David's Mini Lathe......

[Stilldrillin]

One of my pals, died last year. He was a member on here. davidcurtiss021.

Poor chap, never properly, got to grips with retirement, or making swarf. Alternately, he was unwell. Or his lathe was..... 

This was one of his final problems..... https://madmodder.net/index.php/topic,12166.0.html

The lathe is mine now. It arrived, as a  lego set, in several boxes. In serious need of rebuilding.

I started during the summer......




I finished the mechanical work, this weekend.......




Next up. The electricals. Never before, fumbled with Sieg's, mysterious clever stuff.....




Inside the box.......




And, back view of the loose board......




I plugged together, what seemed to fit together.

Not sure which way around the input lead fitted, as both outputs from the emg switch, were black/blue wires.

Switched on. Hoping for a click. Or, a little light...... Nothing!  

HAH! No fuse, in the plug.  

Fitted 3amp fuse. Switched on..... Nothing!  

Metered the supply, into this gubbins. But, not out of it......




No fuse in there, either......  

Fitted another 3amp fuse. Switched on..... Nothing!  

Checked the fuses. Both of them had blown. Quietly.... 


That is the limit of my electrical understanding. It's time now, to hand over to a higher authority.

Hope you guys can sort me out, as you have done several times in the past......

[Deko]

I would love to be able to help Dave, but electrics I am OK with, electronics are way beyond me.   

Sad to hear of your mate dying, but that is one of the things that old age brings with it. I have lost quite a few mates in the last few years. 

Seeing that you are still posting is great, and I wondered if you would be going to the Midlands show next weekend ??? 

Cheers Derek.

[John Rudd]

David,
As usual always glad to help.....

First up, have you got a dvm, know how to use it?
Can you follow a schematic drawing?

Is there an XMT number on the speed control board? ( I think it might be XMT 2335 or summat...)

[Joules]

David, you’re not a million miles away from me (Rotherham). I have a fair bit of electrical test equipment if you need help.   Available weekends.    and a very similar Mini lathe here.

[Stilldrillin]

I would love to be able to help Dave, but electrics I am OK with, electronics are way beyond me.   

Sad to hear of your mate dying, but that is one of the things that old age brings with it. I have lost quite a few mates in the last few years. 

Seeing that you are still posting is great, and I wondered if you would be going to the Midlands show next weekend ??? 

Cheers Derek.

Hi Derek.
 Thanks for your kind words.
I reckon, you will have met David, back in the Harrogate days.....

I'm afraid, me old feet n legs are not up to show standard anymore.
 Only allowing up to an hour at a time. Even if I'm doing something really interesting, in the shop...... 

[Stilldrillin]

David, you’re not a million miles away from me (Rotherham). I have a fair bit of electrical test equipment if you need help.   Available weekends.    and a very similar Mini lathe here.

Joules.
 All the years, I have seen your handle. I thought you were in France! Not just up the road! 

Thanks for your kind offer.
 

[Stilldrillin]

David,
As usual always glad to help.....

First up, have you got a dvm, know how to use it?
Can you follow a schematic drawing?

Is there an XMT number on the speed control board? ( I think it might be XMT 2335 or summat...)

Hi John.
 This is becoming a habit, isn't it!

Dvm? Sounds like my little black box, with a needle in a window.
 Tells me if a fuse is good, or blown.... Also, if a wire is live, or not. (A few other things, as well). 

Schematic drawing? Probably.
 This one will be no problem. Mebbe...   http://littlemachineshop.com/reference/drawings/4507-XMT-C3Lathe.pdf

XMT-2335........




Are we off to a good start? 

[Joules]

I found this, but I guess it’s probably out of date being from 2006.  It is however a starting point.

[John Rudd]

David,

I'm assuming you have all the wiring in the right place...,,?


****With the lathe unplugged from the mains***

With new fuses fitted where needed, meter switched to Ohms range, can you measure between the Live and Neutral pins on the 13Amp plug, do this with the Red E-stop button not latched....
What reading do you get on the meter?

We are looking for a low value that is causing the 3A fuse to blow......

If the result is good, that is there is no short across the supply, I suggest disconnecting the motor and in its place a 100 watt light bulb, then try the machine plugged in..


Joules, good find on the schematic...the circuitry hasnt changed much over the years, they are basically the same as the KB boards from the USA..

[Stilldrillin]

Hi Joules.
 Thanks for the diagram. I'm afraid, it's lost on me, these days.

In the past, I have built a couple of rc, (valved) receivers. But, that was some 60+ years ago......

[Stilldrillin]

Hi John.
 This evening, I have checked the wiring against the little mc shop diagram.
All is correct. Though, several terminal screws were a little loose.

Tomorrow, I'll apply the meter...... 

[Joules]

No worries David, the schematic is here for you and others.   Perhaps over time we can build up a table of test points and voltages for others to fault find from, as it seems a common problem sorting these boards out.

[Stilldrillin]

What reading do you get on the meter?

We are looking for a low value that is causing the 3A fuse to blow......

Is this low enough, John? 

[John Rudd]

David, that is a low reading, likely to cause a fuse to blow....

I see there's a little power supply in one of the previous fotos, can you disconnect the power feed to it and measure again?
If the reading is still low, can you disconnect the mains wires going to the speed board and try again...?

[Stilldrillin]

John.
 The speed control knob doesn't click, off. In the stop position.
Thinking this might be at fault, I disconnected all three wires. No difference.

 The feed wire to the transformer, is already, not connected to anything. In the pic, it lays over the top of the control box.

I have also pulled out the plug, where the wire to readout connects.

No difference...... 

[John Rudd]

David,
The two wires connected to the speed control board at the Line In terminals, can you disconnect them from the board, then:
1) measure the resistance across the L and N pins of the mains plug ( do this with E stop in its normal state) ( this will determine if there is a fault in the incoming wiring stuff)
2) measure the resistance across the two Line In terminals on the speed control board...

[Stilldrillin]

John.
 Wires disconnected. Meter across plug pins... No reaction.

Meter across, the two terminals. Needle fully over, reading zero.

[John Rudd]

David looks like theres an issue with the board then...

Would you like me to look at it and effect a repair?   

( I just checked, a new board is £132... From Arc..Ouch, didnt think they were that much...)

[Stilldrillin]

Please John. I certainly would!

It's a pity, I can't fit one of the spares, you repaired last year.....

No rush. I'll detach, and box it up, over the weekend.

Thanks for your input. I've enjoyed this little fault finding exercise.....

[John Rudd]

Do you have my current address? I'll message it to you...
I dont live in Hull anymore.....

Why cant you fit one of the others? Are these the KB boards?

[Stilldrillin]

John.
 I have your address, from Feb/ Mar, last year. When you repaired two KB boards.

Still not installed/ tested em! The best way to never have a breakdown, is to have spares..... 

[Stilldrillin]

The board is now on it's journey North, to John's. 

I was imagining the chaos, all those loose wires could cause. (Despite having a diagram). 

I thought it best to tape em to each other, before removing the board......

[Stilldrillin]

Several times, over the years. David called here, with lumps of his lathe for modification.

The first project was to replace the orrible saddle strips, with solid ones. Seems they have stood the test of time. No work needed on that area. Still sliding sweetly... 

A couple of years ago, he installed taper roller bearings. Calling here, for the gear spacer mods.

Faced the front one to correct alignment. Then made a 2mm thick, spring "wave washer", from a couple of turns of stainless welding wire.

Just visible, to the left of the Lo gear.......




When it arrived here, I realised, it still wasn't right.

I faced 3mm off this face, to allow for the wider bearings.......




The tumbler gears, are now aligned correctly......

[Stilldrillin]

Next up, was the leadscrew handwheel.

Using a left hand, leadscrew plummer block, bushed to 10mm bore. On the r/h end.

Lopped the end off the leadscrew, and inserted a length of 10mm silver steel.....




Left hand dial, is held onto plummer block, with grub screw.

Right hand dial is fixed to handwheel. 10 thou' between graduations.......

[Stilldrillin]

Next job, tailstocks. Got three of em. The blue one is mine. It's quill thread is rather tired.

Mixing and matching. Hoping to finish with two good uns.

Anyone contemplating a camlock?
 This one is useless. Won't clamp securely to the bed. Slides under quite light pressure......




Making a clamp nut.......




Think that looks at home, under there.......




Can be accessed, over the top of the compound slide.......