ML7 countershaft removal

[Simon CollierParticipant @simoncollier74340]

A young club member was given an ML7 with all the accessories, but in filthy condition and grease not oil evident. The belts need changing and as a first option, I would like to use normal belts, not link belts. I’ve searched for videos and found one where the bloke cracked the boss of the big motor pulley using a gear puller and a heat gun. The manual shows insertion of the shaft from the tail stock end, with woodruff keys for pulley cluster and motor pulley. Can the motor pulley be left on and the shaft pulled out that way? Perhaps the woodruff slots are blind. Otherwise, any tips for removing the big pulley without damaging it? I assume it will be extremely tight.

[Simon CollierParticipant @simoncollier74340]

[HopperParticipant @hopper]

I don't remember any problem getting that large countershaft pulley off mine when I did it up some years ago. It is held on by a woodruff key and one grubscrew. Trick with those types of pulleys is to never put force on the outer rim. If you have to use a puller, hook it up to the central hub, or a metal plate or bearing puller clamshell behind the central hub. And heat from a propane torch should be enough to make it fall off without a puller anyway. Cheap torch that clips on to a disposable can of gas will do the job.

From memory, the keyway in the three-step pulley goes all along the bore so it can come off either way. It has two grub screws that need removed first. Same as above. Don't put pullers on the outer flanges. Support the inner solid part of the pulley, heat it, and tap the shaft out.

You don't need to pull it apart unless you plan to replace the Oilite bushes. A clean out with solvent and re-oiling should do the job if grease is the only concern.

When fitting a new belt, it is worth getting the "cogged" V belt that has the notches around the inside diameter. They run better around the tight bends of small pulleys like the Myford's.  They are AX series belts rather than the standard A series. You can see the belt in this pic.

Edited By Hopper on 04/02/2023 23:11:06

[Simon CollierParticipant @simoncollier74340]

Thanks Hopper, I was hoping you’d answer today. I said to a mate who was just here, “I’m hoping Hopper will answer as he knows everything there is to know about Ml7s”. I’ll report back after I go over to young David’s place tomorrow. I hope the shaft isn’t scored as I am only committing to getting new belts on. I’m pretty sure the chuck is stuck fast too. What fun.

[HopperParticipant @hopper]

Oh yes a regular bonafide know-it-all, me. Except I forgot you have to take that shaft out to change the belts thanks to the closed H frame set up.

And of course the main bearing caps have to come off to remove the headstock spindle. So you might as well check the up and down movement of the spindle and remove a layer or two of the laminated shims if needed.

[Simon CollierParticipant @simoncollier74340]

Yes, it will be interesting to see the condition of the main spindle.
Assuming the chuck is stuck, what do you think about putting the spindle in something like wood V blocks in the vice and levering chuck with wood lever in the chuck jaws?

[HopperParticipant @hopper]

And i forgot to mention is easiest to take the whole belt tensioning H-frame off the lathe and work on the pulleys and countershaft on the bench where you can properly support the pulley while tapping out the countershaft.

Stuck chuck. If you grip the spindle in the vice be sure to do it b between where the bearings go so there is no risk of damaging the bearing surfaces. Hard to get good grip like that though. I would try to loosen it up with the spindle still in the lathe. Myfords recommended way is to grab the belts and spin the spindle backwards with a block of wood under one of the chuck jaws so it smacks into it. Not sure how much force you get like that though.

If you look in the photo I posted above I am pointing at a pin I drilled and either threaded or Loctited into the bull wheel (don't remember which) and then made a tool below that locks the spindle for chuck removal. YOu can do something similar by jamming a block of wood between the little Allen head screw on the back gear drive dog and the headstock casting. Then you can put a length of wood between the chuck jaws as a long lever to yank on. Heat might help too. Be careful not to overheat the spindle and melt the white metal bearings though. Heat the chuck body only.

[Simon CollierParticipant @simoncollier74340]

Thanks, I plan to cut a bit of hardwood for just that purpose. I can size things on my own ML7. Shame a spindle lock wasn’t designed in. Recently someone 3D printed a special spindle locking tool.

[HopperParticipant @hopper]

Yes. The Super 7 has a spindle lock but the ML7 was the budget model when it came out in 1946 and never changed much. I reckon Myford sold a lot of new backgears over the years as a result.

Tell your mate to keep the spindle thread and chuck threads lubed with Never Seize etc and it should not happen again. (There was a thread on this recently with many varying opinions on what works best for this but this is what works for me!)

[Simon CollierParticipant @simoncollier74340]

I got the big pulley off with WD40, heating with propane, tapping with nylon hammer, brass drift on shaft, and finally gear puller. Got it off OK with no damage.
The chuck was another matter. My bit of jarrah under the cap screw head was just mashed when I levered the chuck with a length of the same wood. I’ll try a piece of aluminium next. I don’t want to break the casting I’m levering against. I don’t much like the idea of heating the chuck.

[Swarf, Mostly!Participant @swarfmostly]

Posted by Simon Collier on 06/02/2023 02:59:31:

SNIP!

My bit of jarrah under the cap screw head was just mashed when I levered the chuck with a length of the same wood.

SNIP!

Sorry to post off-topic.

Simon, was your 'bit of jarrah' previously part of a railway sleeper?

My workshop originally stood on a raft comprising five railway sleepers and some second hand scaffold boards, all purchased from a garden centre in Rainham, Essex. I was told that the railway sleepers had originally been part of the track of one of the London Underground lines and were jarrah wood because of its vibration-damping properties. When I moved the workshop to its current location, I upgraded to a concrete slab and used the railway sleepers to form a retaining wall to control the spoil from the excavation.

More recently, I wanted to make a new mantelpiece for our living room but didn't want to pay timber merchant prices for hardwood. So SWMBO and I selected the best looking sleeper from the stack, carefully de-nailed and de-gritted it and cut it into suitably sized slices.

I finished the completed mantelpiece with Osmo oil and am very pleased with the result.

Apologies again for posting off-topic.

Best regards,

Swarf, Mostly!

P.S.: I was going to add what 'Timbers for Woodwork' by J C S Brough says about jarrah but as it's an Australian wood, I'll defer to Hopper.

 

Edited By Swarf, Mostly! on 06/02/2023 11:07:27

[HopperParticipant @hopper]

I know nothing bout the brown stuff. Tis a mystery to me. Woeful for the grandson and nephew of two master cabinet maker/ carpenters whose skill left me in awe. But I do know our Aussie railways used to have jarrah sleepers and they worked well. Since they have now mostly been replaced on main lines by concrete or steel sleepers, you can hear the train wheels singing and squealing for miles on the curves through the hills. So I would say you are right about jarrah's vibration damping effects.

[HopperParticipant @hopper]

Posted by Simon Collier on 06/02/2023 02:59:31:

I got the big pulley off with WD40, heating with propane, tapping with nylon hammer, brass drift on shaft, and finally gear puller. Got it off OK with no damage.
The chuck was another matter. My bit of jarrah under the cap screw head was just mashed when I levered the chuck with a length of the same wood. I’ll try a piece of aluminium next. I don’t want to break the casting I’m levering against. I don’t much like the idea of heating the chuck.

Yes I have used a block of aluminium there. But never had a badly stuck chuck so would advise caution as you say.

There have been previous threads on stuck chucks so you might do a site search on the topic.

Impact rather than steady force will often shift such things (and gear pullers too), done within reason. Something like hold a hex or square bar etc in the chuck with a big spanner on the hex and hit the spanner with a rubber mallet  or soft hammer etc. Others have suggested a large shifting spanner over one of the chuck jaws, but I have not tried that one.

Edited By Hopper on 06/02/2023 11:57:33

Edited By Hopper on 06/02/2023 11:58:11

[Simon CollierParticipant @simoncollier74340]

No Swarf, not from a sleeper but from a fence picket bought new to use for bits and pieces. Jarrah grows in the SE of WA and is a beautiful, dense deep red coloured hardwood that is fire resistant. I made the cab floor of my loco from it. Also jewellery boxes etc.. I’d be surprised if it was used on the East coast of Australia as there was plenty of local hardwood, but I’m not a railway expert so don’t know. It was often used for barbecue trolleys but they are all metal these days.

[Simon CollierParticipant @simoncollier74340]

I am just back from young David’s place and my aluminium tool worked a treat. I leaned on the wood lever in the chuck, and it let go with an intensively satisfying crack. Took off the main shaft and the journals looked OK. There were only single, home made sheet metal shims. The big problem that remains is getting the countershaft out. The triple pulley can be slid on the shaft but not to get at the key, and when I tried to push it out, it comes to a definite stop. I brought the frame home and tried a moderate lean on my 3T press but something stops dead. Grub screws removed, even oilers removed but no go. I will try to polish the shaft that has to go through the bushed so no bit of rust etc can stop it but I don’t think that’s the problem

[HopperParticipant @hopper]

The woodruff key is captive in its part-circular keyway in the centre of the shaft, so can't be removed until it is moved past the end of the pulley. The keyway in the pulley is straight through. So it must be a burr etc hanging up. My countershaft was so chewed up where it ran in the bronze Oilite bushes without oil for years that it was pretty rough. I made a new shaft from a bit of BDMS. You also get burrs where the grub screws were, which perhaps could be drilled out?

The pulley is usually Mazak so will expand a fair bit if heated to 100 to 150C (spit sizzling hot) which may help. Heating the pulley and supporting the frame or pulley on top of open vice jaws or two blocks of wood etc and whacking the shaft with a hammer and block of your best jarrah or brass drift might work better than pressing it.

Pretty sure we had jarrah sleepers in South Australia when I was a kid. Probably came from the west as SA basically has no trees. No idea what they used here in Queensland. They were all concrete and steel by the time I moved here, I think. Not something I spend a lot of time inspecting. But I spent my childhood playing on the railroad track through the Adelaide Hills near our house. Endless source of entertainment for young boys.

[Simon CollierParticipant @simoncollier74340]

All done but a brain teaser. I made a split spacer to go around the shaft and against the pulley with room for the key and used the press to push the shaft with key clear of the pulley. It took a lot of force. Then the problem was obvious and you are right: someone had tightened up the two grub screws, missing the slot in the shaft and catching the edge of the slot, raising two huge burrs that would have help up an elephant. I filed them flush and tapped out the shaft, freeing belt and pulley. A good day, first the chuck and then the pulley. I was surprised how soft the countershaft steel is.
By the way, the chuck is a Griptrue. Also, the tailstock has the Myford lever attachment. The cross slide is the long one, and he has 4 jaw and fixed steady, faceplate and boxes of more stuff. 4 way tool post. Not bad for a gift from another member.

[Simon CollierParticipant @simoncollier74340]

This is the tool from 6 mm Al. It sits in the bottom of the casting. Slots for spindle and oiler. The two front bolts holding the headstock casting on are missing!

[HopperParticipant @hopper]

That's a good result, mate. Yes the shaft is just a piece of cold rolled bright mild steel bar, nothing special. Very easy to make a new one from a piece of stock without need to machine the OD. A typical Myford piece of frugal but practical production engineering.

Sounds like the young fellow made a great score. The lever tailstock and especially the long cross slide are very choice upgrades and rare here in Australia. And the Grip Tru chuck is the Holy Grail. Very nice. And it is good he has someone like yourself and obviously other club members to help him make the most of it.

Good idea on the locking tool. I'd be replacing the missing headstock hold-down bolts asap. Most probably BSF threads but I have never had mine out so not sure. Can be a bit of a hunt to find BSF these days but they are around. Myford still sell most parts including bolts but the shipping has gone through the roof in the past 3 years.

[Nigel Graham 2Participant @nigelgraham2]

Studying the OP again, and as an ML7 owner, I am puzzled about removing pulleys from shafts, when the question is about changing the belts?

The spindle needs lifting from the headstock, yes, but not dismantling.

The countershaft simply needs its outboard collar removing and it should then move sufficiently far toward the motor end to allow changing the belt.

[HopperParticipant @hopper]

Not on mine. There is only about 1/4" of space between the pulley and the Oilite bushing in the H frame on the left hand end of the pulley. But there is a good 3" or more of countershaft sticking out the right hand end of the pulley through the oilite bushing and through the retaining collar. So that has to be driven through the centre of the pulley until the right hand end of the countershaft is level with the end of the pulley, thus creating a gap the belt can pass through. You could leave the large pulley in place to do this.

Doing it the other way is the same. There is more shaft sticking out the lefthand end than there is gap to slide the shaft sideways before the pulley hits the H frame.

If the step pulley is a tight fit on the shaft, like this one, it is easier to deal with it on the bench than perched up on the H frame moving about.

Edited By Hopper on 08/02/2023 09:32:24

Edited By Hopper on 08/02/2023 09:41:00

Edited By Hopper on 08/02/2023 09:43:54

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