which tool to set up a piece to an angle?

[ariz]

I have to make the hole for the spark plug in the head of a little IC engine
the plans state that it is at an angle of 15 deg
this isn't so critical, so probably I could do it by eye

but the question remains: which is the correcty tool to use in such a case?

I have seen on ebay that there are at least 3 possibility:
1. an angle square, as a protractor or something alike
2. thiny angle blocks, sold in a box, with about 10 pieces, with 5, 10, 15, 20, 30, 45, 60 deg or so
3. the 0 - 60 ° adjustable angle block, made of 2 blocks, where the upper one slides on the other at the desired angle

what is the right one (because I cannot buy all them  )?
considering not only this particular job, but the possibility in the workshop generally speaking...



 

[Bernd]

airz,

If you want to get the head done right away then I would bolt it to a piece of aluminum and use a protractor set at 15 deg. and clamp the whole works in a vise.

If you like to make tooling I would build myself an angle plate.

If your not interested in making tooling and can't wait to get something then by all means purchase one of the your listed 3 possibilities.

Bernd

[Krown Kustoms]

Ariz, I use the protractor setup, block under one side of the work in the vise and clamp, but I have never needed to be exact with an angle.
I have been looking into the other 2 you sugested and have the same questions.
I dont think there is a correct way just a safe way.
Either way you do it just make sure it is clamped well.
I have followed your work in another forum, you do realy nice work. I look forward to seeing more.
-B-

[Jasonb]

I use one of the little digital angle meters, the base is magnetic so you can stick it to the workpiece or if nonferrous a bit of bar acts as a straightedge.

I bought mine some time ago from Wixey but there are a lot of other copies about now.

Jason

[mklotz]

Option 3:  Very coarse scale makes it difficult to set accurately.  I have one and hardly ever use it for just this reason.

For most work with simple, integer degree angles option 2 works best for me.

The problem with protractors is that they don't provide support for the work while the mill operation is carried out.  The option 2 blocks provide that support.

You neglected to mention option 4 - a sine bar.  If you need very precise and/or non-integer degree angles, a sine bar is the way to go.

Normally, folks think of sine bars as precision tools used with gage blocks to do setups and measurements and wouldn't risk using one to support a mill job.  While that's generally true, there's no reason to not use a cheap sine bar in the mill as an angular locator.  Forget the gage blocks in this application.  Set the stack height with a micrometer on an adjustable parallel.  Not metrology standards but plenty good enough for the vast majority of home shop jobs.

[ariz]

many thanks to all of you

fortunately I posted this question, and mklotz reply made possible for me to save some money: I wanted to buy the adjustable angle block (option 3) just because it appears beautiful to see, so shiny 

but now that I watch better, the marks of that scale are really coarse, the entire range confined in a small space

I haven't problems in making my own tools, instead I like it very much
but probably I'll go with option 2, a box of angle blocks. unfortunately I see them only in the USA, nobody in Europe sell them...

thank you again
 

[bogstandard]

With the little digi jobs, you have to be rather careful. the base isn't actually flat, but recessed in the middle, so for short parts, I mount it first onto a parallel, then set it up and use it. I think I mentioned them in a post I am working with, they are fine for run of the mill stuff, but because their lack of finer measuring are no use for critical working.

As Marv says, the sine bar is really the way to go if you want good support and accurate angles. Also, unlike what some people think, you don't have to be a genious to use one, if I can, anyone can.

In fact I had a cheapo 2.5" sine bar delivered yesterday, brand new, less than 6 squid (plus tax and post of course), and it is perfect for the rough and tumble of the workshop. Throw it away when it gets too battered, and then buy another.

http://www.mscjlindustrial.co.uk/SIMAY-10055C/product.html

Chronos sells the angle blocks

http://www.chronos.ltd.uk/cgi-local/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2echronos%2eltd%2euk%2facatalog%2findex%2ehtml%3fhttp%253A%2f%2fwww%2echronos%2eltd%2euk%2facatalog%2fcatalogbody%2ehtml%26CatalogBody&WD=block%20set%20angle&PN=Chronos_Catalogue_Squares___Rules___Angle_Gauges___Parallels___Other_Measuring_Tools_206%2ehtml%23a53666021#a53666021


John

[mklotz]

Worst comes to worst, you can make your own sine bar.

While it's convenient to have the distance between rolls a nice even number, like 2.5 or 5 inches, it isn't a requirement.  All that really matters is that the two rolls are parallel - something not too hard to achieve in the home shop equipped with a mill.

Once the rolls are installed, the distance between them can be found with the aid of any precision angle block (beg the use of one from a fellow hobbyist).  Put the angle block on the sine bar and jack up the sine bar with an adjustable parallel until the a  DTI swept across the angle block shows no movement.

Then:

theta = angle block angle
p = height of adjustable parallel
d = distance between rolls on sine bar

d = p/sin(theta)

Once you've calculated d, scribe its value into the bottom of the sine bar and use it to calculate the stack height needed for any angle you wish to set.

p = d * sin(desired angle)

[John Hill]

I had only heard a little of sine bars and had no knowledge until now,  scheesh they sure do look like a clumsy way of going about it?

[Yorkshireman]

I once needed to setup a piece in a rather funny angle in a tight space...
look here (in German, though)
http://www.dampfbahner.net/wbb2/thread.php?threadid=1347

Johannes

[bogstandard]

John,

As explained before, sine bars can be as difficult to use as you want to make them.

Stew and myself , yesterday, explained to Darren just how easy they are to use in a basic configuration without using slips, in less than a minute. I think we have a definite convert.

It is the slip gauges that put people off, mainly because of the very high cost. But with a mic and a bit of thin shim (or feeler gauges) for fine adjustment, you can easily find what is required about a normal workshop, and get yourself to spot on or near enough that it doesn't matter.


John

[Darren]

I had only heard a little of sine bars and had no knowledge until now,  scheesh they sure do look like a clumsy way of going about it?

From the descriptions I'd been told I thought the same John

But when Bogs stuck one in my hand yesterday and explained yet again the penny dropped.

I now believe them to be simple, effective and a sturdy way to set a piece at an angle.

[Darren]

John, maybe a link to the Workshop Calc would serve well here for anyone that finds this thread?

[bogstandard]

Darren,

When I get time, I will make up a little post to show how we explained it to you yesterday.

It will be a rough and ready method, not the purist way of doing it, but I think it would definitely help some of the newer machining members. Not only to help them understand how it works, but an easy method of getting accurate angles without too much cost involved.

John

[ariz]

well, I'm waiting for that post Bogs 

[spuddevans]

It will be a rough and ready method, not the purist way of doing it, but I think it would definitely help some of the newer machining members. Not only to help them understand how it works, but an easy method of getting accurate angles without too much cost involved.

Well I am really looking forward to that, I'm sure it would really help me to understand them.

Tim

[bogstandard]

Try here

http://madmodder.net/index.php?topic=2157.0


Bogs

[websterz]

Try here

http://madmodder.net/index.php?topic=2157.0


Bogs

Thanks Bogs. Something ELSE I have to buy/make for my shop.    j/k  Looks like a very handy gizmo!

Todd