Help Quieting Spindle Down

[steelcogs]

I have a G0704 with AC bearings and a DMM servo spindle motor using Hoss' timing belt drive conversion currently running at 5000 RPM max. Eventually I'd like to get 7500 max for smaller tools, but that's down the road from now. My issue is that even anything over the stock RPM, gets quite noisy. A little bit of noise is alright and expected, but below I'll put of video of what I'm currently experiencing. It's ~60dB ambient noise and ~98dB with it running just at 3500 RPM (which is what I'm limited to until I have a 240v outlet installed for the spindle motor). I've tried with and without the little adapter that goes between the splines and the top portion of the quill with no noticeable difference. FWIW I also used one of those vibration apps to check it and at 3500 it actually wasn't too bad.

I've heard timing pulleys are often the cause of this. I'd like to try the Poly V-belt ribbed pulleys, but I can't seem to find them as easy as I could find the timing pulleys that were on SDP/SI. I'd make them myself, but I don't have a lathe so I can't really do that. Is there a good source out there for these pulleys? If it's somebody who can do custom bore sizes on the cheap too, that's a bonus lol. If not I can just bore it out myself but I doubt it would be as concentric.

Another thing I've heard is that bearing preload has a place in this. I also tried different preload settings, loose, medium, and rather tight with no difference in noise. I did notice that I can't seem to get a perfect balance of preload though, if It's too tight it doesn't move smoothly (obviously) but if it's not tight there's a very small amount of axial play. I think I can work around the axial movement though because if I (when installing the pulley) hold the bottom of the spindle upwards then seat the pulley at the lowest it goes it takes out that slop. Probably not the best way but it seems to work.

https://drive.google.com/open?id=14s...dP0d53YG3DJIpv

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[timlkallam]

I have a Sharp 2412 mill my spindle was getting to the 100db range changed the timing belt now
its back down to 70db . The belt looked fine also check that the belt is not riding to hard on the pulley flange.

[steelcogs]

I have a Sharp 2412 mill my spindle was getting to the 100db range changed the timing belt now
its back down to 70db . The belt looked fine also check that the belt is not riding to hard on the pulley flange.

I do actually have another belt on the way so I'll definitely try that when it gets here. The pulleys aren't flanged but it definitely does ride up or down and I can't seem to get it to sit still. I used a DTI to get the angle of each pulley flat within .002-.003" and used a straight edge to get each pulley parallel to each other. This was another reason I was interested in the ribbed pulleys since it would, in theory, be harder to have the belt ride up or down.

[109jb]

I made my own belt drive and used a poly V belt that I ordered it from Amazon. Once you figure out the length and rib count you need you can just search for iy on amazon. for example, my setup uses a 190J6, so I just searched amazon for 190j6

[steelcogs]

@109jb Yeah I'd make my own if I could. I've seen people 3D print them, I can't help but think these wouldn't last long but it may be worth a try.

[109jb]

You could buy a R8 lathe chuck and machine them on the mill itself, essentially turning the mill into a lathe. https://www.shars.com/3-3-jaw-self-c...chuck-r8-arbor

[steelcogs]

That's not a bad idea, I'd just have to figure out how to set that up properly lol. Seen it done but never tried it myself.

[cncuser1]

@steelcogs 3D printing a pulley out of any polymer is not a solution for a mill that cuts ...metal. The pulley would have a finite life.


The suggestion about using the mill as a lathe is great!

[steelcogs]

@cncuser1 Yeah I really wasn't on board with that idea. I'd seen it done and even seen people selling belt drive conversion kits with 3D printed pulleys but I'd no doubt rather use metal for obvious reasons.

I like the mill-lathe idea, I just need to figure out CNC lathe toolpaths. Never done it before.