bowl turning question - gouge heat

[gsieracki]

As mentioned several times I rarely turn bowls. The last couple times I turned a bowl and a segmented project I noticed I started to feel heat where my forward hand was holding the gouge to the toolrest. It wasn't unusually hot just one of those things you notice.

What would cause that as I never seem to have heat buildup while spindle turning?

My thoughts are tool needs sharpening though mine usually are, too high a speed to be turning at, motor not strong enough for project (long reach there).

Any ideas?

Thanks1

Gerry

 

[Dave Beringer]

Kinda of hard to answer

Warm/hot are relative terms to say the least. I have never had my gouge heat up. I have however gotten stung by the hot shaving coming from a bowl being turned. This is especially true when turning dry blanks. If you think about the amount of shaving created while turning a bowl if you turn at 1000rpm and have a 10" (diameter) bowl. Your gouge will see (10" * PI)/12 * 1000= 2617' or almost 1/2 a mile of shavings every minute. That's a lot of friction. I might suggest trying to sharpen your gouge and consider whether or not you are applying to much pressure to the wall of the bowl by over rubbing the bevel. I would suggest you judge the success of your cuts to more adequately evaluate your problem. How clean are your cuts? Are you leaving marks on the bowl due to crushed wood fibers from over rubbing the bevel?

 

[Brian Hahn]

A dry and hard wood will heat up the bowl gouge. Aggressive turning, especially during the initial roughing out stages of a dry blank can make the gouge down right toasty.

I once was giving a bowl turning demonstration (my first demo ever). The wood was dry hard maple and I was hogging out the inside really fast. The gouge got so hot that I couldn't hold it and I had to switch to a different gouge. And I keep my tools "scary sharp".

 

[GeorgeH]

Brian's experiential comments reflect many of my own memories of heating up the gouge. The other point I'd like to add is that it's sometimes easy to ride the bevel for longer periods than we realize and that's a good source for heating up the tool.

 

[Dario]

The very reason why HSS is recommended for turning tools.

 

[gsieracki]

the wood was pretty dry and definetily hard. Some of it was a good tough oak. Thinking back the heat was a combination from the shavings and the gouge was also hot/warm.

I'm hoping to try lighter cuts this weekend on a silver maple blank and an ash blank. I'm going to make sure I sharpen the gouge(s) before rounding the blank and once I have it rounded to see if that helps.


Thanks!

Gerry

 

[odie]

There have been a few times where the shavings themselves have been so uncomfortably hot that I had to put on some gloves. As with djb, I can't recall the gouge itself becoming very hot....warm maybe.

....odie

 

[MichaelMouse]

One of the several reasons not to press. Others include distorting the piece while turning, shaking it loose from mounts, and white knuckles on the operator.

Fair surfaces want continuous cuts, so it's sometimes necessary to keep the tool in contact for long periods of time. That will build heat, so check your angle of attack and see if you don't want to alter it and/or your grind so that you can drop the shavings rather than pile them against your hand. Sometimes that's enough.

 

[woodwish]

. . . . the amount of shaving created while turning a bowl if you turn at 1000rpm and have a 10" (diameter) bowl. Your gouge will see (10" * PI)/12 * 1000= 2617' or almost 1/2 a mile of shavings every minute. . . . .

Never really thought of it in those terms, that is a lot miles traveled making the average bowl. By the time you finish a big bowl you have many miles of shavings gathering around your feet, no wonder we tired out in the shop!