Thread: Variable Speed for Woodfast Lathe

Hi, is the motor mounted underneath or on the side of the lathe. If it is mounted underneath, there might be a problem of fitting a different motor in its place. A way around that would be to make a lay shaft where the original motor sat, then fabricate a new motor mount to the rear so that a set of pulleys and belt can be used to transmit the power. I have a similar problem with my metal lathe.
Kryn

I have the first M910 VS kit fitted to a Woodfast M908 about 1992 vintage by memory. I pestered Bronte Edwards for one. Contact Woodfast and purchase the Woodfast VS kit, you won't regret it.

Originally Posted by Mobyturns

I have the first M910 VS kit fitted to a Woodfast M908 about 1992 vintage by memory. I pestered Bronte Edwards for one. Contact Woodfast and purchase the Woodfast VS kit, you won't regret it.

I converted my M910 Woodfast lathe about the same time as Mobyturns did, with a Woodfast VS kit also. Best move I ever made. The kit includes a new motor and all the gizmos that go with it. No problem fitting it and I am not even an electrician.

Jim

Dont go the cheap option on a lathe like this as it will limit the work you can do on the lathe .

You pay for what you get.

You will get a motor and electronics that will give you heaps of grunt if needed and also a range of speeds that will suit all purposes

I have a short bed version of the Woodfast M910. It has a DC variable speed conversion done here in the USA and retains the original step pulleys.

I will change speeds with the pulleys to get more grunt with large bowl blanks. The lever to lift the motor and access to the belt for shifting is quite good.

I also use a Hegner 4 speed lathe. When making either bowls or spindles I will start on a slower speed for roughing and go to one higher for finishing. One speed change per piece is not that onerous.

You might use the lathe for a while before converting to variable speed.

There is considerable savings in doing your own conversion vs a purpose made kit.

The savings in money comes at the expense of getting the motor mount and shaft size to fit the lathe and pulley along with the lining up of the motor pulley to the spindle pulley.

The cabinet of the Woodfast is fairly large but a fat motor might be hard to fit.

With a factory kit made for a a given lathe, all the research and trial and error has been done for you.

The electrical connections are quite straightforward. You should have your wiring checked by an electrician if you are not experienced.

There are also two types of VFDs. The cheaper version is used for pumps and fans where the rpm may vary with load. The more expensive keeps a steady rpm under a varying load, this is what you want.

I don't want to get into an argument over conversions, just want to present what I did.
I realise what I did is not for everyone, but as I also have a way of directly measuring HP outputs of motors and how it depends on frequency so I feel I can at least comment on this.

My Woodfast Midi originally had a 1/2HP motor on it and I replaced it with a 415V 1HP, star (Y) connected 3Phase motor, and a "240V single phase to 240 3 phase" VFD.
I maintained the original headstock pulley but as the replacement motor was bigger than the original I had to build a motor mounting and tension system under the bench and while I was at it I needed to fit the lathe into a narrower space in the shed so I built a dedicated bench for it and SWMBO got the original bench for her craft work.

For those that haven't seen it, full details of my lathe conversion are buried in my Shed Fitout Thread and starts here https://www.woodworkforums.com/showth...68#post1506068 It runs from post #299 to #319 so don't stop after the first post.

To maintain its original power on such a setup a Y connected motor needs to be converted to ∆ connection otherwise it will only have half the power. However, this motor was not converted as I wanted to measure the power output and sure enough it was a 1/2HP motor from 50 to about 100Hz. Below 50Hz power is proportional to frequency, so at 25Hz it's a 1/4HP. Above 100Hz the power drops off slowly but it's still about 0.4HP at 120Hz. There are also issues with motor cooling going below about 25Hz that I had to check out.

Now because I mostly turn are tool handles this range of power is more than enough for what I do so I left it as is until I could get round to converting the motor. That was back in 2013 and I haven't felt any need to do perform the Y to ∆ conversion. I can of course still change the belt positions but have only changed the belt position maybe 5 ? times. I have also gained more experience with the speed range and motor heating at low RPM and now feel comfortable with it from about 20 to 140Hz,which is a speed factor range of 7.

Converting the motor it to ∆ would give me >1/2 HP from 25 to 125Hz which is a full power speed factor range of 5 which means I would probably never change the belt position. If a 2HP ∆ connected motor was used then >1/2HP power could be had from 12.5 to 140 Hz for a speed factor range of ~11. The Y-∆ conversion is not for the faint hearted and if you are not comfortable doing it then using Motor rewinder services would cost I believe ~$150 to do this

The new VFD cost $120
The used motor purchased on Gum tree came from an older Woodfast and cost $30
The switchgear and pot etc cost about $20
The piece of 75mm diameter Al round bar for new motor pulley was $18 (see https://www.woodworkforums.com/showth...88#post1602088)
Steel for bench $75
Everything else was scrap or skip collections etc.
All up $277

Ye,s there was a fair bit of fabricating involved but being retired time is cheap and I like these sorts of projects anyway.
So if you are able to perform such a conversion, considerable savings can be made.

The main thing I wanted to point out was that if you are not up for Y to ∆ conversion of the motor and don't want to pay to have it converted then using a bigger motor is one way to get around this. It is also possible to find motors that are already converted to ∆ OR have dual Y/∆ connections. I have used these motors on my DP, MW lathe and compressor. I also have such a motor for a variable speed BS conversion which I am in the middle of like about a dozen others

Originally Posted by Paul39

There are also two types of VFDs. The cheaper version is used for pumps and fans where the rpm may vary with load. The more expensive keeps a steady rpm under a varying load, this is what you want.

One way to deal with this is to use a more powerful motor provided the budget level VFD can supply the necessary power for that motor.
This also generally works out to be cheaper than using the minimum power motor and a more expensive VFD.

A 1HP motor and budget level 2HP VFD will generally maintain the same Torque/RPM (over the same RPM range) as a 1/2HP Motor and more expensive {vector drive} VFD.

If you are worried about a large motor damaging a machine then just make sure the belts are not overly tightened, so if things go pear shaped the belts can just slip.

I have done this on 3 machines in my shed (MW lathe, WW lathe, & DP). The MW lathe has a (more expensive) vector drive on in but I used a large motor on it anyway.

I also have 2 grinders (3/4 and 1HP), llnisher (3HP), compressor (5HP), and large capacity ventilator fan (1/2HP), all running on VFDs - I did not bother to use bigger motors on these as they don't operate over a wide RPM range.

The prices of used three phase motor prices don't seem to be related to power output.
Last year I paid the same price ($30) for a used 1HP as I did for a 5HP motor.
Budget entry VFD prices for 1 and 2HP only differ by a few $, 3HP expect to pay ~ $50 more.

My current variable speed projects involve a BS (motor being upgraded from 2HP up to 3HP) and a 7.5HP 2ft wide thicknesser. The latter is a project for the mens shed and I have purchase a full vector drive Honeywell VFD for it.

Taking nothing away from BobL 's comments, as he is very capable at doing the work involved, this shows that you do need some compitance in electrical work and knowing electronics.

If you are like most people who do not have that ability please do not try and do this unsupervised and stick to of the shelf components that are set up to do the job.

Originally Posted by Jim Carroll

Taking nothing away from BobL 's comments, as he is very capable at doing the work involved, this shows that you do need some compitance in electrical work and knowing electronics.

If you are like most people who do not have that ability please do not try and do this unsupervised and stick to of the shelf components that are set up to do the job.

I fully support Jin in his post. The risks are indeed significant.

Apart from electrocution of yourself and others, incorrect wiring of the motor and VFDs can damage both beyond any sort of repair, and/or start a fire.
It's not just about correct wiring and testing of circuitry, but becoming familiar and comfortable with the capabilities, and programming or setting up of the VFD as it applies to a particular machine.
VFDs are all different in their features and programability and what is relevant to one brand or even model of VFD may not apply to others.
In addition the way the VFD interacts with each machine may be different - see next paragraph.
I have damaged a VFD beyond repair because I did not fully understand the limitations in the setting up of that VFD on a specific machine and the minimal manual did not point it's limitations.
Fortunately it was a used VFD that cost about $80 and I wrote it off as one of the costs of learning about VFDs.

The reason I posted my experience is that some woodturners may know a sparky that can perform the necessary modifications.
However, because sparkies are not necessarily turners there are further complications that sparkies may not be aware of.
e.g. One benefit that VFDs offer is rapidly deceleration of a motor/machine i.e. stops in less than a second, even tenths of a sec. This is great on something like a DP where the rotational inertia is small. However, where there is a lot of inertia involved with the machine and/or workpiece e.g. lathe work, rapid deceleration may overload a VFD and if the VFD does not have sufficient self protection will cause irreparable damage to itself. It can also lead to workpieces coming loose. If you or your sparky do not understand what is involved here then this is one area to get serious advice on or stay away from.

Originally Posted by BobL

I fully support Jin in his post. The risks are indeed significant.

Apart from electrocution of yourself and others, incorrect wiring of the motor and VFDs can damage both beyond any sort of repair, and/or start a fire.

Also illegal doing electrical work if not appropriately quallified in most states that I know of.

electrical work or repair on an appliance does not require a license. customer side of the outlet is the customers responsibility. I have installed many VFD's on many pieces of equipment. the directions and setup are getting easier all the time. Where I am employed they are pretty much a "given" on any new equipment and have been replaced or installed successfully by high school apprentices without supervision. The mechanical portion of the conversion would be the dificult part of the job in my opinion not the electrical.

Originally Posted by oreos40

electrical work or repair on an appliance does not require a license. customer side of the outlet is the customers responsibility. I have installed many VFD's on many pieces of equipment. the directions and setup are getting easier all the time. Where I am employed they are pretty much a "given" on any new equipment and have been replaced or installed successfully by high school apprentices without supervision. The mechanical portion of the conversion would be the dificult part of the job in my opinion not the electrical.

Humm . . . I note you are not from Australia - our rules are different here.

As a result the general population here tends to fiddle a bit less with electrical repairs.

Overall I reckon it probably makes very little difference to death and injury rates.
A few less people who follow rules die from electrocution while a few more foolhardy types die because they ignore the rules, don't always know what they are doing and cannot get the support they need to do things correctly.
Some might say that's natural selection it work.

Electrocution is the number 1 cause of death in DIY deaths in Australia, followed by ladders and then using/working on farm vehicles.

Part of the reason electrocution is a problem in Australia is the higher V (240V single phase and 415V for 3Phase) system in use.
240V results in more deaths per head of population from direct electrocution, but fewer deaths from electrical fires (lower currents), with 110V systems the opposite tends to happen.

BTW the mechanical section of conversions are by far the greater PITA. That's why when a 3Phase motor is already on a machine I prefer to leave it, the pulley, belt etc on the machine and just change the wiring and switches.

You are correct I am from the US. I have a freind who was an electrician in Australia before moving to the Seyshells.Please do correct me if I am wrong because from our many discussions about similarity and differences in the two systems of regulation I came to the understanding of what I stated: if it plugs in it is the responsibility of the user. if it is wired directly it falls under building codes. I believe we are in agreement as to the difficulty of the mechanical vs electrical conversion.

Originally Posted by oreos40

You are correct I am from the US. I have a freind who was an electrician in Australia before moving to the Seyshells.Please do correct me if I am wrong because from our many discussions about similarity and differences in the two systems of regulation I came to the understanding of what I stated: if it plugs in it is the responsibility of the user. if it is wired directly it falls under building codes. I believe we are in agreement as to the difficulty of the mechanical vs electrical conversion.

Western Australian law on this matter clearly states what is mean by "electrical work requiring a Licence" as follows.

Electrical work is defined in the Electricity (Licensing) Regulations 1991 and means work on electrical machines or instruments, on an electrical installation or on electrical appliances or equipment to which electricity is supplied or intended to be supplied, at a nominal pressure exceeding 50 volts alternating current or 120 volts direct current, whether or not the thing on which the work is being performed is part of, or is connected to or to be connected to, any distribution works or private generating plant and, where work is performed on any appliance, whether or not electricity is supplied or may be supplied thereto through an electric plug socket or socket outlet.

There is something called a restricted electrical licence that enables holders to change plugs and sockets but that is about it.

At work several of us worked on specialist scientific equipment that used up to 10kV and it upset the workplace OHS officers that we were not formally licenced and We we had to get a special dispensation from formal OHS policies to keep doing this. The legal liability was then with the Head of our department to deem us capable of doing this work. Later when I was the HOD I hd to hold the can for about half a dozen employees on this. The only person I know that got zapped in 40 years was me - 6kV across one finger. Luckily the base of the finger was touching the earth metal casing but it burn a tack of skin between the tip of the finger and where the finger touched the case. It took ages for that to heal.