The Shop > Tools
What kind of quality to expect for chinese "Precision" tools and stuff
PekkaNF:
You get what you pay for. I know. Sometimes you get more and sometimes less.
But when you buy a cheap tool or mesument contraption how much "accuracy" it is reeasonable to expect?
I would think that you have still right to stick to spec numbers, least to close to them...some roughness, lack of secondary functionality and finess is fine to me. What is fair and what is unreasonable?
Reason is that I bought this one:
http://www.banggood.com/Toolmaker-Precision-Micro-Adjustable-Angle-Block-Milling-Setup-p-1057240.html
Dent, ok it is annoying, but not functional...I don't care too much, but it is annoying because the piece had a dent (or it was sliced from bar and it was at very end....) and ground after it.
More serious to me is that the shor end is not straight in either plane. Error is about 0,1 mm.
I haven't checked it all around, height looks about fine and least zero angle fiducial line is at zero.
But if general description lets you know that the angle block is finished within 0,01 mm, is 0,1 mm reasonable at other direction?
Basically I'm asking for the price am I expecting too much?
Pekka
nrml:
I would ask for a refund. The Chinese auction sites are usually very good about refunding your money if you show clear photographic evidence that the product is defective.
sparky961:
So, this may be counter intuitive, but is it reasonable to expect that surface to be accurately perpendicular to the other? Is it part of the specification? Of course, you do expect that, as would I, but it doesn't necessarily make for an unusable or even "defective" tool. I suppose if you wanted to clamp it on the small end, it wouldn't work well. But it is much more likely that you're using the bottom as a reference. And don't even begin to think about using the scale for any kind of accurate work. You'd need to set the angle with something more precise anyway.
It makes me think of 1-2-3 blocks. I'm not sure how square the high quality ones are, but they aren't really meant to be. They are most often very accurate in size and parallelism, which is exactly as they should be. But I could probably get something more square by eye than by using a 1-2-3 block. Go for it, check out your cheap set...
It wouldn't take much on a surface grinder, if you had access to one, to finish off the Chinese "kit" tool and grind the surfaces in properly.
Think like a machinist, not a simple consumer.
PekkaNF:
Thank you for the answers.
That is part of the problem. How do you read description (spesification) that is not very good:
****
Toolmaker Precision Micro Adjustable Angle Block Milling Setup
Specification:
Material: steel, surface hardened to HRC58-62 °, nickel plated.
Dimensions (LxWxH) 75x25x32 MM
Angular Precision 10 'On Readable Nonius
Micro Adjustable 0 ° To 60 ° With Stop Scr
Uses: In the milling machine, planer, drill press with adjustable angle grinder and regulations on the knife, crossed with other fixtures or clamping the workpiece after the workpiece processing, such as processing slope, slant-hole drilling and the like.
Nickel plated, rust parallelism and verticality precision grinding of each working face to 0.01mm.
It can be a cursor indicates stepless tilt adjustment angle, and then be secured with screws, used to create a variety of fixed angle processing, testing of workpieces.
****
I'm tempted to claim that "rust is not parallel to verticality to 0,01 mm". :lol:
The example of 1-2-3 block is good. They would be completely useless if parallelism would be bad. And pretty near useless if they were not square.
With this V-bloc, the V- must be very true to all working planes and bottom surface. That is the must and I should have a look at it, but it looks fine.
However I don't think it would be reasonable to expect external working surfaces to be accurate to stated number (0,01 mm) unless otherwise mentioned. Bit like parallels....their opposite surfaces has to be parallel to great degree, ends have very little consequence, but you don't expect beaver bites there either.
My analogy would be here try square. What about if you think that you buy a flat square and one side is beveled unevenly? I'm not talking here hair line, but the case that other side of the square is square and other not.
Re. scales...I feel that scales must have more than entertaining values. There are bunch of DIN standards that pretty much states what accuracy scales should be each type of tool and accuracy glass. Here no DIN number were mentioned, but there is this statement "Angular Precision 10 'On Readable Nonius". I agree, it is not for measurement, but that should help the set up.
SwarfnStuff:
Pekka, I think an email to them with photos is well within your rights. Whether you ask for a refund or replacement would be a matter of choice.
Interestingly, I toddled off to fleabay and found many there ranging from $20 to $96 AUD and they all seem to be using the same product description claiming 10' accuracy. If my thinking and rusty math is correct (probably not) that is 0.166deg accuracy.
The tool also is supposed to be "precision", surely that implies a lack of dings, dents and poor workmanship so ask them to rectify.
As has been said, you could make it useful if milled flat and square to remove the dent, assuming there is enough material to do so. Refund plus a usable tool with a bit of work?
Back to my search, the $96 AUD one claims 10" accuracy so price and accuracy works there. Plus, it comes in a box. See link.
http://www.ebay.com.au/itm/4-x-1-3-16-Precision-ANGLE-BLOCK-Adjustable-Toolmaker-Gauge-0-60-Degree-/370841136414?hash=item5657daad1e:g:w~oAAOxyLchRx2FZ
Another at $35AUD had this note that has me confused but I post it for interest and pondering exercise,
"Note: Please allow 1-5mm errors due to manual measurement."
John B
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