Member postings for Chris R 1

I want to make some short threaded adapters, up to 52mm diameter, from say 5mm to 50mm long.

I have use of a "Chinese" lathe. The thread pitches are typically 0.5, 0.75 or 1mm pitch. I know it can do 1mm, at least.

I'm assuming I'd best to start with a piece of Al alloy bar.

What material would you advise, and perhaps, where would you look for it other than "Google"? No great strength or other special properties are needed, internally it'll be painted black.

I rather imagine I'll be cutting the threads using more than one pass, and by rotating the chuck manually. The threads only need to be a few mm long, but some are internal.

Thinking of the 4 surfaces, I think it'll have to be paper supported by a knife blade - washed down well.

I'll start with P3000 and see if it's enough. (Highly tempted to use 00000 wire wool!)

Edited By Chris R 1 on 06/02/2019 12:56:56

Thanks.

I clearly have to get rid of the raised metal!

There's then a question of what grease to use. It's clearly not a critical application, but I'm wondering whether to get something with "anti-seize" properties.

I need also to look at the metal items to see if there's alumin(i)um deposited on the brass/bronze. as that will have to go too.

The type of microscope objective which macro photographers use, has a long working distance. Therefore they can be used as hand lenses. The one I used above (20x) has a field of view of a couple of mm, but 20mm working distance, so it's quite good for inspecting things.

Even the 100x is available (2mm focal length) with a 13mm working distance.

I had another clean- there were some traces of dried grease left which I thought were out of the way - they may have been doing a little. I gave it a hard rub with a dry cloth which appeared to polish the Al.

There are the two carriages running on the dovetail. One is tight, the other is tighter. The tighter one started to bind again. I could just about see smething so I took a picture of it:

Ignore the colour, it's "grey". The colour balance is off, but I found when I made it grey the relief didn't show up as well.

Frame width is about 1mm. Focus depth is about 60µm. How galling, eh?

If you can cross your eyes a bit, try these:

( you have to make it so you can "see" three boxes, with the middle one being one from each eye.)

I expect most WON't see those as 3D - it's not hard but it takes practice:

If you download this (~4MB) it should help

**LINK**

Edited By Chris R 1 on 06/02/2019 01:15:46

For some reason my pc now pops up a large picture if the original is larger, which is fine for the 1024 one above,

Don't know why it started it, possibly the last W10 update!  .  Using Firefox. Maybe there's an option somewhere.

This is bigger, 3000 wide - just to see what happens:

Yup, resized to 1024, but the jpeg  conversion isn't as good as it would have been if I'd used  photoshop.

Edited By Chris R 1 on 05/02/2019 12:48:39

Got it, thanks both!

1) Can I enable notifications for Personal Messages, somehow? Or is it just a matter of looking top right when I visit?

2) Photos. It says 600 wide max; Is that really still the limit?

ta

What I'm saying iis it is the right spacing at one end, but not the other....

Wouldn't it need springs? It's tight in one part of the length and OK at another. My nagging question - how did that happen?

If I tap a razor blade into the join to separate the bronzy side piece, do you think it will go back in the same position, as set by the pins?

I suppose the pins might be "riveted" to some extent. I mean plastically deformed such that they would 't work again if pulled out, unless hammered/pressed back. They aren't roll pins..

Chris T - "binds". Some grease has arrived so I'l try that. I'll get the luggage scales out. Maybe even use a microscope.

On the "particle of grit" debate, IME as an undergrad metallurgist, abrading metals on a series of wet papers is the way you get to a mirror finish (which you then etch with acid to show the structure). But if you didn't throroughly was all the old grit from previous papers away between grades, then you had an ugly score which meant you had to go back and do it again. Grit would rollaround, I don't remember any embedding. Some bearings (I remember "white metal" crankshaft shells as a case in point) were designed to be soft so they allowed embedding of hard particles so they wouldn't cause trouble.
I wouldn't care to predict what could happen in a specific situation, ever, though.

Ugh lost a load of text when I went to upload pics - too tired to put it all in again, it's 02:43.

I was wrong, It's not steel, it's all copper alloy. some plated -as someone suggested.

The screws are out care of graffiti remover which dissolves everything. Even formica worktops. But the bits are still together. Pins of some sort..

Surface with red dot is smoother than it looks.

Hope it's clear, sorry they're grotty pics. Could do better. I have some fine SiC paper - but I'm bothered that the slide is just about jamming for part of its length and free elsewhere. I used lighter fuel and WD 40 - pretty sure all the old grease is off it.

zzzzzzzzzzzzzzz

Edited By Chris R 1 on 02/02/2019 02:52:48

Thanks all, I'll digest what you have all said.
It is possible that I've mis/not represented something.  Bush would have said misunderestimated. Donald (the other one) would have wondered about unknown unknowns.

In the past I've found methylene chloride softens/dissolves many things. Think paint stripper. It softens Aradite and other epoxies, for example. I should try things on the "paint" on the screw(s) I have managed to remove.

As in the top if the first post, the slide is around 150mm long.
The male part is machined from thick solid.

Overall these may help, or not. Item pics to come. I'm a teacher - class prep to do!

https://cdn3.bigcommerce.com/s-yv2qz/products/370/images/838/%252524%252528KGrHqQOKkQE6S7t-O1TBOmuz3%252521oqQ~~60_1_285_1__34941.1421346110.386.513.JPG?c=2

https://thumbs.worthpoint.com/wpimages/images/images1/360/1012/26/360_7e80f6b03ba0181f74e14753b9ff1581.jpg

I have removed an end-stop screw to slide the carriers off one end. One part of the run is less stiff, for either carrier. One carrier is slightly tighter than the other.

It needs some pictures, but they do tend to encourage opinions about redesigning things!.

I have a set of JIS screwdrivers 2,1,0,00, though they elude my search at the moment. I will look for micro ones to buy. These screws do have very narrow "arms on the crosses".

The bronxe(?) parts appear to be pinned, as well as screwed, so I'm guessing they wouldn't "move across a bit".

"lubricants that increase their viscosity under shear" - that sounds right ! I'll look at RS etc.

Edited By Chris R 1 on 01/02/2019 11:57:34

"hundreds" new, each..

I don't want to alter this thing, I don't have the resources or skils to do that. I agree it could have been made better. All I can think of is to try to remove a little material, somehow, then grease it. Any suggestions how I might do that?

I've looked it up, and am still not sure what a gib strip is!. Often rails have a trianglular sectio n adjustable strip, if that's the sort of thing you measn.

The "ally" on the dovetail itself is too shiny to be anodized. It's fairly hard stuff. Maybe one of the hypereutectic silicon alloys.

It's far eastern, when Nikon made stuff in Japan. When this was made, back in the 80's probably, it would have cost around £5k for a set of objectives, a few £k for the rest of the microscope and and a couple of thousand for this part. The "cubes" used with it are now hundred new, each.
Leitz would have been a lot more, and better made, and Olympus a bit less.

I've been playing with a microscope flourecence cube holder. Different issue with it was described in another thread here

There are two "cube carriages" which slide along a dovetail.

Dovetail is about 3cm wide, 4mm tall. and 150 long.

the contacting faces are about 4mm for the angled face then 5mm of flat, each side.

Male part is machined out of Al alloy block, female (carriage) is steel one side, and bronze(?) the other.

I have two of these. One was so stiff that I dismantled, cleaned out the remains of the old grease.... but it's not better. fine application of WD40, still no better. If anything it's worse. It takes a strong thumb pressure to get it to move.

I know aluminium can "pick up" against Al, but does it do that with other metals too?

I've got the carriages off, and though one side should unscrew, the screws are small and "glued" in with something. I don't fancy my chances of releasing them. Is there something I can leave them soaking in to soften thread locking stuff?

What about the slides - is there a metal polish I can put in to work it with to remove some of the Al?

A doodle:

I could try a few wipes with 1200 grit WC paper?

Edited By Chris R 1 on 01/02/2019 00:09:21

Clive - yes, £30 /10g is a figure I remember. Nye make a range.

These rods will do the job, but I've found another, or perhaps the original, problem, The carriers the cubes are on, are way too tight..... "Sliders too tight"

I'll post another thread.

Well you wanted a picture - it doesn't look much after 3 pages

Those screws are para/weakly magnetic so A2/304 stainless perhaps, I've some HT ones coming.

I managed to break a plug tap, then discovered I could have held the tap in the tailstock and hand turned the bar in the head chuck to pull/push the tailstock along. Not sure of my terms here.

Is that a normal way to do it?

Hardest part was parting off the bar. Tool too high and it just reduced it then rubbed, too low and it pushed the tool down and the tool went under the bit that was left. It's a cheap lathe, and I don't know what I'm doing.

Edited By Chris R 1 on 31/01/2019 21:43:05

I don't think there's a manufacturing defect, it works the way it's designed to.

There may be a washer - or perhaps one flat oand one spring washer - missing, but there's precious little thread to put them on as you can see from the close-up.

IF the shiny part into which the rod is screwed happens to be parallel to the outside of the box (there's no reason why it should be, with any precision) then I guess I could recentre the hole in the box, drill and tap it maybe 10mm and make a bush, for each rod (there's one each side).

But if that shiny surface is angled then the rod wouldn't stay in the centre of any hole, so things would bend inside when the rod is pulled/pushed. Can't have that.

My foot of 303 has arrived so I'll go that way for now. A slight annoyance is that the rod is not quite straight. Perhaps silver steel would have been ground, I don't know?

One significant contributor to the trauma is the nature of the dried up grease on the cubes' track, which makes them jerky. A dot of WD40 has helped but it'll evaporate.

Microscope greases ("Nye" tend to be very specific and expensive.

This isn't critical but what type of grease would be light, clean, and long-lasting?

Ta.

The rod doesn't touch the casting, so alignment isn't hurting. A flexible rod would do, though.

I see why it looked like there was stub - it was a reflection. Here it is unscrewed a bit.

Trying a bigger pic..