In the last post I started covering the installation of the glass scales on my Grizzly G0463 (AKA Sieg X3) mill. You might recall that I got the scales loosely mounted on the mill but didn’t have a controller to use them with. I didn’t want to tie-up the unit I’ve been using for testing, so before going any further I had to build a new one. This weekend I got some free time to finally build the controller and [mostly] button thing up.
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| DRO interface ready to go into the garage |
The scale interface uses the MSP430 firmware for the glass scales, but the level shifter board is a bit different. Since I know what scales the controller will be used with, I was able to cheat. Instead of the LM339 comparators I opted for a set of voltage dividers. Using two resistors [per line] with a ratio of 33 KOhm to 20 KOhm reduces the 5V coming from the scales to a bit under 3.2V, which is pretty close to ideal voltage. The quill will use an AccuRemote scale that works well at MSP430’s native voltage, so it can be connected directly to the Launchpad input lines.
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| DRO interface mounted to the wall |
The DRO controller is mounted next to the mill and ready to go. The board is wired for three glass scales and an iGaging or AccuRemote scale for the W axis. I haven’t made the bracket for mounting a scale to the quill, so the last port is not plugged in yet.
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| The W axis is not used as the scale mounting bracket is still not done |
Since the new DRO looked so much nicer than my “duct tape and bail wire” setup, I decided to mount the tablet more permanently as well. That is, if you call a piece of aluminum sheet zip-tied to a large screw hook “permanent”.
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| A more permanent mounting bracket for the tablet |
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| [Almost] finished setup |
The last step was to align the scales. To do this, I loosened the mounting screws on both end so they were just snug enough. Then I moved the scale to one end of it’s travel, tighten the screw, move the scale to the opposite end and tighten that screw.
Side note: I’ve heard from several sources that the glass scales being uber-sensitive to misalignment. In practice I found that this is not necessarily the case. The reading head rides the glass strip on a set of miniature ball bearing and is connected to the carriage via a spring, allowing for a fair amount of misalignment.
I think the issue with glass scales, or any scales, regarding alignment is to not introduce cosine errors. They'll always "work", but you'll get a small error over long lengths if not mounted perfectly parallel to the axis.
ReplyDeleteIn that case I should be fine :) I got it to within few thousandths, so the cosine error should be negligible. Even if it wasn't, the scales are calibrated in the software, so any error will be accounted for.
DeleteThank you
Yuriy
Hi Yuriy,
Deletegreat work!!!, on Mill and also on the development of the DRO and app. I built mine and are on the stage of attach on my Emco PC lathe. Easy and super fuctional your work.
I see you have placed 4 DB9 connectors ready on the electronic Box, so we can see soon the tachometer integrated ?
thanks to share with us your knoweledge,
Manuel
Manuel,
DeleteThe new version of the app (that I will release in a few weeks) already supports tachometer. I just need to design the interface hardware...
Thank you
Yuriy
Good news for the new year !!
DeleteAre you thinking on Hall sensor for tachometer ?, this would be easy to glue a little magnet on every chuck or collect holder. If you need any help or test, let me know,
Many thanks,
Manuel
Yuriy,
ReplyDeleteI was thinking of using the magnetic scales from DRO PROS with my setup. As with yours they are 5V scales so I guess I could use a setup similar to yours. One thing I do not understand though: the scales use 9 pin connectors but they seem to be connecting onto the voltage shifter board with 4 pins.
BTW The guys from DRO Pros sent me a PDF with the technical specs of the Electronica scales they sell. Ill try to email them to you. Could yo check if they will work with this system?
Couldnt find your email so I hope pasting the image here works!
ReplyDeletehttp://i243.photobucket.com/albums/ff121/Helder22pictures/Untitled-1.png?t=1388170971
Hello Yuriy
ReplyDeleteI want to ask you if there is a way to change the axis for the Hole circle.
I m using a Deckel fp3 and quite often i put things on an angle plate so the y axis is the depth.
Also for use on the lathe how easy is to add tool library with offsets for people using a multifix or aloris QTCP?
Kind regards
Kyriakos
Hello again and happy new year!!!
ReplyDeleteI hope you can answer this after holidays. I m trying to connect my glass scales to launchpad but i have a problem: To many wires and only 2 to use.
I did my best to try all the combination but no luck. Every time i test the connection with tablet and fails after few sec.
My green light is always on.
The cables goes like this:
2-0V
4-GND
6-A
7-5V
8-B
9-R
i m powering thought usb and the scales from tp1-gnd
Kind regards
Kyriakos
Kyriakos
Delete#2 goes to Launchpad Ground
#4 should be already connected to the scale's frame/cable shielding
#7 goes to Launchpad's +5V
#6 and #8 go to Clock/Data pins for each scale. (if you connect them backwards, you can change the setting in the app to invert the readout)
The application disconnects if there is no data for more than 2 seconds, so there might be something wrong with the Launchpad (even if the scale doesn't send any data, the board will send X0;Y0;Z0; to the tablet. Have you looked at the troubleshooting posts (at the bottom of the project page)?
Thank you
Yuriy
May i add something (and i hope is correct) for Mac users
DeleteI m using Energia to upload the firmware and since Energia won't handle .hex files i do the import from sketch>add file>Verify>upload.
Is this procedure correct?
Kind regards
Kyriakos
PS: Thank you for the fast response
PS2: is it possible to sneak peak the underside from this (cheat) board? I m planing to use the same config on my mill and it looks sooooo much simpler.
Two resistors instead of the LM339 seems so tempting.
Again thank you for your time.
This comment has been removed by the author.
ReplyDeleteYuriy,
ReplyDeleteReally great work.
I have developed my own Arduino sketch to interface to an X2 mill. I am using your Android app as the coolest DRO I have ever used. However, I encountered a strange issue. The reading dumped out by my Arduino sketch (verified with a virtual serial terminal) is correct, but the numbers displayed on Android is off by a scale of 1.0433. Interesting enough, 1.0433 * 25.4 = 26.5. Don't know how did this happen. I currently work around this by pre-scaling the readings before I transmit them Android. Any idea or suggestion on how to resolve this?
Haw
Haw,
DeleteYou need to calibrate the scales in the application settings. There are individual CPI settings for each axis. iGaging should be set to 2560. Apps default is 2650, which is a bug that is fixed in the upcoming version.
Thank you
Yuriy
Yuriy,
DeleteThank you very much for your quick reply. I have made a small donation. Hope to see more great posts from you.
Haw
Thank you, Haw. :)
DeleteHi Yuriy,
ReplyDeletehave built the DRO with the Launchpad and Ditron Glass scales and all works well, thank you for the work.
Can I ask if it is possible to have a zero button for each axis, it would save writing down each one before losing it.
Eric
Yes. Long-press the "abs/incr" button next to the axis you want to zero-out.
DeleteRegards
Yuriy
Thanks!, that worked a treat.
DeleteEric
Yuri,
ReplyDeleteI am trying to figure out the capacitor arrangement on your strip board (top left of the picture). Without seeing the bottom of the board I am a bit confused. I see the 1uF cap to the right that runs from Gnd to 5v. Then moving left a second 1uF cap that runs from Gnd to ? and then the large black cap that I can't tell how you have it run. If you could clarify this section that would be great. Is this to power your quill dro? I have a G0704 with built in DRO. I plan to use the W to bring that dro reading to the android tablet.
Would love to see that too
ReplyDeletehow about it yuriy
Delete