Retrofitting a 1986 Maho MH400E

Hi Hanno
Big thanks for the update. If you pull the table ( big job) I would be interested in micrometer readings of the ways thickness variation. Ball screws --- seems the standard patch is using a mix of oversize balls. "Main spindle" --- Is that the transmission output shaft or the vertical head or the horizontal spindle ? Hope it is something easy.
Thought you had a second MAHO with rotary table ,looks as if you are making a rotary table ? Tell us more -- nosy Bobs want to know !
Thanks for the up date-
Bob

Hi Bob,

yes, building a rotary table with a Sumitomo Fine Cyclo gear:
www.cncecke.de/forum/showthread.php?1026...chse-f%FCr-Maho-400E

The tool in the vertical spindle seems to get moved under heavy load. It runs smooth without warming under normal conditions.

Hanno
Wonder if the belleville washers in the tool clamping section of the spindle are all working ?
Have heard that it is a pain to disassemble the Ott-Jacobs tool clamp section without breaking stuff. If you have to disassemble the vertical spindle -- I and many others could benefit from photos and Ott-Jacobs part numbers Might look up the spindle bore at the tool holder gripping fingers. I don't know what the gripping force is ,but there must be a +or - specification somewhere for 40 taper holders.
Bob
PS The rotary table is looking good ----

Hi Hanno,

Please post some pictures if you disassemble anything, I'd very much like to see the insides of that machine!

I have a similar problem with my vertical spindle head, in that it started to turn on the hydraulic tool clamping pump when ran at higher speeds with a tool inside. It appears that the tool holder gripping fingers are worn and I should replace/repair them.

Since this is too much of a job for me right now, I switched to the horizontal spindle for all my Maho needs. But I don't really have any proper clamping equipment for the horizontal spindle, apart from an oversized swivel/tilt vise I bought second-hand. It'd be nice to order an angle plate or maybe have one cast at a local foundry and finish it off with a face mill. I've never used a decent fraction of the machine's 400 kg table load.

Yesterday, I saw a used MH800 E2 on surplex.com for 3300 €, with no takers. It was in Germany and had a manually-operated rotary table with an encoder. It looked nice, had all the docs and a horizontal arbor. Sometimes I think that instead of repairing my machine, it would be better to hunt for a less-worn one and replace the controller again, since at least I have some experience with the latter and absolutely none with the former.

Even if you do it yourself, unless you have the equipment, a nice rebuild will cost 5K€ at least (after you count in a surface plate, straight edge, handling and rigging equipment, part repairs and replacements, such as gibs, spindle and table regrinding, mending covers, etc., and not counting any servo replacements for superior dynamics or speeds/improvements over factory specs, and probably not counting worthy ball screws). Specialized companies over here would charge in the vicinity of 10K€, and take 3-4 months.

I'm on the fence whether to do a rebuild, but I can tell you it's a pain to shim everything you work on to get good dimensions on parts that need it. Each time you loosen the vise or a clamp, a bunch of Red Bull can strips fall out

hanmon wrote: Hi there,

Cheers
Hanno

Slow down guys. Everyone got so excited about Hanno's new turntable, that we missed the 800lb gorilla dancing in the background!. Hanno doesn't get to to post a photo of a home made pendant without explanation or comment

Is this made using Peter (Talla83 ) circuit board?


By the way, Peter also designed a cute little 2 port expander for the MESA system. Sort of a 7i74 lite.

He generously posted the Gerber files to Github:
github.com/talla83/RS422-SmartSerial-Adapter

What is it like to watch the videos with Youtubes translated subtitles?

I followed his recommendation to use JLCPCB to have the boards made. $2 for five boards, including postage! The components are another €20 or so. I have a 7i96 inbound for a lathe project, and will use one of Peters boards to interface a 7i73.

Glemigoble wrote:

Please post some pictures if you disassemble anything, I'd very much like to see the insides of that machine!

I agree with that. I still haven't seen any details on the internet on how to remove a Maho ball screw pulley. I know there is some sort of expanding collet which holds them, and there is a trick to removing them, but am not sure what the trick is.

I have a similar problem with my vertical spindle head, in that it started to turn on the hydraulic tool clamping pump when ran at higher speeds with a tool inside. It appears that the tool holder gripping fingers are worn and I should replace/repair them.

Don't really understand that. The hydraulics are not involved in the clamping, only the release (at least on the 400E). What mechanism would cause the control to be aware of clamping finger wear?
Mark

Don't really understand that. The hydraulics are not involved in the clamping, only the release (at least on the 400E). What mechanism would cause the control to be aware of clamping finger wear?

Well, outside of the tool change command, the pump turns on by itself when the pressure drops, without any input from the CNC. It knows the pressure in the system, has a screw you can use to adjust said pressure, and will switch itselft on if it detects that the pressure dropped. I was thinking that maybe the toolholder coming loose in the spindle would cause the pressure to drop and that would turn on the pump. Admittedly, I have no idea how the whole system works, as I've never taken it apart to look inside. I just have some experience with servicing the pump itself. The issue happens only with the vertical spindle, only at higher speeds, and only when a tool is physically in the spindle. After a short while, the pump turns on, like it does when you press tool release (which, needless to say, scared me shitless when it first happened). This didn't happen before.

Maybe one of the lines with the oil is coming loose, or a fitting needs to be replaced. Either way, I'd have to take the head off the machine and take it apart to check, which is a bit beyond me working alone at the moment. That vertical spindle easily weighs in excess of 50 kg, the last time I removed it to change the bearings I did together with the mechanic who was getting paid to take the spindle to his workshop for the replacement. I'd need some proper rigging equipment in the garage to do it alone.

EDIT: watching the automated subtitles on YT videos really sucks.