The wavy ones work well under thin work because they can be compressed somewhat. A pair of straight ones is what I use under work that is wide enough to accommodate a pair of straight parallels.

Thor

I favour the usual straight ones.

I've got quite a pile (in excess of 300!)of slip gauges that have failed calibration for precision use.

Jim

Always use the rigid ones.

Not confident that a wavy one, capable of being compressed would maintain parallelism

Howard

I have a Chinese mill and a Chinese vice. None of them is really accurate. So I made parallels on the mill from mild steel. Marked a corner so that I can place them the same way they are made.

Now I have a reasonably accurate result, most of the time within 0.02 mm. When I damage a parallel, I just mill the top flat again.
Noway I can achieve the same or better accuracy with accurately ground parallels.

In time, when I have a new milling machine, I (maybe) will adjust the vices using a pair of 123 block.

ARC ones are all 150mm x 5 x incremnt.

Warco are smaller at 100mm long and only go upto 24mm tall which woyld leave you a bit short if wanting to hold shallow work in say a 100mm vice as the jaws on them are typically 38mm high.

Wouldn't surprise me if they were identical from the same factory, or from different continents. Parallels aren't difficult to make and they're not protected by a patent. Anyone can produce them. Though I own a set for convenience, I've milled a few of my own to get just the right size.

My bought set were made on a grinding machine. These are very common in industry worldwide, and accurate when adjusted correctly. However:

• An out of adjustment machine could churn out a faulty batch before the operator re-sets it
• A business trying to earn a crust from worn-out equipment on it's last legs might be knocking them out cheap or as fakes
• Manufacturing rejects turn up in the market as 'bargains'
• Unless extra is paid for certificated accuracy, it's unlikely that parallels will be inspected individually.

For this class of item, it's cheaper for everyone to let the customer to detect errors and let the retailer refund or replace. Refund/replace is always a nuisance, extra difficult if the seller is abroad, and the system breaks if the customer buys from a dodgy supplier.

It also winds customers up, particularly those convinced inexpensive tools should be just as good as their top-of-the-range equivalents. In the real world, the cost difference can't be ignored: there's a reason top-of-the-range tools are expensive. It's the cost of ensuring they really do meet a specification, so a 'time is money' customer doesn't waste time sorting out even a percentage of iffy tools.

My set happened to come from Warco, and all the parallels are correct. I didn't expect Warco to guarantee the set would be acceptable on delivery, but I bought confident that they would replace or refund if there was a problem. And in practice, buying from Warco, only one purchase has ever gone wrong, and they replaced the item. Arc Euro have never fouled up, I think because Ketan knows his stuff and puts extra care into purchasing. I don't expect perfection from ArcEuro either, but in the event a dud arrived I'm sure they would refund or replace. Tracy Tools haven't dropped the ball yet either. I've bought successfully from several other UK vendors, but not often enough to find out how well they perform when a purchase goes wrong!

My experience at Shows and buying cheap off the internet has been less happy. Internet 'bargains' I see as a gamble, and I usually win. No tears if the 'bargain' turns out to be anything but, I knew it was a risk.

All my worst junk came from shows. At these, the distance buying regulations don't apply because purchasers can check the actual item. For example, I bought a box of cheap carbide inserts and found later they were rejects. Not a complete waste of money because they all had at least one correct edge, but I kicked myself! My fault – the box had a clear plastic lid, and all I had to do was look.

There's no law that show bought stuff is always rubbish, my best bargain purchases all came from shows. And this is true of all purchases, the buyer always has to apply due diligence and manage expectations.

Dave

Edited By SillyOldDuffer on 15/05/2023 08:55:17

I use pairs of HSS tool blanks as parallels. Providing you use them the same way up using the angled ends as a guide, I cannot measure any difference between the various pairs. I have a selection, ranging from 5mm up to 10mm.

I don't tend to make stuff for NASA , so these are good enough for me.

Sometimes the only important feature of a parallel is that it is parallel and it has a matched pair. Other times the dimension is important as well, perhaps setting up work on a surface table for marking out will require accurate parallelism and dimension.

Mike

Me too. I don't have a mill but for milling in the lathe on the vertical slide and for drilling on my drill press I often use HSS blanks as parallels.The little 1/8" ones are ideal for the tiny Myford milling vice, and can be stacked if needed.

I also often use pieces of key steel as parallels. It comes precision machined to size, square and parallel so ideal. And in a pinch you can drill or mill right through into it as a sacrificial parallel. Available from bearing suppliers. And it comes zinc plated too so never rusts.

I suppose it's heresy but I just use plain old bright mild steel. I doubt if the rest of my mill, vice etc is good enough to warrant super precision. If you always use two bits cut from the same length they are pretty good.