Author Topic: New CNC Design Stage  (Read 1474 times)

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Offline kolias

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New CNC Design Stage
« on: November 02, 2015, 06:45:56 PM »
I started designing my new hobby CNC which will be made with 3/8” - 1/2" aluminum plate, cutting area about 24”x 26” and most likely 3 motors (one for each axis) with the Gecko G540.

Reading on this forum I noticed some folks are using UC300-USB or the Warp9td controllers. At this stage I can’t decide if I want to spend the extra $$$ or stick with the G540. Perhaps there is an advantage to go with USB but I don’t see it right now. Is it woth it?

I would also like this time to use proximity switches instead of limit switches mostly to learn about them. I don’t know if they serve the same purpose as the limit switches but reading on the web there are different types and I don’t know which ones to choose. Perhaps someone can give me more info?

Lastly I can’t decide yet what kind table top to use. I was thinking to go with aluminum T-Slots but I see most users cover it with a spoilboard to protect it. Any other ideas?
Nicolas

Offline bfgstew

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Re: New CNC Design Stage
« Reply #1 on: November 02, 2015, 07:15:59 PM »
Hi Kolias

I don't know about the UC300 but the UC100 does a pretty good job and am ordering one myself following this video ---------http://stoneycnc.co.uk/cnc-control-electronics/

Limit switches and proximity switches do the same job but in different ways. Old style limit switches are mechanical and are prone to failure (springs or arms bent or broken or debris fouling it up), proximity switches are electronic using either IR or magnets to detect the limit. Again I am changing mine over to Proximity switches, simply because they have a smaller footprint and are less prone to mechanical failure.

Get a T slot bed, great for clamping chunky bits to it, use MDF spoiler board for when your not, simply saves the T bed from getting ripped up.

Hope that helps?

Stewart

Online ger21

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Re: New CNC Design Stage
« Reply #2 on: November 02, 2015, 07:54:18 PM »
Quote
Reading on this forum I noticed some folks are using UC300-USB or the Warp9td controllers. At this stage I can’t decide if I want to spend the extra $$$ or stick with the G540.

You still need to use the G540 with these motion controllers, as they are not stepper drives.
Gerry

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Offline kolias

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Re: New CNC Design Stage
« Reply #3 on: November 02, 2015, 08:02:02 PM »
Thanks Stewart, I went to the link but besides the video didn’t say very much about it neither the cost however looks like something to consider

What type of proximity switches are you using?

Right T-Slot bed is attractive but expensive

Thanks Gerry, I understand
Nicolas

Offline robertspark

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Re: New CNC Design Stage
« Reply #4 on: November 02, 2015, 08:09:01 PM »
Nicolas,

I use the warp9TD Ethernet Smooth Stepper with M3 &M4.  It works fine.

Suggest not getting the USB Smooth Stepper as its more prone to electrical noise than the Ethernet version, it can (normally) catch people out with ground loops and requiring an isolated power supply, the driver has not been updated in a while and a few functions are not enabled (although it's the next driver that they intend on updating following the next release of their Mach 4 driver / plugin for the ESS.

That being said, I have a friend with a UC100 running a plasma cutter without issues (electrical noise) and everything works.

The Smooth Stepper will offer you a Mach4 plugin for the future.... not sure what the development plans for the UC100 (or UC300) are.... but they will probably all catch up at some point in the future.

Proximity sensors..... there are basically two "main types" .... capacitive (detect all manor of materials) and inductive (detect only metalic objects [including aluminium but at a slightly reduced detecton distance).   they are normally specified by their detection distance which is defined as a 1cm square of steel (low carbon / mild).

Once you've decided on which type then there are two "electrical" types.... NPN and PNP..... and within each of those types there are Normally Open types and Normally Closed Types.....

Example datasheet of the ones available off ebay with common model references and options.

I have them on my plasma cutter.... to be fair they have been easier to install than mechanical limit switches (allows me to leave the machine to cut unattended).... they run off 24v on my system as it aides in removing electrical noise ..... but ...... they have a lower leakage current which if you do what I did can lead to electrical noise and false triggering ..... basically I paralleled them up and they are of the normally open type (except for one which is used for a Z axis over-run which is a normally closed type.

There is also a good bit of information on here too...
http://www.ab.com/en/epub/catalogs/12772/6543185/12041221/12041227/print.html

And a bit on leakage current here
https://www.ia.omron.com/support/guide/41/engineering_data.html

Note that the input voltage of the smooth stepper is 5V so using a proximity sensor that operates off 6-36v is probably not a good idea (not sure about the limitations of the UC100 or UC 300).

I use a CM126 breakout board http://www.cnc4youstore.com/cnc-mach3-board-7-relay-cm-126.html?sl=EN  to the ESS as it eases wiring (but increases cost... other options are available in the US and elsewhere :
http://www.pmdx.com/ or
http://cnc4pc.com/product_info.php/c32-dual-port-multifunction-cnc-board-p-255?osCsid=cs3cebf7ldelqmo3bdkdebngj0
or the C25 (and I'm sure others too)

T slot typ for clamping + spoil board

Gerry is right.... you will still need a means to control your stepper motors via drivers (G540 or stand alone drivers) I use leadshine AM882H's but the list is long... as the UC300 / UC100 or smooth stepper is just a motion controller ..... think of them as fast parallel port devices .... UC 100 with one parallel port output, the UC300 and Smooth Stepper with 3 each.

There is also the Purelogic controllers too http://www.purelogic.ru/files/downloads/doc/english/PLCM-E3_eng.pdf  (depends where in the world you are).

Rob
Rob

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Offline kolias

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Re: New CNC Design Stage
« Reply #5 on: November 02, 2015, 10:26:11 PM »
I’m in Montreal, Canada Rob, thanks for your time

Lots of interesting info in your post which I have to read carefully and consider what is good for my needs

Much appreciated
Nicolas