Retrofitting a 1986 Maho MH400E

Thanks for that David, I have been pretty busy this week.

Hi Mark,
Nice to see that the bearings look okay.
In the 70's we had a 4 foot diameter spherical roller thrust bearing for a 150 tonne rotary regenerative pre-heater. It arrived with false Brinelling. SKF took it back, reground the races and fitted new rollers. It might be possible to do that with these bespoke spindles if there were damaged.
I re-read the docs for my spindle and realized I didn't include the attached page. It's not all that applicable to your machine except for the end float I think. I heated my bearing to 50 C at they explain but I made a silly mistake. I used my paint stripper gun on low and almost immediately the grease started to smoke. It seems that the grease heats up much faster than the steel. So I repacked it and put it in my Siemens domestic oven. It has a nice thermostat that goes low enough to proof dough. It seems the key thing is to make sure that the races are all hard against the end float shoulders. And yes I put it into may Emmert pattern makers vise and hit it repeatedly with a rubber mallet. I've fitted it with wooden face plates.
It seems they set them up with a few micrometers float and are fussy it isn't larger. It certainly ran hot on first start even at the lowest speed. So I went through the whole stop, cool, start procedure at every speed. And it still got a bit hot at full speed until it bedded in later.
So I think the idea is the spindle runs hotter than the surrounding parts as the heat has to get to the fins behind the cover plate. That means the end float is eliminated and the bearings are pre-loaded. In you case you have  shims. I think I would make a similar tiny float when the races are seated and remember to rotate the shaft to settle the balls and cage. When these taper rollers or angular contact balls operate they nutate like small gyroscopes. The races must drive that nutation or at high speed the balls will scuff themselves and the races. I think possibly the tapered rollers in mine have too much gyroscopic moment to run at your higher speed, so the use balls for that?
If you go back you will see I had some issues with the cooling fan being loose. It very important that it blows down the fin slots. I made a bigger copy of you ring lamp. They work great, but be careful it doesn't block the cooling air coming down those slots
The labyrinth seal on my quill was full of muck from the swarf. So I agree that flood cooling is probably better.
Cheers,
David

Hi Mark,

As always I forgot to mention some things:
At 2:20 on the video you unscrew the hydraulic ram. That is the thread in my instruction sheets that you need to heat because it is Loctited. I'm not sure I like your parallel grip pliers for that job. I used a large adjustable spanner for that, which not much better, and I couldn't move mine cold, for fear of damaging the part. That is when i came to use the paint stripper gun on low. I just held a steady torque and it suddenly came free after a minute or so of heating. Most Acrylic lockers will soften at around 120 - 130 C. Have you found broken Belleville springs?
At 2:35 you show a diagram p7.35-2/3915. First lets mention that there is a thread on the ram that the whole gripper assembly threads onto. So the bolt you remove is part of the system that stops that whole assembly from turning on that thread. In the diagram it seems to show a socket head screw, the head of which I think is used to splay a split collet to jamb the assembly from turning. But when I step through you video you remove a grub screw. So I'm thinking that you actually have the same locking system as my machine 7.35-1 that I put up  with the ball and grub locking?
As you leaf through the drawings at 1:20 you see my type of NT40 tool where I have to machine a groove on the tool holder. The dimensions are exactly the same as mine. I've actually made the setting jig suggested. I don't actually like it much as there is an M16 thread underneath that groove and it leaves alarmingly little meat under the groove, along with the thread stress concentration.
I've had a few second thoughts on my end float comments. I know they make matched pairs of angular contact bearing for common uses like car wheel bearings where they are matched preloaded. It looks like it could be possible that your clamping ring closes the preload on just the inner rings like that. Whatever, it's clear that those bolts should not be loose. They should have some set torque applied. Might be wise to see if Maho can help with end float/ pre-load. At least do the temperature runs after repacking. I would expect it to run hot after re-packing, but come good during the process. Running cold may actually be a bad sign.

Cheers,
David

Hi Mark,
While I looking around for stuff on the previous entries I came across these 2 images, I can't recall where I got them from. They relate to stuff we discussed a way back. I mentioned that the resistors on the gear change were never invoked on my machine. I translated the images using Google, which I know you don't need, but I see at the bottom they mention the resistors are not needed for later Mahos. Mine is certainly fine without them. I'm thinking that the earlier Philips controller would have been much slower and maybe could monitor the cams fast enough. The diagrams are also the first I've seen that explain the actual reason for cams 4 and 5. So it may be that with the massive improvements in clock speeds since then the LinuxCNC conversions may not need them either? Mine still uses cam 5 as I recall to decide which way the ladder code hunts a cam lobe first. Presumably for the case where you've had a crash and it's not on a cam lobe.

Another thing I'm surprised at is that in the LinuxCNC conversions you keep a lot of the relay logic. Wouldn't it be better to shift the I/O for that into the computer and make it "fly by wire". As it stands there is a lot of relay logic outside LinuxCNC that it doesn't know about. You would still need relays for shifts in voltage like 5K1, but it wouldn't be for logic. On my machine it would involve a more than it can do I think. But in both our cases it seems we have a dinosaur brain sitting in parallel with a modern one.

Cheers,
David

Just a couple more files.These are extracted from the Maho Technical manual that you can download from one of my previous links to my Google Drive.
If you just want to remove the quill it's easy to flip the vertical head on it's side as shown. It eliminates the possibility of dropping the whole thing out accidentally.
I've edited the sketch to show a trap. Mine doesn't have the bolt setup for retaining the hand wheel assembly like Marks.I don't have the "U" shaped cover shown in Marks video. Mine has 3 separate plates instead. Under the left plate there is a a tapered dowel scotch key to retain the assembly. As you can see the instructions neither show or explains this. I've added the instruction in red. The machine has these tapered dowels in quite a few other places also.
It has the same travel limiting screw, but they only mention loosening it. Better to remove it completely since you don't know how loose to clear the quill. 5 mm maybe!
The quill clamp on mine is quite different. It can be clamped in any quill position, unlike Marks which is one tooth step on the quill rack. I think both work nicely.
The heating instruction is to remove the tool clamping mechanism.is here, but it might be wise to leave the limit screw in place before you do it. I pulled the whole lot out and heated it on the bench in the vise as previously noted.

Cheers,
David
 

Hi mark,

Finally got around to compressing some photos of the spindle re-grease.

4797 shows the tool retaining system with the Belleville spring stack and the hydraulic ram.

4800 shows the quill clamps. The 2 arced pieces fit in a groove in the head bore. The Kipps handle moves the collar on the bolt. There are thumbnail milled cuts in the ends of the arced pieces (4 places). The collar and the bolt head are sitting in them. So tightening the Kipps slides the collar and brings the ends of the arced pieces closer together, clamping them onto the quill.

4803 Shows the whole assembly laid out.

4805 Is one of the taper roller cages. Looks like cast aluminium with some machining.

4806 Is one of the taper roller inner races. Looks good for 4000 running hours.

4814 Is a view along the bore for the quill in the head. Odd perspective, but what you are seeing closest is the recess that the 2 clamp arcs sit in. The 2 pins fit into the thumbnail cuts to hold the other end of them so they stay immobile when the other ends are clamped. Nice piece of engineering.

4817 The bore where the handwheel assembly fits. My finger is on the tapered dowel that scotch keys the handwheel assembly in place.

4819 Is the clamping assembly for the tool holder retention. I'm guessing it's like yours. Note the slots in the male thread on the draw bar. When the grub is torqued the ball expands that thread and locks it to the female thread on the claw assembly. You can't actually adjust the assembly until it's all assembled back into the machine since you need to have the hydraulics running to put it in the  "release" position.

Cheers,
David