New spindle idea for my machine - DC 1HP

[HiltonSteve]

Isn't that motor just a tadge excessive?

How on earth are you going to channel 1hp through such a tiny tool without blowing it to shards?

If I was going to put in a 1hp layshaft I wouldn't go below 3/4"

Robin,

When I got the motor i too thought it was a bit excessive but based on my simple calculations I ended up looking for a 1HP DC motor and was very suprised at the size when I collected it.

Current Kress 240v AC spindle - 1050W = 1.408073 HP

New big 180V DC motor - 750W = 1.01HP

Then throw into the equation that I have geared the spindle up to increase speed from the 2000rpm motor max which will in turn reduce the torque, so in theory I will have less power than the Kress but I will have slower spindle speeds which is what I am after.

I can't find a torque/speed curve for the Kress spindle but I imagine that when running at its slowest speed (10,000rpm) that it is not developing 1HP, hopefully when my spindle is running I should get decent torque at 3,000-6,000 rpm but time will tell....

Swapped the bearings in the spindle last night which made an improvement but still got a vibration/resonance problem which looks like is coming from the toothed belt, tried different belt tensions which altered when the vibration came in. After a couple of phone calls I think it could be to do with the small amount of 'wrap' i have on the smaller pulley, will be making up an idler pulley to run against the back of the belt to push the belt further round the small pulley.

Note to self - when feeling round for vibration on machine do not put hand on bare motor connections as it makes you jump and shout BASTARD really loud...!

[Robin Hewitt]

Maths isn't exactly my strong point, but...

For sake of argument, consider a 6mm tool at 6000rpm

6mm*pi*100rps=1885mm/s=6.18ft/s at the cutting edge

1hp=550ft.lbf/second

550/6.18=89 lbf=Whoops!

Irving will now tell me where I went wrong :naughty:

Best

Robin

[John S]

Robin,


Swapped the bearings in the spindle last night which made an improvement but still got a vibration/resonance problem which looks like is coming from the toothed belt, tried different belt tensions which altered when the vibration came in. After a couple of phone calls I think it could be to do with the small amount of 'wrap' i have on the smaller pulley, will be making up an idler pulley to run against the back of the belt to push the belt further round the small pulley.

Should have used a Polyvee belt

Nar nar nar nar nar

[HiltonSteve]

Should have used a Polyvee belt

Nar nar nar nar nar

I know your right and you know you are right.....

Still got the tool to make them and the 2 sample pulleys that I borrowed from you! Where did you say to get the belts from?...... smart arse.

[John S]

Still got the tool to make them and the 2 sample pulleys that I borrowed from you! Where did you say to get the belts from?...... smart arse.

See what I mean, BORROWED - huh, fat chance of even seeing those again.

Belts ? try the belt company..............