questions left to ask. Providing you search the site, everything you need to know is there, well documented.

But no, I did find a question. Iíll get to that in the next post, I donít want to start with a bad reputations of my posts being too long

Feels great to be part of this!

Stefan
Reply With Quote
  #2  
Old Mon 17 September 2007, 20:32
stefanv
Just call me: stefan
 
Port-au-Prince
Haiti
So hereís my question. The X-axis is driven by 2 Geckos doing exactly the opposite of each other, mirrored in Mach 3. Why give up the extra axis connection on the break out board? If ever we wanted to add a CNC spindle or a double z-axis, there would be no place on the board to run these.
I asked Bob Campbell if I can try to hook up the 2 geckos that steer the x-axis to the same output on his board. He says it should work with his revision 1.8 board. This way, all we would have to do is reverse 2 wires (1 phase) of one of the x-axis steppers and it would mirror the other one in direction, at the same speed. Just what we need.
Is there any reason I should not try to do this?

Your comments are highly appreciated.

Stefan
Reply With Quote
  #3  
Old Mon 17 September 2007, 22:59
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Welcome Stefan!

Are you French or Flemish? My other language (Afrikaans) is close to Flemish.

Sure, it will work to drive 2 Gecko's from one "channel" of a breakout board, if that bob supplier says it is okay. I have seen it discussed a few times and there are some bobs that will work and some that won't. It also depends on which Gecko you are using. Apparently it is quite easy with the G203 but not so easy with the G201 and G202.

The only negative is that you will not be able to use the Mach feature for squaring the gantry. That is where you can have a "home" switch at each end of the gantry and Mach will drive the two motors separately to contact the switches together. We have never used this feature and I have never heard of anybody else using it - but, it is in the Mach documentation.
Reply With Quote
  #4  
Old Tue 18 September 2007, 02:33
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Stefan,

Welcome aboard. With your electronics knowledge, it sounds like you will be able to make some valuable contributions to this site. Good luck with your build.
Reply With Quote
  #5  
Old Tue 18 September 2007, 06:09
stefanv
Just call me: stefan
 
Port-au-Prince
Haiti
Thanks Gerald and Doug,

Yes my native language is Flemish, my wife is Dutch. When spoken slowly, I understand Afrikaans pretty much, but I propose to stick to English on the forum

Squaring out ?... Hmm Looks like a challenge not worth the effort but interesting to pursue. I could build a small board to be put in the control box that, at a push of a button, steers the x-steppers to where they both hit home. This board would hold some buffers to strengthen the signal from the BOB to make sure it could handle hooking up 2 geckos without interference between, and give you that squaring option.

Interesting that nobody really uses the squaring option, must mean that we lose remarkable few steps here. Or is it done using wrenches and screwdrivers now?

Probably easier straight out of Mach 3, but if ever I needed to free up an axis on my BOB, worth a try, and as I said, I like the “adventurous” route. (I’m already thinking of an independent zero-plate-adjustment-board)

Stefan
Reply With Quote
  #6  
Old Tue 18 September 2007, 06:35
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
We do lose remarkably few steps. Actually, we never lose steps unless we do something stupid - like telling the cutter to go through the clamp that holds the wood down. How do we recover from such a shock . . . . ?

Switch the motors off (the e-stop has already done that). Move the gantry all the way to one end and hold it against the the adjustable screws described on drawing 10 10 200 A, and switch the motors on again so that they "lock". Those screws are the reference and thay are set according to this thread.
Reply With Quote
  #7  
Old Tue 18 September 2007, 06:42
Marc Shlaes
Just call me: Marc
 
Cleveland, OH
United States of America
Send a message via Skype™ to Marc Shlaes
Anyone?

How easy/hard is it to move the gantry by hand if one selects geared motors?
Reply With Quote
  #8  
Old Tue 18 September 2007, 06:57
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I have a single 3.6 ratio motor/gearbox with 24 tooth (metric) pinion and that moves without too much trouble. The 7.2 ratio geared motor with 36 tooth (metric) pinion should still be movable. Realise that we don't try and move it a long distance - it is only for the last 10mm [3/8"] at the stop. The rest is moved either under keyboard control, or by unhooking the motor springs and disengaging the pinions from the racks.
Reply With Quote
  #9  
Old Tue 18 September 2007, 07:18
stefanv
Just call me: stefan
 
Port-au-Prince
Haiti
Moving them by hand, what an invention! I’m sure the $100K CNCs never thought of that Looks like it’s really not worth the effort to create a “square out” board.

I will try to hook up 2 geckos together and cross one phase to see how that works, ( when I get my Mechmate to that point that is,...)
Reply With Quote
  #10  
Old Tue 18 September 2007, 07:39
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
There are a lot of drivers that do not like to be back-driven while switched off - but the Geckos are happy with it as long as you don't go too crazy. In fact, you will find that the Gecko absorbed enough energy to switch itself ON and then you can't move it further by hand. You get slip - stick - slip - stick if you try and move it fairly fast over say 100mm [4"]
Reply With Quote
  #11  
Old Wed 03 October 2007, 06:16
driller
Just call me:
 
If you use one channel to driver two steppers, it is assumed that each stepper is exactly the same. that each gear is exactly the same and each rack is exactly the same.

if you reverse two of the wires on one motor, it will spin in reverse. so the wiring is very simple.

As for the homing of the unit, with the power off, you can move one side of the axis by hand. use dial indicators ? to make sure it is perfect.

you could put in stops and drive against them until the motors missed steps. that would work and not hurt anything.

A side note here . . . topic on coarseness of pitch moved to separate thread

Dave
Reply With Quote
  #12  
Old Sun 03 February 2008, 07:54
stefanv
Just call me: stefan
 
Port-au-Prince
Haiti
Limit switches

Hey there,

There has been so much talk going on about limit switches these last days, I started looking for what's out there. Expensive stuff.
So I came accross a deal on ebay, 4 switches from Siemens. These sell on line for $71.00 each. I got 4 including shipping for that price, new.
There are still 4 left,... just thought I'd let you know.

http://cgi.ebay.com/ws/eBayISAPI.dll...m=270172721655

I downloaded the spec sheet, 0.05mm (0.002") accuracy, if that's the least accurate part on my Mechmate I'll be a happy man! I'll figure out a way to mount them when I get there

Stefan.
Reply With Quote
  #13  
Old Sun 03 February 2008, 11:47
cobra427mnsi
Just call me: Paul
 
Leamington, Ontario
Canada
Stefan

Those limit switches on EBay, it says 500V 10Amps. Will that work on a 110/220 residential electricity system as we have here in US and Canada? Obviously, I know little about electronics.
I would like to buy these switches if they will work.

Paul
Reply With Quote
  #14  
Old Sun 03 February 2008, 13:16
stefanv
Just call me: stefan
 
Port-au-Prince
Haiti
Paul,

Yes, these will work. What we need is only a few milliamps at 12 Volt to steer the breakout board. If it weren't for the fact that we dealing with a heavy, big machine here, we could easily use one of the small microswitches that you find inside a printer and so,...
However, these here are made to be limit switches, so they have a very well defined stable point where they click on or off, as said, within 0.05mm, much better.
The only question is where exactly to mount them as they are 56mm wide. However, I'm sure Gerald will grant us the freedom to be creative.

Stefan
Reply With Quote
  #15  
Old Sun 03 February 2008, 13:29
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
That switch's contacts may actually be too "heavy" for the milliamps needed by the BOB.
Reply With Quote
  #16  
Old Sun 03 February 2008, 14:21
stefanv
Just call me: stefan
 
Port-au-Prince
Haiti
Well, and I quote the spec sheet;

Contact reliability
The movable switch contacts are double moving contacts. This increases the
contact reliability even when the switch has to be operated with low voltages and currents, e. g. DC 5 V/1 mA.

I'm just posting this to make myself feel better
Reply With Quote
  #17  
Old Sun 03 February 2008, 15:24
cobra427mnsi
Just call me: Paul
 
Leamington, Ontario
Canada
Stefan
Go to JR Hatcher's personal pages( 2nd one down on the list). On the last page, he has pics of similar switches mounted on all of the axis. They probably don't have the same electronic specs but they are quite large.

Paul
Reply With Quote
  #18  
Old Sun 03 February 2008, 20:12
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Stefan, that spec is good!
Reply With Quote
  #19  
Old Tue 05 February 2008, 09:54
stefanv
Just call me: stefan
 
Port-au-Prince
Haiti
4th axis

Is there a place to post threads about 4th axis?

The forum got me thinking again about using a fifth Gecko to steer a 4th axis. My idea was to be able to clamp a piece of wood on a horizontal rotary table and position it to bring specific sides up. Then these sides can be worked one by one to make a corbel or so. A challenge in G-code, but as they say in the commercial, "you got to have a dream and a plan,...." (I think itís just different files for each side and moving the rotary table in between, pasting it all into one long G-code file. This could become another thread.)

Anyway, will there be any time to start planning the inclusion of such a 4th axis rotary table into the base table of the Mechmate?
Should we have a "60." under Structure & Mechanics for the 4th axis ?

Anyone else thinking this way? Or has done it already?
I'm building my control box with 5 Geckos, gota keep the dream alive!

Stefan
Reply With Quote
  #20  
Old Tue 05 February 2008, 10:47
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
That type of 4th rotary axis is called an "indexer". You can search this forum for the word.

This thread gives a start:
http://www.mechmate.com/forums/showthread.php?t=314
Reply With Quote
Reply

Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 03:33.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.