Making Parallels

I am sure I have read in an old copy in MEW an article, or part of an article, about shop made parallels, but I can't find a reference in the search engine about this. Can anyone help me find it please. regards, Alan.

From Harold Halls index. Edition 13 page 34. Also edition 237 page 48.

I haven't checked if this info is correct though.

Steve.

Relating to the above, how parallel are new pieces of tool steel as used for lathe tools, as that is what I use, but never had any practical means of test them for accuracy. Never had any reason to complain as they seem to work OK for what I do.John

Hi Alan,

I have made parallels following Harold Hall's description, I just used mild steel but they have worked well. I assume that proper parallels ( hardened and ground) would have better accuracy, but my homemade ones have done the job so far. I also use races from old, dismantled ball bearings.

Thor

No idea John but I’ve been using a couple of pieces of ground flat stock cut from the same bar and that seems to work well.

**LINK**

All of our ground flat stock is supplied to the following standard tolerances:-

Thickness: +0.05mm/-0mm

Width: +0.2mm/-0mm

Length: +10mm/-0mm

An example.

No allegiance to this company but I have bought from them.

pgk

Does all that really matter? Even BDMS flats are good enough for most work. The actual width and thickness may typically be a a few thou down from nominal, but two pieces cut from the same bar are pretty unlikely to vary by more than a tenth or so. If you can't find any significant variation with - say - a Vernier mic reading tenths, it's likely to be good enough for almost anything.

Bearing races are useful but beware - they can have burrs on the edges. My mill table acquired a ring-shaped mark when I clamped something down on a race. The burr can be very faint and hard to feel but still mark as both the race and the table are very flat. Before using rub the face of the ring on a flat diamond lap or something similar.

I inherited a set of toolmaker made small parallels that are very useful. I think the thing that makes parallels expensive is not just that they are matched and parallel but also tightly controlled on size. Depending what you need them for the size may not be too important but they always need to be matched pretty well.

Mike

Thank you all for your responses. I am glad that my memory "remembered" that I had read .........!

I do not need high acuracy, just need to repeat the production. Thin parallels are very good, but I just a bit too thin for what i am doing.

Thanks again,

Alan.

I find what can be more useful (but more awkward to do) is to make a set of milling vice jaws that have a milled recess for a particular job. Seen lots of places do that.

Michael W

Sorry - wrong quote... someone had asked how parallel are new pieces of tool steel. Ground stock should be more than adequate. As you state bright flats are probably better tolerance than the average home shop mill can dust a vice width component to but errors on errors won't help.

pgk

+1 for using lathe tool steel

Old I laminations from a transformer.

Ian S C

Pieces of key steel work well as parallels too. They seem to measure up as parallel as far as I can tell with a standard .001" resolution mike. Comes in a handy range of sizes. I even have some little 1/8" square ones to use in the little Myford vertical slide vice, up to 3/4" square for bigger jobs clamped directly to teh cross slide etc.

And being made of slightly higher carbon steel than mild, and zinc plated, they seem reasonably durable and corrosion resistant. They seem to have more consistent sizing than HSS blanks too, which seem to vary a few thou from batch to batch or brand to brand.

Edited By Hopper on 15/06/2018 13:28:46

Tool steel (I assume you mean HSS blanks) are normally accurately parallel, but are not necessarily accurately sized.

In an old ME article Tom Walshaw (Tubal Cain) suggests taking a large ball race from a car hub, nicking it in several places on the grinder, wrapping in sacking and hitting it with a hammer to make some parallels

FYI, Have been & measured up the parallels mentioned above to give you some idea...



​As can be seen all are within .0005"... apart from the 1/8" pair where the difference is .0006"... close enough for my usage. Measured with Mitutoyo digi mic'... model # 293-766-10... accuracy to 0.0005" / 0.0127mm.

George.

Edited By mechman48 on 15/06/2018 17:48:27

A bit of a 'necropst' but the thread is still relevant and answers several of my questions. This post is pretty relevant.

There is one problem with the DIY approach and that is the need for a fair number of different pairs of stock to turn up in the limited selection I have in my shed. I already use two gash pairs and they are very handy but ti get work as deep as possible in the vise, I need more variety and that would mean ordering a number of different bits of stock - in steel - which could end up producing a lot of useless offcuts'

I sort of came to the conclusion that buying a set of cheap parallels is the easiest solution. But the problem is, I have the 'right' sized vise for my mill - the 80mm Versatile Milling Vise from ArcEuro (Which is very good for my purposes). The 80mm chuck width doesn't really suit the parallels that I can find on line. They are all more than 100mm long and I have already found that my Sealy mill is much tinier than its appearance suggests. The shorter axis means that things get in the way and an overhang of parallels gives no significant extra support.

So I am looking for some short ones (just a bit over 80mm. Can anyone point me at a supply? Anyone know of a source that's not Chronos, RDG, ArcEuro etc.? I guess there could be a far east s source but I don't know how to access it.

I'm surprised that such a useful item for miini Mill owners is not on eBay (not for me, anyway.