Retrofit MAHO MH700c with Philips 432 control

More
11 Oct 2015 02:58 #63674 by aventtini
aventtini replied the topic: Retrofit MAHO MH700c with Philips 432 control
I have also a mh500 that want to retrofit . I need some info on this philips scales . I was thinking to change them but they have a spacial place on the machine body and there is not room for a new one.
More
12 Oct 2015 02:30 #63696 by uli12us
uli12us replied the topic: Retrofit MAHO MH700c with Philips 432 control
Heidenhain have similiar open scales, I fear because the scales are highly precise parts, they are not really cheap.
In the case of Mesa Boards the best way, were the scales with TTL-Output.

www.heidenhain.de/de_EN/products-and-app...tion-guide-for-lida/
More
10 Jul 2016 01:06 #77240 by micges
micges replied the topic: Retrofit MAHO MH700c with Philips 432 control
I removed old scales and installed new glass scales with 1um accuracy (5um should be enough for this machine).
I used those www.ateksensor.com/PDF_files/ENG/ALS4_Datasheet_ENG.pdf
They fit well into original places on machine.

More
10 Jul 2016 08:51 #77245 by akb1212
akb1212 replied the topic: Retrofit MAHO MH700c with Philips 432 control
These scales looks like they are a good match to this machine yes.

I'm assuming you got the TTL output versions as they interface directly to the Mesa cards. But they have an option for 1Vpp output. With that you would be able to interpolate far better resolution. And that would be a good thing. I found my Maho MH600E behaves better and smoother when I use interpolators on my scales to increase resolution to 0,1um.
This was not to get better accuracy, but simply to get smoother movement.

The big question is where to get them, and what do they cost? If they are reasonably priced I'm assuming others here (me included) might be interested in getting some.

In the info they state there is an index pulse every 50 mm. That means you need to ensure it is within a certain position when starting a home search. Or else you might end up with a reference point that is a random multiple of 50 mm offset.
An alternative is to set up an extra sensor to tell it is within the correct range and can use the index pulse.
How are you solving this issue?

Anders
More
10 Jul 2016 11:35 #77248 by micges
micges replied the topic: Retrofit MAHO MH700c with Philips 432 control
I've used rs422 version and connect then directly to mesa 7i77.
I know that interpolated version could be better, maybe I'll do this next time.
As for homing I've used home switch that was mounted on machine,
More
11 Jul 2016 13:49 #77292 by andypugh
andypugh replied the topic: Retrofit MAHO MH700c with Philips 432 control

akb1212 wrote: In the info they state there is an index pulse every 50 mm. That means you need to ensure it is within a certain position when starting a home search. Or else you might end up with a reference point that is a random multiple of 50 mm offset.


Are the indexes all identical? I have heard of systems where the indexes are a variable number of counts apart, so after seeing two indexes you know where you are. Possibly also systems with indexes of different lengths.
More
11 Jul 2016 19:37 #77308 by akb1212
akb1212 replied the topic: Retrofit MAHO MH700c with Philips 432 control
I got this info from the online datasheets and know nothing more about them. And I don't know what kind of quality they are either, but I would like to know as they seem to be a good fit to this kind of machines. And they come in analogue 1Vpp versions, which means they can be interpolated to very high resolution. That is if they are true high quality units with reliable and clean sine curves on the output that is.

You are right Andy, it would be a good idea to have some form of pattern in the index pulses to allow for absolute address (kind of). It would take some logic in the homing sequence, but I guess that's no problem in LinuxCNC. But the datasheets are quite clear it's with 50 mm intervals.
So you do need extra hardware on a Maho. I've been able to keep my original (analogue) scales with index pulses only at the end, and therefore don't need to add home switches or any other hardware to make the homing work. The only danger with that is if you are beyond the index point in the other end you end up with a totally offset coordinate system. But you will be able to reset it simply in LinuxCNC. With the original 432 controller it wasn't so easy, in particular on the Y-axis where it was impossible to move the screw by hand as it has a brake to keep the table from sliding down when shut off. You had to do all kinds of trickery to get it to move past that index pulse.....

But the question still stands, how much do they cost? And where can I buy them?

Anders
More
11 Jul 2016 20:22 #77311 by andypugh
andypugh replied the topic: Retrofit MAHO MH700c with Philips 432 control

akb1212 wrote: But the question still stands, how much do they cost? And where can I buy them?


Try eBay. EXE are 11uA interpolators and IVB are 1V interpolators.
More
11 Jul 2016 20:35 #77313 by micges
micges replied the topic: Retrofit MAHO MH700c with Philips 432 control
More
12 Jul 2016 15:06 #77342 by uli12us
uli12us replied the topic: Retrofit MAHO MH700c with Philips 432 control
IC-haus sell some interpolator ICs with changeable interpolation. All of it can handle 11µA or 1,1V signals, dependent from the
installed passive parts. The price is much lower than the Exes. But you need a good soldering iron and can use it,
The main problem ist, the chips are birdsfeed, TSSOP 20 are really tiny chips.
The MG have software selectable interpolation, with a 20µm scale youcan select 5 for 1µm, 10 for 0,5µm, 25 for 0,2µm or 50 for 0,1µm.

The NV is a simpler Chip in the same small package, with it they are only hardware selectable interpolation factors from
1,2,5,10 all times 4 to have the resolution. The other possible factors 3,4,8,12,16 are not really meaningful.
Moderators: piasdom
Time to create page: 0.089 seconds
Powered by Kunena Forum