Casting a straight edge

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Harold_V
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Casting a straight edge

Post by Harold_V »

Talk about taking the long way around things!
Some time ago I purchased a B&S 6" x 18" surface grinder off eBay. The machine was equipped with a radius dresser and rapid traverse for the wheel head, which, on a surface grinder, is a very welcome feature, as the feed on the head is exceedingly fine (for high precision). The price was right, including shipping from the east coast. However, the grinder had issues that I didn't expect.

It had been taken out of service and was sold by a machine tool dealer in Pennsylvania. Fortunately for me, they hadn't removed any of the maintenance documents from the machine that had been kept in the electrical cabinet, so I contacted the original owners who were more than cooperative, sending me the missing manual and the custom wrenches that are a part of the operation of the machine. In addition, they included a couple dozen wheel hubs, which didn't fit the B&S but are a fit for my #2 Cincinnati cutter grinder. These folks were exceedingly generous, not only with their time, but they wouldn't accept payment for shipping. A win/win situation in pretty much every way.

Down to the problem.

When I tried operating the machine, the wheel head tilted as it advanced. That was mystifying until I dismantled the machine and discovered that the hydraulic cylinder had been attached improperly. Remedy? Simply realign the attachment point, which is made adjustable for obvious reasons.

One of the things that was not obvious (because I couldn't do any grinding) was that the ways for the table are not parallel. They're out by .005" over 32", which renders the machine relatively valueless as is. I can't help but think that the machine was worked on by someone who had no knowledge, or it was sabotaged so a new machine could be provided. My intention is to make the correction by scraping the flat, although I hope to touch up the V as well, depending on what I discover once I have a straight edge at my disposal.

The general condition of the machine is acceptable, so I deem it worthy of spending my time trying to get it operational, and in keeping with my work ethic, I tend to do everything myself. It's a way of me expressing my ability on the machines, and it's a great way to keep me active (I'm now 83). I had intended to build a model steam locomotive, but the time spent building our house and shop was far greater than I had anticipated, so I don't see that happening. Doesn't mean I won't eventually try, but more so for the experience of making castings that are not, nor have they ever been, available. What better way for an old guy to spend his time in the shop, which has proven to be a good reason to get out of bed each morning.

I have made a pattern for casting a straight edge that will suit my requirements for the flats of the grinder. Fact is, I should be able to use it for the V way as well.

I have almost no experience with casting. What little I've done has been plagued with issues that I must overcome. I understand the need for risers, often referenced as feeders, to prevent shrinkage. That is my quandary. Gray iron of a given chemistry is known to cast without shrinkage, but I don't have the capability of analysing my heats, and the brake rotors I use for feed stock appear to create shrink areas if not properly risered.

Anyone here have any thoughts on how this should be gated and risered? I welcome any input, especially from someone who has some practical experience in pouring iron.

The pattern will be mounted on a board, along with the runner gates.

H
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Andy R
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Location: So. Calif.

Re: Casting a straight edge

Post by Andy R »

Harold,

You wrote:
"I had intended to build a model steam locomotive..."

Why not start?
You will enjoy it. And who knows? You might finish it too.

Sorry about not being helpful about the gating question ... Hopefully somebody knows.
Regards,
Andy
Harold_V
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Re: Casting a straight edge

Post by Harold_V »

Andy R wrote: Tue Nov 01, 2022 7:06 pm Why not start?
I plan to, Andy, but before I can, I want my shop to be fully operational, and that's what I'm spending my time on right now.

Years ago I decided I'd build a model of UP's 833 in 1.6" scale, the prototype having been on display in Pioneer Park in Salt Lake City. I like large engines and that one was readily available. Now, of course, it is no longer on display in Pioneer Park, nor am I a resident of Utah, so that doesn't really matter, but I'm still fixated on that engine, especially the boxpok wheels, which have never been faithfully modeled. I can see how they can be, so if I get the shop finished and still have the ambition, my first project will be patterns for the boxpok wheels. I see them as a huge challenge, one I'd enjoy conquering.

Thanks for your comments, Andy.

H
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K. Browers
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Re: Casting a straight edge

Post by K. Browers »

Hello friends
This night come in handy. casting the way the hobbyist does it is old school really old school so here is an old book.. :D

https://archive.org/details/generalfoun ... ?q=foundry

cheers Karel
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rmac
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Re: Casting a straight edge

Post by rmac »

Unfortunately, no help from here regarding the casting process, but I do have a general question. Once a blank is cast and cleaned up, how do you make sure it is really straight?

I've heard of a procedure whereby three blanks are lapped against each other in a particular sequence that renders them all perfectly straight after some time. Is that what you're planning? Or do you have somebody grind them straight somehow? Or ... ???

-- Russell Mac
rrnut-2
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Re: Casting a straight edge

Post by rrnut-2 »

Watch Vintage Machine (Keith Rucker) on You Tube on making straight edges straight.

Jim B
Harold_V
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Re: Casting a straight edge

Post by Harold_V »

rmac wrote: Wed Nov 02, 2022 10:56 am Unfortunately, no help from here regarding the casting process, but I do have a general question. Once a blank is cast and cleaned up, how do you make sure it is really straight?
Once cast, stress relieved and machined, the flat is hand scraped, using a large surface plate as a reference (flat) surface. High quality surface plates are generally flat within .000050".

Hand scraping is the process that has been traditionally used when ultra flat surfaces are required.

H
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rmac
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Re: Casting a straight edge

Post by rmac »

Harold_V wrote: Once cast, stress relieved and machined, the flat is hand scraped, using a large surface plate as a reference (flat) surface.
Aha! Got it. Thanks.
Glenn Brooks
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Re: Casting a straight edge

Post by Glenn Brooks »

Denis foster, up in Bellingham, wa sells straight edge, cast iron castings. He pours and sells the castings with his own patterns and foundry. Does an excellent job. Very talented guy. Iam sure you could call him and talk about what you want to do. He has all the techniques for pouring and aging cast iron down pat…

You could likely cut years off your project by buying one of his castings and start right into the machine work and scraping process.

Here is his email: denisgfoster at gmail dot com

Glenn
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Harold_V
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Re: Casting a straight edge

Post by Harold_V »

Glenn Brooks wrote: Sun Dec 04, 2022 12:36 pm Denis foster, up in Bellingham, wa sells straight edge, cast iron castings.
Thanks, Glenn. I'm acquainted with Denis. We've exchanged thoughts on several occasions. I would prefer to not ask of him in this instance, as what I'm trying to accomplish could easily appear to him that I hope to compete with his venture, which isn't the case. What I do hope to do is learn what it takes to create good castings when conditions aren't exactly desirable. That's true of most any casting where one has cross sections that vary considerably, as they do with a straightedge. How the metal freezes in the mold is all important. I have numerous books pertaining to the subject and I understand the significance. What I do not have at this juncture is any experience from which I can draw conclusions. That I will acquire by doing.
You could likely cut years off your project by buying one of his castings and start right into the machine work and scraping process.
While true, that's not my objective. I will never acquire the required skills that I seek by ignoring the processes necessary to achieve the degree of success I seek. That's not to say that you aren't correct for those who seek the destination instead of the journey.

I rarely rely on the endeavors of others to satisfy my needs. I would not "grow" by doing so.

H
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