TBC still heating up!

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Woodchipper

Woodchipper

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I went into the shop and experimented. I put on a synthetic (generic term) blank and tried to check by turns of the handle of the quill. I started with the handle at 12 o'clock. Turned on the lathe at the highest speed then applied the roughing gouge. The blank spun and nothing was turned off. Next I went to 2, 3 and 4 o'clock. Two and three still had the blank spinning with application of the roughing gouge. No heating of the live center. Four o'clock stopped the blank from spinning and got some shavings off with the gouge. However, after a couple of minutes, the live center started to heat up. Very frustrated and very disappointed with the TBC.
 
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Does your live center heat up when you use a mandrel?
Where did you purchase your live center and what model is it?
Your statement makes it should like that the "TBC" is causing it to heat up, and it is not a problem of the LC itself. Is this what you are thinking or asking?
 
This isn't going to help you but I just want to say I have been using that exact setup for years and mine has never even gotten warm. I think you have a bad set.
 
Dieseldoc said:
Most likely the bearing if failing in live center , sounds like maybe after 8 years time to replace bearing or get new live center.
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I think there is some confusion here about a live center. My 60 degree pointy live center works fine. Go back my post #3 and look at the photo in the link. The part on the right is overheating. It is new and only used once. I tried it today as per post #1 as an experiment. As soon as I tighten the quill to keep the blank from turning, then it started to get hot.
 
Woodchipper said:
I think there is some confusion here about a live center. My 60 degree pointy live center works fine. Go back my post #3 and look at the photo in the link. The part on the right is overheating. It is new and only used once. I tried it today as per post #1 as an experiment. As soon as I tighten the quill to keep the blank from turning, then it started to get hot.
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That does sound like a bearing issue to me. One would think that they should be able to handle not just the spin, but the lateral pressure, too. I mean, that's what they were designed for, right?

To be fair, I do have a triple bearing LC that still gets warmer than I expected it to. Not hot, but pretty warm for sure.
 
Most inexpensive (relatively inexpensive) live centers do not include actual thrust bearings that are designed to support predominantly axial loads, but are simply radial bearings (usually ball bearings vs roller bearings); however although the bearings are primarily designed for radial loads, they may be designed with angular contacts that help with some axial loading also - this usually comes with a higher price tag of course.

For example, the high speed spindles on some of the CNC machining centers we used to have had multiple angular contact bearings along with needle bearings (essentially a long skinny roller bearing) to provide outstanding rigidity and accuracy with TIR's in the range of 50 millionths of an inch or better. Of course they also cost in the tens of thousands of dollars as well.

I concur with the comments about bringing it up with PSI or with Ed if you bought it through Exotic Blanks or to buy another one for comparison. You might have just gotten a poorly manufactured or assembled unit. Maybe someone on IAP has one that they would be willing to let you try using your setup for a temperature comparison between them.

Dave
 
I looked at that link and that is not TBC turning. That system has no "centers" at all, to me it's just like turning on a standard pen mandrel. For TBC turning all you need is a dead center (headstock) and a live center, that's it. If that thing is heating up I'd get my money back, IMO you don't need it.
 
Woodchipper said:
Turned on the lathe at the highest speed then applied the roughing gouge. The blank spun and nothing was turned off.....
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I dont understand this part of the post. You applied the roughing gouge to what? Nothing was 'turned' off? You used the roughing gouge but didnt remove any material?
Woodchipper said:
Four o'clock stopped the blank from spinning and got some shavings off with the gouge. However, after a couple of minutes, the live center started to heat up.
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I can honestly say that in over 20 years of turning (pens, bowls or spindles) I have never tightened the quill on the tailstock applying so much pressure that it stopped the piece from turning. That would mean the live center in the tailstock stopped operating correctly because I'm fairly positive you didnt stop the headstock from turning. If you did then something else is wrong.
IMO, either it comes down to incorrect operator usage of the tailstock/live center or live center failure. My money is on live center failure.
 
Mortalis: Applied the RG to the blank.
1. If I kept the quill at the 1-2-3 o'clock positions, the roughing gouge stopped the blank and no material was turned off.
2. If I tightened the quill to the 4 o'clock position, I could turn off material but the TBC live center started to heat up.
 
Woodchipper said:
Mortalis: Applied the RG to the blank.
1. If I kept the quill at the 1-2-3 o'clock positions, the roughing gouge stopped the blank and no material was turned off.
2. If I tightened the quill to the 4 o'clock position, I could turn off material but the TBC live center started to heat up.
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Ok, that makes more sense to me.
I'd return the whole system then just use the dead center and live center that came with the lathe and use the chamfers in the bushings to meet with the outer angles of the centers.
I looked at the reviews and comments for that system and there were some that noticed wobble as well as the inability to remove the bushings from the stems. It looks like a poorly designed live center to me but I have never had one or been able to disassemble one so is just my opinion.
 
rherrell said:
I looked at that link and that is not TBC turning. That system has no "centers" at all, to me it's just like turning on a standard pen mandrel. For TBC turning all you need is a dead center (headstock) and a live center, that's it. If that thing is heating up I'd get my money back, IMO you don't need it.
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Agree 100%. I have wondered how this got away with calling it "TBC". It is NOT TBC. PERIOD! Thanks Rick.

TBC is NOT a fact that it does not have a mandrel. It is placing the blank between a Live center and a Drive center.

Drive center and live center - ergo1st and second generation TBC on IAP 2007/8
www.penturners.org

Mandrel and Custom bushings

Mandrel and custom bushings can both be used on TBC
www.penturners.org

The "TBC?" iteration of PSI is not a true TBC and only causes confusion to those who accept it as TBC vs real TBC.
 
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This is a bit off topic but I think the OP needs to know this.

The system you have will always have "wobble" in it because bushings with thru holes have to have clearance to fit the shaft.

True TBC bushings don't have thru holes, they have 60 degree "centering dimples". I included my drawing of a Jr. Gent., notice the V-shape dotted lines, those are the dimples where the live and dead centers go.
Jr Gent ll BODY.jpg
 
No matter what the definition, etc....it overheats and shouldn't do it!
I have contacted Ed about this and waiting to hear from him. With that, let's close this thread.
 
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