Disassembling of Minimill / X2-clone / XJ-12 Ballbearings

John,

 

The link doesn't work for me. Can you help?

 

Peter G. Shaw

Not sure what has happened as it obviously has worked and I tested it after posting but it does not work now so here is the link again.

 

 

If that dosent work it can be found as file 'Seig X2 X axis Alignment Aid' in:

 

 http://groups.yahoo.com/group/GrizHFMinimill/files/

 

John

 

Tested and working now.

Still doesn't work, and the yahoo reference wants me to join a group. So I give up.

 

Many thanks, John anyway.

 

Regards,

 

Peter G. Shaw

Ok Lets try this way. (For some reason it would appear that Yahoo URLs change frequently.)

There have been many posts and articles about the need to align the carriage and spindle housing on the X2 or its variants. The following does not repeat the methods that may be used to measure and correct the alignment but shows a simple modification that will take some of the hit and miss out of the adjustment.>>

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Basically the modification is a bar bolted to the motor mounting plate with two adjusting screws with lock nuts that “rock” the casting into alignment. I hope the picture shows the principle and I will not give dimensions as they are not critical. I did originally consider just drilling and tapping two holes in the mounting plate for the adjusting screws but having looked at the under side, its shape does not lend itself to this so the bar was added as an extension. The only modification to the machine is two 6mm tapped holes in the end of the motor mounting plate to attach the bar.>>

> >

The photograph shows the prototype – At some stage I will probably replace the adjusting screws with socket screws. I may also consider putting two locating dowels in the bar/motor mounting plate. >>

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In use the head is lifted nearly off the column so that the four bolts holding the carriage and spindle housing together are slackened slightly. I then used Rolies Dads Method (RDM) that is well described elseware to achieve alignment. The two adjusting screws are initially set to just touch the carriage casting and one of them adjusted to correct the error. I found that very fine adjustment can be achieved without having the four bolts too loose. This and the bar itself means that there is less chance of movement when everything is tightened up. Leaving the bar in place will also help to prevent future movement and provide a reference if you have to dismantle.>>

 

Ok.. i got the mini-mill today..

It is not bad, it seems a good  little machine

I measured the spindle runout (outside): less than 0.01 mm.. the report included  says 0.01 at the end of the spindle and 0.02 100 mm to the end of the splinde

 

Anyone has checked the spindle runout of this kind of milling machine?

 

About the dials.. on the cross table are graduated 0.02 mm.. 75 x revolution total 1.5 mm/rev (0.02*75)  

75 of course is the number of the minor graduations, not 0.75 mm /rev

the vertical fine feed.. 0.025  x 60 ..again 1.5 mm/rev

 

 

 

 

Hi Roberto,

 

Agree with the dials, but still difficult to use. I have a conversion table on my mill giving the number of divisions for varying amounts of travel, eg say 1mm and 0.25 mm. So if I want 1.25mm, I add the two numbers together. Job done.

 

Haven't checked spindle run out.

 

Regards,

 

Peter G. Shaw

Marcus,

 

I changed the bearing out on my X2 clone (Chester Conquest) when I moved over to a belt drive conversion...Taper rollers from a local bearing supplier (SKF brand).

I didnt bother with the smaller bearings as I didnt replace the countershaft.

 

My mill is much quieter post conversion.

Posted by Peter G. Shaw on 09/06/2010 12:48:52:

Hello Peter

it is a very good idea.. i will do the same,  your table is very  helpful !

Thanks

Regards

Roby

Hi Roberto,

 

Does this help?

 

Posted by Peter G. Shaw on 09/06/2010 20:37:26:

 

Hi Peter

 

Yes.. it helps a lot!!!!

ehehe

Thank you very much

 

Regards

Roberto

Well chaps I have just started to convert mine to belt drive.

I have the drawings and info from John Rudd I will need some carefull thought to mod these to suit my WARCO due to the spped controller box location.

 

I have stripped it all down today and after extracting the small gear that had broken into about 20 bits and removed 4 teath from the other gear.

The first job was to replace the bearings with taper rollers.

My bottom ball bearing also fell apart when removing the shaft from the head. The inner race was a VERY tight fit on the shaft. If I did not have a No3 broach press I would not have got it apart.

They have been replaced with Nachi H-E30206J bearings from ARC Eurotrade. These are exactly the same as those used in the mini lathe, as mentioned above.

I also needed the press to get them back on. Fitting these has reduced the length of shaft above the bearing by approx 4 mm.

As I have no intention of using gears ever again I have removed the layshaft from the head.

I have left the small bearing in the head and blanked the centres with grommets.

 

I know the tapers are open at the bottom but so are the ball bearings and the metal fling washer and plastic collar over the bearing obviously do their job as there was NO contamination in the old ball race.

 

If only the rest of the mod would go as easily.

 

Regards Clive

Thanks Clive,

agree to use tapered bearing if you remove Gears from head.

I'd like to use gears for a while, so I'm worried about contamination.

(let me prepare my own belt conversion Kit )

 

Have someone used a couple of 6206ZZ for upper and bottom sides ?

Is the precision worst?

 

regards

Paolo

 

 

It was only recently it ocurred to me that replacing those stupid 75 division index wheels with 60 division ones would give me 0.025mm/division which is close enough to a thou for my agricultural approach. Also 10 divisions = 0.25mm, 40=1mm and I can ignore that discontinuity at 75 divisions. Best of all, its the same as my lathe then, so only one set of thought processes needed!

 

I plan to modify teh existing or make new dials soon.

 

Neil

Yesterday I have  checked the run out  of the stock spindle and bearings

 

This is the video

It seems very good (the dial indicator is metric 0.01 mm).

The accuracy report of the machine says 0.01 mm at the end of the spindle, and 0.02 mm 100 mm to the end of the spindle.

 

Mine is a WARCO mini mill and the switch box gets in the way of both mode I have seen and leaves no space to dog leg round the back of it.

 

After a bit of measuring and ponderingI worked out that I could move it down so the top was level with the head thus giving me space fot the T shaped mounting plate.

 

The draw back is that it is now below the bottom of the head.  The just acceptable news is that that bottom edge is level with the morse taper mouse.

that should not be a problem for me as I nearly allways use an ER32 collet chuck which drops the cutter some 50 mm + below that point.

 

Now to start on the metal.

 

Regards Clive

> morse taper mouse

It's good to know that we can obtain pets that are compatible with our tools. A friend spent ages trying to get hold of a Browne and Sharpe gerbil.

 

Neil

On both my mill, and my friends mill, the fine feed did not work. The manual did not even mention it, and it wasn't until I downloaded a document from the Little Machine Shop in America that I found out how to make it work. What my friend and I discovered is that there is a gross misalignment between the the support block and the bracket adjacent to the fine feed knob such that the support block requires shimming out along its front edge (as you look at it from the front). Furthermore, the support block housing is too short for the actual worm itself, causing binding of the worm inside the block. This is cured by, in my case, adding washers between the end cover plate and the support block thus giving clearance for the worm to rotate. In addition, my friend discovered that his was seized up due to gunge."

 

Peter :

 

Can You please explain a little bit more about the "support block and the bracket adjacent" and also "the support block housing" , my problem here is that i acctually dont understand thoose english words, but i have the schematic with all parts numbered so i can easily see what part that is discussed. 

 

 

 

 

click to enlarge.