Planning a Cast Iron Camelback

[Richard King]

This is an old thread by a Stephen Thomas of a respected member. It's from 2014 but worth repeating it so the new members can see Practical Machinist has years of expertise. Stephen also used to make his own cast straight-edges too. Stephen do you still sell castings?
https://www.practicalmachinist.com/forum/threads/planing-a-straight-edge.287285/

 

[stephen thomas]

Richard -
Thanks!

My straight edge castings seems to have been the kiss of death for foundries.
4 went out of business, sequentially, after casting my orders.

The last one, after i had made the lightweight cored patterns and they cast a few the first batch, I placed a larger order and left the patterns and rigging with them. They were a good foundry. Unfortunately they, too, went under, the courts put a lock on them, and i could not get the patterns back. Both sets of patterns were either destroyed or stolen. That was almost a decade ago. Time sure flies

As you might experience with yours, after the handling, rough machining, heat treat (thermal stabilization) and then packing for shipment, it was difficult to get inspired to do it all over again. I was a little ahead of the curve with the first SE's almost 30 years ago, and the market was slow; plus still a lot of inexpensive kit on eBay and flea markets. More people are into it, and the market might be a little better these days; still probably not real steady & there are more suppliers.

I handled one of the older King SE's your dad made at the scrape fest in Savannah, they are nice tools. IIRC, you got back into producing them yourself.

smt

 

[Forrest Addy]

Richard -
Thanks!

My straight edge castings seems to have been the kiss of death for foundries.
4 went out of business, sequentially, after casting my orders.

The last one, after i had made the lightweight cored patterns and they cast a few the first batch, I placed a larger order and left the patterns and rigging with them. They were a good foundry. Unfortunately they, too, went under, the courts put a lock on them, and i could not get the patterns back. Both sets of patterns were either destroyed or stolen. That was almost a decade ago. Time sure flies

As you might experience with yours, after the handling, rough machining, heat treat (thermal stabilization) and then packing for shipment, it was difficult to get inspired to do it all over again. I was a little ahead of the curve with the first SE's almost 30 years ago, and the market was slow; plus still a lot of inexpensive kit on eBay and flea markets. More people are into it, and the market might be a little better these days; still probably not real steady & there are more suppliers.

I handled one of the older King SE's your dad made at the scrape fest in Savannah, they are nice tools. IIRC, you got back into producing them yourself.

smt

Patterns destroyed or stolen? That's sad news, indeed, Steven.I recall your efforts selecting proportions, design, and improvements. I was much taken by the features and aesthetics of your 30" straight edge. It was a handy length too, suited to work on knee mill columns and the width of the reference faces suited larger machines.

Can you create new patterns by positive/negative FRP molding from a casting?

How are things in Mark Twain country?

I hit 80 last year. While my balance and vision difficulties have pretty much banished me from my own shop, you'll be glad to know my talent for unwonted criticism of the inoffensive and ability to take offence over innocuous trivialities remains unabated. OTH, having outlived my contemporaries, I'm free to lie about my past exploits without fear of credible.

\Life is good.



refutation.

 

[stephen thomas]

Thank you for the compliments!
I did not know we were that close in age....you always seemed to have so much more...gravitas... for being only a decade older.

Can you create new patterns by positive/negative FRP molding from a casting?

Actually, i made such a basic mold a dozen years ago, when making the lightweight patterns.
But i don't have the inspiration, yet, to go through the effort to re-construct the lightweight version. I no longer believe in the original, heavy - though that one does offer the option to machine it for other forms, such as Vee/ inverted V or others. I seem to have killed all the likely foundries in a 200 mile radius. What is the market these days, for a rough planed, heat treated, $350-ish casting?

How are things in Mark Twain country?

Not bad, but winters are too short.
Just want to ski all winter and play with airplanes all summer.
As you probably noticed upon retirement, though, other people have all sorts of designs on your time. Plus, never having planned to retire, i did not plan well, and have to keep doing some work to fund my addictions.

Glad to hear you are ok, sorry to hear about the gradual decline, esp balance.

smt

 

[stephen thomas]

It's the cost and effort of repeating this process that daunts me:

 

[stephen thomas]

To add insult to injury, the last batch had a lot of defects.
Blow holes, shifts, etc.
They said "cut up, send pix, we will credit to next order". Sigh.
(Following photos do not show defects, merely used to show difference in sections between original, and lightweight castings. Someone adept at web searching can probably find my old ads, so i hate to be too specific from memory, but the LW saved some 8 lbs or more depending how each was machined & detailed. (30+ cu inches)

 

[dgfoster]

SMT,

You did some very nice pattern work there. It is sad indeed that you lost possession of them!

You know better than most that making a functional pattern involves a surprising amount of work and care. One of my great fears is that somehow I might lose one or more of my patterns through fire, theft, or, most likely, my own bumbling. That is why I am currently in the process of making working copies of my patterns from purpose-made urethane plastics. I’ll retire the masters and keep them remote from the copy. I have no idea if you used such materials supplied by Freeman for pattern making. But their products are very good and there are even better ones available. I have a nice monograph on silicone, urethane rubber, and rigid urethane suitable for pattern making if you are interested.

From personal experience I can tell you the only sensible reason to get into straight edge design and casting is for the joy of it. As you indicate the market is not large and profit margins are not great, especially if you have to farm out the casting. And that has its own set of issues as you mention. What tipped me over to casting was frustration with the output of a pretty reputable local foundry. They just did not “get” the quality constraints in metrological castings or the delicacy of the patterns to make them.

But, doing your own casting is a kick. Lots of learning curve associated. But still a kick.

Denis

 

[stephen thomas]

I have no idea if you used such materials supplied by Freeman for pattern making.

Everything in the pattern and dupe mould photos except the wood but including the PVA release agent, is from Freemans products.
I've used a few over the years.
As you note, there may be better, but Freeman makes it easy.
And predictable, which is even more of a factor.

 

[dgfoster]

NOW, it makes sense. I could not quite figure out what the “too perfect” white (urethane rubber?) molds into which you were evidently casting repro represented. So the blue patterns were evidently Repro. I am using the next iteration of Repro—-Repro One. Agreed that Freeman makes it easy. On the other hand, the following linked chapter expanded my understanding of the various silicones, urethane rubbers, and rigid urethanes available.

Guerrilla guide to CNC, mold making, and resin casting

Denis

 

[stephen thomas]

Denis -
i was casting a duplication of a rigid foundry pattern i had made (& used for a decade before that); it had draft all over and i preferred a rigid mold to maintain dimensions and shape. It was unnecessary to include the complications involved in accurately supporting a flexible urethane or RTV mold. Rigid is good, here.

Freeman has changed a little bit, but the basic mould making technique is even older, so this video is a good depiction. Basically you slosh the form-to-be-copied with a gel coat for details, when it gells a bit, add some more. Then another coat of a tougher product. Then bond on fiberglass strands and putty with a lightweight filler/bonding agent.

I did not expect to have to use the mold more than once when it was made, so i opted for the cheaper products as opposed to epoxy.

Laminate Tooling | Freeman Mfg & Supply Videos

www.freemanvideos.com

 

[dgfoster]

Denis -
i was casting a duplication of a rigid foundry pattern i had made (& used for a decade before that); it had draft all over and i preferred a rigid mold to maintain dimensions and shape. It was unnecessary to include the complications involved in accurately supporting a flexible urethane or RTV mold. Rigid is good, here.

Freeman has changed a little bit, but the basic mould making technique is even older, so this video is a good depiction. Basically you slosh the form-to-be-copied with a gel coat for details, when it gells a bit, add some more. Then another coat of a tougher product. Then bond on fiberglass strands and putty with a lightweight filler/bonding agent.

I did not expect to have to use the mold more than once when it was made, so i opted for the cheaper products as opposed to epoxy.

Laminate Tooling | Freeman Mfg & Supply Videos

www.freemanvideos.com

So, I guess the copy mold above is no longer available? The work you did on it from the pin-registered finger-jointed Baltic birch box to the perfect execution of the molding materials is exemplary.

I agree that Freeman makes some really awesome videos and has so much experience with there products, that they are undisputed industry standards and I really appreciate the fact that they will promptly respond to inquiries with a phone call from a knowlegeable and patient rep. That kind of customer service is so rare nowadays.

Denis

 

[stephen thomas]

So, I guess the copy mold above is no longer available?

It is still in the loft.
I move it from time to time, accessing the materials & patterns for cue building in the same corner.

My points were 1.) about choice of repro materials for the mould - used cheaper versions since originally the tool was a one-time expectation. (It is still in fine shape last i looked)
2.)What daunts me, as explained in a earlier post is the cost of new casting materials (still some here, but probably not enough for a straight edge) and then the time and effort to duplicate the lightweight pattern that avoids the need for separate cores.
3.)(new point) I have also considered that if the effort had to be done again, a 36" SE might be a better product for most people.

Do you use green sand moulding for your products?
Or one of the no-bake processes?

 

[dgfoster]

It is still in the loft.
I move it from time to time, accessing the materials & patterns for cue building in the same corner.

My points were 1.) about choice of repro materials for the mould - used cheaper versions since originally the tool was a one-time expectation. (It is still in fine shape last i looked)
2.)What daunts me, as explained in a earlier post is the cost of new casting materials (still some here, but probably not enough for a straight edge) and then the time and effort to duplicate the lightweight pattern that avoids the need for separate cores.
3.)(new point) I have also considered that if the effort had to be done again, a 36" SE might be a better product for most people.

Do you use green sand moulding for your products?
Or one of the no-bake processes?

I cast in green sand. I do use sodium silicate to bind cores for the 18 and 26” prism/parallel/level straight edges I make. (The prisms require an odd orientation and 3-level flasks which necessitates the cores.) All except the 8’s are cast in one or two casting batches in my solo barn-based foundry located more or less across the lake shirt-tail relatives of yours who live on Lake Whatcom. The eights I can cast 4 or 6 at a pouring session. Every casting is made in my foundry by me from very high quality iron returns sourced at a regional commercial foundry—-no recycling of brake drums, junk yard scrounges, discarded farm implements etc. Doing it this way helps me maintain consistent quality and protects my patterns not to mention sanity. ;-)

Denis

 

[stephen thomas]

in my solo barn-based foundry located more or less across the lake shirt-tail relatives of yours who live on Lake Whatcom.

That is either very obscure (to me)....
or....
given your age & MD, did you know my uncle who practiced in Bellingham & if so, how did you know he was related to me?

 

[dgfoster]

You and I conversed years ago. Yes, I did know and admired your Uncle Lane and I do know his kids. I'll contact you by PM later today with more. Heading to the foundry to pound sand....

Denis

 

[stephen thomas]

Whooda thunkit.
Closer than shirttail - Monica was one of my dad's older sisters.
But estranged, yes. Not sure why. Seems to have been "difficult" blood among the women.
For me, though, the idea (& photos) of her seaplane on the lake was inspirational.
I may learn more from you than family.

IIRC, sent email with last PM.
That is effective com for me.

I have to give another big "Thank YOU" to Richard for starting this!
Never know where you'll end up on PM.