# Sieg SX2 mill



## Ghosty (Oct 10, 2016)

Hi all,
I purchased the Sieg SC-3 Lathe (brushless motor) and the Sieg SX-2 mill (brushless motor) a couple of years ago. I am now seeing some chatter with the mill. The lathe will have the tapered roller bearing conversion done soon, Have ordered the bearings 3 sets. 
Has any one done the same conversion on the mill? I have checked all slide adjustments and they are all OK.
Both machines have worked with out issue in all the time I have had them.

Cheers


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## Blogwitch (Oct 10, 2016)

I have attached a PDF of an article downloaded from the Arc Euro shop site. Part way down, he discusses about fitting uprated angular contact spindle bearings. It seems it can only be done easily with the MT spindle. But it does show the whole upgrade for the bearings mod

Hope it helps you out a little.

John 

View attachment MEW201_p52_58_X2_Mill.pdf


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## Ghosty (Oct 10, 2016)

Thank for the reply, My mill has the MT spindle, my research had all ready given me that much, the bearings are different to what is used in the lathe conversion even though the two take the same bearing from the manufacturer. Will have to do a search on the bearings listed in the article. The mill I have is a brushless motor powered version the has a toothed belt drive, which has a rpm speed from 0-2500.

Cheers


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## Blogwitch (Oct 10, 2016)

My mill for CNC conversion is basically the same as yours, but with a rigid column and longer table, and one of the things I will be doing, if Arc Euro can sort out the bearings needed, is to fit angular contact bearings to the spindle. 

I don't know where you come from, but Arc should have those bearings in stock, and their postal rates and delivery times are usually fairly good.

http://www.arceurotrade.co.uk/Catal...lar-Contact-Ball-Bearing-7206B-2RS-30x62x16mm

John

I hope that the R8 conversion should be ready to proceed sooner rather than later.


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## Ghosty (Oct 10, 2016)

Blogwitch, Updated location, Live in Australia
Done some research on the two bearings.
7206-B-2RS, Angular contact, Fatigue Load Limit 0.61 Kn, Dynamic Load Limit 22.5 Kn
30206, Taper Bearing, Fatigue Load Limit 4.8 Kn, Dynamic Load Limit 40.2 Kn
Looking at the fatigue limit, I think I will look at fitting the taper bearings, the angular contact bearings are listed on the SKF website at a light thrust load bearing. Yes the angular bearings are the same width as the standard bearings, where the taper bearings are 1.25 mm wider, on the lathe the spacer requires modification, so I will look at the mill today and see if they will be able to be fitted.

Cheers


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## Ghosty (Oct 10, 2016)

Started the strip down.
Undone the motor mount bolts and removed the motor


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## Ghosty (Oct 10, 2016)

Undone the belt cover and removed the belt


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## Ghosty (Oct 10, 2016)

Done several measurements for the location on the drive pulley


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## Ghosty (Oct 10, 2016)

Loosened the locking grub screw, fitted the er32 collet arbour so I could hold the shaft to undo the retaining nut (WARNING - nut is left hand thread)


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## Ghosty (Oct 10, 2016)

Lowered head down onto a support bar, using a piece of scrap of brass as a drift, tapped the shaft down to release the pulley (WARNING the shaft with the key installed will not fit through the bearing)


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## Ghosty (Oct 10, 2016)

Removed the upper and lower bearing dust covers, removed the key


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## Ghosty (Oct 10, 2016)

Removed the shaft


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## Ghosty (Oct 10, 2016)

Removed the bearings with home made puller, scrap plate and some spacers


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## Ghosty (Oct 10, 2016)

Bearings removed, Upper bearing tested OK, Lower bearing had some movement in it.
Now just waiting on the bearings to arrive, will clean up all parts and housing ready for the reinstall.

Cheers


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## Ghosty (Oct 11, 2016)

Blogwitch said:


> My mill for CNC conversion is basically the same as yours, but with a rigid column and longer table, and one of the things I will be doing, if Arc Euro can sort out the bearings needed, is to fit angular contact bearings to the spindle.
> 
> I don't know where you come from, but Arc should have those bearings in stock, and their postal rates and delivery times are usually fairly good.
> 
> ...


 
John,
I done some research on the spindle bearings for the R8 spindle.

Lower bearing size  35x62x14

Timken, Deep Grove 6007 2RS
             Tapper        32007X

SKF Angular Contact 7007 CB/P4A
                               7007 ACE/HCP4AL1

All the bearings are the same dimensions as the standard one.
Hope this helps.
Cheers


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## Blogwitch (Oct 11, 2016)

Thanks very much Ghosty, that info will be useful when I get around to the head part of my conversion.

I am only just getting back into my shop in earnest after a long layoff, so with the backlog of jobs that need to be done, it might be some time before the CNC conversion gets to the top of the pile, but it will get done.
In fact, a good friend of mine will be doing a write up in Model Engineers Workshop about converting one exactly the same as mine, so everything has been got together to make a great conversion. Just got to get him started posting in the mag.

John


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## Ghosty (Oct 12, 2016)

Hi All,
The bearings turned up this morning, turned up the install and removal tools, will start the reassemble after lunch as I have an appointment at 11.30 this morning.

Cheers


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## Ghosty (Oct 13, 2016)

Hi All,
Installed the upper and lower outer bearing shells.

Cheers


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## Ghosty (Oct 13, 2016)

Installed the lower bearing on the shaft


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## Ghosty (Oct 13, 2016)

Greased both bearings and then installed in the head


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## Ghosty (Oct 13, 2016)

Machined the lip off the dust seals and installed the grease seals, then fitted to head, both upper and lower the same.


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## oldboy (Oct 13, 2016)

Hi Ghosty,

Where in NSW are you.  I am in Blacktown about 30km west of Sydney.   Would love to have a talk about your mill and what you have done to it.

Thankyou.

Barry (Oldboy)


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## Ghosty (Oct 13, 2016)

The rest is just reassembly of the machine, had to machine 1mm off the driven pulley to get the correct height. Done some machining of the removal too so it could be fitted into the machine for removal of the outer bearing shells. Now have almost a mirror finish, will have to keep messing around with the bearing pre-load, running a little hotter in the bearing areas.


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## Ghosty (Oct 13, 2016)

Had the material all ready cut so I started machining up some more quick change tool holders, have been messing around with the bearing pre-load as well, I think I have it set about right now. No chatter at all, will have to wait and see now.
Hope this may have helped some one.

Cheers


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## Blogwitch (Oct 13, 2016)

Very nice work G, nicely shown as well.

Unfortunately, there are a couple of problems when using tapered bearings with a preload.

The first and one that should always be followed is to allow the machine to warm up for about ten minutes before use, this is to allow the spindle to expand and reach it's working length by which time the preload should be almost non existent. I do this with my lathe, which has preloaded head bearings, before I start for the day. It might only be a couple of thou, but that could mean the difference between a failed job or not if working to tight tolerances.

The second is that if leaving the machine idle for any length of time, say over a month, you should release the preload to prevent the rollers in the bearings taking up a permanent place in the races causing 'brinelling' or make sure that the machine is run up regularly to ensure that the bearings are sitting in a slightly different position. 

I had this very badly when I was restoring my previous lathe, an old Atlas 10F. I had bought a second hand Timken bearing head to replace the plain bearing one. Because the head hadn't had the preload removed before storage, it was like a heavy ratchet when it was turned, and I had to have the races reground to get indentations out of them. I should have fitted new bearings really, but the Atlas has specially ground shaped races and would have required a second mortgage to pay for them.

There is also the problem of the age old grease or oil syndrome. In a lathe, the bearings are horizontal and usually lubricated with oil, either from the gearbox or a drip feed from the top, I don't know how you can ensure an oil feed to a vertical setup like yours as grease isn't recommended as it can cause 'hydraulicing' on the rollers and cause pitting. My mill has oil cups for feeding both top and bottom bearings.

Even though I have had a long layoff from my workshop, I religiously go  in there every week and lube up then run my two main machines for a time just to  prevent problems occurring.

John


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## Ghosty (Oct 13, 2016)

Thanks John, After doing this, I could retro fit an oil dripper, or oiling point to these machines, but the use of a light weight sticky grease and the weight put on the spindle, as these are only light weight machines, I will just have to see how much time I get out of it.

Cheers


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