Another Denford Bowl lathe hopefully back from the dead!

[Brecien]

Hi all I'm new to the Forum family and I hope I get this" my 1st post out there ok.
So starting restauration of This old school TDS6 SB BL. The plan is to keep as much original as possible. If I can somehow bring the original 3/4HP 3PH Hoover motor and push button start back into service maybe with the use of a .75 KW VFD 1PH-3PH that would be perfect.
My skill set should serve me fairly well with the rest of the project. But dealing with electrics from the 60s is the area I'm most looking for guidance with as electrical knowledge Is mainly Single phase domestic. I have photos and wiring diagram for the lathe. Looking forward to any knowledge you have of this old wiring. Many thanks! Equaly I hope this post helps someone else bring back Old Engineering from the dead. Similarly I've a table saw and a pillar drill I intend resurectiong. Cheers!

 

[Fitzroy]

You can use a VFD to run the motor but the wiring diagram won't help, VFDs directly feed a motor with all isolation and switching beore the VFD rather than after. You can potentially use the original start/stop to send a run/stop signal to the VFD, but it'll take some messing.

 

[Phill05]

Well done you will be pleased with it when you come to use it, I have the longer bed one like in this image.

 

[Brecien]

You can use a VFD to run the motor but the wiring diagram won't help, VFDs directly feed a motor with all isolation and switching beore the VFD rather than after. You can potentially use the original start/stop to send a run/stop signal to the VFD, but it'll take some messing.

Hi, Thanks for the response. I was hoping for that answer. I've no idea whats in that box of electrics and glad I can bypass it with the VFD. Going to take the motor out next and give the terminals a good staring at. Ill put a photo up, Hoping I can convert it for 240V 3PH.
Cheers

 

[Brecien]

Well done you will be pleased with it when you come to use it, I have the longer bed one like in this image.

View attachment 158470

Indeed: Really looking forward to being able to turn some more substancial blanks I've got. My current cheapo lathe is adequete but limited. Were you able to use the original motor and switches?

 

[Phill05]

Indeed: Really looking forward to being able to turn some more substancial blanks I've got. My current cheapo lathe is adequete but limited. Were you able to use the original motor and switches?

No the previous owner had changed it for a 1hp DC motor and bolted on the base under the tailstock was a veriac, it worked well a lot of power and variable speed, you can get some big bowls out of these lathes, I also made a bolt-on extension for the tailstock to move out more so I could turn 24" long as well.

 

[grahame]

Hi Brecien
I went down the same road last year - don't know how to do a link but my thread started in July 22
Mine already had a replacement 1HP motor but even with my beginner's tentative rough cuts the motor can struggle.
If you are planning on big blanks you should consider a VFD which will cope with more power.

 

[Fitzroy]

Hi, Thanks for the response. I was hoping for that answer. I've no idea whats in that box of electrics and glad I can bypass it with the VFD. Going to take the motor out next and give the terminals a good staring at. Ill put a photo up, Hoping I can convert it for 240V 3PH.
Cheers

You can also get inverters that increase the voltage if you can’t change motor. Like this one, not a recommendation just an example. Personally I’d prefer to stay at 220v than work with higher voltage.


https://www.ebay.co.uk/itm/33406905..._mbU4hWQSq&var=&widget_ver=artemis&media=COPY

 

[Brecien]

Thanks for the VFD info Fitzroy. Low cost VFDs are new to me. VFD was very expensive when I bought these machines 20 years ago. I was originally looking at using capacitors to run the motor and converting it to single phase that way. I recently saw a video of someone trying a cheap VFD and it sounds like a tidier option. So I was looking at an inverter anyway as I've only a Domestic 240V supply to the workshop. Keeping within the build design of the machine, I was looking at getting one that was matched to HP of the motor.
If I understand this correctly, my 3/4HP 3PH would work out to 0.55KW and the closest and cheapest option I've found is for a 1HP which equals .75KW. 1PH 240V -3PH 380V.
So you are suggesting getting a VFD rated for a bigger motor say 1.5KW?

 

[Brecien]

Hi Brecien
I went down the same road last year - don't know how to do a link but my thread started in July 22
Mine already had a replacement 1HP motor but even with my beginner's tentative rough cuts the motor can struggle.
If you are planning on big blanks you should consider a VFD which will cope with more power.

Hi grahame So your machine didn't have VFD and was running old school on original wiring? Was it single PH?

 

[Brecien]

No the previous owner had changed it for a 1hp DC motor and bolted on the base under the tailstock was a veriac, it worked well a lot of power and variable speed, you can get some big bowls out of these lathes, I also made a bolt-on extension for the tailstock to move out more so I could turn 24" long as well.

Hi Phill05 Had to google the variac! Teeheeeee. What a thing to be thunk! This potencially adds a whole new direction to go in. Often thought of recycleing a treadmill motor for instance?!!
Cheers

 

[Fitzroy]

Thanks for the VFD info Fitzroy. Low cost VFDs are new to me. VFD was very expensive when I bought these machines 20 years ago. I was originally looking at using capacitors to run the motor and converting it to single phase that way. I recently saw a video of someone trying a cheap VFD and it sounds like a tidier option. So I was looking at an inverter anyway as I've only a Domestic 240V supply to the workshop. Keeping within the build design of the machine, I was looking at getting one that was matched to HP of the motor.
If I understand this correctly, my 3/4HP 3PH would work out to 0.55KW and the closest and cheapest option I've found is for a 1HP which equals .75KW. 1PH 240V -3PH 380V.
So you are suggesting getting a VFD rated for a bigger motor say 1.5KW?

No, as you say matching the VFD to the motor is all you need, although previously the advice has to to be a little over the motor rating, 0.75kW VFD vs 0.55kW motor sound sensible.

What I was just saying is that you can now get VFDs that change single phase to three phase, and also step up the voltage from 220v to 380v. The one I linked does both these functions. I didn't look to see if there was an equivalent 0.75kw model.

I have used these low cost inverters on a couple of my machines for a few years, but previously the voltage step up was not on offer. I had to dig the 'star-point' out the motor to enable me to rewire it to 220v which was a pretty involved job.

F.

 

[Brecien]

No, as you say matching the VFD to the motor is all you need, although previously the advice has to to be a little over the motor rating, 0.75kW VFD vs 0.55kW motor sound sensible.

What I was just saying is that you can now get VFDs that change single phase to three phase, and also step up the voltage from 220v to 380v. The one I linked does both these functions. I didn't look to see if there was an equivalent 0.75kw model.

I have used these low cost inverters on a couple of my machines for a few years, but previously the voltage step up was not on offer. I had to dig the 'star-point' out the motor to enable me to rewire it to 220v which was a pretty involved job.

F.

Ok, I see where you are coming from. I should have mentioned I'd already priced up cheap VFD from Germany Ebay before starting the thread. Excatly the same kit from China as you've posted. just doesn't go via Uk customs to get here in Normandy so no duty. Cheers all the same...

 

[Phill05]

Hi Phill05 Had to google the variac! Teeheeeee. What a thing to be thunk! This potencially adds a whole new direction to go in. Often thought of recycleing a treadmill motor for instance?!!
Cheers

Yes it is a very powerful way to go the original step pulleys are still there to use so gives you the option of really low speed -high torque for the larger work or variable low to high speed it's a win win I think over a VFD.

 

[Deadeye]

That motor isn't set up for star-delta switching easily, so you will need an inverter that takes 1P 240V and gives you 3p 400v.
You the swap the switch for a 240v NVR and put the feed into the inverter (marked E - L - N as normal). Then earth and three come off to the motor input. Check which way it turns; to reverse swap any 2 of the motor inputs

 

[Brecien]

That motor isn't set up for star-delta switching easily, so you will need an inverter that takes 1P 240V and gives you 3p 400v.
You the swap the switch for a 240v NVR and put the feed into the inverter (marked E - L - N as normal). Then earth and three come off to the motor input. Check which way it turns; to reverse swap any 2 of the motor inputs

Great thanks Deadeye, Ive yet to get the motor out, so didn't know that about it. So if understand correctly what you are saying is I can get round having to convert the motor to star by using a NVR?

 

[Deadeye]

Great thanks Deadeye, Ive yet to get the motor out, so didn't know that about it. So if understand correctly what you are saying is I can get round having to convert the motor to star by using a NVR?

Yes....but they're quite expensive, so a replacement motor may be cheaper

 

[Brecien]

Yes....but they're quite expensive, so a replacement motor may be cheaper

Think I might have one kicking about, which I bought years ago to replace the switch on my Startrite bench saw; Will dig it out and post a photo if you dont mind giving it a glace..

 

[Brecien]

Think I might have one kicking about, which I bought years ago to replace the switch on my Startrite bench saw; Will dig it out and post a photo if you dont mind giving it a glace..

Wondering if thats not what I've already got in that photo I posted with the wiring niche. The one with the lettered wheel.
If all else fails might have to go down the replacement motor route as you suggested. I just a bit of a stickler with keeping things original...
Cheers

 

[Fitzroy]

Think I might have one kicking about, which I bought years ago to replace the switch on my Startrite bench saw; Will dig it out and post a photo if you dont mind giving it a glace..

I think you and @Deadeye are talking cross purpose. The NVR (no voltage release) is a switch that releases when it loses voltage, it is being proposed to place this in the feed to the VFD. This will not change the need to convert the motor from star to delta. The only way to avoid having to change the motor from star to delta is using an inverter that takes 1P 240V and gives you 3p 400V.