Blowouts on New Lathe

[vtgaryw]

I was turning some of Smitty's Cabellero pens (Jr Gent II style) today on my relatively new Rikon 70-220, and ended up blowing out 3 different blanks. Each one was the short end, with the 12mm hole (I actually used a 15/32 - where was that darned 12mm bit anyways.)

One blowout was a coolibah burl, which upon further review, I probably should have stabilized, it had more imperfections in it than I thought.

The 2nd was olive wood, and the 3rd was inlace.

Disclaimer: I'm not a newbie, I've turned thousands of pens on my old Shop Fox lathe. I thought I was long past blowouts, except for the occasional defective blank or wandering attention/hurrying.) I haven't blown out an acrylic blank in I can't remember when.

The lathe is setup perfectly as far as I can tell. Perfect alignment, as true as can be.

I've turned maybe a couple of dozen pens on it before now, without any problem.

Was I just having a bad day or is every lathe so different you just have to get used to it? This lathe has so much more torque than my old one, I could stall that thing in a heartbeat, but still, with sharp tools and a little care it made great pens.

Any ideas?

Gary

 

[EBorraga]

When I have those days I just pack it up and go in the house. Tomorrow will yield a better turning day

 

[Monty]

I doubt the lathe was your problem. As Ernie said, quit for the day and start fresh tomorrow (BTDT).

 

[KenV]

My bet is that you were calibrated to the older lower power lathe. That comes with all the senses including hearing and feeling. Those senses are not tuned to the torque and you are coming more aggressive on "auto pilot".

Pay attention to your form and techniques. Go back to basics and get turned to the new gear.

From your wording you are already thinking about it.

 

[MTViper]

I'd look first at speed. I drill at 400 rpm or less, especially with a bit that big. I usually go down to 200 for a large diameter bit. The next thing I'd check is how far the quill moves when each time you crank the handle. It come move farther or faster than your old lathe did. The third thing I'd check is how often you clean out the chips, especially on the inlace, get too much waste built up and it adds to the pressure. The last thing I'd look at is big sharpness. Is it cutting its way through the material or pushing its way thru?

Just my thoughts

 

[leehljp]

I agree with Ken - too aggressive.

As others said - we all have a day like that. After a day like that, I resolved never to take a blank for granted. I pour on CA on the outside if it is not stabilized, and check it. I had some good burls from the SE Asia and they were fragile. I learned to take it easy. If it took me an extra hour to get that perfect fit and finish, so be it.

The end result is worth it.

 

[ed4copies]

Gary,

Sounds like your old lathe had built in protection against blowouts!!! A cool feature, I have never seen before. But, if it STOPPED when you put too much pressure on the blank, that was your "sawstop" mechanism protecting against blowouts!!

Your new one demands that you take it easier or it will allow you to "overcut" in that passl!! This is not to say you are not a good turner, you are GREAT with the tool you became accustomed to--now you need to be great on the tool with new parameters!! It will allow you to cut much more quickly, when roughing---but reduce your cuts as you near finished size. Be especially gentle on the two ends of the blank. In a couple weeks you will love it---meantime turn maple!!!:biggrin::biggrin::biggrin:

 

[vtgaryw]

Thanks all. I think it's a case of getting used to the new power, and taking more shallow cuts, especially at the ends of the blanks.

I'm an engineer by training, worked around a lot of manufacturing equipment my whole career, and I was always fascinated by how a machine operator gets attuned to the sounds and feel of his/her machine.

I not tuned into this lathe yet.

Thanks,

Gary