Member postings for Jon Cameron

I have the Myford ML4 but I think the suggestion from Dave could be the likely issue.

Although I am having to replace the screws in the back of the half nuts on my lathe as one of them has broken and only one half nuts was moving.

Ive broken the sheer pin twice now, not through a crash but trying to use the handle to traverse the saddle without first disengaging the change gears.

Jon

John,

While I agree with the points you have raised, not to stifle the enthusiasm too much Sweet Pea that you mention also has errors, and as pointed out on the first page of this thread. There is many published drawings, all contain some errors, unfortunately it is human nature to miss something.

Just last night I got a reminder of "engage brain, measure twice, and cut once". I was drilling holes for my motor to mount a different way on the fabricated layshaft. I had accurately measured, the width of the holes, the distance between them and marked these on the mounting plate, centre popped the holes and got them spot on, drilled through to 8mm clearance all the while checking they were in the centres of the scribed lines, then went to fit the motor. The holes were 20mm off, after a head scratch and recheck of measurements I realised my error. I had measured the 20mm from the datum for the first hole, then the 76mm for the second hole (the distance between the mounting holes) from the same datum point instead of adding the two for the second hole.

So you see human nature will unfortunately make mistakes even the prolific LBSC made mistakes on his drawings, or referred to previous text to save repeating. Thus making his designs hard going for a beginner without full access to previous articles. His boiler designs are now outdated and need additional bushes fitting and a different stay arrangement in a lot of cases to be brought up to current thinking and guidance on what classes a safe model engineers boiler.

With regards to the rear axle oiling, perhaps a flip top oiling pot could be located to provide oil to the rear axle box, either side of the frames under the footplate, with a pipe running through to provide drip fed lubrication to the rear axlebox. When in steam the oil will become more fluid, and easily run down a thin bore pipe so long as the end of the pipe is chamfered to overcome surface tension in the oil.

One other note regarding axleboxes and their springs, until the loco is fully assembled mounting the springs can cause the axle to not be in running position, to align and set up the motion. It would be better to bolt the axle boxes in position with a 1/8" packer piece of steel that has been deburred on all edges, between the keep and the lower side of the axlebox. This will set the correct ride height allowing the valve motion to be installed and set without adding variables to the mix.

The best that can be done is to study the links and hopefully avoid pitfalls of those that have gone before. Or worse given up.

Jon

Hi Andrew,

The thread on the change gear side to take up end float on the spindle, is that correct????

32tpi rings a bell, its published on the internet somewhere, let me have a look, failing that I can measure it with my thread gauge for you tonight.

Jon

Edit yes it is 32TPI, I would not however run a die down it as the lock nut and spindle thread need to be quite a close fit. So as Howard suggests take a file or even some fine emery paper (1000grit) backed onto a file to clean up any burs. I will be fitting a brass plug under my screw once its back together to prevent the issue you have, (mine is tight but it will still go but I don't want it any worse.

Edited By Jon Cameron on 28/05/2020 10:01:49

To be fair hand filing to within 2.1/2 thou isn't bad going at all for a "beginner", It can only get better but a read of this thread may prove useful to put your mind at ease, 100% isn't achievable in any home workshop. Its more a case of the parts fitting together correctly, been able to rotate a axle without it rocking in the axle block for example. For the body work (buffers) 1 or two thou will not make much visual difference, and id not beat yourself too hard for not achieving it to within a thou. just ensure that the buffers are marked up front and back and you use what will be the top surface to align the angle for mounting the frames. this way when setting up the frames there is little chance of the frames been built twisted. Frames assembled on the upper edge of the frames and buffers)

That looks a nice little height gauge. There are ways to asses the surface plate for accuracy yourself. though it rather depends on accuracy you want to achieve, to within a thou maybe two on running/rotating parts is good enough.

Ps keep the pic's coming, tooling is often forgotten in threads like this.

Jon

Edited By Jon Cameron on 27/05/2020 15:14:51

Hi,

Yes as David says, it needs to be 1.5/8" to match the opening of the slot. the 1/8" top plate needs to have its lower edge flush with the top opening of the slot.

Id also check the hole for the oil to the axle block as I remember something not aligning there quite right. But I may be mistaken on that one, and it was how Id drawn it in CAD that caused the issue???

Jon

It sounds as though you are clamping down hard when you take your measurements with a Mic, there is a little thumb screw on the end of the mic, use this instead of the larger diameter, also when you are on you diameter as you are turning I always give a gentle rock to make sure it is sitting completely square and on the parallel.

Its also prudent to know where your taking your measurement from as if you are already doing the above it could be that you are in fact turning a taper on your lathe. If you take a light skim (0.1 or 0.2mm), then measurements from the far end of a piece of metal 25mm thick and about 100mm protuding from the chuck, then measure the end furthest from the chuck, and the end closest to the chuck, and see what the difference in reading is on your turned piece.

The telescope gauge again could indicate that you are getting a taper turned on your lathe. Either that or there is something going on with your mic. They are sensitive to heat and will expand and contract a little. Try the test cut and some pics may help.

One other thing to note, if you need to take off 1mm cut on OD, dial in for 0.5mm then measure again, if correct take a cut of 2.5mm, check again, you may find that you need to adjust the amount you take off on subsequent cuts as you may remove 5.6mm or 2.55mm on the above cuts but make sure your removing half the material you need to remove on each cut to get to a precision fit.

Jon

Correct however disengage the banjo and change gears first. Sounds obvious but I've done it three times now setting up to machine and broke the sheer pin on the leadscrew on my ML4, simple fix but directing I'm obviously a slow learner haha.

Hi,

To post pictures go to albums at the top of this page, create a gallery and click to add photos select from your device where there uploaded from and click upload once all are selected . Then when you post click the camera button and insert the photos from your album. Hope this helps.

There is also a good build thread for the chassis can be found here. 

The error.on the axleboxes  which may not apply to the drawings and only the magazine articles is with the height of the fabricated horns doesn't match the correct the height of the frame cut out. Use the frame dimension and build the horns to that size. 

Edited By Jon Cameron on 24/05/2020 17:03:46

Brian thanks and noted, I still feel its a bit precarious, but i'll trust you. Having had an item of brass I was machine, twice jump out the chuck due to bad work holding, (gave up that night before serious injury) i'm dubious, but happy to prove myself wrong, it can only go to back and beyond.

Jon

Sometimes, just sometimes, I overlook the blindingly obvious! SPRING! another to add to my to do list. Thanks Jason.

Brian thank you, that is what I suspected it has obviously been repaired in the past.

On the washer would it not try to break free of its Loctite holding as soon as the spigot is removed, I know the pad to the rear would support it, but I feel it would possibly go flying to back and beyond once the hole is opened to 1/4" even with gentle boring. Worth a try I suppose, get it back together to make the parts then strip the apron to fit it.

Certainly.

On the back of the apron the pinion and shaft for the saddle traverse, run on the plain casting. There is a very small 1/4" washer (maybe 3/8" OD) that sits at the back of the gear. The teeth of the pinion are not fully contacting the rack, only around half of the toothed gear makes contact. The apron has a machined flat projection where the gear comes out at the rear of the apron, and I was thinking to "shim" the pinion out with the washer so that 3/4's of the gear tooth width, makes contact with the rack. I looked at the other option of actually packing the rack out but then this interferes with the saddle so is not an option.

This is just two of the issues that I was experiencing when using the lathe before it was stripped down, so I would like to try and get them sorted so I can move onto slightly easier ones to sort, which are basically just replacement washers, bolts, oil cups and so forth.

Jon

double post,

Can one of the mods delete this one please?

Jon

Edited By Jon Cameron on 22/05/2020 12:12:11

Hello guys,

While stripping down and replacing refurbishing my ML4 lathe, I have taken the apron off and removed the half nuts, When I removed them one of the screws that holds the half nut for engagement was bent, (this explains why they were getting difficult to engage and disengage). The bolts are fully threaded, and I will have to make some more when I get the lathe fully assembled before I can continue to use the lead screw for feed..

Should the portion that runs in the engagement lever not be a smooth turned piece to aid in its movement, instead of the threaded stud that it is now?

Also the ones that came out are mild steel, is it best to keep it mild steel. Is this a designed weak point to save further damage to other parts?

I find it interesting having designed weak points on my lathe such as the 3/32" pins that join the gears in compound, and also to the lead screw that breaks in the event of a crash, (or a dimwit that doesn't disengage the banjo before turning the handle on the end of the lead screw, Yes twice now!).

I would also appreciate anyone been able to comment on how to make a 6mm repair washer have a 1/4" hole, how would that be possible to set up?

Jon

Hi,

If I could direct you to Harold Halls page HERE, you'll see the best way i think to machine the bearings, cut them into two sections, mount in 3 jaw, with packing to protect them. Drill and bore, then mount onto a mandrel between centres for the boss to be turned to size. The bores are left undersize to begin with, they can be line bored to set the correct alignment once bolted into position.

So yes bolt to the bedplate, then finish to size when all bolted together. It may well be prudent to gently centre punch the bearing and bedplate so that going forward to finish the build when they are taken out or put back together they always go into the correct place, and your not chasing your tail looking for fault when you assemble a new part thinking something isn't correct with it. (do it discreetly on the inside of the bed plate and bearing. one dot for left side two dots for right side).

Jon

Edited By Jon Cameron on 22/05/2020 11:26:36

Nothing wrong in that logic, to answer the question of drill size, if it was me doing it i'd drill it big enough that I could get my boring tool in the hole and then a little wiggle room too for clearance. Then use the boring tool instead of the risk of taking too much off the bearing by a drill wandering off course.

Jon

Mark,

If I could make a suggestion, (well a request even). That any of the "beginner" questions about machining the 10V you ask in the build thread. There is a lot of very useful information that will possibly be lost now into the depths of the forum that is very relevant to this thread. I always find that I learn more from a build thread, not always about how to do right, or what it looks like after the machining has taken place, but rather how not to do it, when things have not gone to plan how to correct those mistakes. There is a lot on setups, and machining steps that may be lost out on also. Having questions relevant to this build, included in the thread is a good way for a novice builder of the 10v to learn themselves and it will also inspire confidence to carry on knowing that yes mistakes happen but these are ways to correct it.

I'll keep following the build as I possibly have x2 10v and x2 10h incomplete sets to build soon, so I am also picking up tips from your thread, and the other questions posed elsewhere. My worry is that a new person viewing this thread will loose out on all that good advice in the future. This is turning into a good build thread, and that is my only suggestion to make it even better.

Jon

Thanks for that link John, I've not come across it before. Also thanks for another project to add to the to-do list. At work milling cutters, and drill bits, get thrown out so been able to sharpen them even just for roughing out means I now have a free source of drills and milling cutters

Ok I have totally misinterpreted the replies above, I was under the impression that a rod with a centre drilled into its rear and a point on the other end was held in the centre punch mark, and held with the tailstock, this tool then clamps to the rod and draws the circle in the air.

Thanks for the link to the website.

Hi,

May have to make one of these. I assume having the two lengths the smaller end is used for roughing the centre of the work, then rotate 180 degrees, and you have a fine adjustment.

Would be interesting to see how accurate this could be by checking with a DTI. and seeing which method appears quicker to use?

Jon