magnetic cylindrical square

[markgray]

Here is another item that arrived from Shipito last week. We have discussed techniques of how to determine if sometime is square or a surface is at 90 degrees to another. This square provides another means to do this. I want to use it to test some precision scraped angle plates and squares that I have. The magnetic cylinder squares come in different sizes. I have seen them as small as a 1 inch base with a 3 inch stem to ones with a 6 inch base and 12 inch plus stem. This particular one has a 3 inch base and 6 inch stem.

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[morrisman]

That's a neat device . I guess it would be more accurate than Harold Hall's home made cylindrical square

Would the large base on it be a problem if you want to align a angle plate on a milling table for example ? Or if you want to set the cylinder right up against a work piece , the base might get in the way .

[markgray]

Would the large base on it be a problem if you want to align a angle plate on a milling table for example ? Or if you want to set the cylinder right up against a work piece , the base might get in the way .[/QUOTE]



Hi,

You can buy them without a base if required. These models generally have an on/off knob on the end.


https://www.penntoolco.com/catalog/p...ategoryID=4852

https://www.penntoolco.com/catalog/p...ategoryID=4273

[rogerbaker]

Hi Guys
Gudgeon pins from truck pistons make good cylindrical squares.

Roger

[.RC.]

If used horizontally and chasing high precision, you may have to compensate for gravity... It will droop..

[markgray]

If used horizontally and chasing high precision, you may have to compensate for gravity... It will droop..

Hi Richard,

The stems are hollow to try and reduce this to a minimum but you are right. But in practical terms this is generally not something you have to compensate for at our level of precision. Having said that do you ( or anyone else) have any equations to calculate the droop on a 6 inch hollow tube so we can put it into context ( I am assuming we are talking way less than a tenth in this case but that is purely a guess).

Mark

[Techo1]

Hi Guys
Gudgeon pins from truck pistons make good cylindrical squares.

Roger

Only if you can grind and lap the ends dead square to the axis.

[.RC.]

Hi Richard,

The stems are hollow to try and reduce this to a minimum but you are right. But in practical terms this is generally not something you have to compensate for at our level of precision. Having said that do you ( or anyone else) have any equations to calculate the droop on a 6 inch hollow tube so we can put it into context ( I am assuming we are talking way less than a tenth in this case but that is purely a guess).

Mark

Attached picture of the formula... You need to calculate the moment of Inertia for a hollow section... The example shown is for solid circular material.. Online calculator for that is here http://www.engineeringtoolbox.com/pi...as-d_1335.html

Shaft deflection.jpg

[markgray]

[QUOTE=.RC.;1829652]Attached picture of the formula... You need to calculate the moment of Inertia for a hollow section... The example shown is for solid circular material.. Online calculator for that is here http://www.engineeringtoolbox.com/pi...as-d_1335.html

Wow I glad thats not too complicated

Given that 1 3/4" steel sticking out 15 inches only deflects 5 tenths at the end I am assuming that 1 inch hollow section sticking out 6 inches is probably less than my capacity to measure. Anyone care to try and work it out?

Mark

[.RC.]

What is the ID and OD?

[markgray]

What is the ID and OD?

Richard the OD is 1" and the inside diameter is 3/4" with the overall stem length of 6". I presume the material is a medium carbon steel as it seems to have been hardened but that should not make any real difference. I'll try and work through the figures as well and we can see if the end result matches.

Mark

[markgray]

Richard the OD is 1" and the inside diameter is 3/4" with the overall stem length of 6". I presume the material is a medium carbon steel as it seems to have been hardened but that should not make any real difference. I'll try and work through the figures as well and we can see if the end result matches.

Mark

My result came in at 0.00020 so 2 tenths which is more than I was expecting unless I have misplaced a decimal point or stuffed it in some other way. Its been a long time since I have done any maths. I'll see what others get!!

Mark

[Stustoys]

Just to be sure. Is it 3/4" all the way?

And while we are down in the truly teeny tiny. If your are clocking said bar, wouldn't you be better off clocking the bottom than the top?(granted this is likely to be theoretical at best, possibly much worse lol)

Stuart

[markgray]

Just to be sure. Is it 3/4" all the way?

And while we are down in the truly teeny tiny. If your are clocking said bar, wouldn't you be better off clocking the bottom than the top?(granted this is likely to be theoretical at best, possibly much worse lol)

Stuart

Yep its hollow to the base. I always fine it more difficult to measure underneath as you just can't see as well but we are now splitting hairs (literally as the calculated amount is a tenth of the width of a hair!!)

[Oldneweng]

Richard the OD is 1" and the inside diameter is 3/4" with the overall stem length of 6". I presume the material is a medium carbon steel as it seems to have been hardened but that should not make any real difference. I'll try and work through the figures as well and we can see if the end result matches.

Mark

It seems to me that the type of steel would make a difference. I am thinking of the comparison between spring wire and soft wire. Is this a relevant comparison?

Dean