Hello, I am fairly new to woodturning and want to turn bowls mainly segmented bowls, I have a Record Nova 1624 lathe to which I have added a variable speed 2hp motor, how do I know what speed the lathe is running at, is there any type of attachment for lathes like a speedometer, also any advice on a bowl steady would be welcome I am getting chatter on the inside of the rim on 10 inch by 6 inch deep bowls I have been doing, Thank you
Bowl chatter and speed
- Thread starter murphy
- Start date
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You can buy any number of digital tachometers.
For example - http://www.amazon.co.uk/Digital-Tachome ... B00CRGJ2YK
For example - http://www.amazon.co.uk/Digital-Tachome ... B00CRGJ2YK
duncanh
Established Member
I don't think there are many times where you need to know how fast your lathe is running (thread chasing perhaps).
All I really need to know is: is it too slow, too fast or just about right. My current lathe (Wivamac) doesn't tell me how fast it's running and I don't miss knowing.
Start at low speed and turn it up to a speed at which your comfortable to work. This could be when it starts to vibrate and then turn down until it doesn't, or turn up to a speed at which you're confident your glue up or wood will not fly apart.
All I really need to know is: is it too slow, too fast or just about right. My current lathe (Wivamac) doesn't tell me how fast it's running and I don't miss knowing.
Start at low speed and turn it up to a speed at which your comfortable to work. This could be when it starts to vibrate and then turn down until it doesn't, or turn up to a speed at which you're confident your glue up or wood will not fly apart.
The nova is a direct drive machine ?
So if your motor is running at 50hz and it's a 4 pole motor it should be going at 1440 rpm
If your inverter shows frequency it easy to work out what speed it's going at
As Duncan says an absolute speed does not matter just what you are happy with and the cut is going well and no excess vibration
Ian
So if your motor is running at 50hz and it's a 4 pole motor it should be going at 1440 rpm
If your inverter shows frequency it easy to work out what speed it's going at
As Duncan says an absolute speed does not matter just what you are happy with and the cut is going well and no excess vibration
Ian
woodfarmer
Established Member
Chatter is generally caused by a "looseness" between the workpiece and cutting edge.
Often it can due to the blank drying a bit whilst being turned, so always worth rechecking chuck or whatever else holds the bowl.
The other kind of "looseness" is due to the bevel not riding true and snug. This can be cause by differing hardnesses in the wood(s). It can always be helped by having very sharp tools and taking very light cuts.
hope this helps.
Often it can due to the blank drying a bit whilst being turned, so always worth rechecking chuck or whatever else holds the bowl.
The other kind of "looseness" is due to the bevel not riding true and snug. This can be cause by differing hardnesses in the wood(s). It can always be helped by having very sharp tools and taking very light cuts.
hope this helps.
chipmunk
Established Member
I agree with woodfarmer, sharpen your tool, use a smaller tool and take lighter cuts.
Rather than using a steady rest and provided it isn't either natural edge or has any cracks splits or holes in the top, you can often use your second hand to support the bowl beneath the cut as the bowl revolves.
Please only try this if you are confident in your own abilities though, don't wear gloves or have any long sleeves that might catch because one catch and you're only holding the tool in one hand and your other one is in way of that sharp edge!
Jon
Rather than using a steady rest and provided it isn't either natural edge or has any cracks splits or holes in the top, you can often use your second hand to support the bowl beneath the cut as the bowl revolves.
Please only try this if you are confident in your own abilities though, don't wear gloves or have any long sleeves that might catch because one catch and you're only holding the tool in one hand and your other one is in way of that sharp edge!
Jon
Thank you all for your help, I have ordered the Tachometer from Amazon, as it's so cheap it will be handy to have, and I will try taking lighter cuts with a smaller sharper tool, I don't think I am ready for turning with one hand just yet, I am not that good with two, but I have been working on a bowl steady which is just finished so I will try that as well,
Patrick
Patrick
CHJ
Established Member
Just use these calibration disks stuck to a bit of cardboard held in the chuck to make an indicator dial for your adjustment potentiometer, more than accurate enough for a guide and stops the silly chasing of a few RPM as can happen trying to settle a digital indicator at a set speed.
http://www.jeffree.co.uk/pages/speedmeasurement.html
http://www.jeffree.co.uk/pages/speedmeasurement.html
CHJ
Established Member
For someone with limited experienced in turning I would advise you finish the rim of the bowl, both inside and out whilst there is still plenty of body support left in the blank, never attempt to go back to the periphery with turning tools after you have completed the shaping.
It's inevitable that the bowl will have moved out of round and you will get intermittent cuts and tool bounce.
Even if distortion is at a minimum you are likely to get 'bell' resonance the moment you touch the edge.
It's inevitable that the bowl will have moved out of round and you will get intermittent cuts and tool bounce.
Even if distortion is at a minimum you are likely to get 'bell' resonance the moment you touch the edge.
Thank you CHJ for the calibration discs link, that is exactly what is happening I get the bell resonance, so I will work from the rim inwards next time finishing as I go, I have a lot to learn
Patrick
Patrick
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