Member postings for John Smith 47

MY COMMENT
My comments were a guess and probably rubbish (!) but in my defence they where made in the heat of the moment out of exasperation at:
- The fact that their metric radius gauges stop at 0.5mm whereas their imperial ones go down to 0.254mm
- The extreme difficulty in finding anyone who has them in stock, and able to supply the rapidly
- The lack of any keywords for which to search for a L-shaped gauge
... even if one is prepared to pay quite so much money... for what appears to be simple, easily manufactured piece of steel!

Also note that I did use the word "probably" (!)

LASER CUTTING
Re laser-cutting, I recently got some 1.4mm thick steel sheet cut for a dirt cheap price. I was told that the laser in question has a 0.3mm beam diameter, i.e. a radius of 0.15mm. They also firmly told me that "the cutting tolerances are ± 0.2mm", however this appears to be either just to cover themselves or (much like the Digital Chamfer Gauge discussions) in practice the majority of the errors in cutting are proportional to distance and so become more important for larger parts.

My parts were 32mm long and in practice the measured accuracy was +/- 0.02mm!

MY BEST GUESS
Tentatively, my best guess would be that they are cut out with CNC and then ground to exact size. But if making quite a lot of them, maybe they use a laser to do the bulk of the cutting and finish off with a CNC grinder? If making huge quantities (or if they started making them in pre laser-cutting days) maybe the punch them out and then grind them to precise size.

Yes, I did a digital sketch and multiplying by "1.7070789" does work (to within the accuracy of my drawing).
Out of interest, what is the equation for it? Where did it come from?

No, but nice try.

The trouble is that faces are at 90° to each other. i.e. The arc of the radius on the fillet is also only 90°, so it will be slightly hard to determine where or not the drill is fitting snugly into what is only a 90° corner.

All noted. It is of course a compromise.

While we are here, can anyone tell me how to convert a 45° chamfer measurement into a fillet arc (albeit one that assumes a 90° circular arc), in mm units if that's important?

I've been trying to work out if the geometry and whether there is a simple number I need to multiply the chamfer measurements by, or whether it's more complacted that that.

J

My apologies. You are of course correct. I had just come from a .co.uk website that turned out to be despatching from China(!), and I was also distracted by the Euro part of the ArcEurotrade, but mostly I mis-read their message.

Beyond that, to minimise any further duplication, please see the other thread for my response.

What I will put into this thread is a couple of photos of my new toy.

After zeroing, at full extension it looks like this:

And you will be please to know that after x10 full-scale openings & closings, it has returned to looking like this:


Quite dinky. Nice piece of kit.

JasonB - All reasonable points, however I reserve my right to stick to my budget of £15, in case none of them turn out to be particularly useful to me personally. 

Edited By John Smith 47 on 05/01/2022 11:23:39

Dear Robert, this is a free country and nobody is compelling to read this thread, so if this thread is not of interest to you personally, in the nicest possible way, please do not waste your precious life reading it.

All good points.

All I will add re quality is that about year or so ago, I bought some extremely expensive callipers from Starrett and I was NOT very impressed with the quality. From memory they had some sharp edges in the hand that one wouldn't expect at that price point, but worse, I had to adapt them to make them meet correctly.
==> Despite their high prices, not everything Starrett is of premium quality. 
 

Yes. I shall be assuming that my whatever 'non-circularities' each of my deburring wheels (I have 2 to choose between) are creating, is scaling at least roughly. And then I shall use my new Insize Chamfer Gage that was the fruit of the other thread to take multiple indicative measurements.

Quite dinky. Nice piece of kit. Returns to zero perfectly so far.

In the nicest possible way, the pass/fail criteria about a balance of complex competing ergonomic issues that would be too complex to go into here.

J

Edited By John Smith 47 on 05/01/2022 11:27:02

Back to the question.

I've thought about this and I'm not sure I'm ready to pay £30 for something that will be slightly irritating for the rest of time because it isn't metric.

Also, having never used them before, it may be that none of them turn out to be all that useful in the quite way I had anticipated. So, with the greatest respect, as per my original question I think I want to start with just buying
- just ONE gauge,
- metric,
- 0.5mm or less
- sub £15....

[Explanation: I only want it for checking the circularity of my fillets, as I now have that Insize "Digital Chamfer Gage", in my hands to measure sizes. ]

OK that IS embarrassing. I miss-read the direction of travel in their 01Jan message.
I am new to this game. Don't shoot me.
 

Edited By John Smith 47 on 05/01/2022 10:28:10

OK that IS embarrassing. I am new to this game. Don't shoot me.

JasonB & MichaelG.

Yes the smallest 3 Imperial gauges would be usable [Aside: how irritating that the the metric range don't go smaller - GRRR]

But as I said in the other thread... [see https://www.model-engineer.co.uk/forums/postings.asp?th=176298&p=5 **LINK** ]

...the crunch problem isn't just that £30.11 already blows my £15 budget out of the water, but on top of that, because ARC Eurotrade appears to be based on continental Europe, and since 01 Jan this year, this now means that we will be changed:

"On arrival of the parcel in your country, the postal service or courier will contact you to ask you to pay the import entry charge (usually between £6.00 to £15.00 equivalent in Euros), plus Duty (for goods above a certain value)... "

Plus distance of travel delays, plus customs delays...

For these reasons, already having been stung badly a couple of times, I no longer buy anything from Europe, EVER if there are any other alternatives.

Let's not get into politics, but Brexit is an extremely serious problem ​​​​​​for certain activities. ​

JasonB - Yup, I'm right behind you about fair remuneration for innovators. [deep sigh!]

Nicholas - Yes I am more than happy to pay for a well-made, useful piece of kit, and happy to pay rather over the odds for it, if it is innovative as well. But with the greatest respect, please can we just discuss my simple original question at the top of this thread?  

Conclusion:
Can anyone find something similar that (as per my original question) is UK-based?
I have looked quite hard but found nothing.
 

Edited By John Smith 47 on 05/01/2022 10:02:48

@JasonB - thanks.

Yes I did see that offering at ARC Eurotrade.

It's possibly worth a thought, although the set costs £30.11 PLUS ...

[Did you read the "New customs rules and charges for shipments to the EU from 1st January 2021" ?]

"On arrival of the parcel in your country, the postal service or courier will contact you to ask you to pay the import entry charge (usually between £6.00 to £15.00 equivalent in Euros), plus Duty (for goods above a certain value)... "

For these reasons I no longer buy ANYTHING from continental Europe.

I don't want to get into a political discussion, Brexit really is a disaster for certain activities.

J
 

Edited By John Smith 47 on 05/01/2022 09:33:23

PS Do any of you nice folks happen to have a promo code for starrett.co.uk?

Good spot!

Hmmm... let's be honest that is eye-wateringly expensive for a small simple piece of metal, that probably took about 20 seconds to be laser cut out of a sheet of metal!

Was I mad to originally think that I might potentially get several parts - possibly even an entire set, (if second-hand) - for that that sum?

Worse it's a full £22.99 if I want it next day... !

(...which I rather do & which I normally get from the idealogically bankrupt Amazon)


OK, MAYBE! But first I'm gonna have to think about this! And have another look at eBay...

j

Edited By John Smith 47 on 05/01/2022 08:49:01

Thank you. They don't seem to be quoting a price but I have clicked on the Enquire button.

Cheers

J

Nobody is compelling you to visit this thread.
If you have nothing constructive to add, please leave.

No. As I said on Page #1, that style of radius gauge is of no use to me because it does not have these features:

@Dave 2

> They use the same technology, so (for instance) the 200mm caliper is 0.01mm resolution,
> +-0.02mm accuracy, their 300mm caliper is 0.01mm resolution, +-0.03mm accuracy, and
> their 1000mm caliper is 0.01mm and +-0.07mm.

Yes, interesting stuff... however to my point, is that not exactly what you would expect if errors are proportional to the distance travelled by the sensor, no?

And if that is the case, then surely a smaller movement would imply smaller errors.


I know that my digital callipers have their theoretical limitations and are not doubt loathed by purists, BUT what I have been finding in practise (which for me is what counts!) is that reading my Vernier calipers, particularly when in read in sub-optimal lighting conditions, was either:
A) seriously slowing me up or
B) introducing serious reading errors or
C) sometimes both !

Yes you are absolutely correct about there being quite a lot of skill required in order to make accurate measurements. And my digital calipers are quick to scream at me in this regard! But readings are so quick that I generally measure each measurement at least 3 times to 'sanity check' each of my measurements.


Fwiw, yes I have an old x10 to x20 binocular dissection microscope which I sometimes use to see what's really going on! And occasionally this is extremely useful. The downside is that it can be rather difficult to get it into position.

Hello

Nice simple question: "Where in the UK can I buy a Starrett 167M-1/2 Radius Gauge, 0.5mm"

Constraints:
- Must be metric.
- No larger than 0.5mm
- Doesn't have to be the Starrett brand (e.g. Accusize, KRISTEEL Shinwa, is fine) but must be L-shaped (i.e. like the photo)
- Must be currently in stock and deliverable within 14 days
- Must be sold individually rather than part of a set (OR a total cost of less than £15)
- Does not need to be new

e.g.
==> Amazon are out of stock.
(https://www.amazon.co.uk/Starrett-167M-1-0-5MM-Individual-Radius/dp/B000VDVOE2)

And I can't find any other UK-based merchants who sell them individually.

REQUEST: Please don't answer any other question!

With thanks

J

> In which case the answer is to eyeball it, and seeing R0.1mm would need the aid of a loupe.
Yes.

> Finger tips are remarkably sensitive to tiny irregularities as well.
Yes, and that's the whole point.
Small deviations that the human eye can't really see unaided can make or break the user-interface of a product.

> From what you've said, your chamfer can be made as well as is needed without measuring it at all.
A prototype yes, absolutely.
But when specifying a product for someone else to manufacture... absolutely NOT.
If even in small scale production which could initially be done by hand, a loose specification could make or break the entire viability of the product.
Worse, the eventual larger-scale production would of course be done by robots, die pressing, tumbler machines and who knows what.

And really, that's the point, I need to specify the required output not the processes.

Re the Shadowgraph, as I have now said more than one, my some of my fillets are quite long and I have assumed that it would be extremely difficult measure the size of a fillet along the length of a longer fillet on a part. Obviously it would also be well beyond the budget of £100 or so, which I have also mentioned more than once.

Look, I know that all this is rapidly becoming TEDIOUS for most of the community here, but through all this endless questioning of my motives, you are compelling me to explain details that I had no intention of going into. These are details that are of no interest to the majority of this community, for which I get flamed if I ignore any contributor's questionings.

So back to my original question, I was just asking if anyone knew of any tools that would help me measure the radius of very small fillets, at a half-sensible (ideally sub £100) cost.

If you think that the answer is "no", then let's move on.