Variable speed Bandsaw Upgrade

**pjt** · 4th March 2013, 01:18 PM

Originally Posted by simonmags

Hi PJT, why did you end up going so fast in fpm with your blade, is 6000 not a bit on the high side, just going off some of the previous posts? Thanks for the ratios you guys have put up here too, will be very useful to ensure correct cutting when i get mine going.

I''m guessing you guys either run commercial operations or are more talking about bandsaw mills than your garden variety vertical bandsaw. I'm just trying to work out this VFD / VSD stuff my saw. https://www.woodworkforums.com/f27/ce...-450nl-166960/

I did a bit of googling on blade speeds and found a bit of info, looked at what I had as far as pulleys, available machine space (inside cabinet) and decided that I could go faster than what was original, yes, it is faster than typically found on hobby level machines but not as slow as some high production big operation mills cutting say green softwood, horses of courses thing really, my BS is (was) just a typical hobby garden variety, on these hobby machines it is typical to have a low powered motor as this keeps the current draw below 10 amps and this then means a bigger market cos power points in a house/shed are rated at 10 amps (in aus anyway) if manufactures make BS with bigger motors then a requirement is a 15 or 20 amp dedicated circuit and extra cost to a potential customer.

Power=tourque x speed... if you want to go fast you need more power, if you only have limited power you need to look at tourque which is essentially the ratio (pulleys/wheel size) so to get a BS to cut 12" deep in old dry hardwood with limited power means a slow blade speed and a slow feed rate, possible but I wasn't happy with that outcome, so 4hp and a blade speed to match,

but there are downsides, increased frequency of stress cycling of the blade (blade breakage) and when cutting something really hard it would be nice to slow fpm to give a bit more tooth life, moreso on the B blade than the CT blade, this is where a VSD is good such as you (Ian) are looking at.

Pete

**pjt** · 5th March 2013, 11:29 PM

AWR arrived today, having a glance thru and start looking at coolest machines, Micheal Conner has a big old BS that runs a blade speed of 120kph which if my calcs are right is 2000m/min or 6561 fpm.

Pete

**simonmags** · 6th March 2013, 11:34 AM

That is indeed a crazy speed, must sound like a mini jet engine starting up. I'd imagine it would not take a lot of pressure to resaw wood very quickly. I wonder if he has a powerfeed so that he can get the feed in rate just right.

**TurnedByIan** · 6th March 2013, 12:03 PM

At those sort of surface speeds, would there be higher wear and tear on shaft bearings let alone the saw guides?
We casually throw around 6000fps figures but didn't consider it much till PJT put it as kph

Off to Taupo to visit Robbie Graham's place this weekend for nothing but Turning, talking about turning and not much else hehe.
Cheers Ian

**pjt** · 7th March 2013, 12:29 AM

Originally Posted by simonmags

That is indeed a crazy speed, must sound like a mini jet engine starting up. I'd imagine it would not take a lot of pressure to resaw wood very quickly. I wonder if he has a powerfeed so that he can get the feed in rate just right.

At a guess the faster speed hasn't really generated that much more noise (for mine at least) the type of blade that is on the machine does have a big impact on noise and by far the woodslicer is the quietest,
I didn't see a feeder on his machine, I only handfeed mine and at a guess I can feed in at about 2 to 3m/min and faster depending on what I am doing.

Originally Posted by TurnedByIan

At those sort of surface speeds, would there be higher wear and tear on shaft bearings let alone the saw guides?
We casually throw around 6000fps figures but didn't consider it much till PJT put it as kph

For the bandsaw blade wheels and the motor bearings (deep groove ball/grease lub) even if you run a vsd at 60hz and had a blade speed of 2000m/min you won't be getting up to near the limiting speed of the bearings, it will depend on the BS for actual values, the blade guide bearings might be getting closer tho, the surface speed of the blade will determine the rpm of the guide brgs, for mine at a blade speed of 2000m/min and a brg od of 42mm they are at the limiting speed, 15 000 rpm, I have run these brgs for a number of yrs now without an issue, they do get warm and I probably should regrease them but......the BS isn't used every day but can be used for 2 to 3 hrs at a time, if I was worried about the rpm of the brgs I could look into alternatve lub or maybe look at high speed brgs, but I'm not so it stays as it is....

Pete

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