Warming up spindle

[harryball]

ok, here's a dumb question... does "warm up the spindle for 10 minutes" mean have it turned on with the fan running or with the spindle running not cutting? I've been letting the spindle run with no load for 10 minutes or so before starting any work... anyway, a shop visitor just left (another shop) and said he'd always heard you shouldn't run a spindle with no load for long periods...

figured I'd better ask.

Robert

[handh]

Robert,

I let the spindle run for 10 minutes, this is what I have understood you should do. I would think the fan is for cooling not warming the spindle up. I could be wrong but this is what I have been doing. The ShopBot software will time out after a while in case you forget you left the spindle on. Maybe this is to keep from damaging the spindle.

[patricktoomey]

This depends on your spindle or rather the type of bearings used in it. I have the Colombo 5hp with electric cooling fan. You can just fire it up and run if you want to but supposedly you will get more life out of the bearings if you warm them up first. I was told that if I wanted to maximize the life of the bearings that I should turn it on and run it at 9,000 rpm for about 10 minutes to warm it up. Then after shutting down for the day, leave the spindle off but the cooling fan running for about 10 minutes to control cooling and reduce moisture condensation inside the case. I don't think the warmup time is the important part, it's getting the bearings up to a certain temperature where the lubricant will perform properly before you start putting higher RPM or lateral loads on them. In the summer I usually just let it run for a few minutes for the heck of it since it's usually 95-100 before even starting it up. In the winter I start cutting at about 98-100F. Here are the details according to Colombo...
http://www.pdscolombo.com/spindle_maintenance.htm

[gerald_d]

Robert, you started this thread because "a shop visitor just left (another shop) and said he'd always heard you shouldn't run a spindle with no load for long periods... " I don't see any truth/logic in that?

[harryball]

I had a visitor in my shop, he runs a small furniture shop. When he walked in my spindle was running, warming up. He was here to see if I could make a few widgets for him if the need arose. One of his comments was about leaving the spindle running with no load.

Being a newbie I thought I'd hit the board here and speak up thus showing my ignorance but maybe finding a cure.

I think A correct answer is "Don't load a spindle with cold bearings and don't leave a warm spindle running with no load." and "It takes about 10 minutes for a cold spindle to become a warm spindle."

Robert

[gerald_d]

Robert, there may be truth in what he said, but I havn't heard that theory yet. Curious whether other folk have heard this?

Generally, you want to warm a bearing before applying load on it. After having run loaded, you also want to cool it down before stopping it. (Much like a horse or an athlete). This practice is not unique to spindle bearings - it applies to practically all bearings where you want to get maximum life out of them. Even to a router....or tablesaw, or drillpress, etc.

[mikejohn]

Gerald
Are you suggesting all machines should be run for 10 minutes before applying a load?
Or are you suggesting that they should be run for a period of time, but not 10 minutes?

.........Mike

[gerald_d]

Because the spindle bearings are darn expensive, the operators tend to put up with the inconvenience of running them warm first. For a tablesaw, we would change brands if the supplier said that the bearings need preheating.

Yes, ALL bearings will give a longer life if "nursed". The "10 minutes" is not an absolute - what you are basically trying to do is the get the bearing as warm as possible before putting load on. It depends on your patience factor.

[andyb]

Robert,
I have a 5hp spindle and I created a little file that allows the spindle to warm up and then shut off. I run at 9000 rpms to warm-up and 4000 rpms for cooling down. The file is 3 lines.

SO,1,1
pause 900
SO,1,0

I have it count for 900 secound (15 minutes) to give the spindle time to get up to speed. The file allow me to start it and do another things without keeping track of how long it has been warning up.

Andy B.

[patricktoomey]

On the running with no load issue, I was told by a PDS (Colombo) tech that it was preferable to leave the spindle running at a reasonable speed like 9,000 RPM between cuts. His reasoning was that this would reduce thermal changes and keep the spindle at a more stable temperature. Now if you're cutting once an then not again for hours then turning it off would make more sense. But when I'm cutting something and I know I'll be cutting again within 10 minutes or so I just leave it run at 9K. In any case, running with no load is not going to do anything more than keep wearing your bearings slightly and use a little electricity.

[evan]

Ok it's lunch time, you finish the cut file and leave your trusty Bot for a half hour to an hour for some grub, come back nurished and refreshed to start cutting. Do you warm the spindle up again or do you call it good and pick up where you left off?

[patricktoomey]

Depending on the temperature of the shop, I would let it run at least a couple of minutes just for the heck of it. If it was cold in the shop, I would run it all the way back up to near 100F before cutting again.

[evan]

Sound reasonable...

Thanks

[pulse98]

I can think of two reasons why bearings should be warmed up before loaded use:
1. Lubrication characteristic change with temperature. The lube needs to get to the temperature it was designed to operate.
2. These bearing are made with very tight tolerances. Bearing dimensions will change with temperature. The bearings need to get to the designed operating temp so that the bearings will be operating at the correct dimensions.

Bearing dimensions and lubrication characteristics are designed as a system for optimum life and performance. When run outside of the defined temp specs, life and performance will degrade.

Infrared laser temp guns are pretty inexpensive now. Shoot the spindle for its temp and once it gets to your goal temp, you are ready to make precision chips/dust.