Thread: The Journey for a Master Square

I was almost going to mention something similar earlier Pete. I don't know anything about casting stresses, but all the square frame levels i have looked at are made like that, a circle inside the square. There must be a reason....

Originally Posted by Ueee

but all the square frame levels i have looked at are made like that, a circle inside the square.

Hi Ewan,
Got a picture?
The ones I have seen are pretty much a square inside a square. Like this one,


Though I did like this one.


How about it Josh?

I would have thought that regardless of shape.... IF it survived cooling, stress reliving would take care of any other issues. Maybe stress reliving before it cools would help? Looking at an engine block I wonder how they could cast then, of course they could have a couple of goes at it. Surly the foundary would say "well thats never going to work" if they thought they were going to have issues?? But then I wouldnt really have a clue and maybe they assume you know what you are doing?? Fun stuff this casting game.

Stuart

May provide some ideas

Parallels on Busch Precision, Inc.

The main considerations for the design for me in order of priority are: minimal weight for less 2 micron deviation of geometry with 1000N side load, 200x200x200mm size, able to not just measure but also transfer geometry ie: clamping space, simple to mould, ease of machining geometry and thermal stability.


I did few other designs design studies one of which was a circle in a square but the weight was higher than the + design for the same rigidity same went for the X and simple filleted box and a pitch circle kind of thing. Actually X was pretty close to the performance of the + design but the distortion was not uniform it introduced a wave in the faces under load which I did not like. The main problem I had with the "circle in the square"(the weight was not much more around a kilo from memory) was that it provided no easy way to clamp. And when using it as a spotting master you need to be able to clamp it to the surface plate or the wringing will drive you insane. Also need to be able to clamp to it with when used on a surface grinder to transfer it geometry onto the part. There were a few others that were a of various ribbed designs but that would have required cores that I ended up discarding because I thought they would be too complicated and hence too costly to mould.


The purpose of the hub is face to face rigidity and maintains parallel, it is also a handy place to have a handle to manurer it around being about the centre of rotation; as I would hate to drop one :S

Allowance has been made in the pattern for some distortion and rate of cooling problems (the "spokes" are a little thicker than I would have liked), but it is a balance between the processes and intended function. I think I have the balance just about right, but the only way to be sure is to get it cast. Failure is always an option but it is hard to see how it will fail so badly that it will end up being a useless artefact. The heat treatment oven is computer controlled and is capable of controlled ramps and I'm confident that I can remove enough of the residual stresses in the casting.

I'll also point out Taft Peirce honed in on the a similar design concept for their box parallels, maybe this is why they charge $2000 for each one.

-Josh

The ease of clamping with Josh's design is the thing I like, there are plenty of commercial examples of the same type of design.




Series 5100, 5200, 5300,5400, 5500, 5600 , 5800 parallels : box , cube , giant cube , planer/boring machine , 3 dimension, steel , manufactured by Busch Precision


The FEA Josh did, showed surface distortion under load with the diagonal bracing version, but less distortion in parallelism with the orthogonal bracing.

After arguing around for a day or so, the final version is pretty much what you see,

Regards
Ray

Originally Posted by Stustoys

Hi Ewan,
Got a picture?
The ones I have seen are pretty much a square inside a square. Like this one,


Though I did like this one.


How about it Josh?

I would have thought that regardless of shape.... IF it survived cooling, stress reliving would take care of any other issues. Maybe stress reliving before it cools would help? Looking at an engine block I wonder how they could cast then, of course they could have a couple of goes at it. Surly the foundary would say "well thats never going to work" if they thought they were going to have issues?? But then I wouldnt really have a clue and maybe they assume you know what you are doing?? Fun stuff this casting game.

Stuart

Oooo. I Like that second one, who makes that?

I would also assume that the foundry has a pretty good idea of what they are doing, and leave it in the mould long enough before knocking it out to allowing it to cool slower. I also assume that if it did not survive the initial cooling they would be able to cast another one with modifications to the moulding by adding chills and/or changing the ramming pressure.

-Josh

Originally Posted by .RC.

May provide some ideas

Parallels on Busch Precision, Inc.

I really like their hugs and kisses parallel.
a1065.png

Originally Posted by Brobdingnagian

I really like their hugs and kisses parallel.

lol


So glad I took the links out. I had to go find it again lol. turns out its a company thats been linked before.


Machine Checking Square Frame - Machine Checking Frame and C.I. Testing Bed And Floor Plate Supplier & Manufacturer from Indore, India


Nervermind Ewan, while searching for the above link I came across a couple of circles. Thought the second one is a circle so you can move the level.

Stuart

Originally Posted by Stustoys

lol


So glad I took the links out. I had to go find it again lol. turns out its a company thats been linked before.


Machine Checking Square Frame - Machine Checking Frame and C.I. Testing Bed And Floor Plate Supplier & Manufacturer from Indore, India


Nervermind Ewan, while searching for the above link I came across a couple of circles. Thought the second one is a circle so you can move the level.

Stuart

Thanks Stuart.

Christian and I have been swapping different 3d files back and forth until we managed to hit a combination that worked. We split the pattern into halves and then quarters. Here are a couple of pictures he sent me today of a quarter being machined. If I understand Christian right the first picture one actually is an 8th as the end mill is not quite long enough to do the full depth.


small_0004.JPG


small_0005.JPG

small_0007.JPG

small_0008.JPG

Great finish straight off the cutter, it hardly needs to be sanded at all.

-Josh

Originally Posted by Brobdingnagian

If I understand Christian right the first picture one actually is an 8th as the end mill is not quite long enough to do the full depth.

Took awhile but I got there in the end.

Great work guys.
Got the fire on Josh??

Little late to think of this now but how are you going to clean up the side of the Aluminium pattern? Lots of hand work?

How much over 200mm have you made it?

Stuart

That is looking great, gotta love CNC for patternmaking! To me the webs look chunky enough to not cause problems. Christian, I once left a little jelutong dust on the table... instant rust when the coolant hit it on the next job. Used Renshape ever since.
Neil

what renshape do you use?

Originally Posted by Stustoys

Took awhile but I got there in the end.

Great work guys.
Got the fire on Josh??

Little late to think of this now but how are you going to clean up the side of the Aluminium pattern? Lots of hand work?

How much over 200mm have you made it?

Stuart

Fire?

Varnamo shaper, but it has been said, that the wooden pattern has been a staple of the casting industry for years, I could get it cast many many times with just that.

I'll have to check but I think it is 10mm oversize.