Member postings for John Smith 47

Hello

Can you suggest an epoxy adhesive that sets SLIGHTLY slower than the modern "5 minute" type of epoxies?

I would like something that stays workable for say 15 to 30minutes... and then sets as fast as possible thereafter.

Ideally, it should also be:
- be transparent,
- be 'general purpose' (able to bond to most plastics... such as ABS or PS, metals and woods)
- be easy to clean up using a solvent (e.g. Isopropyl Alcohol) before setting
- Must have reasonable rigidity and good strength.

Background
I find "5 minute" epoxy resin adhesives start setting far to quickly and I keep having to make additional small batches, but things like "Araldite Ultra Strong Adhesive Glue Blue Standard" stay repositionable for too long... technically for "80 minutes" and you can't move them (because they stay fragile) for 8 hours... and you can't really sand them for 14 hours.

So I need something in the middle. Even a 10 minute setting time, rather than 5 minutes would help me quite a lot!

J

EDIT: I prefer separate tubes if possible, as I find them easier to dispense accurately.

Edited By John Smith 47 on 17/01/2022 12:16:06

Extremely interesting. I now just need to find a sprayer somewhere!

Out of interest, do you happen to know whether the bond itself ever properly sets/hardens over time? Or whether it just stays super-sticky...

J

Interesting suggestion. For precision work, would you literally paint water on with a paintbrush? Or try to use a fine spray/mist? Either way does the bond end up being just as strong as normal?

J

I did try a couple of different types of Superglue. One had extremely strong instant grab and was an instant disaster. The other was slightly less aggressive, but there was very little repositioning and the rubber quickly swelled like crazy causing it to curl. Also CA seems to denature the rubber, and any spillage on the front surface will leave a nasty reflective marking.

If all else fails, I could probably get it to work... but to be honest I've always rather hated CA, because:
- the fumes rather sting the eyes,
- it requires a good fit (i.e. not good at filling in any gaps) and
- it's such a nightmare to clean up any spillage - particularly if it gets on the your skin!

Have you tried Pinkgrip with rubber?

I couldn't see any mention of rubber...
https://www.everbuild.co.uk/products/adhesives/grab-adhesives/pinkgrip/

> Are you covering the abs with a layer of rubber, joining abs to rubber to something else?
I am using strip of rubber to create a hinge between two plates of ABS.

> Do you need the glue to be thin as possible, or is a thick glue line acceptable?
It doesn't need to be super-thin. I suppose up to 0.2mm thickness would just about be okay.

> Often rubber bits on plastic are 2 shot moulded
Yes, absolutely. This is a model for exactly that.

Since asking the question I have been experimenting further, with various glues. I am finding them all extremely hard to apply evenly and the result quickly gets exceedingly bumpy and messy.

But in my experience, what has been an absolute game-changer, for producing really smart results, is if one can use some sort of glue-tranferring tape, so long as it's thin enough.

e.g. This stuff "3M 9088-200 High Performance Double Coated Tape"

**LINK**
https://www.3m.co.uk/3M/en_GB/p/d/b40070391/

It certainly is amazingly tacky! (i.e. sticky) The results can be seriously smart, and with care it is slightly (but not very) repositionable, in that with patience you can generally peel it back off a solid surface.

However I suspect that it doesn't ever form a solid bond. And so when the hinge is under long-term, sustained pressure, particularly if the item is accidentally left in direct sunlight, I suspect that it may fail... despite what the specs claim!

J

Harold Hall's page looks like a very useful resource. I have bookmarked that. Thanks!

Re the "Zeus book", is this thing published by Roebuck, what you all mean?
It looks like different versions exist... Which one is best?

e.g. This one by RGDTools.

"RDGTOOLS ZEUS CHART 2008 LATEST REVISION"
**LINK**
https://www.amazon.co.uk/RDGTOOLS-ZEUS-CHART-LATEST-REVISION/dp/B00S9SVESM/

Or this one...
**LINK**
https://www.amazon.co.uk/workshop-decimal-equivalents-details-clearance/dp/B00C77BX46/
(Looks similar but seems that it is not from RGDTools)

Or this one
**LINK**
https://www.amazon.co.uk/Precision-Reference-Drawing-Toolroom-Workshop/dp/0999275011/ref=monarch_sidesheet

(But surely that can't be the correct image??)

Fwiw, wherever possible I always use metric.

J

Hello

I need to glue/bond ABS plastic (Acrylonitrile Butadiene Styrene) onto NRL (Natural Rubber Latex). Any suggestions?

Note: The idea glue/adhesive should permit a few minutes of working time (e.g. 5 minutes) to allow for slight re-positioning and it would then bond as hard as possible, as soon as possible after that.

The bond would not need to flex. The bond must not in any way creep - e.g. due to gentle sustained forces – after it has set.

J

PS I have been trying "Bostik 218M Latex Adhesive" but it doesn't bond particularly well onto the ABS.

Edited By John Smith 47 on 14/01/2022 14:59:30

OK now I'm rather bemused. I have a collection of nuts and bolts that I've bought over the years. I have always tried to buy metric, but now that I measure some of them at c. 4mm diameter, the actual diameter seems measure c.3.86 to 3.89mm, but I can't get the nuts to fit onto my "4 x 0.7" metric tap.

Which seems more likely: Have I accidentally bought Imperial nuts & bolts (i.e. "5/32 inch"?), or are are they fine not coarse pitch?

J

EDIT: As a rule of thumb, how much smaller should the hole that I drill be if I am going to tap it? At these sizes would 0.5mm smaller suffice?
e.g. If I am going to fit a M4 bolt should I use a 3.5mm drill?
And if I am going to fit a M5 bolt should I use a 4.5mm drill?

Edited By John Smith 47 on 12/01/2022 23:46:36

Hello

When one buys some "M" system of metric nuts and bolts, by default are they normally fine or course pitch?

e.g. If you purchase some standard "M4" bolts, the diameter of the outside of the thread should be about 4.0mm... but will the pitch normally be 0.7mm ("course" ) or 0.5mm ("fine" ) per revolution?

Background
I need to standardise all my nuts & bolts to the metric system. And I want them all to fit each other. In particular I also want to buy some (internal) metric taps that will work well with my nuts & bolts, so for example I can drill a hole and put a thread into it.

With thanks

J

Edited By John Smith 47 on 12/01/2022 23:10:55

Edited By John Smith 47 on 12/01/2022 23:11:09

My rationale was that it spins at 2850RPM and is cheap and quiet which is what I needed. Yes, some adaptations may be required.

> Simple arithmetic gives a clue as to the spacer thickness required. Job done.

OK I'm out of time on this. I couldn't find where to buy a 15mm spacer with 0.5" bore, for rapid delivery... so I have bought some M12 washers which should arrive tomorrow. Maybe I'll just have to live with some side wobble.

J

To be completely honest, I only 3/4s understand all of that.
> A standard wheel spacer to match the wheel width and bore should be used.
Fine. But where would I find such a thing?

Also, to get clear, do none of you buy into this chat about "self aligning spherical washers"
https://youtu.be/xOKOsBpcQjE?t=18
https://youtu.be/xOKOsBpcQjE?t=18

Edited By John Smith 47 on 11/01/2022 22:19:48

Actually it's the other wheel that has the wobble. For this wheel, I just want the plate flanges to actually reach it... (!) In truth, the specific details don't really matter. But given that I am going to have to buy something... I may as well buy something appropriate, that could be used on all my wheels.

EDIT:
Yes, my Charnwood GB6 was pretty cheap (c. £105 inc VAT & delivery) and build quality for the table etc is very weak, but I quite like how it runs nice and quiet. 

Since you raise the issue of quality, what WAS rather shocking was that the spindle was already rusty when it arrived... In fact it was almost impossible to get the wheels off!
 
I have raised the issue with the suppliers, sending them this photo...

 

The supplier strongly implied that other customers have had the same problem, but he has promised that Charnwood themselves will get back to me. The label says that it was made in China. Maybe it had a dip in the South China Sea on the way over... 


 

Edited By John Smith 47 on 11/01/2022 21:56:42

I have 2 new wheels. One just fits onto a 0.5inch spindle with a fairly snug fit. The other comes with what I can only describe as recessed spacers that are made of plastic. The latter looks like this:



It helps align the wheel centrally but does nothing to help the flange reach the wheel when I run out of thread on the spindle...

EDIT:
Btw, what does it say about the modern world that if I type in "Self-Aligning Spherical Washers" into my search engine (duckduckgo.com), the first search result is THIS THREAD... which I only started at 7PM this evening!

Edited By John Smith 47 on 11/01/2022 21:32:51

Dressing both sides isn't really an option.

I suppose another option would be to use a stack of M12 washers like this:

e.g. "M12 Flat Penny Washer (Pack of 10) Plain Wide Round Metal Alloy Steel Washers for Screws – Zinc Coated Plated Galvanized Heavy Duty Certified Standart ISO7089 DIN125 M12 (13mm x 24mm)"

https://www.amazon.co.uk/dp/B08C3554WM
https://www.amazon.co.uk/dp/B08C3554WM

Maybe I could just jam the odd sheet of paper between one or two of them to help line things up?But from watching the video (see original post, above) it looked like self-aligning washers would magically sort out the problem (if that is the problem was caused by the thread on the spindle being slightly mis-aligned...) ??

J

PS When people say "alloy" do they normally mean stainless steel or aluminium?
I mean technically speaking aren't almost ALL industrially available metals in fact alloys?

EDIT
> I don't doubt that the spherical washer pair will work well, albeit rather expensively.
What did you make of the what was said in the youtube video? 

Edited By John Smith 47 on 11/01/2022 20:54:41

What a curious situation! I would have thought that if everything was made accurately one could just use a gentle push-fit and tighten it up using one plate flange on either side of the wheel... but that's obviously not how the world works!

> Have you tried a plain spacer?
No. To tell the truth, I don't have any plain spacers. Nor spare washers that are large enough.
So either way I'm going to have to buy something... !    

Or maybe I should just buy some washers with 13mm holes. 
Either way, do you have any firm views on what material it should be made out of?
e.g. Buy default would you suggest nylon/steel/aluminium & where would you buy them from for rapid delivery?

J

Edited By John Smith 47 on 11/01/2022 20:19:15

Hello

Should I buy these Self-Aligning Spherical Washers?

Background:
I am trying to fit a new wheel onto my Charnwood 6inch Bench Grinder (BG6). My new wheel is:

A) Thinner
My new wheel is thinner at only 25mm thick compared to the 40mm thick (fine white grinding wheel) that it is replacing.

B) Wobble
There is also a small amount of side-wobble in the new wheel.

My BG6 off-the-shelf grinder looks like this:


==> It is the white wheel on the right that I need to replace.
 

The spindle is 1/2inch. Due to the new wheel being thinner, the thread it not long enough so I need some sort of spacer to make up the 15mm difference (from 40 - 25mm).

I am also keen to eliminate some side-wobble at the same time.

This guy on YouTube is recommending "Self-Aligning Spherical Wheels"



**LINK**
https://youtu.be/xOKOsBpcQjE?t=18

For example do you think this "Indexa - FC25 13mm BORE 2PC SPHERICAL WASHER SET" would do the job?

**LINK**

https://www.cromwell.co.uk/shop/cutting-tools/fixing-components/fc25-13mm-bore-2pc-spherical-washer-set/p/IND4252860D

Any advice?

J

Edited By John Smith 47 on 11/01/2022 19:10:21

OK thank you for the clarification, Michael. Good to hear.

J

UPDATE

Time's up!

Just to let you folks know that I have - albeit through gritted teeth - finally bought that set of Imperial radius gauges from ARC, because sourcing individual Starretts that could be delivered in a half-reasonable period of time proved to be impossible, here in the UK.

Meanwhile, in slow time, I shall see if I can find a metric set of those Starretts on eBay. Yes, there are a number out there, but they always seem to be coming from the US which then of course incurs hidden time & fincancial penalties...

Thanx all

J

Dave in the nicest possible way... I have not told you every single detail about what I am doing.

> From what you've said of your prototype, it seems unlikely that this radius needs to be measured at all!

You don't KNOW that. And even if true, it is arguably none of your business. I know you meant to be helpful but I am struggling not find that comment both invasive and quite offensive.

Look, I am not building a space rocket, but what I am doing is quite complex, and involves a balanced judgement between competing issues. Even if it were IP appropriate, all of this would take too long to go into, and would be a waste of your time and mine.

Where I have a specific question, I ask it. And yes, almost all of the advice given the framing of the question that I have provide HAS been excellent.. and yet, even whilst it engages, interests /amuses some users, the mere existence of the whole damned conversation seems to irritate various users.

Maybe they are jealous of the attention, I don't know. And if so, sorry but that's simply not my problem.

And to be completely honest, talk about wasting of resources, I see this persistent pestering for me for the absolute full details of exactly what I am trying to do, not just a deep waste of my time but also as an attempted to violation of my privacy.

YES, there will always be a bit of banter and a few interesting deviations and weird facts that people bring to the party - all good fun - but the persistent stream of critical patronising advice and endless critical sniping & bitching about my budget, my level of technical experience... my strategic decisions, my motives, my tone, whether & when I do or don't buy some specific product and then taking umbrage if they are ignored... Although I have been pretty self-restrained in my replies... it's EXHAUSTING.

....Is it too much to ask for the nice folks in this forum to just answer the specific questions that I am asking about tools for model-making?

I know that us 'innovators' necessarily are required to develop thick skins not least because you can't please everybody, not ever. We ask 'naive' questions, make endless mistakes, but we learn and more importantly with fresh eyes we see things that others have failed to. It's what we do.

And, please for the love of God, just let me make my own mistakes.


PS Back to tools, yes, of course I am using CAD. Both 2D & 3D software (Xara & OnShape).

Edited By John Smith 47 on 06/01/2022 14:45:39