Denford Triac Spindle making an odd noise. Bearings at fault?

[Lieutenant Swarf]

Hi, thanks for reading this
My Triac spindle has started making a horrible noise when increasing in speed. It doesn't seem to matter whether the jump in speed is a relatively large one as shown in the video (link below) or a smaller incremental increase. The slowest speed I have noticed it making the noise is between 800 and 850 rpm. It is also possible to get it to settle down by increasing the speed well beyond the desired rate and then backing it off to the original speed. EG if the noise occurs at 2000 rpm, increasing the speed to 3500 rpm and then stepping back down to 2000 rpm stops the rattling sound.

I have also noticed that the top bearing support is getting almost too hot to touch after running the spindle for a few minutes whilst it makes the noise. I'm leaning towards a problem with the bearings and hoping that some of the members here will be able to give some insight
Many thanks in advance for any advice offered
Video Link:
https://youtu.be/8KDG7i_jGmE

[Chaz]

Hi, as per my email to you, the belt is loose.

The bearings getting hot might be due to a lack of lube or perhaps they need to be replaced. But based on the video, the belt is lose.

[m_c]

It does sound like the belt is flapping around, but I'd be wondering why, as unless somebody has recently been slackening the motor of, it shouldn't suddenly become slack. However the spindle does seem a bit noisy in general, but that could just be the video.

Also it heating up that quick is not a good sign. I'd be taking the motor of, and giving the spindle a spin by hand to see how it feels. I'd also be checking for play with a DTI, but to check for correct adjustment, you really have to take the cylinder and the top support housing/bearing of, as the top bearing will mask any play in the main spindle bearings.

[Chaz]

It does sound like the belt is flapping around, but I'd be wondering why, as unless somebody has recently been slackening the motor of, it shouldn't suddenly become slack. However the spindle does seem a bit noisy in general, but that could just be the video.

Also it heating up that quick is not a good sign. I'd be taking the motor of, and giving the spindle a spin by hand to see how it feels. I'd also be checking for play with a DTI, but to check for correct adjustment, you really have to take the cylinder and the top support housing/bearing of, as the top bearing will mask any play in the main spindle bearings.

The reason for this is that the mounting system is not ideal. The bolts are also not locktighted (is there such a word) which means that they can and will come lose.

Ive seen another way to do a servo mounting, which is the extend a shaft down and keep the motor mounted higher up. When I did this mod (this is my old machine), I opted to do something to get me running as my DC motor had died. Multiple ways to deal with the bolts coming lose (there are only 2), ideally 3 or 4 if possible.

The bearings might be tired, perhaps if the lot is being stripped / sorted, a new motor mount could be machined and used that is better than what I had originally put in place.

[m_c]

That'll explain why it's come slack then. IIRC the original mount used 3 bolts, as the other corner is cutoff due to the head casting shape.

To the OP, if you search for my Triac retrofit thread, you'll find how I made a new spindle motor mount to fit a servo, along with some details to rebuild the spindle with new bearings.

[Chaz]

That'll explain why it's come slack then. IIRC the original mount used 3 bolts, as the other corner is cutoff due to the head casting shape.

To the OP, if you search for my Triac retrofit thread, you'll find how I made a new spindle motor mount to fit a servo, along with some details to rebuild the spindle with new bearings.

Ah, that was your mod, wasnt it? Yes, 3 bolts but when I did the bracket I could only get to 2, as the motor effectively is too big to fit. Your idea is better but needs more work.

[andy_con]

Also the spindle bearing is 20 odd years old, mine went and i had to change it.

Bearings don't last forever

[m_c]

My mod was quite a bit of work. I think the lathe work alone took about 3-4 hours, as it was a big lump of bar to hollow out.

Now I've had time, this post gives the process of renewing the bearings - http://www.mycncuk.com/threads/10344-Yet-another-Denford-for-the-collection-%28Triac-Retrofit-thread%29?p=88817#post88817

And the spindle motor mods start a bit further down that page - http://www.mycncuk.com/threads/10344-Yet-another-Denford-for-the-collection-%28Triac-Retrofit-thread%29?p=89732#post89732

[Lieutenant Swarf]

Thanks to everyone who has replied, it really is very much appreciated.

Chaz-Tightening the two bolts holding the motor has eliminated nearly all the noise for now. However the top bearing support is still getting hot. Thanks very much for your rapid response and friendly advice.

MC- Thanks I will take a look at those links you have posted and hopefully get some ideas about a long term solution to mounting the motor.

Andy- I looked at an old post of yours on the Denford Forum and hoped that you might have some good advice. Did you replace your bearings like for like or did you upgrade when you made the swap?

Thanks again guys

[Lieutenant Swarf]

My mod was quite a bit of work. I think the lathe work alone took about 3-4 hours, as it was a big lump of bar to hollow out.

Now I've had time, this post gives the process of renewing the bearings - http://www.mycncuk.com/threads/10344-Yet-another-Denford-for-the-collection-%28Triac-Retrofit-thread%29?p=88817#post88817

And the spindle motor mods start a bit further down that page - http://www.mycncuk.com/threads/10344-Yet-another-Denford-for-the-collection-%28Triac-Retrofit-thread%29?p=89732#post89732

Wow MC that is outstanding work on that Mod! Really inspiring stuff.

[m_c]

Wow MC that is outstanding work on that Mod! Really inspiring stuff.

I was lucky in that I had time to design a suitable mod, and didn't have to rush and make do with whatever I could my hands on.

If you want the fusion 360 files or any drawings, let me know and I can email them across. To design it I had to create a model of the head casting, so I could see what would/wouldn't fit.

[Lieutenant Swarf]

I was lucky in that I had time to design a suitable mod, and didn't have to rush and make do with whatever I could my hands on.

If you want the fusion 360 files or any drawings, let me know and I can email them across. To design it I had to create a model of the head casting, so I could see what would/wouldn't fit.

That would be fantastic. Thank you very much. I will PM you my email address.

[andy_con]

That would be fantastic. Thank you very much. I will PM you my email address.

Where in the UK are you?