spindle temps?

[Jeff-Birt]

I've never heard of this either, and I don't have any Taig documentation that mentions this.

Possibly Nick Carter could chime in as he's been a fantastic Taig Dealer for a very long time, and may know more on this subject.

A friend of mine purposely trashed a boat load of Taig spindle bearings doing some tests for part of his thesis. We rebuilt two different spindles about a dozen times each so I do know what I'm talking about here.

This is not a phenomenon unique to Taig spindles though. Anytime you assemble a new rotating assembly with bearings it will initially be a bit stiff and will likely run a tad warmer. After a bit of time running, things will loosen up.

When they build the mills at the Taig factory they run the spindle for several hours straight to break them in. I don't think they do this when you buy just the bare spindle but after a few hours of use it should be at its 'normal' broken in state.

I don't know if this was contributing to the OPs situation or not but the point is you need to run a new spindle for a bit before trying to determine if it is running a bit warm.

[xaruum]

Just to clarify, what I found to begin with was a spindle running hot, I have since run it in, and still get 160+degrees. I also found what I thought to be play in the spindle, but it turns out is coming from somewhere else. So I am just adding my investigations to this thread so that more experienced people can point out where I may be incorrect or could improve my practices.

I wasn't sure how to determine play/deflection in a manner that would simulate normal usage so I ran a quick experiment. I have a spring that has 10lb/in of stretch ( I picked it up for a different project ) and connected one end to the top of the column and used my steel straight edge to measure the amount of stretch. I then mounted my vise to the table and clamped the indicator snug in the jaws and tested in both x and y directions against the z way ( the big block that the dovetail mounts to ). The indicator is level and is sitting 1.75" off the table.

It only takes a about 5lbs of force to start causing movement in the y direction. The amount of deflection increased to about .001" at about 15lbs and did not increase above that even at 50lbs.

The x direction saw only .0002 of movement even at 50lbs.

Being that the force was applied to the "lever" at 15-3/8" from the fulcrum that would be equivalent to x amount of force at 3-3/4" from the fulcrum. I don't remember how to solve for x. But if I recall correctly, a general rule is that the amount of force applied increases by a factor of 2 for every inch? I will have to look that up when I get home. Either way, with 269oz/in steppers and feedrates limited to 18ipm max I don't think the column itself is the source of play, so I will ry to measure the play between the z table and column next.

I also went ahead and removed the spindle from the headstock to see what condition it was in. It had to be getting -extremely- hot on the inside bearing race/spindle shaft surface because the oil residue has all been scorched dark brown/black and is flaking off. It only has about 5 hours of run in on it, 99% of which was at the lowest speed.

The assembly is a 6203R-oo at the bottom with a spacer that goes up to 2 face-to-face bellville washers that press against the outside race of a 6203z. I assume the washers allow the tension to be maintained regardless of heat lengthening the spindle. I found that when I removed the spindle nut completely, the bearings remained in place, so the spindle fit is really tight. I also found that the spindle nut is not mating flat to the bearing race, one side meets the bearing about .015 before the other side does.

I think 6203 are just deep grooves. That is fine for the top, and I am pretty sure it is ok for the bottom at the low loads this little mill will see.

More tomorrow.

[Jeff-Birt]

Hopefully you did not press the spindle cartridge out. You just need to evenly heat the spindle housing with a heat gun and it will drop right out. If yours is 160 deg F after 5 hours of use then there is a problem.

[xaruum]

I haven't used a press, I have been using my daughters hair dryer, it has several settings, so just 4-5 minutes and the spindle scooted out with just finger pressure.

Still trying to figure out how to measure the play between the z table and the column.

[xaruum]

I am trying to come up with a way for the spindle nut to meet the race completely flat. I believe the fact that the nut is applying more force on one side of the race than the other could be a major factor in the Heat issue. This is because as I attempted to take the bearings off I found that the majority of the scorching is at the top of the spindle right under the threads for the spindle nut.

One idea is to take a load bearing washer and grind down one side of the face that will meet the face of the spindle nut. The problem would be making sure that the washer and nut stay lined up correctly.

Another idea is to grind down the side of the spindle nut that faces the bearing race. But I think the spindle nut may be hardened which would make that more difficult and the grinding process would weaken the nut.

I don't really want to attempt to run the spindle any more without clearing this up. At this point I am also considering just saving the money to buy an ER16 spindle, but my concern is whether or not the spindle design is the same. If that is the case then I would rather just use the money towards building my own spindle ER spindle maybe a 20 or 25 using real p5 ac's.

Does anyone know if the taig ER spindle design is identical to the Original 3/4-16 spindle?

[Dean W]

Does anyone know if the taig ER spindle design is identical to the Original 3/4-16 spindle?

Sorry, they are not the same. The ER spindle has a 22x1.5mm nose thread to fit the ER-16 closer nut.

Dean

[xaruum]

Hi Dean,

I admire your work and enjoy your website. Just to be fair, Jeff aren't you the author of soigeneris? and of course everybody knows mr. carter, I have browsed over all of your sites for years and they have been the biggest influence on my purchases, as well as very inspirational. I thank each of you for taking the time to respond.

As to the spindle design, I wasn't being clear - I meant the actual build, as in the use of 6203 bearings, spacer, bellvilles, and nut.

I like the simple design and high quality of the taig equipment. I don't want to needlessly pester taig if the spindle is actually functioning as designed. I just have a hard time believing that the amount of heat being generated was intentional.

[Jeff-Birt]

The spindle should not get to 160 deg F. If you run for hours at 10K RPM it will get warm, maybe 110 deg F but that is about all.

Oh yes, I do run Soigeneris but I'm not allowed to mention that here...

[Dean W]

Xaruum, thanks for the nice remarks.
Like Jeff from Soigeneris says, your spindle is still running way hot. I can't imagine why it's still doing it. Both my Taigs can run for hours and hours and they won't get more than slightly warm. Like the warmth from another person. You can barely notice it. My laptop gets warmer than the Taig spindles!

I think you should talk to the people at Taig about it. They're nice, and I'll bet they can make a suggestion or offer you a solution.

Dean

[xaruum]

Well I got home and took the spindle completely apart. It took a lot of time with the hair dryer but I won.

There was a light film of scorched residue between the spindle and the top bearing race. The spindle itself has slight discoloration that gets lighter as you looked down towards the bottom bearing.

There is a slight concave dish milled into one end of the spacer and the other end is completely flat.

Both of the bellvilles are a complete waste, they are distorted beyond belief, they look like black steel Lays potato chips.

I decided to test the axial play in the bearings, clamping the spindle gently and lining up the indicator on the outside race, I read .011 play from the bottom bearing and .0085 from the top bearing. When I rotate the spindle by hand with just the bottom bearing mounted I can feel flat spots. Doing the same with just the top bearing feels smooth but sluggish. The top bearing is a ZZ - the top shield looks fine but there is some lube squeezing out, the bottom has 2 size able dents in it.

I reassembled it with the bottom bearing in the original position, the spacer with the concave side down so it is preloading the bottom bearing correctly, the bellvilles i went ahead and put in the original position with as much face-to-face area as I could manage and the top bearing upside down so that the dents in the shied should not interfere.

It is dinnertime, so I will have to see how it performs later.

I will definitely give the folks at taig a call tomorrow.

[xaruum]

I haven't had a chance to call taig yet, but I do have some results from running the spindle last night.

After 4 more hours of running with no load the temperature is down to 118f. The tir started started out at .0005 and after the run in it is now .0002.

I went a ahead and chucked up the endmill I use most, a 3/16 hss, with only enough shank showing to get a good indication off of it. The tir on the shank is reading .0039.

That seems rather high to me.

[Dean W]

Sounds like you have the temp under control fairly well.
The TIR on the spindle sounds fine.
The TIR on the end mill is not. Almost 4 thou is a big gob of runout. Suspect the end
mill or collet.
You're using ER 16 collets, right? Lightly tap the closer nut on a piece of aluminum to make sure there are no chips in the threads or behind the spring. Same for the collet. Tap it to dislodge any matter, and puff it out with air. Then try again.

On the shank of a good end mill, like Atrax, mine runs out less than .0005". You add a thou to that if you're putting any pressure on one side of the headstock while you turn it, like if you rest your hand on top to turn the pulley. Turn the spindle between your fingers at the collet nut to check the runout on the end mill. Use a light touch.

Dean