Measuring tilt angles

[Chris TickTockParticipant @christicktock]

[Chris TickTockParticipant @christicktock]

Hi,

There seem to be many options to do this so no harm asking for what you guys use / recommend. Scenario you are told to mount a piece of metal at 15 degrees in the mill vice…which tool do you use. To date just been using an old school protractor but you can get stainless ones with attached straight edge also digital levelers etc?

Chris

[David George 1Participant @davidgeorge1]

Hi Chris.

How accurate do you need to be. I use a steel protractor with an adjustable rule for general use and have a few pieces of gauge plate with included angle on for better work but use a sine bar to accurately set pieces which must be right.

David

[Ady1Participant @ady1]

phone app, bubble level was good

https://play.google.com/store/apps/details?id=com.gamma.bubblelevel&hl=en_GB

[Nick WheelerParticipant @nickwheeler]

Digital bevel gauge does everything I need. Works on car suspension too.

[Dave HalfordParticipant @davehalford22513]

The digital ones are good comparators just check the bed then the work

[not done it yetParticipant @notdoneityet]

Is that 15, 15.0, 15.00 or 15.000 degrees. There is a difference, and method of measurement should undoubtedly reflect this. I actually tilt the vise if the angle measurement is not approximate. It may also depend on other factors, of course.

[Howard LewisParticipant @howardlewis46836]

You have a wide selection of methods.

A Digital angle gauge; a Digital Protractor; a Vernier protractor, a metal Protractor, with either a round or a square head, and Angle blocks.

Each has it's advantages and disadvantages. From time to time, I have used almost all of the above.

Choose whatever best suits: the work that you propose to do; and your budget.

Howard

[SillyOldDufferModerator @sillyoldduffer]

Posted by not done it yet on 13/08/2020 13:00:05:

Is that 15, 15.0, 15.00 or 15.000 degrees. There is a difference, and method of measurement should undoubtedly reflect this…

Examples always help:

• A decorative bevel along one edge of a plate need only be accurate to a degree or two, so a protractor is suitable. Mine can just about manage to get within ½°
• However, if the same bevel is carried completely around a rectangular plate, the edges have to be cut at almost exactly the same angle. It's because the human eye is good at spotting differences at corners, or in reflected light. Better than ½° accuracy is needed, and the angle has to be repeatable because the plate will have to be reset to do each edge, . A Wixey Digital Gauge is a reasonable choice because they manage about ±0.1° accuracy, roughly 5 times better than a protractor.
• However, when repeatable angles are involved, I prefer angle blocks to Wixeys because blocks are faster to use, about ten times more accurate, and less error-prone in use. A limitation of my angle set is the blocks can only be stacked in ¼° increments, so they're not a cure all.
• A Sine Bar with thickness gauge blocks allows any angle to be set with considerable accuracy. Useful when two parts have to be machined to meet precisely at a non-standard angle. Not had that challenge yet in my workshop with one exception – matching tapers.
• Tapers have to mate accurately and have inconvenient angles, for example MT3 is 1° 26' 16" ( ie a slope of 1 in 19.922 ) For tapers I reach for trigonometry. Basically the lathe's cross-slide is carefully angled to match accurately measured taper Length and Depth dimensions. Much the same technique can be used on a mill.

When milling my favourite angle tool is a Rotary Table. I also have a Swivel Angle Table, or grip work at an angle in the machine vice, or bolt it direct to the table with blocks to control the angle. My swivel angle table gets least use, but it's really handy for some jobs.

Dave

[Oily RagParticipant @oilyrag]

Swivel the table! and then check it with a gunlaying clinometer.

[David NobleParticipant @davidnoble71990]

Posted by Oily Rag on 13/08/2020 14:51:56:

Swivel the table! and then check it with a gunlaying clinometer.

David

[BazParticipant @baz89810]

All depends on the accuracy required, a cheap plastic protractor up to a sine bar.

[Gary WoodingParticipant @garywooding25363]

As others have said, it's really a question of what accuracy you're aiming at. A sine-bar and gauge blocks is probably the ultimate, but how accurate is base on which the sine-bar is referenced relative to the mill spindle? Pretty good results (to about 0.1&deg can be obtained with a digital gauge (Wixey?) that is zeroed on the mill table or vice, then used to position the workpiece. An error of 0.1° at an angle of 15° is equivalent to about a 6 thou error in the gauge blocks on a 4" sine-bar.

[Chris TickTockParticipant @christicktock]

Posted by Baz on 13/08/2020 15:18:23:

All depends on the accuracy required, a cheap plastic protractor up to a sine bar.

Funny you should mention a cheap protractor Baz, I have ordered in amongst a couple other items a zero edge one as this has some benefits.

Chris

[SillyOldDufferModerator @sillyoldduffer]

Posted by Gary Wooding on 13/08/2020 15:53:08:

…

An error of 0.1° at an angle of 15° is equivalent to about a 6 thou error in the gauge blocks on a 4" sine-bar.

Yes, but given a gauge set has tenths accuracy there's no excuse for making 6 thou errors with it!

Dave

[Enough!Participant @enough]

For"standard" angles I usually find a set of these makes it easy:

[Martin KyteParticipant @martinkyte99762]

I agree with Bandersnatch. The setting guages are the simplest solution to most set up's. I have never had to resort to anything more sophisticated. No doubt having said that I will now need to.

regards Martin

[Mark Gould 1Participant @markgould1]

Posted by Bandersnatch on 13/08/2020 17:26:37:

For"standard" angles I usually find a set of these makes it easy:

Good recommendation, I have the same set, very handy. Arc sell that set too, but for less

https://www.arceurotrade.co.uk/Catalogue/Measurement/Parallels-Angle-Blocks-Test-Bars/Precision-Angle-Block-Set-17pcs

Mark

[Chris TickTockParticipant @christicktock]

Posted by Mark Gould 1 on 13/08/2020 20:27:13:

Posted by Bandersnatch on 13/08/2020 17:26:37:

For"standard" angles I usually find a set of these makes it easy:

Good recommendation, I have the same set, very handy. Arc sell that set too, but for less

https://www.arceurotrade.co.uk/Catalogue/Measurement/Parallels-Angle-Blocks-Test-Bars/Precision-Angle-Block-Set-17pcs

Mark

On my list, many thanks

Chris

[Chris Evans 6Participant @chrisevans6]

Over the years I have made a set of angle setting "Wedges" from 1/4 degree to 50 degrees. for most work they are good enough. I do have 2" 3" and 5" sine bars but they are only used occasionally.

[mechman48Participant @mechman48]

Like others I have a couple of ways of setting angles; Stainless protractor with pivoting straight edge, Digi gauge, M & W protractor /rule, plastic protractor ( from school pack ). Using the digi gauge I always set the zero relative to the mill table. I have since made a set of angle gauges using trig' some previous write up a member had written up ( can't remember where   )     & checked relative to the Digi gauge, all within +/- 0.1* which is more than acceptable for my use. I would like a sine bar, but would I use it… probably once a year, if that . a couple pics of home made set …

 

George.

 

Edited By mechman48 on 14/08/2020 11:53:32… flippin smiley!

Edited By mechman48 on 14/08/2020 11:55:05

[SillyOldDufferModerator @sillyoldduffer]

Posted by mechman48 on 14/08/2020 11:52:46:

. I have since made a set of angle gauges using trig' some previous write up a member had written up ( can't remember where ) & checked relative to the Digi gauge, all within +/- 0.1* which is more than acceptable for my use.

…

Bad news: confirming George's angle gauges with that Digital Gauge is no cause for celebration! Good news: as there's no reason to doubt Mechman's craftsmanship, his gauges should be more accurate than that type of Digital Gauge. Although digital display precision is 0.1°, accuracy is more like ±0.2°, meaning home-made gauges should outperform the bought item. I'd bet money George's do!

Although it doesn't matter for many applications, a 0.1° angular error is non-precision. Some tasks are more demanding! Waiting for rescue mid-atlantic a 0.1° navigational error makes the search area about 1100 square kilometres. Could be a long cold swim…

Apart from tapers, tramming and other right-angles I can't think of any home-workshop jobs needing high-accuracy angles. What's the most accurate angle the team had to set, and why?

Dave

[Enough!Participant @enough]

Just noting that 0.1° amounts to .009" or .22mm over 5 inches – roughly the width of a vice.

(… if my trig is correct. I'm sure I'll find out if not).

[Oily RagParticipant @oilyrag]

Making a W20 toolholder for a 3" shell mill. The angle of the nose on the W20 is listed by Schaublin as 8 deg +/- 5' (i.e less than 0.1 degree) – the accuracy required is due to the shortness of the taper probably.

Set it up by milling a 4 degree taper on a 2" bar, then clamped it into the 4 jaw, making sure it was running true, set it 'square' with a T square off the bed of the lathe and then adjusted the compound slide by clocking back and forth along the taper to give less than 0.0001" run out.

Turned the taper, blued it and it fitted the socket with excellent marking.

As I mentioned in my earlier reply the angle was set on the mill by using the swivel table by reading off the scribed angle and gently adjusted by using a Munro made gunlaying double opposed bubble clinometer Recently calibrated to a level of confidence of 10" of arc. with accuracy at 4 degrees being recorded as +/- 'zero'.

Best single piece of kit I own!

[Author]

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