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New to me MH700C, cleaning, disassembly, power up.

L.Svedberg

Plastic
Joined
Jan 16, 2021
Hello everyone, Im a longtime lurker just registered on this forum. I was able to save a nice Maho from the scrapyard a few weeks ago. I got it for free, and I am now in the process of bringing it back from the abyss of death... there will be a lot of questions Im sure, but first off;

I disassembled the z axis ballscrew for cleaning off the caked on old lubricating oil/dirt, and upon assembly I find it odd that the six separate ball recirculating circuits are not filled with balls completely...to make each circuit full there are 4 or 5 balls missing. For all I can tell, the ballnut has never been disassembled before, so my question is if this is normal for this kind of internal recirculating ballnut? The machine is from 1986, and the ballscrew assembly is the original part.

Cheers/Lasse Svedberg
 
I decided to assemble the z ballscrew unit using new 3.5mm balls. I filled each circuit completely, and the ballnut felt smoother. Time to put the machine back together again. I'll begin with the x-y assembly, then the z ram. Nice to work with clean pieces! Here are a few pictures of the machine in its current status.

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Getting closer. I just love the gantry crane I built some time ago, its a great help when working alone. Next up is hooking up all the lube hoses, sensors, switches and so on.



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I decided to assemble the z ballscrew unit using new 3.5mm balls. I filled each circuit completely, and the ballnut felt smoother. Time to put the machine back together again. I'll begin with the x-y assembly, then the z ram. Nice to work with clean pieces! Here are a few pictures of the machine in its current status.

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Great, glad it worked out. FYI, if you contact Ross (AlfaGTA), he has done this operation several times using trial and error to size the balls to get perfect results.
 
Back at it!

The machine is now back in one piece. All new wiring, a lot of work for someone like me not used to this...well, upon first power up, the control throws a bunch of error.
Power-up hardware check says the drive 1,2 LMS has failed. See attached picture.
I cannot find much of anything in the CNC3000/Philips432/10 manual regarding this power up check, but I am leaning towards maybe a broken board in the control. I have a spare control, but I don't know which board is "drive 1,2 LMS". Is it the one marked LM/LM?

Any help very much appreciated here��

Thanks/Lasse20210413_222114.jpg
 
There should be 2 LM boards in the control. LM and RM boards output the +or - voltage (10 volt ) to servo drives . Could trace LM output wiring to servo drives ,see which LM board goes to two different drives . the other should only output to one drive. Note single axis LM boards only have half of the circuit components that a two axis LM board has. Can use a two axis LM board to replace a single axis board .
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Does your MAHO have a rotary ("B' axis ) table ? Do you have the manuals an electrical schematics ?
Bob
 
I do have the manuals and the electrical documentation. The machine has an nc rotary table but its not in place right now.

I saw today that the machine constants were not correct, could this be causing a failed power up check?

Ordered a new battery, and will rewrite the constants.

Thanks for all help possible!
 
If the rotary table has a servo motor then the control might be getting a motor over temperature alarm thru the servo drive unit . I remember seeing wire jumpers needed if a rotary table is not used . Also a jumper (emergency off button ) needed if the hand controller is missing . Might just hook up the rotary table electrical connections for a test . Lub oil low alarm will prevent a startup . Also phase rotation if wrong will keep hyd pump from building pressure , No pressure affects tool clamper release and may be also giving a alarm .
Might be useful to save the existing machine constants an compare them to so called correct constants .
Hope you are aware of the special MAHO three finger start up sequence .
Cheers
Bob
 
Thanks for the quick response! Right now Im mostly interested in getting rid of the failed power up check...seems almost meaningless to chase other errors at this time, or am I wrong?

I'll try some more in the morning!
 
It's officially alive!

I had to replace the LM/LM card, and repair one of the Philips read head, but other than that everything went well. Very happy to save this nice Maho from the scrapyard!
 
Glad the Maho is running again .
Could you be more descriptive about the - "repair one of the Philips read head "?
Thanks
Bob
 
I was lucky enough to find one of the socket connections onto the small circuit board inside the head to be broken. I simply soldered it back, and the head was good to go.
 
Good to see you got it together and going. Their good old iron. If you haven't read about it yet there are electrolytic capacitors on a couple boards that are past their life expectancy if they haven't been changed yet.
Looks like rs125's in the background
 
That's my 1998 RS125R, good spotting! Can you guess the other one?

The Maho is perfect for me, and since my last visit here I have finally sourced a table for it as well. So, now complete back up and running, though I would like to have the axes configured like any other vertical milling machine. Been fiddling around a little with the MC:s to switch the Y and Z axes, but no luck so far. Looks like I'll need some help with that...anyone?
 
Okay, first I thought CBR600RR by just the swingarm, but that can't be right, so then I thought RC51 SP2 by the exhaust that is nearby and the large tube above the adjustable top shock clevis mount, but then I looked up photos and the RC51 looks a bit different than that.

Can't seem to place the chassis.

GP bikes are awesome, I have 2x TZ125, RS125R, RS250R and have custom built (Engine swap) a Moriwaki MD250H for a client.

I would show a few pics but something with my computer(s) is preventing me from uploading to PM anymore.
 
Haha, good reasoning there! It,s actually a modified RC51SP2 swingarm mated to an also modified RVF400 NC35 frame. It's one of those forever projects and has been stood for over five years as life in general has gotten me...but hopefully I'll be back at it sometime soon to finish the bike. 400cc, 70-ish HP V4 engined race bike. Aiming for good handling and low weight rather than outright engine performance. The Honda 125GP bike gave me a love for lightweight race bikes. I'd LOVE to own and race a 250GP bike, but the prices has gone through the roof lately, so we'll see about that...
 
I had a feeling that was a RC51SP2 Swingarm... honestly when I looked closely I kept saying to myself, that's a V four engine, but the RC30 and 45 had single sided swingarms?! You can just make out that there are a pair of rear facing exhaust pipes. I started trying to find out if there was a special build they did that fit this description but couldn't find anything with that swingarm.

I raced Pro Superbike at the National level here (CDNSBK) as well as a few races in the USA and once I started riding 125 GP's I also fell in love with the amazing handling and corner speed. Custom Supermono builds are what I'm into these days. One of the reasons I started getting DMG 5 axis mills myself. I have an Aprilia RXV550 here that I was going to put into a proper GP 125 chassis, though I suppose that isn't really a super-MONO it certainly is light!

As for changing machine constants, take the time and build an excel spreadsheet that breaks out the constants by category and add descriptions. This makes it much easier to tweak down the road. I've done this for all my CNC532/Millplus mills. (532 is Millplus, just a name change when they went from v300 to v310, if memory serves)
 
As luck would have it, I've been offered to have my Maho tweaked axis orientation-wise by an absolute expert on the subject. I work as a machine service mechanic in a very large plant where powertrains for heavy trucks etc are manufactured, and one of my colleagues on the electrical side of things is a good friend of the former top DMG technician here in Sweden. I mentioned my dilemma to my colleague, and he got me in contact with his mate. The guy has now moved on to managing duties within the DMG sphere, but still has a big love for the older Mahos of his younger years, and has offered to swing by my workshop to get my machine just the way I want it. He is VERY experienced on working on these old controls, and said it'd take him an hour at the max to get it all done. A little money, a beer and a nice dinner would be the cost for me to avoid lots of wasted time and ugly words trying to fix it myself. I'm all for it, needless to say!

Supermonos are oftentimes awesome bikes, but seem to have an uncanny appetite for self destruction...single cylinder, big HP, prolonged periods of high revs and light weight 4-stroke engine is a recipe for expensive racing seasons from what I've heard...The V-twin should stand a better chance! Please share a pic or two!
 








 
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