Member postings for Maurits van Dueren

Ok, I am making some progress:

- Made a bull nose adapter (basically a big 45 degree cone that fits round the 60 degree life center. This already makes a huge difference.

- Used the back gear. I had completely forgotten i had such, someone here mentioned it. It is the first time I use it. Now working in the 60~120 RPM range with plenty of torque.

- Put the cutter a bit more above centreline, as suggested.

Result: Much better. Some new problems, but much better,
Did not build a rear post yet, as I felt I wanted to see how this worked, and much better.

Now, what I am seeing, especially in the 60RPM range that my eyes can follow, is HOW MUCH everything bends. It's like the whole thing is made of plastic. My god, all the iron needs to be twice as thick! Not sure I can do anything about the cross-slide itself bending over backward, but that tiny 0XA toolpost that I selected because no other quick change post would fit between topslide and centreline, well, it is too tiny.

What stops me now however, is the fact the toolpost is only secured by a centre-bolt. The cutting tool is of course left of the bolt, so a rotation force is created, and I cannot tighten it enough to keep it from rotating, thus rotating the groove tool to the side.

I had seen it before, where a PIN prevent such rotation, but my topslide, nor my QCTP have those.

Edited By Maurits van Dueren on 23/06/2023 17:14:32

Have no steadyrest. Have no 4-chuck. Can't centre drill, as the 46mm piece is also 25mm hollow. I did start yesterday making a sort of bull-nose adapter cone for my live centre, but did not try using it yet, as it got late.

I guess I will use the bullnose anyway, even if only see the difference, but I think I need to go for the rear-post as default parting option anyway.

Mind you, the steady/centre/bullnose and the rear post address different problems. One addresses stability of the part, the other of the tool, so they may at times both be needed.

@Hopper

Way too far. About 100mm but I have little choice in the matter, it is way to big to fit through the spindlebore. And I have no steady rest. But at least the workpiece is 46mm, so it least quite rigid itself.

I realize these things compound it all, but as stated, I have the same problem (but less extreme) with simple pot iron that I hold 5mm in front of the chuck, so I felt apart from these obvious faux-pas, there is also something deeper, like incorrect angles.

@Kiwi Bloke

That part about the rear-end upside-down cut, bending the tool up and away (well, down and away) rather then into makes a lot of sense. It almost means we should do all cutting like that, if it were not for the problem of obscured visibility.

Talk about just above centre is also interesting. I was already trying that because I felt it would naturally give a negative top-clearance, making it want to dig in less. I had not considered the tool bending down also meant the tool post bending it in. (but that is now suddenly so very obvious)

It also means that any rear build post should ideally still be adjustable. At least at first, to experiment with this height. I think I'll make a simple block to mount the same QCTP. If nothing else, it would mean changing only one variable at the time gives better understanding.

As to the metal, unknown but suspected a reasonably quality, but non-hardened one.

However, as mentioned, I have this all the time. It is worse now, as this is the largest diameter i've tried and a bit away from the chuck, but I have the same problem with stuff that in Dutch we would discribe as pisspot steel

Lowest poulie gear on the Myford for best torque, tried on the VFD from 30 to 70Hz, which translate from 210 to 500 RPM on the chuck.

Low seemed most stable chatterwise, but it stalled too easily. Typically it stalls by the blade digging in, and the lathe then slipping the gearbelt, not to motor or the motorbelt. But I already have it very tight. I think when it digs in like it does, no belt or belt ratio will be enough torque, the trick is to avoid the digging in, not more power.

I even tried running it by hand. (what is that? 6 RPM?) Manual scraping the iron basically. Same thing, goes well for a while, but then digs in. Which in that case cannot be chatter.

---

For the rear toolpost, is it an option to buy a chunky bladeholder, and weld it to a suitable piece of steel?

So how high is your blade? If any potential rear holder is dedicated, it may as well hold a tall blade. So like 3/4" instead of 1/2" (20mm in stead of 12mm) Or at least, I suspect such would also work benificial?

BTW: If I have a dedicated holder, mounted directly on the topslide, would there still be an advantage mounting it in the rear? Or is that merely a habit, so you need to remove it not quite as often (only when it is in the way)

Thanks all. So parting was always struggle, but this 46mm part/groove is just proving too much.
I am confident there is no slop. Whether there is enough rigidity is of course another matter. I did screw the entire lathe to a 700x300x20 slab of iron to support its backbone. (it also serves as oil tray with gutters)

What really upsets me is this tendency to pull the blade into the workpiece. It even does this on smaller diameters, closer to the chuck. It is very unsettling.

I guess I need to pause this project, and first do another one I was already considering: Making a post directly on the crossslide, without the topslide. And by the sounds of it, two of themne in the front, still with a QTC
And one mountable in the back, with the sole purpose of holding a nice tall cutoff blade upside down.

Anyone has some nice ready made, field tested, plans for a myford?

Sorry, cutting upside down?

You mean coming in from the back, or with the chuck spinning in reverse? The latter seems like a really bad idea on a chuck that is only held by it's right hand side threads and no key.

I did indeed quare my tool holder against the chuck

So if I would grind HSS, what would be the angles?

As to "go with Jason's suggestion". Maybe I am misinterpreting, but did he make a suggestion?

Heavens no. It is a tiny Myford.

No, it is a 2mm wide insert.

So I have a small Myford lathe and am a beginner. I am trying to make a groove (but I ran into the same in the past when doing cutoffs).

My problem is, once the blade makes contact, it wants to "dig in" to such an extent I can feel the backlash of my handles go slack. It literally pulls the insert, blade, carriage, to the other side of the spindle slack. Meaning it tries cutting too deep and starts to chatter horribly.

In fact, if I do not start 'pulling" on the slack instead, it digs in so deep it stalls.

I must be doing something wrong. Please advise

Setup:

I have inserts tooling (I am not setup to grind HSS) on a small 0XA 250-000 quick tool post and I am trying to make a 5x5mm groove in a 46mm diameter cilinder

I feel no slop anywhere (other then the wheel backlash), in fact I turned on the gibs a little on the tight side to make sure (I have to works the wheels a little)

I am thinking maybe I have my approach angles wrong, but it is a pre-made cutoff tool in a 250-001 holder. I notice the dedicated 250-007 cutoff holder is slanted slightly up, but so is the insert in my insert holder, so that should be the same.

I have the height such that it is on centerline. But I now wonder, should it be slightly higher to avoid it biting in? Or should I somehow counter the slant that is build into the insert holder?

Any suggestions

@speelwerk You know, I had completely forgotten about the guard,

The problem was/is, I have only half of it. The outer guard I have, but not the inner shield to which it is mounted. So I put the outer guard to the side, and it slipped my mind.

The lathe did come to me in parts, and has been in parts for who knows how long, perhaps decades. I had to collect several other parts, but the shield was never 'essential' so not high on the list.

I may need to make a bracket of some sort.

Just a (overdue) followup: Got it all assembled and working last year, picking up on the hobby now:

Thanks

1 F35 Tie bar spacer is correct (actually, I had found that I needed it there yesterday) The tie bar itself is non-original but it fits.

2 F37 also seems correct on the exploded view. But in reality I do not know where it goes. There is no place. No threaded hole. What is it supposed to do? It's just a set of parts floating in the middle of the exploded view.
I am vaguely thinking it is needed to hold up the shroud, and thus probably also the other 2. But I am not looking too closely at the shrouds at this moment.

7 Both F39 are already in there.

5 is definitely not an oil nipple. Not hollow. Just a 3/8 long set screw with a weird concave point.

3 You are probably right about F34/F36 (I did find part F36 also) but it is still not quite clear to me what it does. The whole belt tensioner works quite well already. Maybe it will become clearer when I do final assembly. I think I am about ready for that anyway

Or at least, that part of the lathe. Still missing both top and cross lead screws/nuts/dials/handles. That is a bit of a bummer, because not cheap, and rather essential.

I guess I will just start to actually assembly anyway. I think I know enough now to not completely mess it up. At least get the chuck spinning and the saddle moving.

Thanks

The trust-collar 3 has not one, but two places for a set-screw, at a 90 degree angle
I think it may be F34 in the motor assembly, but I am not quite sure how it goes together with F36 and F18
Is F18 the short stubby 1/4x1/4 flat point set screw labeled 4 in the picture?
And even this collar is F34, what is its function? In that position, it is not a trust collar.

I do not know where 5 goes
Special about it is it looks like a set screw, but is cupped instead of pointy

6 is is a shewed up, coarse thread pointy stud (or broken bold) bold.
I was thinking it could be for the main motor pulley, but that is a 3/8 screw
It could also be for the triple pulley on the same axel. But being shewed up, I do not want to force it in there.

7 are 3 generic screws, 3/8 x 1+3/4. One seems non-original.
But I was hoping the half-height nuts would trigger someones memory.

I cannot find collar 1 on any exploded view
I mean, it could be A51 in the geartrain, but that is not disassembled and appears complete.
So where other then in the geartrain would a part like this be?
It is 1/4 inch inner diameter, 1/2 outer, and 7/8 high

The 3 studs number 2 are 1/4 diam and 1+1/4; 1+5/8; 2+7/8 long
On one of them someone jammed an incorrect M6 nut
I don't know where they are supposed to go.

Thanks everyone.

It is definitely a ML7, from 1950. And I identified almost all loose parts in the loose bags.

Ignoreing some generic bolds, nuts, washers, these are specific parts I have left (see photos)
Maybe someone recognizes them? On the next posts some more detail on the specific items in these photo's

I went through the whole top-slide carriage assembly exploded view, and all bags of parts. It seems I am missing both feed screw sub-assembly. Both feed-screws, feed-screw nuts, one micrometer dial and both ball-handle assembly are missing.

Pretty sure they all ended up in the same bag, and over time that bag got separated from the lathe. I know where the lathe came from, but there is not much chance that is going to turn up.

Also the actual clamp is broken, and it was not the original clamp anyway. But I suspect that would have been upgraded afterward anyway.

Messed that up. Again:

Images

I told google to allow others to these photos.
Not sure if they now appear in the original post, but this link should work, including zoom capability.

https://photos.app.goo.gl/PhPU38GwuNsfqXm77

Images

Edited By Maurits van Dueren on 24/11/2021 17:51:35