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Smart and Brown 1024 tachometer (from S&B insert tooling)

billmac

Stainless
Joined
Oct 17, 2004
Location
Lancashire, UK
These are some photos of fitting a tachometer to a Smart and Brown 1024, along with some other wiring changes to convert it to a VFD drive etc. The photos were requested in the S&B tooling thread.

This is the optical sensor arrangement:
P1010407C.JPGP1010406C.JPG

and this is how it is attached to the back of the headstock
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This is an early photo - I later increased the number of black/white sectors to give better resolution at lower spindle speeds.

This is the inside of the control box containing the tachometer display, spindle current meter, variable speed pot and selector switch to change between the original pre-selected spindle speeds and continuously variable.
P1010460C.jpg

This is the lathe in finished state
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I have more photos showing the wiring for the electrical enclosure and the wiring of the original speed selector drum switch etc if anyone is interested.
 
Are you still using the three speed motor and if so, does the vfd disengage while you are changing speeds on the drum switch ? Do you have the vfd programmed for more than one motor parameter?

The tach pickup looks quite large. I've seen smaller ones and thought about mounting at the front behind the back plate using the chrome ring. Dave
 
Are you still using the three speed motor and if so, does the vfd disengage while you are changing speeds on the drum switch ? Do you have the vfd programmed for more than one motor parameter?

The tach pickup looks quite large. I've seen smaller ones and thought about mounting at the front behind the back plate using the chrome ring. Dave

I replaced the three speed motor with a single speed inverter rated motor, as you have. I thought for a long time about this because the original three speed motor was in good condition and high quality. In the end I changed it because the complexity of swapping the motor connections when under power from a VFD, whilst also synchronising three different sets of motor parameters looked to be a bit tricky and probably unreliable. In addition, I had only 230V single phase available so I really wanted a motor that could be operated in delta configuration. That adds to the difficulty of using the original motor. Changing the motor required a new motor mounting plate and a new (crowned) pulley. I changed the ratio from te motor to the gearbox to get the best compromise of speeds and torque. I am sure I don't need to tell you that fitting new motors in these lathes is a physically difficult job. I have photos if you are curious. I fitted a thermistor relay to safeguard the motor. Mine is just a generic motor and I was slightly concerned about running it with lower than rated speed and heavier torque - the fan is not rated to cool properly in these conditions. I have never had it trip.

The drum switch is used to provide signals to the VFD so that it can change to the pre-seected speeds. That requires deciphering the drum switch contacts but leaves the controls looking exactly as they did and peforming in the same way.

The actual tach pickup is tiny, it is just a general purpose LED + photo-transistor package. It is mounted on a circuit board, which I trapped between some Delrin plates, which were in turn attached to an Aluminium plate which attaches to the headstock casting. This arrangement gets the pickup into the best position to see the matt black/reflective white paint.

I don't have a chrome ring near the spindle on my lathe so not sure what you have in mind.

If you want more details I have a long write up on the whole project.
 
The ring is actually the back plate and yours looks to be black. I agree on the motor. Mine had a problem and was wired 550 so rewinding it and fixing cost more than the TENV motor I found. I have seen people wire a computer fan into the vfd to blow air over the motor at a preset hz.

I won't keep the original speeds but they were wrong anyway. Mark Jacobs here did the wiring schematic but I had covid in november and now working 12 hr days so the install is slow. For now i run it with a remote keypad. DSCN3913.jpgDSCN3952.jpgDSCN3904.jpg The Matrix gave me grief but I bought a scissors lift table and that made taking it out easy. For the motor, I put the lathe on. blocks so I could get an auto jack under the frame and lift the motor upside down to the bracket. You can see i had to chew on the mounting feet to clear the existing studs to the mounting plate of the machine. Attached is a picture of that.

Some 1024 had a two belt V pulley but mine still had the crowned pulley. I bored it out to 1.125 and had a friend with a working lathe recrown it as it was out of round

Dave.
 
A few pictures showing the old and new motor arrangements and wiring.

This is the original 3 speed motor. Great quality and fitted with a brake. It was in near perfect condition.

P1010361C.jpgP1010360C.jpg

The new motor pulley before broaching the keyway

P1010371C.JPG

The rotary switch before 're-programming'

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The new motor and motor mounting plate hanging under the Matrix gearbox

P1010415C.jpg
 
The main switch panels rewired, including the new rotary switch arrangement

P1010395C.jpgP1010393C.jpgP1010394C.jpg

The electrical enclosure, not quite complete, which is fitted to the rear closing panel at the back of the lathe

P1010392C.jpg

This ended up being heavy and awkward to fit as well.
 
My panel is 20x20x12 and heavy too. It must be located above the holes that allow for pipes to be inserted to lift the machine by forklift. I put the brake resistors in the spot where the Crabtree starters were located. Four 50 ohm if I remember right, two parallel and two in series. The vfd is a Hitachi WJ 200-.055. I run three phase into it from a Phase Perfect but it is big enough to handle single phase input if I sell. At age 67 I have started thinking about that more

Zoom in and tell me what the various boxes are. Are the drum switch connections going into relays? The Hitachi can't handle maintained switching so most seem to go through relays.

Did the old pulley have a problem or did you just want to change diameter and bore? Dave
 
Zoom in and tell me what the various boxes are. Are the drum switch connections going into relays? The Hitachi can't handle maintained switching so most seem to go through relays.

I will need to do some annotation on the photo for that, but most of it is fairly simple.
The Mitsubishi VFD is for the spindle motor. The small VFD is for the suds pump. I may change this because that particular VFD is prone to causing RCD trips. The main VFD has a mains input filter and a fairly big brake resistor. This is rather important because I lost the brake when I changed the motor. The brake resistor allows you to stop the spindle fairly fast and in addition some DC injection can be used. Without the resistor you will not stop the spindle quickly, there is too much inertia, particularly with a heavy chuck. There is a PC power supply that provides 5V and 12V. The 12V is used for a powerful LED machine lamp - I converted the original lamp to take this. I can't remember what I used the 5V for. I will need to look at the schematic.

There is a thermistor relay for the motor and a series of commoning blocks and terminal blocks to connect everything up. The grey box on the outside is a switched waterproof mains socket to power the DRO and anything else that needs it.

There are no relays required for the drum switch connections. You just use the VFD to provide the voltage needed to drive logic level inputs. The only issue is getting the number of inputs required in the VFD and that did need a bit of thought - but no relays.

The 'inching' or jog function is wired in much the same way. Modern VFDs are wonderful things, and can do all of this for you, but you need to work throgh the manuals to get what you want.

Did the old pulley have a problem or did you just want to change diameter and bore? Dave

Two main problems - the old motor was inch based, the new one is metric of course and so is the keyway so I would have needed an adaptor. Certainly do-able, but the other problem was that the original pulley diameter is good for the range of speeds from the 3 speed motor. The characteristics of the replacement motor are very different, as will be your motor. After doing the sums, I found that a change in the pulley diameter would allow me to acheive the same range of speeds and with a sensible amount of torque when the motor was driven in Sensorless Vector mode. The original pulley diameter would not. There is much more to this but you probably get the idea.

The fact that the ratio has changed does not make any difference to the achievement of the original three switched speeds via the drum switch. Simply calibrate the VFD so it gives the correct speed at each of the settings.
 
I don't need annotations. I didn't think of the coolant pump as I don't have one in my system. As i said, I added resistors too. In addition to the VFD power supply output, I have a 12 and 24v auxiliary. Probably overkill but some electrical stuff is cheaper than shipping so extra stuff is OK. I have a building full of extra stuff my heirs will have to deal with. I had an old mag starter in inventory that looked appropriate so that serves as the on-off for the vfd.

Since my motor keeps full torque to 0 and is rated for 6000 rpm, I didn't need to worry about changing pulley size. At 3500 rpm or 120 hz, I will be getting close to 3000 rpm which should be higher than I need. The Matrix is limited to 3000 and I'm a poor machinist so I can deal with a little slower. At 90 hz I'm still getting full torque and when I dial down to 1 hz I still can't stop the spindle by hand. Having a back gear and the 3.6-1 Matrix really gives a lot of flexibility in motor choice. Dave
 
I watched a shed made video where he tore apart his drawbar and it looks like I'm missing at least the large steel collar. Could you send a picture of yours to verfy. Here is mine.DSCN3856.jpgDSCN3858.jpgDSCN3859.jpgDSCN3857.jpg Mine also looks different with the larger end opposite the handle. Dave
 
Dave -

Yes, you are missing the large steel collar that anchors the end of the drawtube. There may also be something a bit odd about the assembly just behind the handwheel, but I can't make out the details in your photo.

This is what the collar looks like.

P1020468C.jpg

P1020467C.jpg

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The collar is attached to the end assembly by a pair of set screws that locate in a groove.

This is what the end of the draw tube should look like without the collar:

P1020464C.jpg

P1020462C.jpg

Maximum number of photos reached, see next post.
 
This is what the drawtube end should look like with the collar attached.

P1020470C.jpg

The drawtube assembly should be a good sliding fit in the headstock with the collar attached.

You could easily make a collar - there is no complicated machining required, although you will obviously need a working lathe. If you want to do this, I could measure my collar and make up a drawing, but it would take me some time to do that.

It looks like your drawtube has had its internally threaded end replaced?

The ability to take 5C collets directly in the spindle is one of the big advantages of this lathe and I use this very frequently.
 
Thanks. I think I can get enough dimensions from the video. Is 1018 or something cheaper OK as there doesn't seem to be strength requirement. 3.5" diameter 1018 varies in price here in US from $40-140, ft. I don't know why.

I'll have to check the length again to see if the replacement end didn't make the bar longer or shorter and make the collar useless. If so, I will modify. Dave
 
Adding a needle thrust bearing at left end makes it nicer to use. Maybe billmac’s has one, can’t see.

L7
 
I didn't see the earlier pictures and yes I think the small washer is a replacement. I will look this weekend to make sure the thrust bearing is still inside the inner collar. If so, the large outer should be all I need.

There is a ball thrust bearing inside rather than a needle. Dave
 
I have had a quick skim through the Hitachi WJ200 VFD manual. It actually has some very good facilities - better than the Mitsubishi model that I used. You should easily be able to get the switched speeds you want and a jog without needing any relays - in fact all you need is some simple logic level wiring and a bit of work on the drum switch. If you look at section 3.19, you will find a description of 'multi-speed and Jog' functions. You need to set the appropriate parameters to enable this. You will see a truth table showing which speeds are selected for each combination of inputs on terminals CF1, CF2 ... CF4. All you need is to get a set of signals from your drum switch and jog switch which corresponds to these and then wire them to the terminals. You will need to investigate your drum switch to see if you can get the required signals in positions that correspond to the chart on your lathe. I could not, and I had to reorganise the switch layers so that it worked out how I wished. This is fiddly but not hard - all you need is a multimeter.

If that doesn't make any sense, let me know and I will get into it in more detail.
 
Adding a needle thrust bearing at left end makes it nicer to use. Maybe billmac’s has one, can’t see.

L7

Not as far as I know - I think it only has a ball bearing. I haven't taken it all apart. I can see how a proper thrust bearing would ne nice.
 
Is 1018 or something cheaper OK as there doesn't seem to be strength requirement. 3.5" diameter 1018 varies in price here in US from $40-140, ft. I don't know why.

I'll have to check the length again to see if the replacement end didn't make the bar longer or shorter and make the collar useless. If so, I will modify. Dave

I don't think the collar material will matter at all. It is in compression. Use the cheapest steel you can get.

The length of the draw tube is pretty important so a check would be a good idea. You could make a new tube, but it is quite thin walled so would not be an easy job.
 
I'll stay with the original plan for now but good to know that three speeds can be programmed into the drum switch. My machine had the original Santon removed and replaced with a cobbled up two separate drum switch arrangement. I believe it was not correct and led to some of the motor problems. I found a Santon and replaced it so I have one for " someday ".

I wonder if the draw bar threads got mucked up and the replacement was welded on and then the people realized the collar did not fit over the end of the bar. Does the collar need to be a slip fit over the bar or can it be enough larger to fit over the enlarged end and still do its job? Dave

PS Looking back at the pictures it looks like the bore fits over the larger diameter on the handle end so it should clear the other end.
 
I'll stay with the original plan for now but good to know that three speeds can be programmed into the drum switch. My machine had the original Santon removed and replaced with a cobbled up two separate drum switch arrangement. I believe it was not correct and led to some of the motor problems. I found a Santon and replaced it so I have one for " someday ".

I wonder if the draw bar threads got mucked up and the replacement was welded on and then the people realized the collar did not fit over the end of the bar. Does the collar need to be a slip fit over the bar or can it be enough larger to fit over the enlarged end and still do its job? Dave

PS Looking back at the pictures it looks like the bore fits over the larger diameter on the handle end so it should clear the other end.

There should be plenty of clearance for the welded on end. The collar does not get near to the drawtube.

Regarding the rotary switch - you don't really need the original Santon version to do what I suggested. Any switch arrangement cobbled together will do fine. You are working with control voltages only (24V) and tiny currents, so you could easily use a cam and microswitch arrangement or even a new rotary selector switch from an electronics store if you want - in fact that would probably be simpler than fiddling with the original switch. The original Santon switch was carrying the full motor current at 415V or more so it needed to be robust

On extra modification I made with my drum switch might be useful if you go this route. I felt that the handle was a little bit wobbly, since the handle just connects to the switch shaft. I made up a small plastic bush that supports the shaft in the switch panel.
 








 
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