Thread: Design Advice to Drive Machinery

dave i hope you have a lot of panadol that could be nightmare to sort out.I would think along the lines of fast/loose pulleys rather than a clutch

G'day Dave

I would be worried about not being able to see what the belts were doing.

I would be more worried about friction and the belts rubbing against stuff, as you know friction causes heat and heat causes fire. ( how long would it take a dog to hump a bucket of water until it boiled?)

Besides, seeing the wheels and shafts is the best bit. Hide the motor but show off the belts

Be

Mark


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thx guys for your thoughts guys ... watching closely for any other thoughts

Sounds like a good project. You may get some ideas plus possibly some shafts, bearings, etc from old shaft drive overhead shearing gear. Some old sheds which now have individual electric stands still have the old gear sitting idle. My father had a drill press and grinder running off an overhead shaft driven by petrol motor before electricity came to town. Flat belts were only put on their pulleys when that machine was being used. I would think that overhead would be easier to install and maintain and keep free of chips and dust than under floor shaft. Take care with safety, guarding, usage practices, etc, especially if others will be assisting or watching. Take advice from Work Cover and/or your insurer if in doubt. Cheers.

Geoff - thx. I will ask around town and see what might be around for unused machinery. There is shearer over the back fence from me that might be able to help.

I like under the floor as I can bring a belt up at each machine and have a guard there so it wont be seen or a risk. Keeps the shop clear for moving longer lengths without fear of hitting a belt.

Dave

Dave,
I would get a lecky to make up the VFD on a board feeding a 3phase outlet, and then have identical plugs on each machine, and just move it to the machine you want to use. I have 1, 3phase outlet in my shed, and extra long cords on each machine and keep swapping, and i am actually a lecky, just too busy sawing timber to run the new circuits,
hope this helps,
rgds,
Crocy.

Originally Posted by Old Croc

Dave,
I would get a lecky to make up the VFD on a board feeding a 3phase outlet, and then have identical plugs on each machine, and just move it to the machine you want to use. I have 1, 3phase outlet in my shed, and extra long cords on each machine and keep swapping, and i am actually a lecky, just too busy sawing timber to run the new circuits,
hope this helps,
rgds,
Crocy.

maybe I should come and do some carpentry for you and you can do some electrical for me

Running a whole bunch of different machines from the same VFD is just not making the best use of motors or a VFDs.

Lets say you have a machine with 1440 RPM max - the chances are the motor has bearings that enable it to spin well beyond 3000 rpm so you can use a wider frequency range and hence a wider range of RPMs. This situation would allow you to set your VFD to say a max of 100 or 120 Hz.

Now lets say you have a 2850 rpm motor. The max you could probably go here is to say 3600 or 4000 rpm so maybe 70Hz. Spin this one to 100 Hz will be asking for trouble.

Then you may like soft start on some machines and not for others, maybe slow stop for some and not for others.

Sure you could do all this by programming the VFD every time you switched to a different machine but that would be a RPITA.

Using one VFD is a bit like using one motor for a range of vehicles - the final outcome would be a serious compromise.

BobL - what machines would you suggest not to start with soft start. I see your point on the frequency though I am by no means a sparkie and dont 'understand' how that works but see the what your saying

Hey Dave,

At the risk of taking a backwards step, perhaps you could go into some more detail as to why you want to run everything from 1 motor and off a VFD. What sort of HP you need to run and what power you have available. I am thinking you only have single phase? If so do you have enough single phase amps available?

I am just trying to get a clearer picture of what you are trying to achieve, and also if you are anything like me, trying to pull you back from the most elaborate solution. My first idea always turns out to be 10 times more complicated than it needs to be

Don't get me wrong, I would love to see you go down that rabbit hole, and would make the trip for the unveiling, but as 1thumb said, it would be a big headache, but a FUN one.

Cheers,

Camo

Originally Posted by DaveTTC

BobL - what machines would you suggest not to start with soft start. I see your point on the frequency though I am by no means a sparkie and dont 'understand' how that works but see the what your saying

When I say "no soft start" I mean different levels of soft start. You don't really want some machines to take too long to get started or to slow down too slowly, for example a Drill press. Slow "slow down" might also be a safety. Others it may not be less criticial for and sometimes it is useful

Camo & BobL

Originally Posted by camoz

Hey Dave,

At the risk of taking a backwards step, perhaps you could go into some more detail as to why you want to run everything from 1 motor and off a VFD. What sort of HP you need to run and what power you have available. I am thinking you only have single phase? If so do you have enough single phase amps available?

Cheers,

Camo

There are a few factors but I am not set in any one thing

1) I want to set up for making an income
2) I want my workshop to be a tourist attraction (small scale)
3) I want predominantly old stuff like a working museum
4) If I had everything run off some kind of 'switchable' drive that runs off one motor it is both different and I can swap the motor easy if something goes wrong - it may be something some guys will travel to see.

5) I dont know availability of amps or how much I would need. There is an old stove circuit which is 2 phase (440 volts)
6) shed is being rebuilt so can work around issues easier, still a few months or so before I even start the shed
7) there will be plenty of crawl space under a heavy duty timber floor

Originally Posted by BobL

When I say "no soft start" I mean different levels of soft start. You don't really want some machines to take too long to get started or to slow down too slowly, for example a Drill press. Slow "slow down" might also be a safety. Others it may not be less criticial for and sometimes it is useful

Drill was the one that most came to my mind was just wondering if there was anything else you can think of.

The only kind of machinery I can think of that may benefit from multi/variable speed is lathe and drill. If there are others you think I have overlooked I am all ears. Once I have done what ever I decide on I am hoping for a 'keeper'. Don't want to be changing things later

Hi Dave ,

I saw somewhere?? I think in a fine woodworking publication a workshop that was a drawing that had a line shaft that drove all the machines . I think it ran under the floor.

I have a workshop with a few younger guys , doing most of the hand work, and most my bigger machines are 3 phase , we do hand made furniture , the machines convert the boards down to the right square and true sizes and the hand tools take over from there .

If I make a table and it's a 50 hour job to make it and a 20 hour job to polish it I think the buzzer , thicknesser , two band saws ,radial arm saw , tennoner and 1 phase mortiser would be running for a total [ Guess ] 3 hours with me or one of my fast young guys .
6 with a learner and 20% more timber going back to the rack to one day be used on a smaller job forget the learner .

Ive thought if I had to go to a remote peaceful work shop that a diesel 3 phase generator may be the go. plan the work around a few machinery bursts in the morning . If a 3 phase generator and a single phase one as well were run for 5 hours per $5000 table what would the fuel bill be ? $50

what do you think ?
Rob

Thanks Dave,

That gives me a better idea of what you are trying to achieve

Originally Posted by DaveTTC

it may be something some guys will travel to see.

You can put me down as a visitor.

Based on what you have said, I would definitely be investigating your power further, before going too far (especially if you are looking at it as a way to make an income, its best to know what you are in for upfront). I am definitely no electrician, so perhaps Crocy might be able to give some better information regarding this. What I am getting at is if you want to run say a table saw or spindle moulder or perhaps 2 machines at once, I would imagine your motor will have to be at least say 4 or 5 HP and probably more.


Given that Amps = (HP X 746 Watts)/Volts, a 5HP motor is about 8.5 amps at 440V and 15.5amps at 240V, which doesn't factor in the fact that motors are obviously not 100% efficient (so it draws more than it outputs), and neither are VFD's, and you need a lot more current for that small time as the motor starts (which as I understand it is another advantage of soft start?), which is why a 3HP single phase motor generally comes with a 15amp plug (even though the math says 9.3amps).

I don't know what the old 2 phase 440V stove circuits can output (but it is certainly better than just having a 10 or 15 amp 240V circuit, so I would imagine that is good news), but is it enough, and given the fact that it is an old circuit will the wiring need to be upgraded? When I ran 3 phase to the workshop, I decided I wanted to be able to go as high as 32 amps, although at this stage the breaker and plugs are only 20amp, to do this I had to upgrade the wires all the way back to the street (not something I had anticipated initially).

Well I just read what I have written and boy does it sound like I am bringing things down, not my intention at all, but these are things to check first, then into the exciting stuff.

Cheers,

Camo