The Sajo mill is here

[Trion]

Thanks guys, I'll look into clamping the head of the vise when I get myself a clamping kit. I'm lacking tooling and funds at the moment.

DMION: I had forgotten all about the ram adjustment

But yesterday I gave it a go




Then I figured I'd loosen the vise and position it a bit further onto the table, but when looseining one of my homemade t-studs it broke off. Looking at the broken zone, I can see see something looking like a big grain growth in the HAZ of the weld. Must have weakened the bolt quite a lot, but I'm still amazed that it broke. Could it be hydrogen enrichment from the snow hardening?


Well, here the vise is temporarily fixed and the head adjusted to a usable position

[Divided he ad]

On another note, I said I'd post a picture when the Nissan is running, and guess what happened yesterday?

Hi Trion,

I've not been here for a while and only just found your thread.... That's a nice huge mill and a vice to compliment it!!!    

If you have any endmills/slot drills I'd make a few new T nuts first job    scary having ones that snap  


But I also just had to say.... Nice motor    SX?  I'm hoping there's a filter to protect that huge shiny snail somewhere too?  





Ralph.

[Trion]

Thanks! Yeah, s14 as you probably have noticed. I have a 4" intake pipe and HKS mushroom filter, but for the first startup after a rebuild, I like to double check that things are working. After snapping 2 rockers, bashing two hks cams and bending 4 valves I have learned not to trust the SR...
There is a 4000 picture build thread about the car on the members area of the norwegian Silvia forum. Good for killing a few hours, if you speak norwegian (and have paid the membership fee)

[Trion]

It's been a while since I have posted here, haven't done much either. Most of my time is being spent driving the Nissan, and reading for my exams.

But I have managed to sneak in a few hours, where I have changed the oil of the vertical spindle gearbox


The spindle is running nice and smooth, and all gears work fine. With one exception at about 800rpm, which is making a slight grinding noise


Here's the table feed gearbox being drained, and new hydraulic oil is soon to be poured into it


That's about all there is to report. I have bought quite a few new Mitutoyo measuring tools, and finally got around to order a ER32 collet set for the mill. Beware, there might be a bit of gloating in the next post

[Trion]

I sai'd there was going to be gloating

You are looking at a MT2 live center with exchangable tips, MT2 collet chuck for the tailstock, MT3 collet chuck for the spindle, 25mm shank collet chuck for future QCTP and ofcourse ISO40 collet chuck for the mill. I also bought a few spanners and ofcourse a complete set of ER32 collets


I first tested the poor mans collet chuck on a valve I had tried to turn in the 3-jaw, with loads of scatter.


It turned out like this, valve-grinder ground valve in front and turned valve in the rear


Here's the tailstock collet chuck for the times i need to chuck a reamer or a large drill



I only have a drawbar for the vertical spindle for now, so I tried the collet chuck there


But being a newb, I got into truble right away. I put the collet in the chuck and put the nut on, but when tightening it, it stopped far from the edge. So I took it apart and noticed some slight damage to my 10mm collet


So I figured, something must have been wrong. When I looked into the collet nut, I found the bugger. As you can see, there is an edge which is very out of round


So I put it on the lathe so measure the runout of this edge, but it was more than the 0,8mm of travel my new Mitutoyo DTI (gloat gloat) had to offer..




At first I was thinking, thats why they were so damned cheap. Should have spent the money on the real deal instead
But then I started looking at the other collet nuts, and strangely they had all the same runout. And then I realized it. One is supposed to put the collet into the nut by slightly pressing it in by hand, and the put the nut on the chuck..

After that, I was ready to make the first swarf


Yup, thats some milled aluminum. I took about 0,5mm cuts back and forth, climb milling definetely gave the best result


Some of you might remember that my homemade t-slot studs broke a while ago. Well, here's yesterdays setup. The milling cutter is rotating away from the car, I'm not crazy


On another note, i ran the vertical spindle again, and tried to chang the rotational direction. In what seems to be the right direction for drilling and such, there is a lot of noise coming from both the head and the gearbox. The noise increases with rpm and sounds like something hammering in there. I might be looking at a head+transmission overhaul this summer

[Trion]

Today, I tried filming the head noise. The audio is pretty bad, but the noise of the horizontal spindle is like a light whine, as from an electro motor, in comparison to this hammering/crunching sound.

[Bluechip]

Trion

Does sound a bit gruesome .. although it would be about normal for a Chinese Mill      

Try turning the spindle by hand, if it's rough, maybe just a shot bearing .. not good if it's gear driven though ..

Wonder what others think  ...

Dave BC

[Artie]

Trion

Does sound a bit gruesome .. although it would be about normal for a Chinese Mill      

Dave BC

I know nothing about the Sajo, obviously, but I do have a chinese mill and yes it is a noisy geared head machine but...... nothing like that!

That does not sound good.

Im thinking about dismantling mine as its been said that a decent bearing set can radically reduce the noise... I would definately be looking inside yours before something nasty happens..... looks like too nice a machine to waste....

Rob T

[Trion]

Todays shop time revealed that things are worse than I initially thought.

I spent some time listening to the various places on the machine, to locate the hammering sounds. The gearbox makes a loud hammering noise in the higher gears, and the upper part of the quill head does the same. I cannot feel any bearing wear, so I'm afraid it's the gears.

But I have two heads for the mill, so I figured it might be worth a shot to try the other head on. So off came the heavy bastard..


While changing heads, I started the vertical motor without any load. All of a sudden, the gearbox was quiet and only made a light whine as I would think was normal.

But when I put the angled head on, the hammering sound from the gearbox was back. But the head didn't hammer, instead it made a deep rumbling sound.


Then I noticed the play in the spindle....


Yup, thats about 0,72mm (0,03") of radial play


Well, leesson learned (for the hundreth time), you get what you pay for..
Both vertical heads and the vertical gearbox need an overhaul. Bearings will be ok, but replacing gears might be a costly story! On the other hand the horizontal spindle and transmissions seem fine. But considering how worn the vertical spindle is, I'm beginning to wonder how drastic the wear on the ways might be. If the table doesn't move straight, even light precision work is out the window and i might aswell use an angle grinder instead... How do I measure the table wear?
I seem to have to make a decision wether to sell the machine as it is, or to start an expensive and time consuming overhaul. Any opinions?

[Bernd]

That .030" might not be that bad. It depends on what radius your checking it. I'm sure if you check it on a 12" distance from center your indicator reading would be much more.

Have you tested the machine under a cutting load? Like perhaps milling a part to see how the noise is then. Might sound completley different under a load.

I personally would say it's the bearings and not the gears.

Bernd

[Artie]

Before I made any decisions regarding the fate of the machine Id find out exactly what, if anything, is wrong with it. It may well be 'normal' for the beast. Mine annoys the hell outta me but I know that many of its type do it and I also know that quality bearings will make it much quieter..one day...

Do you know of any repair or service company that has experience with this brand? Maybe they would be willing to talk to you about whats good and whats not. Talks to sales companies they may be able to point you in the direction of others who can help. Is it easy to have a look inside the heads?

Only once you know what the cost is going to be can you determine if cutting your losses is acceptable and move to another machine as opposed to repair this one.

Good luuck... that looks like a nice machine... I hope its got life left in it yet...

Rob t

[Artie]

You say that you cant feel any bearing wear so you are afraid its on the gears.... in my experience, for a bearing to be noisey it doesnt need to exhibit wear or free play. Its often impossible to check a bearing in situ.... but they can usually be felt as bad things when in the hand... dont discount a simple (relatively) cheap fix yet...

[dsquire]

Trion

After thinking about this for a bit. 

I have a feeling that it is in the bearings where most of the noise and excess play is coming from. Worn gears might give you some backlash but not side to side. The rumbling that you hear may well be some square balls in the bearing from a bearing breaking down. I would be tempted to put an end mill in and make it do some hard work for a few minutes while listening to it and watching how it acts before I started tearing it apart. Weather its bearings or gears I don't think a minutes hard work is going to make any difference but it may help you pin point the problem. I hope that this is of some help. 

Cheers 

Don

[Trion]

dsquire: I've been thinking a bit about it too. If only thetable is moving straight in all directions, then I can replace the bearings in both gearbox and head and use the machine. The gears might still make some noise, but it won't affect the accuracy of the milling, right!? Considering that the machine is going to be used rarely and only under hobby-load, I believe the gears will last many years to come. By the time they let go, I might even have a dividing head and a module cutter laying around Or who knows, maybe they still sell spare parts for this machine?

Selling the machine as it is, I'm either not going to get any money for it, or I would have to fool some poor guy. But I like my wallet thick and my concience being good, so it seems my only option is rebuilding

Bernd: The play in the bearings of the angled head is very noticeable. At first I noticed it with my hand, and guessed it was about 2mm. I was amazed to find it was only 0,7mm.

Artie: That is what I'm thinking too. Find out all the bad things and make a decision. There was a repair/spare part company called sajoservice, but they seem to be out of business.
Having a look inside the heads is going to be a bit of work, but I'm sure it's going to be worth it. Once open, I'm going to replace all the bearings I can find in there

Next up: Making a new pair of t-slot studs and try a bit of milling. Maybe also try measuring the table wear.

[Trion]

I have not yet purchased any more milling tooling, so i have not been able to test the mill fully. Althoug i redrilled a pair of brake discs a couple of weeks ago, using the quill head. I only ran at about 300rpm so everything was running nice and quiet, and the drilling was no problem.

Therefore I have decided that the quill head is in best shape and may stay on the machine until the other head is rebuilt.

Here's a picture of the head already slightly disassembled


In order to get the spindle out of the head, first the bearing tightening screw has to be removed




Then the spindle bearing block may be turned out of the housing


But then a problem reveals itself. The gear which drives the spindle is a 45degree helical gear that sits on the shaft with a press fit and uses a key to secure rotation. This gear is too big to exit the housing still mounted on the shaft, and therefore the shaft has to be pressed of the gear and the gear is then to be removed out through the hole which the picture is taken through. Sort of


The shaft may be removed as far as this, but then the gear is stopping it


Big gear vs. small hole


I tried pushing it out like this, but the "clamp" was just slipping on the bolts I mounted. Will have to improve this fixture to try to remove it again. I really hope the gear doesn't damage the inside of the housing when being pressed off!


After many attemps to remove the gear, i went on to disassemble the the other part of the head


This part of the head uses angular contact ball bearings on each shaft and an adjustment nut to tighten them. The bearings felt quite good, but I figured I should replace them while being at it. It is hard to feel if a bearing is worn without having it in your hand anyways. Here's the housing for the outgoing shaft.


Housing and ingoing shaft


Disassembled


But the inner ring of one bearing kept to the shaft, so I had to think out of the box to get it off


Voila


Now off to the garage to try removing the bad gear again

[Trion]

Been a bit lazy about taking pictures as progress goes along, but here goes.

I got the gear of the shaft, after having made these super fancy brackets


Rough illustration of the assembly


After having disassembled the whole lot, I wrote up all the bearing numbers and went shopping


The spindle main bearing is a tapered roller bearing.


Though the foil is in on this picture, there is actually a notable height difference between the new and the old bearing..



Before starting the assembly I figured I should make a tightening tool for the spindle, as previous tightening attempts seem to have set its marks


Some M6 screws and flat iron became this


A bit of grinding and welding later, the finished tool has emerged



Then I began with the assembly. I started off with the ingoing shaft of the 90 degree transmission. All parts cleaned and lined up for assembly


I made a relief cut in the old inner ring of the bearing and used this to punch the new bearing in place.


Afterwards I could pull the cut bearing ring of by simple hand force


I also hit in a new bearing in the housing. These bearings are angular contact ball bearings, and are positioned such that by tightening the screw on the end of the shaft, bearing play is eliminated


Then i soaked the bearings in grease


Before I assembled the whole lot


Then I fitted the washer and the key


And fitted the gear, with some more grease being applied to the new bearings



Next up was the outgoing shaft of the 90 degree gearbox


Bearings mounted in the same manner


I chose to preheat the gear to ease the installation. Heated it to a surface temperature of about 70 degrees celsius


It slid much nicer onto the shaft


But the retaining nut had some ugly marks on it


So I chucked it in the lathe to skim of the marks


I didn't bother about the marks that didn't protrude out of the surface, as I wanted to keep as much of the threads as possible


After having deburred the edges, I mounted the nut and locking ring and tightened



Finally the main spindle assembly. As you can see the main bearing is a big tapered roller bearing. It is tightened towards a flat ball bearing, while sideways movement also is supported by the top bearing which is a flat roller bearing without any locating edges to only support the sideways motion of the shaft.
What concerns me about this setup is the location of the gear (previously known as the bad gear). The axial movement of the gear is only limited by it's counterpart. So when assembling the unit, the shaft and gear coming in from the side has to be mounted, then this gear has to be pressed onto the main shaft until it contacts the gear coming in from the side. It will get clearer when I assemble the unit again.


To give you an idea, the total height of the gear and the bearing is 51,98mm. If the gear is pressed on until it reaches the edge on the shaft, the top of the bearing will be below the lowest threads, making the adjustment nut useless.


Judging by the marks, this is about the way it was mounted before I disassembled the head. Like I said, the only thing limiting the gear from traveling further down is the othe gear coming in from the side. To add to this, the gear sitting on the main shaft is fitted with such a press fit that the only way to move it along the shaft is by using a hammer! Again making the tightening nut useless


I started mounting the main bearing, but ran out of grease so stopped the assembly here



In the meanwhile, i started stripping the heads for paint


The old badge was removed and is probably not going to be refitted again


I also started sanding down the housing, but the paint is thick and requires a lot of sanding to become even. The dust also smelled quite toxic, so I will need a good mask before I make further progress.

[dsquire]

Trion

Thanks for the update on the repair. You certainly should have a very fine mill when you are finished with the repair and cleanup that you have undertaken. It seems like a lot of work now but it will be worth it in the future. 

Cheers 

Don

[Brass_Machine]

Trion...

Wow. What can I say, but this is a very good post to read. Lots of pictures! Ingenious use of shop made tools! Did I say lots of pictures? Clear ones at that. I am sure you will get the Sajo up and running again. Probably even better than it has in a long time!

Eric

[djc]

I notice that you are using grease in the bearings during assembly. Is this mentioned in the manual? There is an external nipple for periodic lubrication. What are you supposed to pump in there? What happens to it when it gets inside the head? I'm not saying you are wrong, but it may be that the bearings should be _oiled_ not greased.

With respect to the mitre gears, one or the other needs to be movable to set the backlash and the depth of mesh. You might have to do a trial assembly without the mitre gear and set the bearings. Measure from the underside of the bearing to the shoulder (or the top of the shaft). Disassemble and fit the mitre gear with a spacer up to the preload nut. Set the position of the gear (using cigarette paper or something between the teeth as a spacer). You might have to make a very temporary fixture to keep the top of the spindle central, or do it all with the head inverted so it hangs from what is normally the bottom bearing. Measure its position relative to the top of the shaft.

Make sure there is no clash between top of gear and bottom of bearing, remembering that you might need to readjust the bearings after running in. If there is, you might have to grind a little off the top of the gear. Much better if there is a gap that can be shimmed as it's easy to remove a shim.

In operation, the forces will tend to push the gear nearer the bearing (loosen the mesh), hence I don't think it would harm if you lapped out the gear so that it is a tight but sliding fit on the shaft (have you checked that the gear itself WITHOUT THE KEY is too tight on the shaft as it is possible that it is binding on the key?).

[Davo J]

Hi,
I have been watching this thread from the beginning, and for someone new to milling machines you sure have taken to it like a fish to water.
Good onya for getting in and fixing it up, it will be a dream to use with all it's rigidness when you have finished.

Dave

[Trion]

Thanks for the kind words guys

To answer some of the more technical questions:
- The bearings and the internals of the entire gearbox are only lubricated by grease. Recommended lubrication on the grease nipples are once a day in full time production, that's why I figured it might be a good idea to lube them up at once. The main bearing seems to come short on the daily lubrication, therefore I am extra carefull to get this one greased up before assembly.
- I have checked, the gear still needs to be hammered to slide on the shaft, even though the key is not fitted, so the internal diameter of the gear is a bit too small.
- I believe I have not explained the assembly of the head thurhoughly enough, will have to take more pictures as they say more than wat I am ever going to be able to explain. Briefly, the main bearing is tightened against a flat ball bearing. Both bearings sit in the lower part of the head, and the main bearing is tightened by turning the big threaded ring sitting beneath it. The flat ball bearing has one side facing the main bearing, the other side faces the lower part of the housing. The main bearing may therefore be tightened without the upper (regular roller bearing) ever being mounted, as the entire tightening is done in the lower part of the housing. The top bearing is a roller bearing as said, but it has no lip to take axial forces. In other words, The inner ring and the rollers may be pushed out of the outer ring only by the force applied by one finger. I believe this is made that way to allow for movement, when tightening the gear adjustment screw.
- I like the idea about lapping the inside of the gear to make it a tight sliding fit. This would ease assembly, disassembly and tightening. But then I would have to learn how to lap first Input is much appreciated!

[Trion]

Made some more slow but steady progress

Sanded down the housings and started masking them




Here's the main spindle assembly, hopefully my explainations about how it is assembled makes more sense now


The flat ball bearing is located where the grease comes out. The ring with a bigger OD above it is laying against the inside of the spindle housing


Somewhere in here


Both housings and a cover sanded down, washed and ready for paint. Yup that's an original Porsche 944 desktop paper I'm using as bench protection, old rubbish.. If it only were nissan


Here the housings have all gotten their first coat of paint


Then I turned my attention to the gear which had a very tight press fit on the main shaft. Since I know little about lapping and how to get about increasing the internal diameter of the gear, I decided to reduce the diameter of the shaft instead. I though about turning it, but when I chucked it up in the lathe I got minimum 4/100mm of runout on the surface to be turned. This was very far away from the chuck, much closer to the tailstock, and I don't know how to adjust runout when something is aligned on the live centre. Considering that I only wanted to remove about 1-2 hundreds, I started looking for a better(?) solution
I decided to chuck the shaft in the lathe, and to sand down the surface in question, but first those new bearings needed to be protected from dust and such..


I used 120grit paper and WD-40


After many attempts I finally reached a tight sliding fit on both the bearing and the gear (with the key also fitted)


Now a few coats of paint remain, then it's off to the assembly line

[cidrontmg]

You sure go to some lengths with the rebuild. It will be (and look) better than new when you´ve put it together again.  It´s a nice mill, although in my shop, it would fill the entire floorspace, and would have to be operated from out of doors   

[Trion]

Thanks!
I see what you mean, when I'm buying/building myself a house, there is no way around having a proper size garage!

I was just out and applied the third coat of paint just now. I thought I'd get a better surface using a roller brush, but instead I ended up with loads of small hairs in the paint If it looks too bad, I'm going to sand it down and apply another coat with the trusty old brush. After all, painting this is not something I plan on doing again the next 20 years..

[Trion]

Beware, many pictures to follow

Here are the housings after three coats of paint


I used a fluffy roller brush on the last coat, and unfortunately it lost many of it's hairs to the paint


But, I was anxious to get it assembled, so I removed the paint masking


Cleaned all the parts and lined them up


Outgoing side of angular housing assembled. What worries me is that the bearings of this shaft have no means of additional lubrication as the machine is being used, while the other two shafts have grease nipples that lead grease in to the middle between the bearings


Then I put the housing on wooden blocks and assembled the ingoing shaft as well


Next up was the main spindle assembly. I had gotten hold of some more grease and lubed up the bearings before assembly


Then I laid in the gear, before I put the shaft in, slid the gear onto the shaft and was able to start tightening the spindle bearing nut


Here you see the gear lurking inside its housing


Here's a view from the top, without the top bearing in place


Before continuing with the assembly of the main spindle, I had to put the two housings together


Then I found the top bearing and cleaned of the hard oil with some wd40. I hope this picture explains what I mean about roller bearing without a locating edge.


I used the cut inner ring of the old bearing to carefully knock the new bearing in place, after having knocked the outer ring in first.


Quick trial fit of the assembled head


Then it was time to get the quill head of


A bit of fiddeling later, the new head was finally on


I managed to damage the paint a bit during the mounting as it is just at the limit of what I can lift by myself.


Before doing anything more, I let the spindle run at 110rpm for a minute, then I tightened the top and bottom bearing nuts.


Out of interrest, I got the dial indicator out, to measure the runout of the spindle with the ER32 collet chuck mounted


On one full revolution I only had 0,01mm of runout, and that might also be from the outer surface of the chuck


I dug out the little MIG welder and tacked the previously broken T-slot bolts together again


Put them under the vise and dialed in to within 0,02mm. (The surface I measured on was not perfectly flat so it was difficult to get an accurate reading)



Then I figured I had to set the tram on the mill, so a tramming tool was needed. I found some random steel rod and put it in the lathe


After a bit of turning I had a shaft with a <10mm shank


I planned on cutting of another section of the same shaft and mill it, but I got too carried away, so I just put the newly turned part in the vise I guess I'm not getting any awards for proper milling setup either


Just out of curiousity, I tried milling a flat on top of the bar, to aid in seeing how straight it was mounted and to get an idea of how the tram was


After having knocked the bar to a semi horizontal position (lacking parallells), I chucked up the centre drill in the collet chuck (lacking drill chuck) and drilled a hole for the dial indicator location.


Then I drilled the hole with a 7,5mm drill, before I stepped up to a 8mm drill to get close to the final size


Then I flipped it over, and again by eyesight measured that the new hole would be somewhat perpendicular to the previous one.


After having centre drilled the hole, I drilled it to 4,5mm to allow for good space around a M4 screw. I also made a relief cut with the hack saw, but it was so tilted I don't dare to show it here
Since I had drilled the original bar, I had to turn up another one. I grinded it a bit on the end, making the parts ready for welding


The MIG welder was used again, and here's the result


I also welded a M4 nut to the back of the tool, as this was much easier than trying to tap the poor thing


And woila, the tramming tool was ready for use


It was a bit of a pain to tram the head as the tramming tool was offset from the centre of the boom and gravity only wanting the head to rotate in one direction.. But after some swearing, I managed to get it pretty close to straight. From what I could red of my dial indicator I was about 0,01mm of when I settled with it. But my table has a very rough surface so it was hard to measure accurately.


Now that everything seemed fine, I lobbed up a piece of odd shaped aluminium in the vise and felt ready for milling


My first chips (with the vertical head)
But I must admit, I'm a lazy bastard. I only turn the handwheels for positioning of the tool, then the auto feed does the rest of the job


I cut the surface back and forth with no thought about climb milling or other stuff, just to see how the surface would look


It's a rough one. The depth of cut was definetely the largest to the right, where the marks also are the largest. There is a noticeable ridge between the paths where the tool has traveled. Not quite sure what the cause of this is



Previously I had tried to measure the table wear by putting the dial indicator on like this and then pushing/pulling at the end of the table (as to rotate it arond the vertical axis), and I got 0,48mm of indicator movement. I also tried putting the indicator on top of the table, lifting/leaning on the end of the table. The indicator traveled 0,50mm, accompanied by a squishing sound as from an oil film being broken


When doing this test, I had not locked the Y- and Z-axis (not that the Z-axis lock is working anymore anyways) so the measured movement probably comes a bit from each axis.
I thought about adjusting the table gibs, so I cranked (not really, I used the rapid power feed ) the table to each end to look at the adjustment screws.
On the small end of the adjusment gib, the screw is unscrewed until it stands against the lubrication pump housing.


On the big end, is is adjusted as far in as possible. My only option seems to be shimming..



I thought it was time to try making some T-slot nuts, but only found a stainless plate in the suiting dimension. So I tried milling the top of it, before I called it a day.
I need to think out a way to make those nuts without having neither parallells nor a clamping kit



Todays questions:
- Where can I buy a 0,20mm shim that is 400mm long?
- What can cause the ridge on the milled aluminium part?
- How can I make my mill table flat and shiny?