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Mill spindle trouble?

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Wolfie07/01/2012 19:23:58
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OK as you know I have finally acquired a milling machine, an Amadeal XJ300-12.
 
It arrived yesterday and I've been setting it up and cleaning that awful grease off it and finally started to use it this aft..
 
I have an ER25 collet set so was using that. The first thing I had to do was drill a number of holes and I started to notice that the holes were slightly different diameter top and bottom. Tapered slightly in other words. Wider at top than bottom.
 
Looking at the top of the spindle where the drawbar pokes out, there is a clear wiggle going on. Not much but I can see it. Same at the bottom but I couldn't see it until I started using an endmill which is much bigger than the drill I was using.
 
The implication here is that the mill spindle is slightly out. I'd like to strip it and put it right but I'm not very familiar with these machines. I do have the manual with it but the translation leaves something to be desired, (apparently it has foxes but I haven't found them yet!).
 
I do however have an exploded view of the spindle but its not very clear. What should I do?
V8Eng07/01/2012 19:29:04
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Hi.
 
Personally speaking (if it's new & under warranty), I would stop using it and contact the suppliers about the problem on Monday.
 
 
 

Edited By V8Eng on 07/01/2012 19:42:31

JasonB07/01/2012 19:50:56
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As said if its new have a word with Amadeal first.
 
I had similar on my X3 when I got it, the adjusting nuts on the spindle bearing were loose and just needed nipping up to get rid of teh 0.030" play in teh spindle.
 
J
Ketan Swali07/01/2012 20:06:16
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I don't know the machine, but it looks similar to an X2 head. If so, I go along with what JasonB has said. It may be that the locking nuts may have become loose.
 
If it is similar to an X2, look on ARC's website at the C3 mini lathe preparation guide and/or bearing change guide. The X2 head is more or less a mini lathe head stock turned vertical.
 
Ketan at ARC.

Edited By Ketan Swali on 07/01/2012 20:07:57

Wolfie07/01/2012 22:11:20
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I suspect you are right. Thanks for that Ketan it looks similar-ish.
 
I've sent Amadeal an email just in case but I'll go have other look at it tomorrow now I've seen that C3 stuff.
 
Am I likely to need bearing presses?? And does it also follow that replacing chinese bearings with taper bearings will improve matters??
 
Still ain't found the foxes
Wolfie07/01/2012 23:14:04
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You are absolutely right Terry and I will not be fobbed off.
JasonB08/01/2012 07:47:14
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Wait to hear from Amadeal first, I'm sure that if you mention that you have asked on a Forum they will want to ensure the matter is resolved quickly
 
You won't need to actually remove the bearings so no press required, it just that the two bearings may not quite be set close enough together and just tightening the nut will close them up enough.
 
The main thing to establish will be is it due to the bearings or is there a bend in the spindle, you may be able to feel movement by holding the chuck and pulling back & forth.
 
J
Ketan Swali08/01/2012 09:06:10
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Posted by Wolfie on 07/01/2012 22:11:20:
I suspect you are right. Thanks for that Ketan it looks similar-ish.
 
Am I likely to need bearing presses?? And does it also follow that replacing chinese bearings with taper bearings will improve matters??
 
Still ain't found the foxes

Hi Wolfie,

To establish how close it is to an old/original X2, go to this link and open up the exploded diagram as suggested near the top of the page.
 
http://www.arceurotrade.co.uk/Catalogue/Machine-Spares/X2-Mini-Mill-Spares

Broadly speaking, if the head is similar, what JasonB suggests is correct, and hopefully, just tightening the nuts which might have become loose in transit, or incorrectly assembled, could solve your problem. Before tightening them, take them out and have a look at them, to avoid cross threading, if you feel that this might be a concern.
 
A bend in the spindle is rare. Too tight spindle diameter tolerance could effect how easily the bearings were/or not mounted onto the spindle, and how they are sitting on the shaft/in the casting. Assembly could be an issue. If this is an issue, then a puller of some description will be required, and you may or may not wish to rectify this part of the assembly yourself or send back to Amadeal to solve for you, if you still want the machine and not want to send it all back.
 
Replacing bearings is a secondary issue to be considered only if you are not happy with the results. I don't know what bearings are inside your machine. Have a look on the parts list and state what bearing are there - it does not matter if it is a Chinese bearing number or an SKF number. We can then figure it out.
 
If they are ball raced bearings - doesn't matter if they are Chinese or European in this particular instance. You can put a better pre-load on taper roller bearings or angular contact ball bearings then you can on ball bearings. So, in this respect, the results will be improved if you use these bearings over ball raced bearings.
 
If you have 6206-2RS bearings inside, you could replace them with 30206 taper roller bearings. We have not tried this, but we are aware that others have, with improved results. the concern here is that 30206s are wider than 6206-2RS, so some modification to a spacer may be required, but as we have not tried this on an X2, I cannot say for sure.
 
We will be offering 7206B-2RS sometime this month. Dimensionally, they are same as 6206-2RS. They will allow faster running than 30206 taper rollers, they are sealed. 30206s are not.
 
Ketan at ARC.
 
 
Wolfie08/01/2012 09:25:34
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502 forum posts
Looking at that diagram, its identical in the spindle area. I'm going from memory, the machine lives in my workshop which is elsewhere in town. There are differences elsewhere but I'm pretty sure the spindle and motor unit is the same.
 
Which is the bearing nut, if its no119 (spindle nut) then I've already removed it, cleaned it and tightened it back down. Thats the one I can see has a wiggle on when its turning.
Ketan Swali08/01/2012 09:38:41
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Yes 119. Is it a wiggle because of the way the nut looks - i.e.machined on the o.d., or does the nut look properly machined?
 
If the nut looks properly machined, then it does seem that there could be an overall assembly issue. So, from here on, it is up to you how you wish to deal with it.
 
If it was me, I would speak to Amadeal and ask them if they are happy for me to take the spindle out and have a look, for the purpose of correcting or replacing.
 
Ketan at ARC.
JasonB08/01/2012 09:50:33
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The fact part 119 is retained with a grub screw from the side could be wahts making it look eccentric or its just bored off centre, its the spindle you want to see the wobble on or not.
 
J
 
PS My X3 mentioned above did not come from Ketan@ARC
Ketan Swali08/01/2012 10:41:50
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Hi JasonB,
 
...I don't think it matters that your X3 came from ARC. From time to time, all sellers have problems with machines supplied by them...even ARC...
 
I was just interested in this particular post, and wanting to figure if and how it was possible to solve this problem.
 
Forums are a good place to try and find constructive help.
 
Thanks, Ketan at ARC.
NJH08/01/2012 11:12:16
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Ketan
 
It's greatly to your credit that you are prepared to jump into this bear pit and offer informed, constructive, advice on another supplier's problem. I'm not in the market for any more machinery but, if I was, I would certainly consider yours.
 
Regards
 
Norman
Wolfie08/01/2012 11:38:32
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502 forum posts
Thanks all for suggestions, I will check it with a DTI this aft. Its terminology again, what are:
 
run out
 
up and down slop?
 
Don't think that grub screw was done up, would that make a difference?
 
I agree with Nigel, Ketan  your help is very welcome to a beginner.

Edited By Wolfie on 08/01/2012 11:39:13

JasonB08/01/2012 13:23:18
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"Don't think that grub screw was done up, would that make a difference? "
 
Yes it will could have allowed the nut to come loose and therefore the bearings will be sloppy.
 
J
Wolfie08/01/2012 19:18:34
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502 forum posts
OK chaps looks like its egg on face time.

I went back up to my workshop (parents garage) today and had a much closer look. I believe as someone said that I have been fooled by the way both the nut and an endmill look when turning at speed assisted by the fact that the top of the drawbar isn't quite concentric with the spindle.
 

 
As they have projections/indentations it gives the effect of movement side-to-side. So I put a piece of more or less parallel bar in the collet, tried to move it and then applied the DTI.
 
Results as follows: Couldn't find any play in spindle by moving bar.

DTI on morse taper and collet holder, very little deviation at all
 


I then applied DTI to bar, top, middle and bottom. Top and middle, 0.1mm deviation and maybe 0.3 at the bottom.




I can also report that having milled the tops of some clamps I'm making, they are square both ways on so I reckon its OK.
 
Looks like I got that one wrong, fooled by a bloody nut doh! Apologies all round but thanks for the help anyway.

HOWEVER! I tried to slot mill for the first time ever and on plunging the slot mill I encountered an awful lot of vibration. This was countered to a degree by doing up the gibs, but still was a bit rough.
 
I was cutting a slot in 8mm steel, and when I went all the way through and then cut the slot, the slot is a bit ragged but when I went down a bit and then across and then down again and across it was much better. Is this normal?
 
Clamp on right, slot cut in one hit, note the wandering, clamp on left, slot cut in 4 passes. Much better but note top end where it is slightly larger due to vibration on plunging.
 


 
JasonB08/01/2012 20:26:36
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On an X2 size machine I would think an 8mm cutter would take about 1mm depth at a time in steel.
 
J
Wolfie08/01/2012 20:39:20
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So doing the 8 mm slot in one hit was a no-no then?
 
I did 3 like that
Ady108/01/2012 21:01:14
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You'll get a nice purring whirry noise if everything is perfect as a milling cut progresses.
 
If there are any issues then you'll get various noises and vibration.
 
Like with a lathe, but with a lathe a good cut produces a nice hiss.
 
I also drill some strategic holes with a drill bit first when possible.
Drills cost buttons and can be resharpened in seconds and some strategic holes can save a fair amount of work for a slot drill

Edited By Ady1 on 08/01/2012 21:08:00

Stub Mandrel08/01/2012 21:17:01
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Wolfie,
 
It all depends. On my X2 I have happily been taking 11.5mm wide cuts in cast iron with no trouble- its lovely 'soft' cast iron. Then today I hit real trouble on a much smaller cut -blunted a freshly sharpened cutter - it turned out there was some moulding sand stuck to the iron under old paint and the shallower cut didn't get underneath it
 
I also was milling 3/8" by 1/16" slots with no trouble.
 
I would say go by the amount of vibration - the machine will tell you when its unhappy.
 
Neil
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