Camel(fish)back straight edge

[pressbrake1]

Did you see that one I sent you?

Yes thanks, tempted as it’s half the money a casting will cost

 

[Brad93]

Yes thanks, tempted as it’s half the money a casting will cost

Didn’t think of it that way.

It’s probably only 3 or 4 foot though isn’t it?

 

[Shox Dr]

50” parallel under wayView attachment 254257

Wow. How do you ensure it doesn't flex, or bow if not supported enough.

 

[Maker]

Presumably as it's a parallel not a straight edge, it would be fully supported by a machine table when it's in use?

 

[pressbrake1]

Wow. How do you ensure it doesn't flex, or bow if not supported enough.

Because it’s a very strong structure and cast iron doesn’t like to flex.
Everything is plastic but cast iron is one of the least plastic

 

[pressbrake1]

 

[Matthew Tinker]

Wow. How do you ensure it doesn't flex, or bow if not supported enough.

I doubt it will flex significantly more than a fish back, it's an "I" beam, probably heavier than a fish back. I have a 72inch one this shape that I checked on the diagonal of my 36"x36" surface plate, over 49" or 1.25m the sag was less than1/100mm, under 4/10 of a thou. for scraping a lathe bed, that's acceptable for me! By the way, my 72" straight edge weighs 40kgs!
Cheers, Matthew

 

[Brad93]

That’s not bad for cast aluminium 8 tenths over that length

 

[pressbrake1]

That’s not bad for cast aluminium 8 tenths over that length

Bearing in mind that’s machined not scraped!

 

[Brad93]

Bearing in mind that’s machined not scraped!

That is impressive.

 

[pressbrake1]

I doubt it will flex significantly more than a fish back, it's an "I" beam, probably heavier than a fish back. I have a 72inch one this shape that I checked on the diagonal of my 36"x36" surface plate, over 49" or 1.25m the sag was less than1/100mm, under 4/10 of a thou. for scraping a lathe bed, that's acceptable for me! By the way, my 72" straight edge weighs 40kgs!
Cheers, Matthew

There shouldn’t be sag as I’m guessing 49” support points should have been very close to the airy points.
40kg isn’t too bad my windley bros 72” fishback has got to be 70kg plus!

 

[Matthew Tinker]

There shouldn’t be sag as I’m guessing 49” support points should have been very close to the airy points.
40kg isn’t too bad my windley bros 72” fishback has got to be 70kg plus!

It's supported well outside the Airy points! I compared the difference between the straight edge lying flat on the surface plate and raised up at the extremities with blocks. 1/100mm is OK. I know the weight of my straight edge is 40kgs as it was weighed transport, it's a bear to wield single handed!

 

[pressbrake1]

Prototype squares

 

[pressbrake1]

18” and 30” which I sent to USA , gentleman posted pictures of them painted

 

[atomant48]

Prototype squares
View attachment 257334 View attachment 257335

What size are they ?

 

[pressbrake1]

What size are they ?

12/18” and 18/24

 

[pressbrake1]

Squares all fettled waiting for machining .
Foundry properly pulled my trousers down on these. There again they would be 1000s from Taft pierce or windley

 

[mike os]

sexy

 

[Shox Dr]

Very nice. I picked 2x 2’ high squares off ebay about 10yrs ago. He messed up and put £40 buy it now, instead of starting bid..

cast aluminium with a steel face with tee slot, so not as nice as yours. But easier to pickup

 

[Munkul]

Those are absolutely beautiful

Are they cost effective to sell, then? I couldn't justify it, I don't have the need... but someone surely will!