Unbalanced Blanks

[antman]

Hi all,
I have a nice big piece of silky oak that is about to become a platter, I hope. The problem is that it is very unbalanced even after cutting the shape on a bandsaw. Are there any tricks to making the blank safe or holding it well until it is turned down to a more balanced form? I haven't tried anything like this yet, all my turning so far has been nicely balanced blanks.

I have screwed it to a face plate and have the live centre supporting the back of the blank. It just seems a little too 'wobbly'.

Is this the best approach to take or should I do something else?
Anthony

[Zed]

turn it slowly (about 40rpm) and make sure the tail stock is butted up against it nice and firm, use your roughing gauge to round the piece as first thing to complete.

cheers

[Bunyip]

I read this tip on another post here recently - thought is was a good idea as you can get a pretty good balance before turning on the lathe …

Rough up the blank as you have done, attach it the lathe and then spin the blank a few times by hand and see which part of the blank consistently is on the bottom. This is the heavy part, and will need some wood removed. Attack is with an electric planer.

Repeat this process a few times until the blank is more evenly balanced - ie the same bit is not always on the bottom.

You may have to remove the drive belt if applicable to allow free movement of the blank.

[rsser]

Well you could blow your budget and buy a Kelton counter-balancing faceplate! But for one piece, bit hard to justify.

Some people have talked about using wheel balancing weights, but I'm not sure how'd this go. Could need a heap with a big piece of wood.

Something to consider anyway if going slow doesn't work.

Good luck,

Ern

[Jeff]

When I'm turning a piece that is to be symmetrical I'll balance out the piece by balancing the weight of the piece, by cutting away the wood as in my earlier post abovementioned. :D HOWEVER...... :rolleyes: not all pieces are best turned symmetrical, as in some of the finest burls. Some work also is done with multiple centers. In these and other situations the solution includes firmly attaching your lathe to a solid object with adequate fasteners. That done, you'll need to learn some of the myriad of balancing tricks already widely published and probably create some unique solutions of your own. The one hard and fast rule I've learned in woodturning is that an unbalanced piece of work is more likely to come off the machine than a balanced one is. :eek: But if you play well with others, including your lathe, they'll play nice with you. :confused:

[Sir Chiz]

Another option is to remove it from he faceplate and mount it between centers.Mounting between centers will give you a lot more room to adjust it.Then you can rotate it by hand to find the heavy side that settles to the bottom and adjust it from there.
Once you have it balanced,mark those center points because you may have several holes,then remount to the faceplate using those center points.

Chiz.

[DarrylF]

Anthony,

All of the above, plus... You really do need to be able to deal well with unbalanced blanks to produce the best work - not only to produce the unusual stuff, but also to be able to use the nicest timbers, which are often odd shaped and unbalanced.

Having your lathe on a decent base makes a huge difference. I don't know which lathe you have, but if it's anything like my MC900 the stand it came with is probably rubbish. I built a stand for mine that made a HUGE difference out of pine & MDF. I can now turn an unbalanced blank - just got to take it reasonably easy to start, attach it properly and use your head.

[smidsy]

That's a nice stand.
I have an MC900 and the stock stand is adequate in terms of stability, but I like the idea of being able to make the stand so the lathe is at your own height and I like the storage underneath where you can store tools away from the shavings.
Cheers
Smidsy

[ptc]

get a symtec and "rock and roll"

[Dean]

I need something similar. After turning a few pens with the lathe on the standard stand, my back aches a little.
What type of construction Darryl? I think I see a few half-laps there?

[DarrylF]

Dean,

It's real simple - you guessed right, half-lap joints mostly, 2x3 pine, sides & back from 12mm MDF, top from 25mm MDF (with 5 pine rails underneath running front to back). The lathe is supported on 2 pine 2x3's with a gap in the middle so you can get to the nut on the underneath of the tool rest. Each end that is supported by 2 x 2x3 pine pieces running front to back on top of the 25mm MDF. The lathe is bolted in 4 places right through 2 x 2x3's on their side, then the top, then the front rail.

The lathe is mounted very close to the front edge - front bolt holes right in the middle of the front rail - so nothing gets in the way when you need to get up close. The top is a bit under 600mm deep (500 maybe?). Good wide stance so it's very stable.

It also has 2 x 90mm PVC grills inset into the top just behind the chuck leading to 4" PVC ducting to the DC. Picks up sanding dust pretty well.

[antman]

Hi all,
Thanks for the advice. I ended up using the idea of mounting the blank then using a power plane to get it roughly balanced. That done it was secure enough at really low speed to rough it out to be balanced.

DarrylF, I also have a MC900 lathe and I agree that the stand is rubbish. I was playing with a relatively light piece of silky oak but something heavy would remove it from the ground! In the end I braced the stand with some scrap steel and a handful of clamps. This worked OK but it isn't pretty. I think maybe the time has come to build a decent stand like yours.

Thanks again!
Anthony

[DarrylF]

Final straw for me was when I bolted a chunk of coachwood to the faceplate, turned on the lathe at the slowest speed and it bounced itself about three feet across the floor before I managed to turn it off. Scared the hell out of me :) I started building the new stand the next weekend.

If you wanted something like mine I'll take some better photos for you if you like, and some basic measurements. Let me know.

[John Saxton]

Not one to put a spoke in wheels here guy's but irrespective of the stand you build any unbalanced lump o' wood is gonna give you a heap o' grief.

Knew a bloke been turning for years ..thought he was comfortable with the blank he had mounted...woke up on the workshop floor with an enormous lump on his head and an almighty headache with said blank over the other side of the workshop..needless to say he spent time in hospital under observation for concussion ...and an embarrassing monologue at the next woodturning meeting.(poor bloke has passed on since ,bloody good turner too).
He had sand bags on his lathe to deaden movement as some was wont to do.
My lathe is welded frame steel and bolted to the floor but any out of round will still give me problems irrespective of inboard or outboard..so its imperative for you and tour family's sake to TRUE up as near as possible before taking the chance with mounting.
I'm not about to tell you folk how to suck eggsbut please take care with no short cuts and use the tail stock on the blank until trued up.

Take care out there.
Cheers :)

[RETIRED]

P.S. Don't stand in the line of fire.

[rsser]

Yeah Antman. Welded steel, bolted to the floor. Slowest speed you've got (like 100 rpm). Tho from memory the MC900 only goes down to 500rpm, so yes, plane away!