Member postings for John Smith 47

@Jeff Dayman - Good suggestion. I have used the "ignore member" function on you. And would be delighted if you would do the same if it would help you keep your negative, unconstructive, offensive, border-line hysterical personal attacks to yourself.
 

Edited By John Smith 47 on 19/01/2022 13:15:52

[Re-written]

@John Hinkely
Not a bad idea, particularly if using a straight edge. 
Fwiw, I have a hand nibbler but it does deform the surface slightly. But maybe a powered one will create a cleaner edge. 

@Watford
In the nicest possible way, I would prefer not to answer that question.

@Mike Pool
Yes I am using 2 junior hacksaws. One I keep straight and use it to start my cuts. The other I keep at 45° which I use when the straight hacksaw no longer reaches.
It's broadly fine but a high level of skill is required and I find myself filing and grinding more than I would prefer.

But NO, I think that overall people have been extremely helpful and for that I am extremely grateful. What gets boring is that for some reason a few people seem to resent... the attention or something... and start having a go at me from all manner of directions. EVENTUALLY I am compelled to respond and then others take offence that I am criticising THEM, when they are the very people I am particularly grateful to. Or they flame me for talking off-topic! 

The other thing you miss is that yes, I am outsourcing where I can, but it always takes at least a 1 week to get some work done, plus it costs a minimum of £40 or £50 for even the smallest job.

You also miss the fact that I enjoy picking up new skills & learning messing about with tools. Plus during the act of fabrication, new insights about the designs often emerge.

OK enough, please can we stick to the question?

Edited By John Smith 47 on 19/01/2022 13:04:57

@Nicholas Wheeler
Thank you for the clarifications.

No, I am not going to show this forum the overall design of anything, not least because once it comes to market, you might then want to buy my product and that would be in violation of this forums rules!

You need to let me make my own mistakes, and let what is private stay private.

John Doe
a) Yes, fair point. I shall look out for suppliers who offer a laser-cutting service, next time I am buying materials.
Yes, a good reminder about clamping parts together. I used to do more of that. It sometimes works very well so long as the part is held accurately at 90°.

b) Yes, I use a belt/disk sander, rough & fine hand files, and rough & fine diamond hones

c) In the nicest possible way, I would prefer not to answer that question.

d) You may have a point... but I do already have 3 desk lamps and a 4-way overhead LED room light.

e) Yes, EDM machines are AMAZING. But I dont' have the fixed table-top space, money nor spare time.

@JasonB
Ah I get you re how to use slitting saws. Thanks - good food for thought.

Re hacksawing yes, clamping between 2 boards definitely helps. For longer cuts, what do you do once your cut is deeper than your saw permits? At present I put the hacksaw blade at 45° simply in order to keep cutting. However as I keep finding, it does make cutting straight lines much harder!

@John Hinkley
Good suggestion. Fairly hard to be accurate but when used with a fence it should work OK.
Fwiw, I have a hand nibbler which turns out to make a slight mess of the sheet. I suspect that a powered one would probably work much better. I did a very long cut with one the other day and eventually - even though I was extremely careful and keeping everything dead in line - I was simply too strong for it and broke the tooth off it. I think it didn't like the big curl of steel that was forming due to the length of the cut.

[To get clear, this forum did a hiccup and I lost my other replies. I am not ignoring you others!] 

Edited By John Smith 47 on 19/01/2022 12:57:49

Tug - What are you talking about? I have been extremely grateful for all your comments and have responded accordingly. In fact I intend to buy some Zap's 30 minute Epoxy shortly.

I have no bloody interest in TELLING you knowing about my VAT issues either but the endless snide commentary in this thread from others about such matters forced my hand.

Peace, brother.

J

 

Edited By John Smith 47 on 19/01/2022 11:26:49

1. I'm sorry if my bothering to claiming my VAT back (or not claiming VAT back) for some reason offends anyone here.

2. No, I am not retired.

3. Yes, I am employed. Self-employed.

4. No, I am emphatically NOT promoting my business or my products. (We have been through all this before.... deep sigh).  In fact I have studiously avoided describing them in any detail.

5. My business is a start-up, that is very much self-funded. Most people here probably have much more money to throw at their tools than I do.

6. Nowhere in the rules/terms & conditions of this site does it say "no inventors".

7. Many people here seem to enjoy my threads, and have expressed as much. But if any of my naive/beginners questions bore your or in some way irritate, please do not answer them. I have mostly been pretty self-restrained in my answers to some of your personal/off-topic comments, but do not guarantee to stay that way.

Please can we try stay civilised here. 

J

Edited By John Smith 47 on 19/01/2022 05:06:09

UPDATE:

OK I've done some more research on kick-back.

I found a number of videos about kickback on table saws & circular saws.... particularly when working with wood. I've never done any of the stupid things mentioned and I've never experienced any significant kick-back myself and so I hadn't realised the potential size of the problem.

Strangely nobody in the videos I found seemed to mention kick-back when cutting metal. I'm not sure why. (Maybe it's less of a problem if you just cut over the edge of a bench??)

J

> To cut thin material with a circular saw without restraining the material risks kick-back
> with the potential for serious cuts.
Can you say more about this?
Do all table saws suffer from "kick-back"?
Or are you saying that a circular saw that is not part of a table is what is dangerous?

(Part of my problem is that I can't find a small precision table saw that is designed to cut metal...)

Nobody seems to have directly mentioned the Dremel I was talking about. (see post #1)
Maybe I could clamp the metal sheet to a piece of sacrificial hardboard and set the depth of the cut to be just thicker than the sheet... (or just use the edge of the bench?)  and then clamp some sort of straight edge on top to run against... 

i.e. I'm thinking of doing what this guy is doing, but this time with everything on a much smaller scale.... no?

Edited By John Smith 47 on 19/01/2022 02:17:49

Yes the extremely shallow curves of a treadle guillotine look like they would definitely work. However yes, most definitely too large & heavy. I need something I can lift off a table at the end of each day and put onto a shelf.

I'm guessing an 80 ton press could also stamp without unintended curves too...   

Edited By John Smith 47 on 19/01/2022 01:35:06

If it works anything like this video...

https://www.youtube.com/watch?v=HUOcE6onDX4

...then it looks like it the small teeth that grab the steel rather damage it.

And like most (all?) sheers, the steel that is cut off also gets bent & twisted...

Please can you clarify what you mean?

If you google "Multi tool" you mostly get a lot of these sort of glorified pen-knives:

.... which I am assuming that you don't mean.

Alternatively presumably you mean these oscillating things:

...which yes, I have tried but without much success. I find them big, heavy & clunky, and I have yet to cut anything remotely close to a straight line with one. In fact I cut very much straighter lines using a hacksaw(!) but no doubt I am doing it all wrong.

What do you mean exactly? How are you using yours?

@pgk
> If the lines you are trying to cut are generally straight, then adhesive tape as a guide would be more visible than scribing.
Obviously I'd need to get the tape dead straight, rather than just drawing a line using a ruler, but for dim lighting conditions that sounds like a great idea! Thanks.


@David Noble
> I hesitate to enter the fray but a guillotine would do it.
I would absolutely LOVE to use a guillotine - believe me! - but I'd need to find one that doesn't put curves into what is coming off. (But maybe very expensive, high force ones exist that only put a very small curve into the metal and from which it can spring back?)

@Nicholas Wheeler
In my experience, even when using a soft hammer tapping always tapping marks and nice more or less optically flat metal is never the same again. Personally I'd rather have a bit of mess and a rough edge that has to be filed down.

> Cuts made with grinding wheels on thin materials are horrible things.
In what way are they "horrible"?
To get clear, are you calling 1mm of steel "thin"?

@Martin Connelly
> Buy a suitable mill and some slitting saws.
So the slitting saws would be horizontal, yes?

> Clamp the stock between two plates to support the material.
Sorry I don't understand quite what you mean. Can you say more about this configuration. Are you suggesting using a milling table that can do a very wide amount of travel?
 

J

Edited By John Smith 47 on 19/01/2022 01:12:00

Tapping it straight?!
In my experience, unless you put it through a special straightener you never EVER got the metal completely flat again.

> Have you looked at buying metal inlay strips.
I have found it hard enough to find the metals I require e.g. Grade 430 stainless 1.0, 1.2 & 1.4mm thick without trying to find the exactly correct width. In any case, I have now bought the sheets. It would be a shame to waste them.

Yeah the lines are generally straight, just not in the correct direction!
Over 15 to 20cm even the smallest errors mount up.

> I would have suggested 4.5" X 1 or 1.5mm cutting disc in a small angle grinder.
Is not a small angle grinder precisely what I was suggesting?
But 4.5inches (11.4cm) is even larger than the machines I found. I don't see how a larger, heavier machine would help with accuracy.
Exactly what is your point?

> Good luck
Thanks you.

@JasonB
> If you can't see the line to saw to what hope...
At no point did I say that I "can't" see the lines, I said that it is harder to see the lines in less good lighting conditions. Yes, I have various portable lamps which I can and do set up when necessary, but you have to get the light to bounce off the metal just right to see the scribe marks properly. Sometimes this means pointing the lights to the floor... For best results, I may also need to change between different magnifications of reading glasses. Either way in practise if I need a more accurate cut then I have to keep stopping and checking multiple times.
==> Ergo, it's not about possibility/impossibility it's about difficulty, inconvenience & speed.

Look let's stop the smart-ass comments. There is no use pretending anyone here, no matter how many thousand years of sawing-by-handsaw experience they might have, will ever be able to saw as accurate parallel lines as a machine such as a table saw can cut.

@Redsetter
> Just order your materials cut to size.
When I can, I do. But not always possible.
And where possible implies delays & potential over-orderings...


@Dave_S
> <popcorn>, <chair>, <beer>
My pleasure. FOC entertainment at your service.... :^P

IME, wax earplugs work well.

Fwiw, on my street there is always a LOT of building work going. And much of it is exceedingly noisy being as it happens outside from rooftops... for days on end! However nobody seems to mind, and I would be amazed if anyone even noticed a new noise from indoors.

J

Hello

I hardly dare re-kindle this old thread....
"Small saw. Proxxon or something else"
https://www.model-engineer.co.uk/forums/postings.asp?th=172361&p=1
**LINK**

...However I find that I do keep needing to cut long thin strips of material. It's usually either wood/plastic (e.g. ABS/PS/Nylon), or stainless or mild steel.

My requirements have evolved since that thread so I shall this new one.

My cutting requirements are:

1. Material thickness:
My steel is generally between 0.9mm and 1.4mm.

2. Lengths:
My lengths might be say 10 to 20cm,
with a width of maybe 2 to 5mm.

3. Materials
Steel is obviously the hardest of the things that I need to cut. So a small machine that could even cut just steel would be a revolution for me. But would it be too much to hope for one machine that could cut both materials? (Like my fine-toothed hacksaw can!)

BACKGROUND/PROBLEMS
To be honest, my hacksawing skills aren't very accurate. It's particularly difficult, particularly after dark when there is less daylight to help me see what I am doing. Seeing marked lines on steel (even when using Dykem Steel Blue) is quite difficult...

So I find that I keep having to hacksaw somewhat over-sized and then hand-file or grind down and remove quite a lot of material to get them down to the precise required sizes.

==> So I find myself fantasizing about a precision/micro table saw that can also cut steel! Or possibly some rig to enable me to do hacksawing with great precision?

From memory (and without re-reading the entire previous discussion):

a) Small table saws (e.g. Proxxon) ==> just aren't designed for steel

b) the Proxxon band saw definitely wasn't

c) Larger, more powerful table saw just aren't designed for cutting small precision parts.

d) A nobody seems to make small grinding disk wheel (e.g. 1mm thick) embedded into a cutting table. [And no, I don't really have time to mess about making one!]

e) My strips are too long to readily fit onto my MF70 milling machine.

f) I don't think a guillotine will work because the leave one side of the cut steel sheet curved.

[ NOTE: As before, I do not have a permanent works space. Everything needs to be cleared away at the end of each day. So tools need to be fairly light and compact. ]


MY POSSIBLE SUGGESTIONS:
What about cutting using micro-sized angle grinder.
...And then finding some way to line up next to a ruler/straight edge?
[But how exactly? Have any of you tried this?]

A. "PROXXON LHW LONG NECK ANGLE GRINDER"
https://www.axminstertools.com/proxxon-lhw-long-neck-angle-grinder-702027


- with cutting disk fitted
or

- "For steel, non-ferrous metals, glass, ceramics, wood and plastic"
- 50mm diameter discs
- 100W DC motor.


B. Or possibly a DREMEL would be better (??)
e.g. "DSM20-1/5 710W Compact Saw 230V"

**LINK**
https://www.cromwell.co.uk/shop/power-tools/compact-saws/dsm20-1-5-710w-compact-saw-230v/p/DRE2674120F
- Blade diam: 77mm
- No load speed: 17000rpm
- Power: 710W (?)
- Weight 1.7Kg
- Dust extraction port for clean working environment (vac cleaner attachment)
- "1 x straight edge guide"

I was thinking that something that cuts with a very thin disk would create less dust, but the dust extraction port could mitigate that problem. Also claims to have "Excellent line of sight for accurate cutting"

Yes, seem like it will be damned noisy...
> Noise K Factor: 96 dB(A)
> Noise Sound Power: 108 dB(A)
> Noise Sound Pressure: 1.59 Pa
...whatever that really means, but I live with that. (With earplugs if necessary)

BUT it is quite big & heavy (at 1.7Kg), for more precise work.

Have any of you got one? Have you had much success in cutting straight lines with them by lining them up against straight edges ?

What do you think?

J

It becomes particularly relevant when making larger purchases of course, but yes correct on both accounts

J

Zap Epoxy seems to have a lot fans here.
Out of interest, what specifically is so good about Zap epoxy?
e.g. Is it just it's bonding strength? Or ease of application.... or what?

J

Do any of you have experience of Zap's "Z-Poxy 30 Minute" epoxy resin adhesive?

If it sets in 30 minutes, in practice what is it's working time...15 minutes?

J


PS Re buying from eBay, I need VAT invoices. And they seem to be the exception on eBay! Whereas on the dreaded eBay they are generally (albeit not always) automatic.

Edited By John Smith 47 on 17/01/2022 16:36:05

Noted. Thanks.

Personally I hate using eBay because of the difficulty of getting proper invoice out of anyone. And worse they have a mysterious way of sometime (but not always) archiving your purchases off their website after something painfully short like 3 months.

J

To answer my own question, I have found this stuff:

"MID-CURE epoxy 15min (BSI203)" made by Bob Smith Industries (BSI)

www.align-trex.co.uk/bsi-epoxy-mid-cure-15min-128g-4-5oz-bsi203.html

...Which looks like a reasonable compromise. i.e. www.bsi-inc.co.uk/mid-cure-epoxy.html say allow "45 minutes before handling parts and 2 hours for full strength."
Amazon.com say it has a "15 minute working time"

Wait, the US parent website www.bsi-inc.co.uk/mid-cure-epoxy.html says
"MID-CURE can be worked for about 10 minutes, with adhesion beginning after about 15 minutes. Full cure in 2-3 hours."

In truth, a working time of only 10 minutes is still a BIT fast for me. However it is certainly much better than their "5 min" Quik-Cure™ Epoxy, which begins to set in 4 or 5 minutes, in my experience.

Zap sounds promising and will be top of my list if BSI is no good, but I needed the stuff TOMORROW and ran out of time for this decision. 

I already use BSI's 5 minute epoxy which I find excellent. I like its strength, clarity, range of materials it bond well with and plus the way unset surplus can be cleaned up with Isopropyl alcohol, but too fast for this application. 

I'll let you know how I get on with the BSI 15min Mid-Cure.

J


PS
FWIW, BSI also make a "30 minute Slow Cure", but I think that will be annoyingly slow "Full cure in 6-8 hours" but "cured epoxy reaches full strength within 24 hours". So realistically you can't touch it for a whole working day... :^(

Edited By John Smith 47 on 17/01/2022 13:46:21

Zap looks promising. I need a faster supplier though. Yandles only seem to do 2nd class post.

Araldite Crystal only claims to have a "4 minute working time"

I don't know of any boat chandlers near me... But good suggestion.

Edited By John Smith 47 on 17/01/2022 12:41:41