Lathe Vibration

[Maca]

I'm new to wood turning so need some advice on turning rough blanks.  I have an Elektra Beckum HDM1000 lathe which I made a wooden bench to sit on.  The bench is fixed to a concrete wall at the back but the legs at the front are not bolted down.

Recently I got a few beech logs which I cut into rough blanks with a chainsaw as my bandsaw is too small for the size of logs.  So the blanks are not terribly well balanced but not too bad.  I've just about managed to rough out the outside of a bowl (approx. 12") but the lathe was vibrating a lot.  It doesn't help that the lathe is fixed speeds so at its slowest its at 300 RPM. 

Anyway, for future ones I plan on finding the centre of mass of the blank more accurately but I'm also thinking about bolting the lathe down and wanted peoples opinion on this.

[seventhdevil]

i would add weight to the lathe rather than putting bolts everywhere.

the extra mass will make it more difficult for out of balanced items to rock your lathe.

[Twisted Trees]

12" not quite balanced will vibrate at 300rpm no matter what you do, it is why lathes need weight. adding your workshop to the weight of the lathe and bench with brackets may help, but it will still be vibrating until you get it in balance. Which will be stressing your bench and brackets, so if you do it use heavy ones with good fixings.

I would be starting at about 150rpm maybe even less, and even then I would expect some vibration when starting with that load attached.

Trick is to then get in in balance quickly, and starting from the best center will help that.

[Les Symonds]

Sometimes one has to take a step back and consider whether or not a piece of timber, even if its size is within the capacity of one's lathe, is beyond its capacity in terms of weight and balance!

Les

[bodrighywood]

Be areful as off balanced wood that vibrates can also shake loose from it's fixing be it a screw chuck, face plate or some other way. If your lowest setting is 300rpm I'd advise limiting the weight you try and turn off centre.

Pete

[Sandy]

    "Recently I got a few beech logs which I cut into rough blanks with a chainsaw as my bandsaw is too small for the size of logs.  So the blanks are not terribly well balanced but not too bad."

As Les mentions, and if this is the only time you're having vibration issues, perhaps you need to consider accepting
>  you need to trim these logs more to remove the issue
>  you are pushing the capacity of your set-up and equipment too much

[burywoodturners]

I have an alder burr which I was asked turn a bowl from. I was worried about the balance so I mounted it on the lathe and I not only unplugged it, I took the drive belt off, and after turning it by hand let it come to rest, the rest was just making the lowest point and trimming some of the wood of and spinning it again, once the blank stopped in a different position each time, it was balanced.
I rebuit the lathe, stood to one side and swiched on and it ran smoothly allowing me to make a decent sized bowl.
Ron

[Lazurus]

You can always start between centers to find the balance point of a blank, have a look on YouTube at Lyle JAMIESON he uses this method every time when making bowls and he has a video on what and how to do it safely.

[hughie]

Sometimes one has to take a step back and consider whether or not a piece of timber, even if its size is within the capacity of one's lathe, is beyond its capacity in terms of weight and balance!

Les

Good advice, take your time before start to evaluate the blank. But most definitely add more weight to the lathe and it can be done very simply with a bag of sand and if needs be a darn big bag of sand.