PDA

View Full Version : Squaring up



oldtiffie
05-11-2008, 07:37 AM
I thought it was about time I made myself some "master squares" and (re?)trued/squared-up my angle plates.

The master squares in a "Metrology" environment are precision ground cylinders that are round, straight and as parallel, with ground "faced-off" ends. They are as accurate as possible to very high orders or precision. When the ends are placed on a precision flat surface (ie Metrology standard surface plate) the cylinder is perpendicular/square to the surface plate to very high orders of accuracy. They are used to check other instruments and guages etc. for "squareness".

I needed some of these squares to face off my angle plates to assure/restore the faces as flat and square to each other as near as I could get it in my shop.

I started off with 2.30 meters of 3" OD x 1/4" wall thickness precision cold-drawn steel tube. Cost was AU$245.00 (~ US$230.00) which approximates to US$100.00 per metre ~ US$38.00 per foot. I thought the price was pretty good as they were "off-cuts/left-overs" etc. It was beautiful stuff to machine. It was within 0.02mm (0.0008") maximum indicated run-out any-where so it was good enough for me in my shop. I machined 4 pairs (8 squares) varying from just less than 3" long to just less than 9" long.

There are are 3 pairs in this pic. as one pair was on the mill. Note: the "brown stuff" is the preservative that I use (Lanolin-based) - magic stuff!!
http://i200.photobucket.com/albums/aa294/oldtiffie/Squaring-up/Squaring1.jpg

The HF-45 vertical column mill was correctly trammed. I used a 6-piece/toothed indexable TC cutter about 80mm diameter with 45 degree "lead" angle, "trailing scrapers" and about 10 degree positive rake running at 540 RPM and being fed at about 270mm (say 9") per minute. It ran beautifully. I "balanced" the cut so that the "Conventional" and "climb" milling components were about the same. I was able to climb-mill with ease with a light fast load and a heavy table etc. and a very good cutter. It ran beautifully!!.
http://i200.photobucket.com/albums/aa294/oldtiffie/Squaring-up/Squaring2.jpg

This is the set-up with the square tubes clamped to the mill table and the angle plate clamped to the tubes and resting on the mill table. This face was 9" x 8". It was as flat as ....................... .
http://i200.photobucket.com/albums/aa294/oldtiffie/Squaring-up/Squaring3.jpg

This pic is of the 8" x 6" face which when checked with a Class 1 square was "spot on" - no variation in the narrow beam of light at all!!
http://i200.photobucket.com/albums/aa294/oldtiffie/Squaring-up/Squaring4.jpg

The next 2 pics are of my smallest angle plate (3" x 3" x 2 1/2") using the smallest squared tubes and a "Kant-Twist" clamp.
http://i200.photobucket.com/albums/aa294/oldtiffie/Squaring-up/Squaring5.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Squaring-up/Squaring6.jpg

Those "Kant-Twist" clamps are invaluable in my shop as they are easy to use, powerful, sensitive, have copper jaws, screws and nuts and get into some very awkward places!! I use them on the welding and grinding as well as the mill and the surface and T&C grinders. I have 2 of each the whole set from 2" to 8". My "C"/"G" and similar clamps have not been used since I bought the "Kant-Twist" clamps!!

The ends of the angle plates were also milled and were as square to the faces of the angle plate as I could wish when checked against the Class 1 square.

The tubes were set up in the lathe with each end being set to a maximum TIR between highest and lowest being 0.02mm (0.0008") with maximum indicated differences between opposing jaws on my 4-jawed chuck of 0.01mm (0.0004").

I first tested them as pairs by putting them on my mill table (to show those without a surface plate that it is not always needed for even very good HSM shop accuracy). I put one against the other and rotated one each 90 degree and checked again. There was no discernible variation in the width of the narrow line of light. I inverted the same one and repeated the process - same result. I repeated the entire process for the other of the pair - same result. I then repeated the process for remaining 6 (3 pairs) of tubes - same result again. I also carried out a check with the Class 1 square - "spot on".

So I now knew that the ends were square to the axis of the cylinders.

The cutter performed faultlessly - excellent finish.

All of the angle plates were as I bought them. All were ground finish which I don't particularly like, as I prefer them to have a machined finish. A couple of faces were not as flat and/or as square as I'd have liked. Further, I had them for about 2 years and I guessed that they have had sufficient time to "cure" and "stress-relieve" themselves.

Using these "square-tubes" all but guarantees that the face clamped to them is at 90 degree to the mill/machine table. They are much better than an angle plate quite often as they can fit into small spaces. I have used them on mills, drills, slotters, shapers, grinders etc. They are very handy on a marking-out or surface plate as well. They are light weight, very robust, easily repaired.recovered and just store on their ends until needed.

The mill or grinder tables are excellent for use with the tubes as well as those tables have "T"-slots to clamp the tubes to the table/s. They work very well on a pedestal drill table or base as well.

I deliberately steered clear of using my surface or T&C grinders or from using the magnetic chucks as surface plates. I just wanted to show that very high orders of accuracy can be achieved in the HSM shop with just what is usually available. I am not sure that I would have done significantly better if I had used a surface plate and grinders.

I recalled using all of these processes to repair or recover angle plates and the making on the tubes/squares when I was an Apprentice and a Tradesman. It was all part of on-going machine and equipment maintenance in the shops.

DENedbalek
05-11-2008, 08:12 AM
Oldtiffie, your write up was / is very timely for me as I needed to make a couple of squares myself. Thanks for sharing.

Dwayne

deltaenterprizes
05-11-2008, 11:05 AM
Excellent method of insuring squareness easily available to a HSM from readily available materials.

lazlo
05-11-2008, 11:36 AM
Great post Tiffie. One suggestion: your post might be more visually appealing if you made those pictures inline (by wrapping them with ... ).

By the way, your surface finish looks great, but if you switch one of those SEHW inserts with a wiper insert, you can get a mirror-smooth surface finish (the wiper will "erase" the milling marks).

http://bbs.homeshopmachinist.net/showthread.php?t=26803

Cheers,

Robert

jimmstruk
05-11-2008, 11:51 AM
Very good post Tiffie, especialy after some of the other posts that did not make chips. JIM

Swarf&Sparks
05-11-2008, 12:01 PM
Mick, can I take it that this is similar to just turnin a dia in the 3 jaw, then facing?
That should get pretty damn near square within the limits of the lathe.
And the float glass which is my only surface reference.

oldtiffie
05-11-2008, 12:17 PM
Great post Tiffie. One suggestion: your post might be more visually appealing if you made those pictures inline (by wrapping them with ... ).

By the way, your surface finish looks great, but if you switch one of those SEHW inserts with a wiper insert, you can get a mirror-smooth surface finish (the wiper will "erase" the milling marks).

http://bbs.homeshopmachinist.net/showthread.php?t=26803

Cheers,

Robert

Thanks Robert.

I did think about "imaging" instead of "linking" those files but I had in mind the people with "dial-up" connections. I wanted to give them the option of "calling them up" or not. With 6 pics at a maximum of 4 pics per page it would have taken two pages.

Its too late now to change it to "images".

I will try to get some wiper inserts - thanks.

oldtiffie
05-11-2008, 12:27 PM
Mick, can I take it that this is similar to just turnin a dia in the 3 jaw, then facing?
That should get pretty damn near square within the limits of the lathe.
And the float glass which is my only surface reference.

Yep, that's so Lin - any size you like but it must be round and the same diameter through-out its length to within "tenths".

There is no need for any two tubes/squares to be the same diameter or length as each is a square on its own. Its just a matter of using any two squares.

As long as there is a hole through the centre for weight reduction and to pass the clamp stud/bolt/screw through.

The principal is the same irrespective of how you do it. I just wanted a tube that was sufficiently strong so as to not distort under lateral clamping loads - 1/4" wall-thickness was as I recalled it after 50 years!! Worked well. I milled with the majority of the load being directed towards the tubes/squares so as to minimise the "pull" on the clamps.

That sheet of float glass is an excellent reference flat surface and will do the job nicely - as will the table on your drill.