Member postings for Alex Collins

Hi. You can repair the board yourself, I have done this twice.
You need to replace the 4 (sometimes 6) output transistors. The square black doofah's mounted on the heatsink.
There will be 2 types and cost about £1 each form people like CPC or RS Components.
Simply unsolder the old ones, replace like for like and away you go.
Worst case, it's cost you ~£5 and you still have a broken board.
You can test the board is working with a Light Bulb. It should dim without flickering.

The motor will probably have to be from Warco. I looked at re winding mine and it was cheaper to buy a new motor.

Alex.

On a wet n windy Friday what could be better than a visit to the local High St Electronics retailer....
It's great when does not match what the website says.....

Anyway. TI Launchpad and Bluetooth modules bought online.
The rest I got this morning. Not bad for a days work.

Credit to **LINK** for the build plans.

Another Edition and no bits to make

I'll have to get on with my DRO's instead then.
**LINK**

Sending a command to the stepper Driver results in the stepper motor doing what it's told.
If it doesn't do what it's told you are telling it wrong !
Garbage in, Garbage Out...

Counting the steps you send is of little value if the motor is driven to fast or stalls and misses steps. If your requirement is to /know/ how many steps it's actually moved you will need a rotary encoder. You can read the encoder with the same arduino, and maybe even correct errors with some programming.
I'd however advise (as others have) that you use 2 separate devices.

hmmm - something is not right then...
Could be a broken red button or a lose connection. They are a bit Chinese.....

Suggest a local someone to have a quick look before you contact Chester.
I have in the past had very good service from them and they may well try and talk you through their thoughts on the phone.

It's almost certainly one of the safety interlocks.
Give the red stop button a twist to release it and make sure the chuck guard is closed.

Sievert torch finally turned up yesterday.
More offcuts of master board pressed into service ( My Hearth ).


Ok I have now got dribbles of solder on both sides of the boiler, they can be dressed down and will be covered up.
So easy with the right kit and a bit of thought about keeping the heat in.

It's still cooling down at the moment, then into the pickle for a clean up.

I'm in Chelmsford in Essex.
If there is another club I'm not aware of them.

Wot no bits to make in the latest edition !

I need to go measure. Until I do that nothing is final....

Hi Martin.
The Chelmsford Track has 3 1/2", 5" and 7 1/4" Tracks.
None of these gauges are suitable - they are to wide.

My Thoughts are, with narrower Axle spacers I can move the wheels apart and run on the track between the 5" and 7 1/4" gauges.
I'm aware that running on these rails would be totally unsupported but briefly spoke to a member who has done just that.
I did intend to measure the actual gaps last weekend. I forgot to take a suitable measuring stick.

Maybe my ideas are crazy at times............

Hi Geoffrey.

You have a Mk1 ML7 there. 1952/53 adds up for it's age.
The accessories you have are not much beyond the standard set that came with the machine.

The Milling Slide may fetch £50 on it's own.
I have no idea what the doofah in the last picture is or does. (the 2 micrometer screws) Maybe sell that separately.
It looks like you have a 127 tooth gear. That may be worth selling separately but it's not worth much. ~£30 - £40.

Whats it worth ?
Tiered looking ML7's have gone for under £500 on the auction sites.
Yours has a lot of tooling and while it looks well used you suggest it's not worn.
I'd put a 'Job Lot' value somewhere between £700 and £1000 if it's not badly worn.
On Here is a great place to advertise.

I now have smooth motion.
Centre Popped a Jig through the frame rails. Ground up a bit of 1/4" silver steel to a point.
Soft soldered the rods (to the jig as well most of the time). Took a few goes to get them right.
Making Bushes to go over 6BA screws (2.6mm ID / 1/8" OD) was not going to be easy. I also think the crush factor as we do up the screws may be rather high.
Drilled the motion rods 4mm and made some shouldered screws.
8mm OD Head. 4 mm shank for the bushes to run in 6BA Thread for the crank arms.

Motion was a tad sticky so drilled the bushes to 4.2mm and all is good.

Wheels all line up but I don't have a suitable track or place to put the track.
The CSME (Chelmsford society of Model engineers) Track will allow me to run between gauges if I shorten the axle bushes.

Hi. The Myfords have a ~16mm spindle bore unless you find a Big bore version.
Not sure on the other suggested makes.
**LINK** have good tech info on most lathes.

Throwing the spanners in the works.

For a ~£1,500 budget you could do much better looking on the used markets. Most of the British lathes (Colchester, Myford, Boxford, Harrison to name but a few) can be found in very good order with tooling for your Budget.
You may however need to get an Inverter if the motor is 3 phase.

Spoke to the Boiler man today. CSME had a members open day.
He is happy with the general construction and soldering. As expected commented that the 2 top bushes were not up to standard.
I need to re flux them and get the solder that is on them to flow. At that point the boiler should be fine.
Spoke in detail and it's obvious to me that my Hearth is not good enough. I should have enough heat with the tools I have but the heat is escaping.

The frame also got favourable comments. Picked up some tips on the motion bars. I need to make them on a jig.

Some great Models on display and running. Guy had his first run in a polly. The grin went full circle.

DOH!
Thankyou Jason

You may have to forgive me this one.
Fig 17, Page 873.
The drawing for the eccentric says:
Throw 0.236
Center offset half of this = 0.118
That's fine.
I get a bit of round bar Offset it by 0.118.

What size round bar do I start with ? ( or what size is the lobe )

Wheels complete. Just need to drill and tap for the grub screws.

Hi Martin.

I cut off 100 mm of bar. That gave me enough for 4 wheels + the option of a 5th.
For the first 2 I used a steady + the centre. The 2nd pair I ditched the centre.

Cleaned the lathe tonight. The parting issues were probably caused by the lash in the cross slide getting sucked in.
I'll add in a bit of friction on the slide locks next time....

John. Will wonder over to that site and have a look.

Thanks