VFD conversion for Smart and Brown 1024

[StinkworksUK]

It's worth the cost to buy a set of Whitworth wrenches too. They are just enough different in size from UN to make it a pain to adjust bolts. They aren't very expensive. Dave

I've already got some Everything is stripped off the machine which needs taking off (including all the wiring). I literally just need to drop the motor. Just looking at your pictures, my control panel looks a bit different to yours as you have 2 knobs on the left, and I think mine just has a lever. I'll see if I can find a pic of mine before I took it apart.

 

[StinkworksUK]

Here we go.

 

[Beckerkumm]

I was missing the original Santon drum switch. I found an original and a bunch of other stuff in the UK. I replaced the two separate cobbled up switches but then found my three speed motor was defective and rewinding was not a great option. As you know, the downside of using a motor to increase the number of speeds is that there are only three speeds over 872 which is where all the action is on a small lathe, except for threading. The Vector motor can run from 5-120 hz so the speed can increase to 3000 although it is seldom needed. The Matrix clutch is important and you need to make sure that is working properly. They are often misadjusted and the bronze shoes ( gluts ) get worn to the point the clutch doesn't function properly. Dave

 

[StinkworksUK]

I was missing the original Santon drum switch. I found an original and a bunch of other stuff in the UK. I replaced the two separate cobbled up switches but then found my three speed motor was defective and rewinding was not a great option. As you know, the downside of using a motor to increase the number of speeds is that there are only three speeds over 872 which is where all the action is on a small lathe, except for threading. The Vector motor can run from 5-120 hz so the speed can increase to 3000 although it is seldom needed. The Matrix clutch is important and you need to make sure that is working properly. They are often misadjusted and the bronze shoes ( gluts ) get worn to the point the clutch doesn't function properly. Dave

Thanks for this info Dave. Before the motor went up in smoke, the machine worked perfectly. I was even commenting to the wife how awesome it was, then I changed the speed and the motor went . I can't wait to get it back up and running.

 

[Beckerkumm]

Which speed went? The motor has two separate windings . One has a Dahlander connection that drops two poles out to deliever the extra speed. They are still made but rare and expensive. The existing switches aren't really good to use with a vfd so everything is best gutted and replaced. There is a guy who used the original stuff and set his controls up to mimic the old speeds. Way above my pay grade and just using a pot and a tachometer is handier. Dave

 

[StinkworksUK]

Which speed went? The motor has two separate windings . One has a Dahlander connection that drops two poles out to deliever the extra speed. They are still made but rare and expensive. The existing switches aren't really good to use with a vfd so everything is best gutted and replaced. There is a guy who used the original stuff and set his controls up to mimic the old speeds. Way above my pay grade and just using a pot and a tachometer is handier. Dave

I think it might have been the high speed that went pop. I have gutted all the wiring on the machine now. I do plan to use the original tumble switch for the 3 speeds so the machine will look from the outside like its standard. I can program the vfd to go to a specific frequency based on the switch position. I did this on my old lathe and it worked a treat. I'm still a bit confused about the motor though as all I can get in the UK at reasonable price is either a 2 pole motor at 2900 rpm or a 4 pole at 1400 rpm.. I'm steering towards the 2 pole, but worry about the low speed torque.

 

[Beckerkumm]

Torque remains the same, it is the HP that falters at the extremes. I'd go with the 4 pole and overspeed. To get the same toque, a 2 pole motor needs twice the HP so a 3hp 1400 = a 2800 6 hp. The 3 or 5 hp will have the same frame size so both will fit. The 1024 has a stout build in the bed and headstock but the apron is a little more delicate so it isn't a remove metal machine. Ian Robinson in the UK has a great knowledge although he is a Holbrook fan now. I can put you in touch if he is OK with it. There is a Clive over there too that has info and I can forward his address if he approves.

The 1024 is known for the fine finish it leaves and a two pole motor at lower speed will muck that up somewhat. I'd avoid it. You really don't need speed over 2500 rpm.

Dave

 

[StinkworksUK]

Torque remains the same, it is the HP that falters at the extremes. I'd go with the 4 pole and overspeed. To get the same toque, a 2 pole motor needs twice the HP so a 3hp 1400 = a 2800 6 hp. The 3 or 5 hp will have the same frame size so both will fit. The 1024 has a stout build in the bed and headstock but the apron is a little more delicate so it isn't a remove metal machine. Ian Robinson in the UK has a great knowledge although he is a Holbrook fan now. I can put you in touch if he is OK with it. There is a Clive over there too that has info and I can forward his address if he approves.

The 1024 is known for the fine finish it leaves and a two pole motor at lower speed will muck that up somewhat. I'd avoid it. You really don't need speed over 2500 rpm.

Dave

Thanks for this Dave, yes the finish with a 2 pole was somewhat of a concern. I'll order a 4 pole 3hp (my machine is one of the old ones with a max 2hp motor) to account for the loss if torque at higher speeds. If I'm honest, I'm not too bothered about the really high speeds (although it might be nice to creep up to 2000 ish rpm`). Please feel free to put anyone in touch with me who might be able to offer any knowledge (although you have a been a massive help and I send huge thanks to you).

 

[Beckerkumm]

I'd go a little larger to compensate for the loss of hp. 3hp is worth the extra at either end of the range. The drive pulley will need to be bored out to 1.125 from 1" if similar to mine. If the motor is not vector duty, your hz range is about 20 on the low end but between the two speed clutch and the back gear, you have some help. Torque and hp go down on the top end too and that is helped with the larger motor. English machines tended to have lower hp motors than they were built for. Probably due to lack of power being easily available.

I need a PM with email info to forward if you want to go that route. There are also threads on Practical Machinist that are worth looking at, including a vfd conversion that sounds like what you are doing.

Dave.

 

[StinkworksUK]

I'd go a little larger to compensate for the loss of hp. 3hp is worth the extra at either end of the range. The drive pulley will need to be bored out to 1.125 from 1" if similar to mine. If the motor is not vector duty, your hz range is about 20 on the low end but between the two speed clutch and the back gear, you have some help. Torque and hp go down on the top end too and that is helped with the larger motor. English machines tended to have lower hp motors than they were built for. Probably due to lack of power being easily available.

I need a PM with email info to forward if you want to go that route. There are also threads on Practical Machinist that are worth looking at, including a vfd conversion that sounds like what you are doing.

Dave.

I must have edited my post as you were typing, changing from 2hp to 3 hp (it's late in the Uk and I'm tired)

No probs boring out as have a Bridgeport and a shaper to make a keyway.

I'll see if I can sort this on my own I think before I call in for more help.

I think my biggest headache will be gaining access to the bolts which hold the motor to the plate, but I'll get it off somehow ?