Member postings for John Smith 47

Congrats Don!

KBO, eh?!

J

Woohoo - hello People!

I saw my name being mentioned.... so I thought I'd drop in.

I have to tell you people, that this thread is absolutely HILARIOUS.

I don't know if you gents are being serious or whether it is deliberate self-parody but this thread is absolutely heaving with self-parody.

Poor you Don - now you know what I went through. The wolves won't let go until you publish every single detail of your life & your project... At which point expect to be told that your living in the wrong house and doing the wrong project!

How you people have time to write all this Lord knows, but I hope everyone is enjoying themselves... or is it "oneself", I forget grammar never was my strong suit.

Good luck!

J

PS Don, you have no right to any opinion on which hobby model engineering materials to use on until you have done at least a degree in mathematics, radar signalling and Fourier transform processing algorithms, and obviously you need to have read several papers on how to write an engineering specification before daring to seek any such advice.

But if your PhD is on "Comparing and contrasting the social anthropology of washer-women with online forums of highly educated gentlemen with too much time on their hands, based on the the competitive power dynamics of male specimens of the common Chimpanzee" then you've come to the right place.

Wait, I have just the book for your PhD: "Chimpanzee Politics" by Frans de Waal. I'm told it used to be on the list of required reading for US White House interns.
https://www.amazon.com/Chimpanzee-Politics-Power-among-Apes/dp/0801886562
It's an excellent read, BTW. Highly recommended.

I'm going to scuttle away now before Armageddon kicks in!

Have fun chaps! Byeeeee... xx

Edited By John Smith 47 on 29/04/2022 16:52:30

Hello

If Epoxy adhesives don't set properly within the first 24 hours, is there any hope that they will EVER set?

e.g. Would applying a sustained gentle heat have any hope of working?

Background
I have bonded some stuff with Zap's "30 minute" Z-Poxy. Unfortunately although I measured it quite carefully by eye, and although it has now "set" in that it has become brittle, it is still distinctly sticky to the touch.

Cause
It was a fairly small blob - about the size of a couple of peas - and I mixed it with a cocktail stick for a full 4 5seconds. So I can only assume that I failed to get the proportions correct. It's very surprising because it's the first time in about 5 years that I have failed to get 2-part epoxy resin/adhesives to set.

I was bonding at a slightly low room temperature (c.18C). But maybe Zap's Z-pox requires super-accurate proportions.

The parts in question are quite valuable and almost impossible to replace.... but it's now too late & would be too time-consuming try and scrape everything back to start again. So I fear I shall just have to wait to see if they actually break and then patch them up. Unless applying a sustained heat (e.g. 35 to 60C??) might work...?

J

Btw, I have been in touch with the manufacturers. And they are still talking a big game about what they can bond that nobody else can bond. I think I have found some a 'good enough' solution using the E41, which does allow a bit of repositioning time, which the tech-bond stuff doesn't readily offer (not without tweaking their protocols that is).

They are US-based and when I asked them about UK distributors they said that there aren't any. But he then asked me if I knew of anyone who might be interested?

So... anyone here interested?

It does SOUND like amazing technology...

Truth to tell, I couldn't find Mike Cox's design, although I did look for it online.
But if involves building anything substantial, with welding etc that will be beyond both my workshop skill level and possibly my storage capacity for storing large cutting contraptions!

Meanwhile, although I have now completed quite a lot of hacksawing by hand instead and the immediate for cutting of steel sheet has now passed...

But FWIW, so far the idea I like best is that of using:
- A small(ish) angle grinder (that cuts in line with ones hand rather than pulling the device sideways in one hand),
- A clamped straight edge,
- Cutting over the edge of a bench if that works
- But being able to set the depth of the angle grinder so that it only does a shallow cut (as this would attempt to pull rather than bend thin sheets
- for longer cuts I would need to find a way to support the cut materials, probably using some kind of sacrificial wood or board.
- If it came with some sort tooth (i.e. riving knife or splitter) to fit into the cut trench that would be a bonus.

But thank you everyone for all your suggestions thus far.

I shall revisit this thread when my next requirement for cutting long strips of c. 1mm thick steel sheet looms...

J

I'm not entirely sure how relevant it is but yes,
"Challenge to recycle Coca-Cola！/ Make a simple alcohol stove (soda can stove)"
is very zen/meditational. If one has a few minutes to spare... Good fun.

Thanks

J

Have any of you come across "Poly Kits" from Tech-Bond

**LINK**
(https://tbbonding.com)

They claim to be able to bond basically any plastic to any plastic including PP, PP and even PTFE...!

Too good to be true?

J

No, I confess I haven't tried any more adhesive tapes - neither double-sided or transfer tapes - because I have been unable to identify anything that sets hard. Do you have any specific suggestions/recommendations?

Also I am extremely keen to have something that permits a little adjustment time. Although I have bought a water sprayer for the purpose, if I can find something that claims to set rather than just use tack.

J

> there is also a precision track saw that is incredibly accurate.
Stephen - could you possibly provide a link?

TBH, I don't really have the workshop to do much making of my own tools, but what these guys have made caught my eye:
"Universal Rail System for Grinder, Circular Saw, Router and Film Cutter"

Wonderfully inventive, no?
If/when I get a large workshop I might even buy one! One can but dream...

Re this thread, to be completely honest, no only have I now done all the cutting I need the hard way (by hacksaw) but also for me personally, the physical size/scale of this whole conversation is getting rather out of control, as I am only looking needing to make precision cuts to create lengths of stainless steel sheet (c.1mm thick) that are about 20cm to 30cm long.

Good fun to think about though.

J

Edited By John Smith 47 on 26/01/2022 11:27:19

Good spot, but now too late to edit... 
The first stretch was of course the silicone rubber.

At a quick re-test of my rubber sheets, I am getting Silicone rubber x2.5, and NRL about twice that at x5.

To be fair, it's not 100% clear where the elastic limit lies. Not least because it depends on how long you hold the stretch. That said, the exact degree of elasticity is less important than the model falling to pieces due to shear forces overwhelming inadequate adhesives.

J

Edited By John Smith 47 on 26/01/2022 09:32:33

Back to this thread's question...

UPDATE

I have been doing quite a lot of testing of materials. I now have found a less watery and slightly less aggressive type of CA/Superglue called Powerflex made by Loctite, which goes no more like a gel which would definitely help reduce spillage...

Unfortunately, although the bond to rubber latex (NRL) is good/sometimes excellent - even a thin layer of the Powerflex causes swelling/warping of the latex, which then unavoidably seem to cause lumps & bumps in the outer surface of the RNL. See upper half of this photo:

In the lower half of the photo is my only real success so far, which is Elastosil E41 + NP2 primer, which combine to product a REMARKABLY good bond onto 1mm thick Silicone Rubber. In fact you may not really need to primer.

And crucially it forms it's bond in a very 'civilised' manner giving you time to wipe off excess (using IPA) and has a reasonable repositioning time - which can seriously help when model making.

Adhesive/glue FAILS include:
- Repair Extreme
- Dowsil 732
- Loctite Plastic Bonder
- BSI Epoxy 15min
- Collall All-purpose
- Zap Z-poxy
- B7000
- E6000
- Professional Welder
... } all of which TOTALLY failed the fingernail test (not even close!) when bonding each of NRL rubber and Silicone Rubber. That said, some of the glues claim to keep getting stronger for 48 hours so I may be being slightly premature...

Interestingly, almost all of them bond wonderfully well to my ABS plastic despite it's high-gloss finish. Ironically the one notable failure was Plastic Bonder!

I am delighted with Elastosil E41. My sight problem is that an extremely despite a soft shore hardness (of 40° my silicone rubber is nothing like as elastic a natural rubber latex. Latex can be stretched to a length of about x2, whereas the latex can easily do x3.

J

Crumbs. I rather hope that people here have better things to do with their lives that read "all" of John Smiths posts.

Ignore button being fingered... Ooops!

Dave

> Angle grinder: fast, noisy, messy, broad rough cuts. Inaccurate.

My point was just that if used against a straight edge and with a fine metal-cutting blade, surely the Dremel DSM20 would be pretty accurate.



One thing slightly worries me - do these things ever suffer from kick-back?

Talking of which, out of interest, in order to increase accuracy on longer cuts, is it possible to get as an attachment an equivalent of the "riving knife"/"splitter" like table saws have?  i.e. That would go into the cut left by the cutting wheel... to keep the cut straight.

> Dremel Multi-tool: slow, slightly noisy, versatile, good for fine cutting,
> delicate grinding, polishing, and small diameter drilling. Much favoured
> for delicate accurate work, skill required.
Yes but - back to the question - how would you cut long thin straight lines through metal, using a device whose spinning wheel tugs you sideways when you make a cut?

J

Edited By John Smith 47 on 25/01/2022 23:19:08

Tempting though it always is to descend into a war of words, I have shall ignore the all personal attack. I have learned to develop a thick skin, when people are being unreasonable... and fighting back with similar personal criticisms & comparable attacks back ever EVER helps.

But please try get your facts correct...

> He then wishes to measure a hand filed radius with precision,
Wrong. I have never wanted to measure with precision the radiuses that I have only hand filed. This is factually incorrect. What I have been measuring is the consistency of radiuses/radii on edges may or may not have involve a hand-file to do the grunt-work, but that have always then been either finished either with a deburring wheel or made with a precision diamond hone (possibly using with a modified honing guide), or both.

But nope, never just with a hand file.

Whilst we're here Robert, although:
a) my workspace is exceedingly tight and
b) although I had no immediate requirement for a lathe of any size and
c) although I also have basically no idea how to use a lathe and
d) although I don't really have the time to spend learning how to use one and
e) although it has a circular pillar (which is not ideal) and
d) although the Unimat 3 being an exceedingly old, and second hand product, so being a novice I would be extremely likely to buy a dud with shot bearings or some such problem...
...and probably not even know!
...However the point here, is that I have - many months ago in fact - already thanked you for the suggestion and have also - many months ago - eaten the humble pie of conceding that I should have bought that darned thing!

That said, the Unimat 3 would not help me ABS plastic to NRL rubber, so I'm technically we committing the crime of being in the incorrect thread.

Hey-ho.

But I am gratified to hear you are enjoying these threads... Me too

And I have learned a LOT about tools. And I am deeply grateful for that. Sadly my technical knowledge is so limited (or so I keep being told!), and the expertise around here is so high (mostly!) that there isn't much I can offer in the way of knowledge back.

J


PS At some point I may just use a new email address and start again. And hopefully people will go back to answering the questions I pose, let me make my own mistakes and stop trying to join do join dots about what my various private/IP protected projects involve.

Btw, what are the pros & cons of using a notched adhesive spreader?



I suppose the idea is to helps you get the correct thickness of adhesive on.
On the down-side, your adhesive layer ends up with lots of lines through it...

Have you ever used them?

Re buying sheet solid PTFE, I rather tempted. But it's not cheap stuff. What thickness do you think would suffice? 2mm? 3mm? I have no idea how flexible and/or physically strong the stuff is.

J

EDIT:
I still haven't managed to find any sensible-looking, reasonably wide PTFE (/PTFE-coated?) spatulas, but I did find these:

https://www.amazon.co.uk/CrafTreat-Teflon-Bone-Folder-Set/dp/B07QXNTJSV


They certainly CAN be used to apply glue...

Although the Ergo Square doesn't have a handle it it might have had merit in boing thinner & much more flexible... but either way, being PTFE I guess they would be dead-easy to wipe clean. Might work (??)

Either that or yes, buy a load of lollypop sticks. At least they wouldn't be quite so bad for the environment as  innumerable, single use, plastic spatulas!
 

J

Edited By John Smith 47 on 25/01/2022 01:11:30

To get clear, my understanding is that absolutely nothing will stick not a nice smooth surface of PTFT (Teflon) or FEP (its transparent close cousin).

I find my Pinflair spatulas are rather useful and can help with spreading adhesives, particularly the thicker stuff, broadly flat. Depending on what you're doing, it's also useful having a choice of widths... However like I say, I am finding that adhesive does slightly stick to them, worse where they are slightly frayed... And it would be nice to be able to use super-easy to clean ones made from PTFE/FEP/similar. 
Also even though if others here think it's fine to b*gger up the environment with spatulas (even if they are plastic?), the Pinflair ones also cost me c. £7.00, so I'm keen not to just chuck them out for both reasons.

J

PS On another none, re rags, when not using disposable paper, I actually use a load of lint-free (pale blue) microfibre cloths to wipe stuff down with, including say very small amounts of epoxy adhesive (which will then set hard) which I then throw into a washing machine and re-reuse. They look a bit rough, eventually of course I will throw them out if/when they get too damaged, but it works great for me.

Edited By John Smith 47 on 25/01/2022 00:41:03

> No good for the environment, of course.

Exactly.

I have a plastic Plastic Spatula Set from Pinflair.

https://www.pinflair.co.uk/pinflair-plastic-spatula-set

I think they made from PP (or PE??). Either way, I am finding that glue is quite hard to remove if you allow any, albeit accidentally to set/start to set. Part of the problem is that they have slightly frayed. Either way, they are certainly don't shed glue anything like as well as PTFE/FEP would.

Kitchen spatulas seem to be mostly made from Nylon or silicone rubber, neither of which would be OK.

J

Edited By John Smith 47 on 24/01/2022 22:28:00

Hello

Is it possible to buy a spatula made for Teflon (or something similar that is totally non-stick) for spreading glue?

Thanks

J