Current breed of eBay VFD's for lathe upgrade

[Oddy]

I've had my starter lathe for a while now and am quite happy with it (an old Woodfast in perfect shape), but am considering a cheapish upgrade to variable speed. I plan to go with a 1.1 to 1.5 kW motor and only have 240V for input.

Will probably have to get my step pulley bored out to fit new motor shaft - current .75kW motor only has a 5/8 shaft, but otherwise the mounting configuration is going to make it very easy to replace the motor.

Anyone have any experience with the current crop of VFD's selling on eBay these days? Any decent ones out there among the cheapies?

[BobL]

A 1.1km motor is likely to have a 19 mm shaft while a 1.5KW is likely to have a 24mm shaft
Before you bore out the pulley make sure you have enough meat left on the pulley for the keyway and grub screw.
I couldn't do this on my Woodfast pulley without risking making the pulley walls too thin so I turned up a new pulley.

Any of the cheap VFDs will be adequate to run a small WW lathe.

[chucky]

My woodfast cobra lathe was converted a few years ago with the same problem of 5/8 shaft and pulley size, I ended up purchasing a 3 phase .72 kw (1 hp) CMG motor (made in Aust) product code CW34075 that has a 5/8 shaft which fits the Woodfast pulleys. It is up to you what motor size you use but I have no problems turning products inboard or outboard with the current motor sizing . It is worth noting that my Vicmarc VL175 also has a 1hp motor,

[hughie]

I've had my starter lathe for a while now and am quite happy with it (an old Woodfast in perfect shape), but am considering a cheapish upgrade to variable speed. I plan to go with a 1.1 to 1.5 kW motor and only have 240V for input.

Will probably have to get my step pulley bored out to fit new motor shaft - current .75kW motor only has a 5/8 shaft, but otherwise the mounting configuration is going to make it very easy to replace the motor.

Anyone have any experience with the current crop of VFD's selling on eBay these days? Any decent ones out there among the cheapies?

Depending the capacity of your Woodfast. I would be looking at maybe 2.2kw if it will physically fit in the Woodfast. The reason for the increase in power is that as you lower the speed on VFD you will lose torque. One of the problems with Woodfast is the motor space is limited, but I would still go with the bigger motor option where possible
One way to counter this is to have a stepped pulley arrangement to increase the mechanical advantage. But on 1.1 or 1.5 you probably wont obtain enough mechanical advantage to over come the loss.
As to which one might be the better, look for those that have a guarantee, say 12 months and are sold by an agent etc here in Australia. At least you will some recourse if it goes pear shaped.

[Oddy]

Thanks for the replies so far.
@hughie I don't think I would have problems with any practical size motor. My lathe is mounted on a custom steel stand with the motor mounted on a platform below the bed. The platform could take just about any motor you would want to throw at it. The lathe is an MC908 with a 42cm swing over bed and possibility of larger outboard turning, though at this stage I don't think I would attempt anything bigger than 40cm.
I just don't want to go overkill on the motor though. It seems new lathes of a similar size tend to have motors in the 1.1 to 1.5kW range.

[hughie]

Thanks for the replies so far.
@hughie I don't think I would have problems with any practical size motor. My lathe is mounted on a custom steel stand with the motor mounted on a platform below the bed. The platform could take just about any motor you would want to throw at it. The lathe is an MC908 with a 42cm swing over bed and possibility of larger outboard turning, though at this stage I don't think I would attempt anything bigger than 40cm.
I just don't want to go overkill on the motor though. It seems new lathes of a similar size tend to have motors in the 1.1 to 1.5kW range.

The new ones have a different variable speed set up that offers full torque through the speed range, hence the suggestion. I have rebuilt a couple of lathes with electronic variable speed drives one of which was a M400 Woodfast and the motor bay could only handle a 1.1kw.
http://www.woodworkforums.com/f8/overhaul-complete-tested-138076?highlight=Woodfast+400


I am currently building another with the same set up but the drive will be external so as not have any hassles with space.

[powderpost]

Why not contact Woodfast? I fitted one of their variable speed kits to my Woodfast lathe about 10 years ago. I have turned down a block of maple 500mm diameter and 250mm thick on the outboard until it fitted inboard down to a lace bobbin. I only have good words for their kit. Will add also the kit is not real cheap, but it is excellent quality.

Jim

[Oddy]

Yeah, I did look into the kits - Woodfast and Vicmarc, but they are extremely expensive compared to the ebay vfd's + used motor, or even a new motor. The kits are even more expensive than buying the components separately e.g. decent quality new motor and same VFD.

[BobL]

The new ones have a different variable speed set up that offers full torque through the speed range, hence the suggestion.

If you are referring to vector drive VFD? then while they do have improved torque across the speed range it is far from full torque.

Below are some test measurements for a nominal 1HP motor free running at 770 RPM @ 50Hz using a Non-vector (V/F) drive and a Vector drive.
The torque outputs for the vector drive are clearly superior to the non-vector drive but as you can see the torque is far from constant

Under load if the 1HP motor can maintain 770 rpm then it generates about 9.3 NM of torque.
The reason that some torques in the graph are greater than this is because most motors can generate more HP and torque than their specified rating.
It's not unusual for a 1HP to output 1.5HP and hence correspondingly higher torque

In practice the max torques generated by the vector drive are (over a limited low speed range ~5 to 25Hz) about the same as that for double the frequency of the non vector drive.
EG the torque generated by a motor running via vector drive at 10Hz is about the same as that generated by the non-vector drive at 20 Hz.

At very low frequencies (<5Hz)where the non-vector drive just dies, the vector drive will allow the motor to still generate some torque.

Above about 25Hz the Vector drive does allow the motor to develop the same torque as at 50Hz. Above 50 Hs they work the same as the non-vector drive.
So in practice the Vector drive enables the motor to have more or less constant torque from about 20 t0 50 Hz.


373546

BYW this was done directly on my Hercus MW lathe by clamping my De Prony Brake onto the bed of the lathe (using suitable padding of course) and mouting the brake drum in the chuck.

On terms of price the vector drives used to be double the price of the non-vector drives - at least that was the case hen I bought the VFD for my MW lathe in 2011.
Now I see there are some cheap brands that cost about 50% more but I haven't tested these to see if they are any good.

[nalmo]

I picked up a Vacon (new old stock) on ebay which I am competely satisfied with.
I was a bit concerned about the safety aspects (electrical/fire) of some of the cheaper ones on ebay.

I wrote to Vacon overseas for some advice on programming the unit, and got a call the next day from their Australian office with all the information & diagrams I needed.
They were extremely helpful & I was very impressed with their service.

[BobL]

I picked up a Vacon (new old stock) on ebay which I am competely satisfied with.
I was a bit concerned about the safety aspects (electrical/fire) of some of the cheaper ones on ebay.
Of the 12 VFDs I have in my shed since 2011, 10 are cheapies and one of these died when I tried to force it to do something it's limited instruction set would not allow it to.

The cheaper ones are basically copies of the more expensive ones but with reduced instruction sets and programability.

While they use cheaper components, the standard safety mechanisms such as current limiting facilities are still available so they are still able to protect circuits and motors.

If the VFD had to be used in operator free environment that might be a good reason to invest in a more expensive unit, but or wood working, especially where the operator is present 100% of the time, 95% of the programability of the more expensive ones will never be utilised.

[hughie]

Bob yeah vector drives are the ones I was referring too.

[John T]

HI ALL,
I have just converted my woodfast c 1000 from 1hp single ph to 1,5 hp three phase vdf am very happy with the result,Ample power at low rpm I have retained my 6 speed pulley 35 rpm at 20 htz on small pulley 4500rpm on 125 htz on5th section total cost of $800 dollars, john t

[BobL]

. . . total cost of $800 dollars, john t

$800 Sounds expensive.

A basic 2HP VFD suit able for a WW lathe can be obtained for $150 and a used 3P motor can be obtained for under $50.
$30 for a pot, remote switch and a plastic box to hold them.

Even a basic Vector drive VFD can be obtained for ~$250

[Oddy]

HI ALL,
I have just converted my woodfast c 1000 from 1hp single ph to 1,5 hp three phase vdf am very happy with the result,Ample power at low rpm I have retained my 6 speed pulley 35 rpm at 20 htz on small pulley 4500rpm on 125 htz on5th section total cost of $800 dollars, john t
What VFD did you end up going with John?

[John T]

HI ODDY,
My VFD drive is a inverek ip66/type4x at around $350 dollars

[Oddy]

Vector drive is looking attractive but have to drop a fare bit more cash to get it though. Looking at Chinese options around the $250 mark, or for an extra $50 to $100 can get more of a name brand like Omron or an Invertek as John mentions above. I don't know much about the Invertek's but appears you would get good support and warranty on either Invertek or Omron, plus the manuals for both of these are excellent. The manuals for the Chinese brands I have seen are a joke and I am finding eBay sellers are either quoting wrong model numbers or wrong capacities on some of their listings - as they don't match the specs in the manuals (e.g. selling a .75kW drive as a 1.5kW). eBay is looking like a bit of a mine field so I may be end up going with a more trusted source and spend the $300 and hopefully only spend once vs the $130 non vector Chinese drive that maybe I'll find inadequate at low speeds but maybe not. Originally was hoping to do the upgrade for under $400, but starting to look like stretching my budget if I don't find a decent used motor and have to buy new.

[BobL]

Vector drive is looking attractive but have to drop a fare bit more cash to get it though. Looking at Chinese options around the $250 mark, or for an extra $50 to $100 can get more of a name brand like Omron or an Invertek as John mentions above. I don't know much about the Invertek's but appears you would get good support and warranty on either Invertek or Omron, plus the manuals for both of these are excellent. The manuals for the Chinese brands I have seen are a joke and I am finding eBay sellers are either quoting wrong model numbers or wrong capacities on some of their listings - as they don't match the specs in the manuals (e.g. selling a .75kW drive as a 1.5kW). eBay is looking like a bit of a mine field so I may be end up going with a more trusted source and spend the $300 and hopefully only spend once vs the $130 non vector Chinese drive that maybe I'll find inadequate at low speeds but maybe not.

If you double the motor power you won't have any problem with power at the spindle. It's not really advisable to use low speeds with a vector drive for an extended period anyway, as the motor may over heat. If this is what you want to do then additional cooling is advisable.

This $172 unit is interesting
1 5KW 2HP 7A 220VAC Single Phase Variable Frequency Drive Inverter VSD VFD | eBay (http://www.ebay.com/itm/1-5KW-2hp-7A-220VAC-Single-Phase-Variable-Frequency-Drive-Inverter-VSD-VFD-/361155386082?hash=item541689dae2:g:XJ8AAOSw0vBUkjm0)
It claims to "Support Open loop vector control"
Also claims to have an "Independent cooling channel design:Prevents dust and corrosive gas damaging the circuit board, and slows down the aging speed of circuit board".
If I was a little more flush I would buy one to test.
Has anyone found a manual for these?

[Oddy]

Good find there Bob. I missed that one because it didn't have "vector" in the title and was otherwise on the expensive side for the run of the mill drives. I found the same listing on the eBay Australia site and got the manual from the supplier. Supplier was quite responsive, with adequate English and at first glance the manual looks ok, so will take a proper look at it over the next day or so. Will PM it to you Bob.

[BobL]

Thanks for the manual Oddy.

Based on the manual I'd say this looks like a decent budget level unit.
It is limited to 300Hz but that's heaps for WW machinery.
The manual says something about using it to controls several motors but not under Vector drive control.

[Oddy]

Well I have ordered one of these KCLY drives. Picked up a 1.1kW motor today. Will report back on how the VFD goes when its all hooked up and tested.
Just need to find someone to bore out my step pulley for me to fit the new motor shaft.

[chucky]

Oddy

Check to see you if there is have enough metal to enable you bore the existing 5/8 hole larger and the allen key slot. I know that when I convert my Woodfast Cobra the stepped pulley did not have enough meat to machine out and be safe. This was checked by 3 qualified Fitter & Turners . I ended up fitting a CMG 3 phase motor with 5/8 shaft. no problems. Good luck with your conversion.

[Oddy]

Oddy

Check to see you if there is have enough metal to enable you bore the existing 5/8 hole larger and the allen key slot. I know that when I convert my Woodfast Cobra the stepped pulley did not have enough meat to machine out and be safe. This was checked by 3 qualified Fitter & Turners . I ended up fitting a CMG 3 phase motor with 5/8 shaft. no problems. Good luck with your conversion.

I went ahead and had the pulley bored out (thanks Andre over on the metalwork forums).
On the old motor there was no key in use - just 2 grub screws, one of which screwed into the key slot. The key would only extend into step 3 and step 2 of the pully on both old and new motor, with step 1 (the smallest) furthest onto the shaft and beyond the key slot. Steps 5 and 4 are hollowed out (or cast) well beyond the shaft diameter. There is still plenty of meat on the 2nd and 3rd steps for a key but I may just go with the grub screws as it is currently.
There is not a lot of meat left on the pulley first step - about 6 or 7mm around the diameter. I'm not sure of what the sheer strength of this would be. While I don't see it as a danger I guess it would be possible for a high torque load running off that step to shear that step off from the larger body of the pulley that is locked to the motor shaft. All I believe that would happen if this were to occur I think would be that that disk would be trapped between the motor frame and the larger portion of pulley and would just slip on the motor shaft.
To avoid this happening though I am considering using locktite on the pulley so that the smallest step will not have a tendency to slip on the shaft and shear from the larger pulley steps. Also with the VFD I might be able to avoid using this step at all.

[NeilS]

My 1.5Hp motor is adequate for everything I throw at it other than coring of very large blanks. An extra 1/2 to 1 HP would be better for coring very large blanks. If not coring to that diameter, 1.5HP should do everything if the VFD is adequate.

eg, this 20in (50kg) blank was within the capacity of the 1.5HP motor and variable speed drive that came on my Woodfast.

375676

[BobL]

There is not a lot of meat left on the pulley first step - about 6 or 7mm around the diameter. I'm not sure of what the sheer strength of this would be. While I don't see it as a danger I guess it would be possible for a high torque load running off that step to shear that step off from the larger body of the pulley that is locked to the motor shaft. All I believe that would happen if this were to occur I think would be that that disk would be trapped between the motor frame and the larger portion of pulley and would just slip on the motor shaft.
To avoid this happening though I am considering using locktite on the pulley so that the smallest step will not have a tendency to slip on the shaft and shear from the larger pulley steps. Also with the VFD I might be able to avoid using this step at all.

When you say first step I assume you mean the smallest pulley?
If so then you won't need to use it at all.
The ration between the smallest and next biggest pulley is unlikely to be more more than a factor of 2 and their can easily be achieved with the VFD.

I have 6 step pulleys on WW lathe and in 4 years have yet to move the belt off the 3rd pulley position - not that I am a regular turner.

[Oddy]

Well the KCLY drive turned out to be a dud. I can't complain about the ebay vendor (superistore), they were very responsive and attempted to help troubleshoot. We concluded that the unit is likely defective and I have now returned it for a refund (will wait and see how that goes). The vendor also offered to send a replacement free of charge and still provide a refund if the second unit did not work either.
I declined the offer and have decided to go with a brand I have some faith in. So in the end wasted a bunch of time and ended up going back to original instinct.
The unit I ordered was the 1.5kW model and I was trying to drive a 1.1kW motor. The unit refused to autotune for vector drive and was unable to drive the motor at all when it was wired in Delta mode - always giving overcurrent alarms. Wired in star it was able to drive the motor up to 17Hz but always tripped out on over current when I went above 17 Hz. I have another VFD for my dust extractor that I tried on the motor with no problems and currents looked normal. I spent a lot of time exhausting all the relevant settings in the KCLY drive with no luck. So my conclusion is this device is extremely cheap for a vector drive for good reason. It was a gamble and it didn't pay off so 1 strike and you are out in this case. Lesson learnt.

[BobL]

. . . It was a gamble and it didn't pay off so 1 strike and you are out in this case. Lesson learnt.

And thanks to their forum we have all learned something useful.