Harrison M300 No power to the leadscrew or drive

[northwest]

But I know why. No, it's not the shear pin or clutch pack, definitely the gearbox having an issue. I went online to see where to start and although there is one old boy made a series of quite informative video's some of his techniques are questionable at best, also, one of my pet hates, a carpentry hammer used in an engineering application:

So, this is where I started, ally plates off then the selector knobs (lookout for the detent balls and springs):



Then there are a few important bits to do, the on/off control needs disconnecting then screw the extension off the rod so you can physically remove the gearbox, then take out the two bolts holding the leadscrew drive rod and on/off lever control at the tailstock end, wind the saddle towards the headstock, lift the bracket off the pins at the tailstock, engage the half nuts and wind the whole lot out of the drive ends, like this:



You did remember to remove the bracket from the on/off control right?
Then you need to look at getting the five bolts and one button head holding it in place, you will need a 6mm Allen key for this and something like a ring spanner or piece of tube for leverage.

You will also need to remove the 80tooth gear from the input shaft, you can see where the button head came from, it holds the guard in place:


Then drain the oil:



It was never not going to be messy! Gearbox off and exposing the dried on crud of soluble oil from years back:



Now the gearbox on the floor and I can start to work out where the damage/fault is. I set it up exactly where it was when I broke it and worked back from there:



Bit of fiddling and twiddling and it was this roll pin here, at the tip of the screwdriver:



New paragraph:-)

 

[northwest]

Using a bit of dexterity and a sacrificial drill bit I spun the roll pin end and managed to dislodge it from the gear, to my astonishment I was very, very close as to the exact point on the shaft where I could punch the broken roll pin out

Then a look through the drawer handily marked "roll pins":



Then I made one fit, these were Imperial size but I "modified" one to fit:



Absolute result, so far, so time to put it back together, AFTER I cleaned the crud out (@Parm, look away now) in my experience the best stuff for this job is a good quantity of 98 octane so I splashed some about, just be bloody careful eh!



It came up a treat:



Now, about three hundred years ago, in a previous existence, I ordered a full set of gaskets for this machine, but I have slept a couple of times since then so the usual pantomime of searching for the bloody "safe place" began, I did eventually find them but there was a bit of choice language going on as I berated myself first:




Amazingly the gasket did not fit properly (bought from Harrison) so I was a bit put out, got there in the end with it though

Getting the gearbox back up and into the machine was a Ba$$tard of a job and I used up all my swear words in one go:



Another, final installment:-

 

[northwest]

So, it all went back together, getting the leadscrew and drive shaft AND the control bar all in in the same operation was a challenge but a bit of perseverance and steady away and it all slotted together nicely, need to sort out the control knobs though as they fit where they touch and don't represent the settings labels at all, but tomorrow is another day and right now it is back together and it works. I could have done without this to be honest but hey ho, one of life's challenges.

Just to show, it came up nice and clean with the petrol treatment:




Back where it belongs:





Some of these pics are possibly a bit out of sequence but it's late, i'm tired :-)

 

[Smouser]

Good work!

 

[northwest]

Good work!

Thank you. Now that I have had chance to reflect I am not convinced it was necessary to remove the gear change knobs, I wouldn't bother if I did it again, there is no need to remove the bottom one at all as the bolts are accessible with it still in place.

 

[123hotchef]

hopefully you will not need to do it again!

 

[northwest]

Well, I just might, I was tempted to carry on yesterday to prepare for this:

I need to drive this from the tailstock end as that is the most practical installation, I am only dithering about as I cannot yet decide the size of motor I am going to use. (which one to buy) Servo or Stepper? Big or massive. Then I am going to fit the drive pulley to the leadscrew, either by drilling and tapping it or otherwise threading it, I am not averse to welding something on to extend it.

 

[Mark Davison]

I fitted a closed loop nema 34 with the Clough42 ELS to my Bantam. I fitted it with a short HTD belt driving a pulley fitted to the gear box input shaft. It does make life a bit easier, no swapping gears to change from metric to imperial.

 

[indy4x]

I wasn't that lucky, my M300 lost drive to the leadscrew as one of the gearbox shafts had sheared where the roll pin went through

 

[northwest]

I fitted a closed loop nema 34 with the Clough42 ELS to my Bantam. I fitted it with a short HTD belt driving a pulley fitted to the gear box input shaft. It does make life a bit easier, no swapping gears to change from metric to imperial.

I may be contacting you for a bit more info before I jump in :-) The M300 requires a bit more grunt than a Banty. Twin start threading has an attraction for me along with high speed to improve finish.

I wasn't that lucky, my M300 lost drive to the leadscrew as one of the gearbox shafts had sheared where the roll pin went through

Yes, but with a lathe you can make a new shaft, it's when you destroy a gear or a casting the tears start.