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Arc Precision Parallels - Which set?

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Mark Slatter17/01/2021 12:42:33
62 forum posts
7 photos

Hi all,

I'm trying to decide on which set from Arc to get, either the 14 piece set or 20 piece set. The 20 piece seems better value, and only slighter looser tolerances on the non-important dimensions.

Which would you go for?

Here's the link to Arc's page showing the parallel sets:

https://www.arceurotrade.co.uk/Catalogue/Measurement/Parallels-Angle-Blocks-Test-Bars

Any advice appreciated!

Edited By Mark Slatter on 17/01/2021 12:42:43

Edited By Mark Slatter on 17/01/2021 12:43:12

Brian H17/01/2021 12:50:47
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2032 forum posts
111 photos

I bought a set of the thin economy ones and found them to be perfectly adequate for workshop setups.

Brian

not done it yet17/01/2021 12:55:01
5596 forum posts
20 photos

They are (almost) entirely different sets? Choice is the set that most suits your machining needs.

‘How tall are your vise jaws?’ might be one consideration.

Henry Brown17/01/2021 13:01:24
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410 forum posts
92 photos

You need to consider how they will work with the size of your vise and the parts you are making if you are using them on a milling machine. Must admit I've always bought parallels second hand and often use matched bits of tool steel.

JasonB17/01/2021 13:03:52
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19902 forum posts
2169 photos
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As NDIY says you really want them to come to within 1mm of the top of your vice jaws so the 20pc metric set may be found wanting if you have a 6" vice. I have a wavey set and this is their biggest shortcoming when in my usual 100mm K4 vice, not so bad in the smaller 80mm universal

Myself I seem to manage OK with the imperial set, the large couple of pairs don't see that much use in the vice as too tall but do get the odd use.

SillyOldDuffer17/01/2021 13:39:39
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6861 forum posts
1538 photos

I've got the 20 piece set and jolly useful it is. It's a good match to my vice and the size of work I do. The main shortcoming is I occasionally need bigger than 100mm, and the other set would partly fill that gap.

I'm not the best example on the forum of good workshop practice but I use the set in various ways:

  • work holding when they happen to be just the right size.
  • accurate spacing, especially for lifting stuff parallel above the bottom of the vice,
  • checking my digital calipers haven't gone mad, tramming, and checking lathe and mill set-ups.
  • Measuring with a height gauge and improvised surface plate. (Not very often: I don't do castings.)

The 20 piece set meets almost all my precision requirements apart from angles. However, for general purpose work holding I've created a set of blocks and strips in various sizes from Bright Mild Steel stock. Over short distances BMS is dimensionally good. (Most of mine is anyway! Your mileage may vary.) Usually off-the-shelf finish, with some machining to size and tidy up as needed. Not as well made as Arc's economy set, but they cover the specific range of sizes I need. I made them as and when required rather than to a plan and now I have about 10, the need to make more has almost vanished. I started with home-made blocks and parallels and only bought a precision set when it became apparent why I needed them. Buying early wouldn't have been a waste of money - they are handy.

Dave

Ramon Wilson17/01/2021 13:40:31
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1032 forum posts
202 photos

Yes it depends on your vise size really.

Small thin parallels can be a bit of a pain if having to use several to make the height required but then again do have their uses. I have a fair mixture of pretty accurately ground ones I made myself at work but bought a set of ten, 6" long pairs, in the plastic box 1/8" thick and 1/2" to 2" wide.

Use them a lot, they are reasonably thin and for most part more than accurate enough for the machining I do. The only thing I did to improve them was to put a very slight radius on the four corners on the linisher and stone the grinding sharpness off the edges. Some are still in the paper covering but in my mind they were very good value for the price paid - unfortunately I see Arc are currently out of stock of these

Just bought a tilting vise from Arc along with a couple of other items - time from phone call to receipt less that 48 hrs - Brilliant service yes no, I don't have an interest - just very satisfied

Tug

martin perman17/01/2021 13:46:04
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1939 forum posts
81 photos
Posted by Brian H on 17/01/2021 12:50:47:

I bought a set of the thin economy ones and found them to be perfectly adequate for workshop setups.

Brian

+1 With Brian, they do what I need nicely.

Martin P

Mark Slatter17/01/2021 14:59:20
62 forum posts
7 photos

Thanks for the replies everyone much appreciated! Some good info to mull over.

Nicholas Farr17/01/2021 15:27:37
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2621 forum posts
1225 photos

Hi, I also have the thin economy one's as they are best suited to the width of my vices I have for my mini mill, as regards to how high they come, well to my mind I like to have as much work in the vice as possible, I have some taller and thicker ones that I made myself from a piece of scrap flat cast iron which can be used to hold thinner work at the top of the vice.

Regards Nick.

Ron Laden17/01/2021 15:38:34
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2124 forum posts
426 photos

I have the 4 pair economy set and the tallest pair sit 2.0 mm down from the top of the jaws of ARC,s 80mm versatile vice which I also have. I also quite often use 6, 8, 10 and 12mm pairs of square tool steel depending on the job and been able to fit them in.

Ron

Bill Phinn17/01/2021 17:15:38
443 forum posts
77 photos

When I first bought a set of parallels (the 20 pair set) I thought I probably wouldn't feel the need for further sets. But I did, more than once, and the needing is probably not yet over.

Yes, you can get by with a limited selection [they can, after all, be stacked one on top of another if necessary, and you can always make supplements yourself], but the more parallels you have, the quicker and more convenient it becomes to achieve all of those random and unique set-ups life throws in your way.

What would be a useful supplement to the Arc range is a set of very thin ones, viz around 1/16" thick. When you're drilling right through a small part close to its edge I find it's preferable not to have to remove the parallels before drilling, especially if you're drilling multiple parts the same. Of course, the swarf gutter in most vices won't allow you to put your thin parallel right at the bottom against the fixed jaw, but once you're accustomed to stacking that's easily solved.

Douglas Johnston17/01/2021 18:23:36
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728 forum posts
34 photos
Posted by Bill Phinn on 17/01/2021 17:15:38:

What would be a useful supplement to the Arc range is a set of very thin ones, viz around 1/16" thick. When you're drilling right through a small part close to its edge I find it's preferable not to have to remove the parallels before drilling, especially if you're drilling multiple parts the same. Of course, the swarf gutter in most vices won't allow you to put your thin parallel right at the bottom against the fixed jaw, but once you're accustomed to stacking that's easily solved.

one way to get a cheap set of thin parallels is to cut up a steel ruler into short lengths. I used a 24" stainless steel one from the pound shop and made up a small set using a thin cut off abrasive disc. A carbide cutter in the mill was used to bring the height of the parallels to the value needed..

Doug

John Hinkley17/01/2021 18:40:13
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1028 forum posts
346 photos

Another way is to do what was suggested in MEW issue 292 page 20, under "Reader's Tips". That is to say, utilise a set of old/cheap/broken calipers and cut the scale in half. I remembered that I had a redundant Aldi digital caliper in my spares box and duly modified it with a Dremel cut-off disc. Only took a couple of minutes and Hey Presto! - two perfectly serviceable, thin (and pretty accurate) parallels. It's been very useful on many occasions since.

John

And no, it wasn't my tip!

Edited By John Hinkley on 17/01/2021 18:41:36

Roger Best17/01/2021 19:24:49
215 forum posts
31 photos

Thanks for the question and comments.

I was looking at sets for Christmas but gave up, i couldn't imagine what I wanted all those bits for and how I would want to set up parts and I don't want to "invest" in stuff that takes up space for a few decades.

I did note that pairs of parallels are readily available and sets are not a massive discount relative to buying pairs, so I decided to wait until I had some jobs identified.

One good tip on Blondihacks was using a long precision bar to set up the vice. So I guess I need at least one pair.

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