Need Help! Optimum BF46 Vario spindle getting hot and tool holder sticking


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Thread: Optimum BF46 Vario spindle getting hot and tool holder sticking

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    Default Optimum BF46 Vario spindle getting hot and tool holder sticking

    Hello everyone, apologies if this is not the best place to ask, but google search seemed to show this machine being quite popular here so hopefully another owner can help.

    I've got a CNC converted BF46 Vario, converted by a company called Mobasi which I'm overall very happy with, got it late last year and after a while learning the basics of CAD and CNC by doing a bit of drag engraving with it I'm now trying some actual milling. I'm now finding the spindle gets hot quickly and the tool holder gets stuck in the spindle.

    I've tried emailing Optimum to ask about this but so far haven't got much useful aside from some advice on getting the tool holder out and saying they would not expect this on ISO40 tooling and do I actually have a MK spindle (which I assume this is Morsekegelschaft or german for morse taper). I am certainly using ISO 40 DIN2080 tool holders and the machine was sold as such and they fit perfectly (until run for more than a few minutes).

    I've experimented just running the mill at 1600 RPM for a few minutes just in the air, not cutting anything and the temperature quickly hit 50'C, do any of you know if this is normal? I'm hoping Optimum or Mobasi will get back to me soon saying yes or no, but I'd love to hear from anyone with hands on experience.

    The other question is I've had a clean and a feel around inside the spindle taper, the taper itself seems perfect, but the section at the end of it where the Din2080 pull stud (Is that the correct term?) goes felt rough and unfinished. If any of you own a BF46, is this the same for you?

    Hope someone can help me as this is the one issue that's stopping me from continuing until I can find a solution.

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    Member arizonavideo's Avatar
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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    All the RF clones have tapered roller bearings and they make a lot of heat if the preload is high. The spindle will also need to be broken in by running it in both directions at med speed and then high speed while watching the temps.

    It takes at least 10 hours of running to be mostly broken in but really it takes longer.

    If after a few hours of running its still that hot and if you have good grease in the housing then you will want to re set the bearing preload.

    The preload is set by a spanner nut at the top of the spindle and the top bearing vary well may be a press fit on the shaft do you will have to tap the shaft to loosen the bearing pressure. If it fits that tight which most do then the bearing will stick slip the fit which makes setting preload much harder.

    I would loosen the nut by the smallest amount and smack the shaft with a heavy hammer protecting the shaft with something soft. Getting it right is fairly fussy.

    Too loose will chip tools and let the bearing chatter.

    youtube videos of the G0704 under the name arizonavideo99


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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Thanks for that, I've started running it in the evenings (without a tool holder) at 500rpm for a few hours, I'll reverse directions tonight, up the speed to 1000rpm tomorrow and repeat until I get up to high speed and see what happens.

    I'll have to study some pictures on dismantling to set preload. I had a look at the top of the machine but all I could see was a shielded bearing and a look at the diagram doesn't show anything to set a pre-load on, everything seems to be held in place using snap rings.

    Thanks for the help arizonavideo!



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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    You have to remove the quill.

    The feed rack need removal by taking off the return spring on the left and on the left there is a hole that has TWO set screws that stop the quill from rotating and coming out.

    youtube videos of the G0704 under the name arizonavideo99


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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Sorry to bother you again.

    I've run the spindle a fair bit, exact hours unknown but probably at least 10 now with no noticeable difference. I've not tried changing the pre-load as the machine should be under warranty so I don't want to go messing with things before I've been given the go ahead.

    I have taken the spindle out after speaking with optimum and noticed that the top of the spindle, just above the spindle taper where the DIN 2080 pull stud goes is rather rough and unfinished. I've tried asking asking both Optimum and Mobasi if that should have been machined/ground smooth like the spindle taper but so far everyone has avioded answering the question despite my repeated asking.

    Here's a picture of the inside of my spindle, its section right where the cone of the spindle ends. Does that look normal to you guys?

    https://i.imgur.com/XHFo3MF.jpg

    I have found when the tool jams its pulling the protective plastic cap off, mobasi have claimed this is because the cap should have been removed prior to use, but the tooling guys have said it should be left in place. I ask as I would have thought that section should not actually be grabbing the edge of the pull stud at all, as my understanding is the taper should be centering the holder and presumably its not necessary for there to be any contact with the pull stud and probably shouldn't be any at all to ensure full contact with the taper.

    Blue cap in the link below.

    ISO40 ER32 Collet Chuck - 8,000rpm



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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Luke,
    When I got my BF30 clone machine, I had similar issues with spindle heat. Not the sticking tool holders though but I use MT3 tooling. On ISO 40 taper tooling the location is done only on the taper, the hole that is rough in your image would just be clearance anyway and looks to be simply drilled. I can't see a problem with that. The sticking tools are probably a consequence of the heat, I would look to sort that out first and hopefully all the problems will be cured at once.
    One way to check the preload isn't too high is to spin the spindle by hand when cold and check for the amount of friction in the bearings. There shouldn't be much. If your spindle spins down very quickly like there is a lot of drag, it is probably set too tight. I think you need to try slackening off the preload slightly as Arizonavideo suggested. The taper roller bearings in these are pretty robust, you won't damage anything by running them a little loose especially as you aren't actually cutting.
    I used an IR temp gun on mine and graphed the temperature over time. That way I knew when I had reached a plateau and whether that temp was one I was comfortable with.

    LongRat
    www.fulloption.co.uk


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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Thank you for your reply

    So this is way too stiff?

    Last edited by LukeHall; 04-29-2017 at 04:52 PM.


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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Way...toooo....stiff.

    Understatement. That should rotate with minor application of force. You should be able to spin it with your finger.



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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Thanks Kenny! Guess someone got a bit overzealous at the factory.



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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    As an example this is all the effort it takes to rotate my spindle with the motor engaged in high gear.





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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Thank you! I'll give adjusting it a go in the morning

    Edit: now adjusted to be like this




    After 30-40 mins running



    Last edited by LukeHall; 04-30-2017 at 11:31 AM.


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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Was the second temp I saw you take at the top of the spindle? the 50c reading? That's 122f and I would consider that a little hot for the upper bearing still. If that's the case you could probably reduce the preload a little more. You essentially want it just tight enough to not have any vertical play in the spindle. Adjust them just hair past not having any vertical play and you should be go. You'd really like that upper bearing temp to be in the 39-41c range after running for a bit.

    It's really a feel and temperature thing. Leave them too loose and you'll get excessive end play and the bearings will skip and slide in the race and beat the bearings to death. Adjust them too tight and you get what you saw which was elevated temperatures. There is a window of adjustment that will see no end play but allow room for the growth of the bearing material as they warm up.

    I have a test running in the garage at the moment. It's 26c or 80f in the there at the moment. I'm have the spindle running at 2400 rpm's and will leave it for 30 minutes to see what the temperature swing is on mine. I think it normally gets up to 42c or 109f after a long run.



    Last edited by Kenny Duval; 04-30-2017 at 08:14 PM.


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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Sorry, the second reading was the motor temp which seemed to peak out about 64c. I didn't check the upper bearing, but good point I'll give that a check.

    Currently it seems the spindle is barely warm to the touch, the casing around the gearbox seems warm but guessing only a bit above 30c motor is properly hot, not sure if it should be but guessing at 2.2kw its going to be dissipating a fair amount of energy as heat.



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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Then you should be in the window now. Do some cutting and keep track of the temps for a bit.

    This is after 30 minutes of running. Upper bearing is at about 34c or 94f.





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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    You will notice a deterioration in surface finish and an increase in part wall taper before the bearings start to clatter and skid if you are running insufficient preload. So the chances of damaging the bearings are slim, especially this type. It's clear that your preload was indeed set massively too high originally!
    Motor temp is a different issue, remember it may be a 2.2kW motor but running in free air it won't be pulling anything like that amount of power. I'd keep my eye on motor temps once you are happy with the preload tests and actually start cutting metal, to make sure the motor doesn't get excessively hot once it actually starts doing some work.

    LongRat
    www.fulloption.co.uk


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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Thanks I'll keep an eye on the motor temp.



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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    TRB make heat and if new should get fairly hot. If you run for a hour and the lower bearing is still below lets say 100 deg F then its too loose. It does look like you got it close.

    youtube videos of the G0704 under the name arizonavideo99


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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Hi Guys,

    Firstly, I have a BF46 Vario and had no idea that the spindle was not supposed to get that hot. I have measured temps of 90 degrees C/194 degrees F.

    Yeah now I realise, crazy hot. I run the spindle of 3 hours at 2500 rpm for it to get that hot. I had no idea that you could set pre-load on the bearings etc. I am also getting noise from the gear box. Like a rattling at say 2100rpm so now I run it at 1800rpm to avoid that harmonic. Not ideal I know.

    I read these posts and it was that moment when you realise you have been doing everything wrong for a long time and had that sense of quiet embarrassment. Oh well lets get it right from here in.

    I have added a video of the noise it makes past the 1800rpm mark.

    (Don't mind the black plastic. Enclose is being built at the moment. Its a stop gap so that chips don't fly everywhere.)


    This is the sound it makes at 2100rpm.



    I would love to get rid of that gear box and just put in a belt drive. Just for noise reduction.



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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    Hi GusBiz,

    If you're not having issues with the release of tools I wouldn't be that worried as I'd expect them to get hot after running a at higher speeds for and extended period, but someone with more experience would probably be better advising.

    Out interest, that noise when running at high speeds, does it still happen if you were to let it warm up at a lower speed first?



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    Default Re: Optimum BF46 Vario spindle getting hot and tool holder sticking

    I am about to do a complete tear down and I see if I can't create a new mechanism for a belt drive and get rid of the gear drives all together.

    No I haven't run it while warm and then increased the speed. I will try that today.

    Having them too tight is a problem. It increases wear. It could be the source of the knocking in the gear box, I don't know I will see after the tear down.

    Thanks for the response.



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