Lathe accessory, Sub-faceplate balance ring?

Re: Lathe accessory, Sub-faceplate balance ring?

john lucas

What would be cool would be some sort of stackable pieces that could be screwed on and stacked up to increase the weight. Maybe even connect together and then stack up for even more weight.

What diameter faceplate?

Dick Coers

And who's faceplate? 10 pounds on a 3" faceplate won't do much. Also some cast faceplates aren't very flat on the back. Adds a whole new bent to safety, swinging steel and wood! You might look at using a flat head bolts coming through from the front to back, and lock nuts on the back side. Depending on the blank size, it could take a really big block of steel! And not easy to setup if you have to take the blank off to relocate the counterbalance. I'm thinking some of the eccentric chucks have a counterbalance system.

Re: Lathe accessory, Sub-faceplate balance ring? *LINK*

Karl_TN

Here's another design idea. Check out Vicmarc's balancing system which works on the outboard side to reduce vibrations from out of round turnings.


Vicmarc V00060-3 Balancing System

Re: What diameter faceplate?

Keith Newton

My small faceplate which I use most often is 6", and about 3/4" thick cast iron, on a 2" arbor. I was thinking about a 3/8" thick plate, with a 3"L section of 12" D or larger pipe welded on the outer edge of this disk. Then magnets could stack on the inside of that, and would be pushed outward / tighter from the centrifugal force. Magnets could easily taken out to adjust as the work comes closer into balance.

And of course, I'd chamfer all the corners as a measure of safety.

Re: Lathe accessory, Sub-faceplate balance ring?

Keith Newton

Thanks Karl, While that might work on a lathe with bed ways, mine is strictly a bowl lathe, with floor stand tool-rest. If I did something like this, it seems to me that it would actually double the problem if used on opposite ends of the arbor, and would be a serious arm whacker if used behind the faceplate.

Re: What diameter faceplate?

Dick Coers

Don't you think you will have to add like 8-10 pounds to balance some 50 pound blanks? That's a lot of magnets!

Re: Lathe accessory, Sub-faceplate balance ring?

Leo Cuellar

I know that Terry Scott was working on a safe system to do this. I don't know if he has had any luck yet as we fell out of touch because of my work schedule. I'm not at liberty to discuss any details.

Re: Lathe accessory, Sub-faceplate balance ring?

john lucas

If you started every bowl with a faceplate that was 20" it would be pretty easy to rig up a way to attach weights to it to counter balance. The problem when roughing bowls is that it would need to be changed constantly or the weights them selves would create wobble.

Weighted bucket above the lathe headstock.

john lucas

There was a lot of discussion years ago about extending a weight on an arm above the headstock to counter vibrations at the lathe. I tried it and it did work. However the weights had to be constantly adjusted because the weight of the bowl constantly changed. People were using All thread rod to make the adjustments easier and found out that the inexpensive all thread you buy at the local hardware stores would break possibly from some sort of fatigue. I abandoned it and apparently so did many others. I think it was in an article in the AAW magazine. If I have time later today I'll try to look it up.

Dynamic balancing

John K Jordan

Once I dreamed up a design using accelerometers and actuators to dynamically balance a spinning blank. You know how the sensors in the balancing machines at the tire shop can detect how much weight is needed and where?

Imagine spinning up a lathe and a "smart" chuck would dynamically rotate and shift weights to adjust the balance then keep it balanced as wood is removed. It's certainly possible, but is it practical?

Several problem. First, it would probably be huge, especially the prototype! I think it would be a lot easier to build in into a big lathe than to make it into an accessory.

There is also the small problem of the $200,000+ needed for development and the $2000 cost of the production model you could actually buy! Let's see, you'd just need 200+ people to put $1000 each into a kickstarter campaign! :-)

Or get one of the companies who specialize in dynamic balancers interested.

JKJ

Re: Weighted bucket above the lathe headstock.

Ron Bauer

I did this. It works. I figure I gain ~ 50 - 75 RPM with my TVA "Tunable Vibration Attenuator". Mine is on a 3/4" O-1 steel rod hung from the back of the (PM4224) head stock with about 20# of old barbell weights. I never change it. As the piece comes in to balance it just stops vibrating. I also tried a hollow wheel with lead shot inside on the theory that the weight will self distribute to the "light side" as the piece gets to speed. There was some evidence it worked but the required mass of shot was so high that I never completed the tests. This is patterned after use of ceramic in tires to gain balance. The tires are nowhere as out of balance as a 20" piece of hard maple. I usually start slow and bring the piece up as it gets into balance. Also, as I am sure you are aware, all pieces have several modes of balance. It may be bad at 350 but smooth out at 600, or whatever. This is just my experience.

Seems like this Vicmarc outboard ........

JamieDonaldson

....balancing device would put terrible stress on the spindle shaft and bearings?

Re: Lathe accessory, Sub-faceplate balance ring?

Lyle Jamieson

If you have seen my figurative sculptures, I hollow on multiple axis's, so I have tried all the suggestions and more. They all work for smaller turning but when you try bigger pieces most fail. The problem is when you have a weight that is on the headstock or even on the faceplate, the added weight is not directly countering/opposing the out of balance of the work piece. The added weight would fling in a different direction than the wood piece. I could get a static, perfect, balance with the lathe off, but once I turned the lathe on all went crazy. I found the ONLY way to balance the off center, out of balance, work piece was to screw weights directly on the wood opposing the turned blank off-center weight.

With traditional turning I always start between centers on the balance point so I can get the lathe speed up for the roughing out stage than move it incrementally to the axis I want to finish the piece on.

Re: Lathe accessory, Sub-faceplate balance ring?

Brent English

Spot on Lyle, that's the difference between static and dynamic balance. The Vicmarc balancing weights that go on the outboard side are also a perfect example of that good static, but terrible dynamic balance. At zero speed, you can get the piece very balanced, but turn up the RPM a bit and you have two out of balance things on opposite ends of the spindle that are actually working against each other. That's probably why they don't sell very many of those set ups. In Mr. Lucas's picture above, he would have had it balanced better, and maybe had an easier time of turning, it if he would have screwed another piece of similar size and weight directly opposite the one he was making. Then he's of either had two, or one to keep and one to throw away.

Agree, well said

Re: Lathe accessory, Sub-faceplate balance ring? *LINK*

George Balock

A bunch of years back, I saw Keith Holt do a demo for his sculptureal pieces where he had a system he designed to do exactly what you are talking about. It was so long ago that I cannot remember the design. You could reach out to him to see if he has a picture.


http://www.kholtartwork.com/kholtartwork/

Brent- I did

john lucas

You can't see it in the photo but there is a blank of the same wood close to the same size hot melt glued to the backside of the wooden faceplate. It wasn't perfectly balanced but extremely close.

Thanks for the description of dynamic balance vs static balance. Makes perfect sense and is probably why your lathes are so well designed. I Robust is going to be at the TAW symposium. Look forward to seeing you there. By the way I used one of your tool rests for all of this mirror except the 2 off center parts shown in that photo. I have one of the mini tool rest with the large post that you made for me and it stays on my lathe probably 95% of the time.

A few questions about what you've experienced?

Keith Newton

You stated that when you started spinning, that the magnets? moved?

Did your lathe have a soft start and stop, or was it the vibration from the cut that caused a jiggle or something?

Re: Brent- I did

Brent English

Hi John, sorry we're going to miss TAW this year. My son is in the Air Force and hasn't been home in over two years. He has leave to bring his new bride back to the old ranch for a visit that weekend. Paul Judkins from Chucks Plus is one of our dealers and he'll be filling in for us at the symposium. We'll see you again soon, I'm sure.

Re: Brent- I did

john lucas

Great I like Paul. I spent a short time in the Air Force. We called it the Hair Farce back in those days because it was the early 70's and of course we wanted hair but couldn't have it. Glad you get to spend time with them.

Re: Weighted bucket above the lathe headstock.

Chuck Engstrom

I put one of these together many years back, and I still probably have it somewhere, but it didn't really seem to do all that much for me.