[popspipes]

Recently had an increasingly noisy spindle on my PCNC1100 Series 3. Complete spindle came from Tormach maybe 250-300 hours ago. Pulled it apart to discover the lower bearings minimal grease left on lower bearings (coolant getting in there wiping it out I believe, have a fix in mind). Ordered up new bearings and pulled, cleaned, lubed, etc. lower bearings and reassembled while waiting for the new units to arrive. Pretty sure I have preload correct. Even ran them through a breakin cycle again and paid attention to spindle temp, all seems good. They're quiet etc. BTW - new bearings have arrived but I haven't installed.

Question is I seem to be down on power. Somewhat significantly. Full width slotting cuts with 3/8" endmill in aluminum (99.5% of what I mill) bogs down significantly such that I've dropped my feed to 55-60% of my normal formula. If I try to run at previous speeds (say full width and .100 DOC, 5K RPM, 25-30 IPM) she just bogs, bogs, bogs...to the point I think she'll stall. Doesn't stall, but doesn't sound right either. No chatter or nasty noise, just doesn't seem to have the grunt the mill always has had before.

So, my simple question is, before I go ahead and swap in the new bearings, can this be bearing related? Should I be checking motor, etc. I do not have a load meter for reference. I don't recall this being an issue before I pulled the spindle apart, but I'm old, and forgetful.

Obviously this must be bearing related - I'm just trying to understand the correlation. Too much preload? Not enough? Bad bearing?

Appreciate all input - while it's apart and down I'd like to be thorough.

Bill

I use a spindle shield on mine that I use to keep coolants out of the lower spindle bearing, water based coolants or oil can get into the lower bearing, either will degrade the grease or cause corrosion. All of the spindle failures I have read about on the Tormach are due to the bottom bearings failing. I have a Bridgeport, 1952 vintage, I have had it over 20 years and never a hint of spindle trouble, I dont use it in production though, just to make parts as needed in my business.


A pic of what I use, made from a piece of scrap UHMW, aluminum would work as well, with an oring in the inner bore to give it a friction fit to the spindle, works very well, as it acts as a slinger as the spindle rotates.


.Attachment 315908

[wildwhl]

Thanks for this - pictures always help.

B

I use a spindle shield on mine that I use to keep coolants out of the lower spindle bearing, water based coolants or oil can get into the lower bearing, either will degrade the grease or cause corrosion. All of the spindle failures I have read about on the Tormach are due to the bottom bearings failing. I have a Bridgeport, 1952 vintage, I have had it over 20 years and never a hint of spindle trouble, I dont use it in production though, just to make parts as needed in my business.


A pic of what I use, made from a piece of scrap UHMW, aluminum would work as well, with an oring in the inner bore to give it a friction fit to the spindle, works very well, as it acts as a slinger as the spindle rotates.


.Attachment 315908

[keen]

I have done quite a bit of study and work on machine tool spindles over the years. The Tormach spindle design is rigid and low cost.... but not designed to last well.

Bearings that are that far apart need a more sophisticated preload to account for thermal expansion.

I upgraded my machine many years ago to disc spring preload and it runs cool and quiet, and should last much longer than stock.

See pics. Keen

[keen]

Re the addition Slinger disc a the bottom of the spindle - I think that is a good idea to further reduce the chances of coolant and contamination getting up into the bearings.

But remember there is already one there below the bottom bearing. I have been running my spindle since the above mod in 2007 and the bottom bearings are still fine - with only the factory Slinger disc.

Keen

[popspipes]

Re the addition Slinger disc a the bottom of the spindle - I think that is a good idea to further reduce the chances of coolant and contamination getting up into the bearings.

But remember there is already one there below the bottom bearing. I have been running my spindle since the above mod in 2007 and the bottom bearings are still fine - with only the factory Slinger disc.

Keen

Keen,
My machine is a 2012 Feburary, I used the machine with coolant one day shut it down and tried to rotate the spindle a week or so later and it was bound up slightly, once broken loose it ran freely again, I made up the slinger after that incident, I have read several accounts of the bottom bearings going out, so I figured a bit of insurance was in order.......probably overkill but thats OK, also makes it easier to rotate the spindle by hand using a coaxial indicator etc..

[wildwhl]

Spindle is quiet and cool now. Ran a few test programs this afternoon trying to optimize the shear hog and the nose never even warmed up. All sounds good and cuts good. Pretty impressed with the ease at which the SH removes material.

There was certainly coolant getting past the slinger disc/up into the spindle before. I'm going to take measures to reduce this risk as it is both cheap and easy to do.

The bearing preload idea Keen is interesting. I wish I understood what your pictures show.

Bill

[popspipes]

Glad to hear it's up and running normal again!

[wildwhl]

Just thought I'd share the formula I've settled on for the Shear Hog. Mill feeds comfortably through 6061 with this setup.

4000 RPM
65 IPM
.55 WOC
.15 DOC

Works wonderfully for roughing and hogging out with adaptive strategies via Fusion 360.

WW

[keen]

I have done quite a bit of study and work on machine tool spindles over the years. The Tormach spindle design is rigid and low cost.... but not designed to last well.

Bearings that are that far apart need a more sophisticated preload to account for thermal expansion.

I upgraded my machine many years ago to disc spring preload and it runs cool and quiet, and should last much longer than stock.

See pics. Keen

Hi Wildwhl.

To explain the pics. They show a two part disc spring , one apart and one together as it is installed.

It has from memory about 1mm travel.

This make preload setting easy - just apply a small amount of compression via the preload nut. Now with thermal expansion differences between the spindle and housing top and bottom bearing sets distances....this is taken up automatically via the disc spring, and the preload does not vary. The spindle runs cool and quiet.

keen

[tmallard450]

Where did you get those disk springs. Looks like a good upgrade. Is it worth adding better bearings and more of them in this type of spindle. Ive seen lots of advertisements for Bridgeport spindle rebuilders who put in extra bearings?


Sent from my iPad using Tapatalk

[keen]

I developed and made that Disc spring in 2007 thinking if it lasted well and gave no problems I might manufacture them for sale one day.

It has run fine since then including very heavy tool steel machining jobs that tested the 1100 right to its limit.

But I think most Tormach owners do not run up a lot of hours... and so the limited spindle design is not really an issue for most.

I approached Tormach in about 2007 with the design and their response was along those lines.....So I concluded the market would be very small.

keen

[pickled]

Not to hijack this thread, but does anyone happen to know the threading specs (diameter/pitch) of the pre-load nut for the 1100's spindle off hand? Mine "loosened" up over the weekend during unattended operation and backed up while beating the hell out of the internal threads as it bounced around. Definitely more damage was done then can be fixed with a file unfortunately :-(. Sorry guys I meant the TOP NUT on top of the pulley....too little sleep here this weekend LOL!

[Eldon_Joh]

can confirm 140F is hot enough you don't want to hold onto it for very long.

Green masking tape has as high an emissivity as stove black over iron pipe (very rough surface, not smooth) in my experience. no need for black sharpie.
Green masking tape has a higher emissivity than black stove paint on polished stainless steel, in my experience. I would expect blue tape to be just as good.

[wildwhl]

can confirm 140F is hot enough you don't want to hold onto it for very long.

Green masking tape has as high an emissivity as stove black over iron pipe (very rough surface, not smooth) in my experience. no need for black sharpie.
Green masking tape has a higher emissivity than black stove paint on polished stainless steel, in my experience. I would expect blue tape to be just as good.

Thanks for sharing. The point of the black sharpie was just so I measured at same location/angle each time.

Running today spindle never even felt warm..

[wildwhl]

Keen -

I'm considering making up a disc spring and installing. Please clarify - is it installed between the two upper bearings?

Thank you,

Bill

[keen]

Keen -

I'm considering making up a disc spring and installing. Please clarify - is it installed between the two upper bearings?

Thank you,

Bill

Hi Bill. If you look at the photos, it is installed under the preload adjustment nut, which is under the pulley.

I have had mine on since 2007 and the bearings run quiet and do not heat up. In addition to providing constant bearing preload, it makes the task of setting the correct preload much less critical.

I am thinking of producing a range of products like this for sale. But I am not sure of uptake numbers will make it worthwhile.

EG. I imagine most folk will just run the spindle with less than ideal preload, and if they do enough miles, when it gets noisy and fails, worry about it then and build then. I get the feeling only a handful of users would bother making this improvement.

Keen

[wildwhl]

Thanks Keen.

I actually became a bit curious, so built one today and installed it just as you describe. I expected that location is where it went, but from your photos, wasn't certain. Peace of mind, if nothing else.

I expect people would buy one from you (I would have/still may).

Bill

[kstrauss]

Along the line of your possible range of products, some time ago you were testing a breakaway probe. Any further results in that area or plans to market or plans to publish the design or...? Would your design also work with the Haimer?

[keen]

Hi. kstrauss.

Yes I have been progressing on a new design crash proof passive probe. I am also trying to sort out the current passive probe contacts degradation issue so the new design Probe will run reliably long term at the same time and so have a really appealing product.

It is going really well but I only work on it when my contract work runs thin. sadly good R&D takes a lot of time.

This is a complete probe to address the contacts issue and so not applicable for the Haimer.

Keen

[keen]

Good work Bill.

Did you notice the spindle runs more quietly and does not heat up as much? Of course this will depend on how you have proportioned the disc spring and hence the actual preload it produces.

Keen