What would you buy?

[deema]

I’d really appreciate knowing what you think, what you would prefer if you were buying your next wood working machine. I have three choices for the electrics of a bandsaw(SCM S45) which is currently 3 phase I will be restoring and don’t know which solution to go for.

Option 1. This is my usual method for this type of machine. I replace the motor with a high quality single phase unit, new starter etc. I’ve usually gone down this route in the belief that it’s simple, no complexity for the new owner and it’s easily understood. The solution is normally a replica of the single phase option for the machine (Or an upgrade depending on age so it’s PUWR compliant)

Option 2. Keep the existing motor and replace the starter with a Variable Frequency Drive VFD. This will have the advantage of providing variable speed to the saw which it presently doesn’t have.

Option 3. Keep the existing motor, and rather than a VFD add say a 4KW digital phase converter. This will be a separate unit that can drive any 3 phase machine by simply plugging the machine directly into it. A digital phase converter is a box that produces full 415V 3 phase so the new owner won’t need to worry about dual voltage motors / tinkering and could buy other 3 phase machines and use them with it. This is the latest technology for creating 415V out of a single phase supply.
To plug

So, if you were in the market for a secondhand bandsaw, which option would you prefer?

 

[marcros]

For a bandsaw, I think that you would attract the most interest being able to say that it is single phase, particularly on eBay. I don't cut metal but I haven't found a need to change speed of the saw on my wood cutting bandsaw- blade and feed rate are my variables.

For other machines I can see the advantages.

 

[Doug B]

Both 2 & 3 involve an extra piece of kit that can go wrong, slowing a motor with a VFD loses torque so isn’t always the best way to alter speed though it can give 10 second stop.
Personally I’d opt for single phase motor swap as there seems to be plenty of larger 3 phase bandsaws out there compared to single phase so probably more interest & there’s less to go wrong.

 

[Ttrees]

I like VFD's as I can use my 3hp machines from the household plug,
Costing less than a hundred quid 'all in' (I can make the cabinet myself (and boxes for switches if need be)
I have heard of folks stating that VFD's aren't as desirable, but for me the opposite.
I reckon VFD's might get a bit more credit nowadays than they used to.
I removed the pot from my saw, as the drive kept tripping out, never used it anyway.

Mind you I don't have extraction, but not so much of an issue with a 24" bandsaw, but for the compact saw you are working on, might be so, as I seem to recall my more compact 20" machine being a heck of a lot dustier.

If your looking to make money on the machine, I'd keep as is now, and sell the machine as option 1, option 2 or option 3 package, plug and play.
Obviously with pictures and a write up of the benefits of each, that would surely be the most profitable of the lot?

How much does the very very very cheapest 4KW digital phase converter cost,
for one who doesn't value their time, and who has patience to learn/no rush to use (as in, say a year to figure things out)
Not looking for a brand that would be recommended, but the opposite like my cheapo VFD's which a few knowledgeable folks in the field would shudder at.

Thanks
Tom

 

[heimlaga]

I have three phase from the pole and avoid single phase machines as far as I can. Unfortunately there are no three phase hand held routers and drills on the market.

However concerning bandsaws I would absolutely not shift the motor on a direct drive bandsaw. They generally had motors specificly designed and built to take up the great sideways load on the axle. When people shift the motor to a standard unit it usually doesn't last long because it is not mechanically strong enough.
I am also very sick and tired of missfitting replacement motors found on various secondhand machines. Most of the conversions aren't mechanically sound. Of cause there are instances when the original motor wasn't powerful enough (for instance some Wadkin-Bursgreen 10"AGS and the infamous Jonsered FM-C) and hence should be shifted but in most cases I prefere the original motor. Because it fits the mounts and has the correct power and speed and the correct rating for it's use.
Actually I have once gone through the trouble of rewinding the armature and shifting the commutator of a burned out single phase motor just because I knew that a proper replacement would involve a lot more than the motor. No professional rewinder was willing to do it so I rewound it myself at home under guidance from my uncle who has quite a bit of knowledge left from when he rewound motors as a side income in the 60-ies.

 

[mikej460]

I like VFD's as I can use my 3hp machines from the household plug,
Costing less than a hundred quid 'all in' (I can make the cabinet myself (and boxes for switches if need be)
I have heard of folks stating that VFD's aren't as desirable, but for me the opposite.
I reckon VFD's might get a bit more credit nowadays than they used to.
I removed the pot from my saw, as the drive kept tripping out, never used it anyway.

Mind you I don't have extraction, but not so much of an issue with a 24" bandsaw, but for the compact saw you are working on, might be so, as I seem to recall my more compact 20" machine being a heck of a lot dustier.

If your looking to make money on the machine, I'd keep as is now, and sell the machine as option 1, option 2 or option 3 package, plug and play.
Obviously with pictures and a write up of the benefits of each, that would surely be the most profitable of the lot?

How much does the very very very cheapest 4KW digital phase converter cost,
for one who doesn't value their time, and who has patience to learn/no rush to use (as in, say a year to figure things out)
Not looking for a brand that would be recommended, but the opposite like my cheapo VFD's which a few knowledgeable folks in the field would shudder at.

Thanks
Tom

Hi Tom
Do you know if a VFD could control a permanent magnet synchronous motor that I salvaged out of our scrapped Bosch washing machine?

thanks

Mike

 

[Ttrees]

Sorry Mike, I haven't a clue about anything, nor experience outside of the standard
dual voltage motors, which I specifically studied on out of necessity, being on a shoestring
Mostly from myfordman's (Bob Minchin's) induction motors write up underneath.


Induction motor information here https://drive.google.com/file/d/0B_GZrXNsNxTlQzd6aldlQjJtUDQ/view?usp=sharing
and maybe a little help from this forum also.

The only thing I could bring to the table, would be some info on Huanyang VFD's
or should I say fake Huanyang VFD's?
I might know some things from the CNC pages if anyone has issues with one.
(saying that I have one that I can't fix, but know them in a sort of consumer way, resetting them by pulling out the ribbon cable, and allocating other switch terminals if they don't work.
Consumer related, not electrical related really, if that makes sense.


Beyond that, I can barely change a capacitor on a single phase motor, and maybe change some bearings.
You'll have to wait for the rest of the crew who actually are knowledgeable.
I wouldn't even know what your motor is, never heard of one.
Surely someone will be along to answer your query shortly.
All the best

Tom

 

[ndbrown]

I had the same bandsaw (S45) for many years. It was single phase, fantastic machine, bought ex-school for £500, only needed a wheel bearing change and sold 2 years ago privately for £800, could have sold a few of them, based on the number of enquiries I had. My opinion would be an OEM motor if you can get one at a reasonable cost ( have included a photo of my S45 s/phase motor if that helps), option 2 rewind to single, again if not cost prohibitive then VFD. I have a VFD on my Elliot 2GS Pillar Drill and Myford Super 7, both machines I got for free as they were going to be scrapped in a school changing to modern H&S compliant machines so I had a budget to change to single phase motors but decided to leave as 3-phase to gain the variable speed advantages. Perhaps not so much of an advantage on the bandsaw. If installed well, I dont think the VFD detracts from the desireability of the machine.
S45 OEM single phase motor plate

and VFD on my Elliott 2GS

 

[deema]

Thanks for the photo of an original motor. I’m rather surprised to see that its not a high torque motor, i.e. separate capacitors for start and run.

 

[deema]

Thanks everyone for your input