Cast Iron Straight Edge

[Pete.Participant @pete-2]

Hi, does anyone know where you can buy cast straight edges, for the purpose of printing dye on to ways for scraping?

I found some companies selling them in India and China, but no retailers in the UK whatsoever.

[Pete.Participant @pete-2]

Retailer of cast Iron straight edge

[Pete RimmerParticipant @peterimmer30576]

Don't know of any new finished ones in the UK. There's a guy in the South West sells the odd casting for 12" dovetail straight edges and they are nice to scrape in but you'll have to machine all the working faces first.

Kblast straight edge

Other than that you can buy King castings off eBay but they also need machining, perhaps stress-relieving and then scraping to finish before you can call them good to use. You're looking at 400 quid for an un-machined casting, plus import and vat most likely.

Used ones are very thin on the ground.

[Speedy Builder5Participant @speedybuilder5]

I don't know how accurate these would be ??
**LINK**

[Brian OldfordParticipant @brianoldford70365]

PMed

[Ketan SwaliParticipant @ketanswali79440]

Try Ian at Rotagrip.

Ketan at ARC

[Nigel McBurney 1Participant @nigelmcburney1]

Better to get an old English made straight ,where the castings were allowed to "weather" to relieve the internal stress and were often rough machined and then left to stand for some time before final finishing,Using new "green" castings is not a good idea,Try the second hand tool dealers.

[Pete CordellParticipant @petecordell95786]

If you have deep pockets and long arms this guy has them

Edited By Pete Cordell on 21/01/2019 11:41:54

[SillyOldDufferModerator @sillyoldduffer]

Posted by Nigel McBurney 1 on 21/01/2019 10:03:21:

Better to get an old English made straight ,where the castings were allowed to "weather" to relieve the internal stress and were often rough machined and then left to stand for some time before final finishing,Using new "green" castings is not a good idea,Try the second hand tool dealers.

The need to weather cast-iron castings means the maker is using the wrong type of cast-iron! Cast-irons that don't need to be allowed to de-stress were developed in the USA during the 1920s and were widely used in Europe before WW2. (Meehanite etc).

Craftsmen often see weathering as a sign of care and quality; on the other hand it gives accountants and shareholders apoplexy! A hundred years ago it was costly to store items for months before they could be finished and sold. These days it's disproportionally even more expensive. I think a Production Manager would look carefully before agreeing to any process that made untoward weathering essential.

Of course, a big advantage of buying an old tool in good condition is that you know it isn't going to warp! Quite a lot of cast-iron is carp and for things like weights and street furniture it doesn't matter. With new cast-iron there's always the possibility of buying from a cowboy. A small foundry making small tools as a sideline might not bother with using the right alloy or weathering.

Dave

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[SillyOldDufferModerator @sillyoldduffer]

Posted by Barrie Lever on 21/01/2019 16:38:09:

SillyOldDuffer

BMW used aged crankcase castings in their first Formula 1 turbo engine in the early 80's and a mighty powerful engine it was as well.

The aging was acheived by using crankcases from road car engines that had completed at least 100,000 Km, these were then modified to the specification required for the F1 engine.

To be clear these were cast iron crankcases.

Regards

Barrie

Hi Barrie,

That's interesting. Do you happen to know why they did that? It seems an extreme way of eliminating warping. Presumably the advantage was that old crankcases have been put through a huge number of heat cycles between ambient and hot over a long time. Racing being extreme perhaps the idea was to select crankcases with absolutely no tendency to warp in an extra hot engine run flat out.

However, I stand by my comments about Production Managers – what's done to a Formula 1 engine isn't typical value engineering!

By the by, I'm not familiar with the reasoning behind Formula 1 engine design especially as it's changed over the years. Mostly I expect them to be using exotic materials for triple-extra go-faster performance and then discover the rules don't allow it! Can anyone explain what the state of the art for high-performance engines is, and what's allowed on the track?

Dave

[Nick WheelerParticipant @nickwheeler]

Posted by Barrie Lever on 21/01/2019 16:38:09:

BMW used aged crankcase castings in their first Formula 1 turbo engine in the early 80's and a mighty powerful engine it was as well.

The aging was acheived by using crankcases from road car engines that had completed at least 100,000 Km, these were then modified to the specification required for the F1 engine.

To be clear these were cast iron crankcases.

They were using a very old design of engine!

[Martin Harris 9Participant @martinharris9]

I recall being told that good blocks from high mileage van engines were much sought after for building Top Fuel and Funny Car drag racing engines.

[Michael GilliganParticipant @michaelgilligan61133]

A reasonably lucid account of the BMW story, here: **LINK**

https://f30.bimmerpost.com/forums/showthread.php?t=1350137

MichaelG.

Edited By Michael Gilligan on 21/01/2019 18:08:50

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[Martin ConnellyParticipant @martinconnelly55370]

There are a couple of scraping straight edges on ebay at the moment.

Martin C

[Neil WyattModerator @neilwyatt]

Posted by SillyOldDuffer on 21/01/2019 17:10:05:

Posted by Barrie Lever on 21/01/2019 16:38:09:

BMW used aged crankcase castings in their first Formula 1 turbo engine in the early 80's and a mighty powerful engine it was as well.

Do you happen to know why they did that?

Maybe BMW engine castings are of poor quality

Neil

[Pete RimmerParticipant @peterimmer30576]

Raw straight edge castings need stress relieving. The HKA-x ones you see on ebay are King design and the finished ones they used to sell were stress relieved, rough-machined, stress relieved, machined then scraped, sometimes with a third round of stress relief thrown in. The ebay ones have one round of stress relief and are said to require no more but it's still possible they would move during machining.

Even old, previously-finished straight edges can develop a twist over time. I bought a 36" one which looked pretty good but had about half a thou of twist in it.

[Brian OldfordParticipant @brianoldford70365]

Deleted

 

Edited By Brian Oldford on 21/01/2019 21:44:06

[Pete.Participant @pete-2]

Posted by Pete Rimmer on 21/01/2019 01:21:37:

Don't know of any new finished ones in the UK. There's a guy in the South West sells the odd casting for 12" dovetail straight edges and they are nice to scrape in but you'll have to machine all the working faces first.

Kblast straight edge

Other than that you can buy King castings off eBay but they also need machining, perhaps stress-relieving and then scraping to finish before you can call them good to use. You're looking at 400 quid for an un-machined casting, plus import and vat most likely.

Used ones are very thin on the ground.

Thanks, the one in that link looks like what I'm after, do you know this seller?

[Pete.Participant @pete-2]

Posted by Pete Rimmer on 21/01/2019 20:48:13:

Raw straight edge castings need stress relieving. The HKA-x ones you see on ebay are King design and the finished ones they used to sell were stress relieved, rough-machined, stress relieved, machined then scraped, sometimes with a third round of stress relief thrown in. The ebay ones have one round of stress relief and are said to require no more but it's still possible they would move during machining.

Even old, previously-finished straight edges can develop a twist over time. I bought a 36" one which looked pretty good but had about half a thou of twist in it.

So what is the process of 'stress relieving'? I was under the impression it was the casting being left for a period of time? you mention several rounds of stress relieving? what is involved in this?

Cheers.

[Pete RimmerParticipant @peterimmer30576]

Parts are heated in a stress-relieveing oven to a specified temperature over a specified time period then controlled cooling. Any good heat treatment place will do it.

[larry phelan 1Participant @larryphelan1]

My spindle moulder came from a "Well known and respected" maker,brand new.

First time I used it,I found that the two fences were not in line with each other. This was due to the horseshoe casting being faulty. I believe that this was due to stresses which were not released because it was not left long enough to "weather". It seems this is no longer done,for cost reasons,I suppose.

Returning it to the makers was not an option,due to cost,so I took it to a local machine shop to have the faces ground true. I was told that there was quite an error,most likely caused by the casting being machined while too fresh. The unit did not strike me as being a very good design,since it went from fairly thick sections to very thin ones,not a good idea ! I was advised to "keep an eye on it" since it might go off a little more later on,but if it does,bring it back and we will skim it for you" Fair deal !

They said castings are treated using "New methods",which dont always work,they believed the old way was better.

[BazyleParticipant @bazyle]

A good observation by Larry above about the design going from thick to thin and the designer not realising that might be a problem. I think we will see more of this as companies rush out designs by the youngest (cheapest) graduates who can knock out impressive CAD renderings but have no experience.

[JasonBModerator @jasonb]

But then again they can probably click a button and much like FEA get a computer simulation of how a part may move.

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