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New MAHO MH500 User Here! Advice is welcomed!

mematyi

Plastic
Joined
Apr 21, 2015
Hi guys!

I've posted before, but finally, I arrived at the machinists' league.
I got an 1989 MAHO MH500M model for a very fair price. It is a late manual model with basic Heidenhain DRO, no rapids, Variator feed and speed selection. I think the rapid feed version came around 1990.

It is believed to have few running hours, came from a pneumatic manufacturer's in-house repair facility. The cosmetic flaking is almost untouched on the head and cross slides. Only little wear shows on the edge of the vertical flat ways where the heavy column rides. It has tilting table, so I plan to compensate most of the sagging, if exists.

More pics: Google drive link (sorry, too high res pics)

I believe there are some forum members who had machines like these, so if you see it, your advice is welcomed!

It needs some TLC, but otherwise ready for action. My biggest sorrow is that the original plastic oil fill and drain reservoirs are cracked thus leaking some oil. These pieces are unobtainable, of course.


My first question would be, Is lifetime-lubrication means really lifetime?
The headstock has some nasty high-dollar bearings, four B719XX series and two custom order ringless clyindrical roller cages, like the deckels had. I want to preserve them as long as possible, but still, I don't want to risk damaging them while disassembly, if not necessary. In the picture, it does not show any kind of seal for the bottom roller cages. The drawing might be simplified, as it is a part drawing, not an engineering plan, but still.





1669711498411.jpegsnapshot.JPG
 
Nice looking machine. Not questioning your statement, but no rapids??????? How can this be....Deckel had full 3 axis rapids (FP2) since its introduction in the late 50's/early 60's
Can't believe Maho was that slow to adopt such a basic feature on a manual mill.

As to seals on the spindle, that is the way almost every metal working machine is built, even grinders.....Spindles are built with close fitting slingers or labyrinth type mechanical seals...Close fitting of the running surfaces, but no actual contact and never (in my expirence) any rubber lip type seals.
Don't see anything in the spindle that would make it difficult to disassemble. Might need a bit of press work ot push the spindle out of the quill depending on the amount of interference on the upper 4 bearings. Dashes lines on the drawing show the thrust direction of the bearings so i assume that they are angular contact. Also appears that there is a pair of spacers (#8 inner and outer) that likely set the preload of the bearing pairs.
Would think that the same Kluber lube that Deckel uses in their spindles would be what you need.....the important thing is to keep track of the position and direction of all the rolling elements in the assembly and align the run out marks on the angular contact bearings.
Need a spotless work area that is draft free to do this kind of work.
Been some postings here about spindle rebuilding might wish to search for better detailed info. Won't be fot your machine bur rather the Deckel setup which is somewhat different, but the overall technique is the same.

Might want to do a bit of testing prior to disassembly.
Need a good 10's (.0001") indicator. Test for side to side movement on the spindle nose, using hand pressure. .0002-.0004 side total move would not be problematic. Those needle rollers need a bit of clearance to run.
Might also be some end play.....might not due to the angular contact ball bearings that control the thrust.

Might show a good close photo of the leaking oil fill and drain reservoirs, might be an avaliable soulotion to replace or repair these.

Cheers Ross
 
IMHO, lifetime means until the grease dies, and nobody knows when that is without taking a look inside. If you don't know the prior history of spindle greasing service, it needs to be done. It is not that hard, but requires care and cleanliness. I have done it on several flavors of Aciera and Deckel spindles. Don't tell my wife, but a clean granite kitchen countertop is a great place for reassembly in a clean environment.
 
Nice looking machine. Not questioning your statement, but no rapids??????? How can this be....Deckel had full 3 axis rapids (FP2) since its introduction in the late 50's/early 60's
Can't believe Maho was that slow to adopt such a basic feature on a manual mill.

As to seals on the spindle, that is the way almost every metal working machine is built, even grinders.....Spindles are built with close fitting slingers or labyrinth type mechanical seals...Close fitting of the running surfaces, but no actual contact and never (in my expirence) any rubber lip type seals.
Don't see anything in the spindle that would make it difficult to disassemble. Might need a bit of press work ot push the spindle out of the quill depending on the amount of interference on the upper 4 bearings. Dashes lines on the drawing show the thrust direction of the bearings so i assume that they are angular contact. Also appears that there is a pair of spacers (#8 inner and outer) that likely set the preload of the bearing pairs.
Would think that the same Kluber lube that Deckel uses in their spindles would be what you need.....the important thing is to keep track of the position and direction of all the rolling elements in the assembly and align the run out marks on the angular contact bearings.
Need a spotless work area that is draft free to do this kind of work.
Been some postings here about spindle rebuilding might wish to search for better detailed info. Won't be fot your machine bur rather the Deckel setup which is somewhat different, but the overall technique is the same.

Might want to do a bit of testing prior to disassembly.
Need a good 10's (.0001") indicator. Test for side to side movement on the spindle nose, using hand pressure. .0002-.0004 side total move would not be problematic. Those needle rollers need a bit of clearance to run.
Might also be some end play.....might not due to the angular contact ball bearings that control the thrust.

Might show a good close photo of the leaking oil fill and drain reservoirs, might be an avaliable soulotion to replace or repair these.

Cheers Ross
Hi Ross!

This is the oil reservoir. Old, german made, nonexistent anymore. "Hiesinger" brand.
It loses about 1 ounces of oil every week. The drain port is cracked upwards in multiple places due to overtightening, as well as the large horizontal threads are broken. I planned to make a new one using the machine, but by the time I get all the accesories and skill, it loses the whole oil charge 5 times :D



It indeed does not have rapid feed. On the plus side, the leadscrews/nuts are not worn that much by the use of rapids.


In fact, I've yet to actually use the machine. I'm still cleaning it and waiting for an electric pushbutton, so the spindle may be perfectly fine, but I am curious if anybody had problems with it and successfully disassembled it. It does not sound ill at all.
 

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A little update on the Project....

After searching through the net for a replacement part, I did manage to find it, for 55Euros, plus 20 shipping (~80USD total), which seems irreal for my hobby budget, I settled on a home shop solution.

I made a similar piece out of brass plumbing fittings, little soldering and milling, plus an hour of work.
With a 3D printed decorative piece, I think it will work for a 35yr old hobby machine. The total cost was 15USD.


The next chapter is going to be the variator speed control with excess runout in the pulley.
 

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