Topic: What is sandcast?

[Seyser]

Ok I was looking at CB750's on ebay and I often see the term "Sandcast" What does that mean? I found the term describing bikes and also parts so It just got me curious.

-Jeremy-

[Sam Green Racing]

It means that the outer engine components have been cast in sand as apposed to being cast in a die.

[kghost]

Roughly the first 7500 bikes produced in '69 had engine cases that were sand cast. All the later bikes had pressure cast Cases.

Now obviously the early bikes are more collectable, as they only made 7500. Parts for them command a premium.

"Sandcast" is used by E-bayers to attract and get people to look at thier item. Most times it has absolutely jack #$%* to do with what it it actually fits.

[Seyser]

Ok, gotcha!
Thanks

[cb750_chris]

Don't bother bidding on items that say sandcast.  If in fact the item is sandcast specific the bidding with go pretty high.  Even if not a good # of dumb dumbs will pay more than the item is worth anyways. 

[MRieck]

If it says sandcast on ebay you can bet it's not.

[Ted Nomura]

Roughly the first 7500 bikes produced in '69 had engine cases that were sand cast. All the later bikes had pressure cast Cases.

Now obviously the early bikes are more collectable, as they only made 7500. Parts for them command a premium.

"Sandcast" is used by E-bayers to attract and get people to look at thier item. Most times it has absolutely jack #$%* to do with what it it actually fits.

You're absolutely right. I usually ignore the "sandcast" claim and just look at the parts carefully. The first 7414 engines are so-called "sandcasts" but many were destroyed when weak main drive chain ripped apart the cases and were replaced by diecast units under Honda warranty. "sandcasts" are actually gravity casts which caused rougher finish.

[Bob Wessner]

"sandcasts" are actually gravity casts which caused rougher finish.

Can you elaborate on this process also? What is the difference between it and sandcasting?

[damn_yankee]

Sand casting is just one of the gravity type casting methods. A negative pattern is made of the object being cast and then a mold is created form the pattern using a fine sand like material. Permanent mold is another type of gravity casting. In permanent mold casting the mold is usually steel with a higher quality surface finish than that of sand casting. Both are gravity processes where the metal is just poured into the mold without pressure or vacuum assist. There may be defective parts in this process where the mold does not fill properly. Tooling for sand casting is low and it is suitable for low volumes. Permanent molds cost more but last longer and piece parts are lower. There is additional cost associated with the manual labor involved with filling the molds and cutting/grinding off the sprues and gates.

Die casting uses pressure in expensive automated equipment suitable for high volumes and where piece prices are to be low. Initial tooling is very expensive but when amortized over 10-100 thousand parts the cost is much lower than the gravity type processes.

[supersport_CB400F]

Sandcast = expensive 

[Bob Wessner]

Thanks for the explanation. So, if I got it right   all sandcasting is gravity, does that mean the later K cases were gravity as well, just using steel molds?

[supersport_CB400F]

injection preasure speeds up production......faster 

[damn_yankee]

I'm guessing the later cases were die cast and not gravity cast as the volumes made sense to move to a more cost effective process. If it is die cast there will be ejection pin marks in certain areas - but usually not on cosmetic surfaces. If you look at the inside of a die cast part you'll see what I mean.

Injection molded plastic parts also have ejection pin marks on the non-cosmetic side. Take a look at the inside of your side covers.

[Ted Nomura]

"sandcasts" are actually gravity casts which caused rougher finish.

Can you elaborate on this process also? What is the difference between it and sandcasting?

Of course, "sandcasts" are not casted by sand but the first 7414 CB750 cases were created by a low pressure "gravity casts", thus giving a rough sandpaper type finish, but when early casts were destroyed by broken drive chain (Honda solved this problem by changing the engine drive sprocket number from 16 to 17 and reinforcing the area), they were replaced by a more sturdy diecast cases which were high pressure fed, thus giving more strength, we assume. This is the reason why original sandcast cases are rare, because Honda originally created them cheaply to keep the price down.

[Ted Nomura]

It means that the outer engine components have been cast in sand as apposed to being cast in a die.

Sandcasts are not cast in sand, its diecast under low "gravity cast" pressure, thus creating a sandpaper type finish. Later casts were done under high pressure diecast, thus creating a smoother and more durable finish.

[damn_yankee]

Die casting and sand casting are completely different processes. I have not seen an actual sandcast 750 but I am assuming they actually were "sandcast" - you can call the material sand, dirt or whatever you want. The point is hard tooling was not made - sand casting uses a pattern to which "sand" is then poured to make a mold. If you've never seen the process it is quite interesting...

[Ted Nomura]

Although I have three early 1969-1970 Honda CB750s, none of mine have sandcast cases but when I was in Japan, I had a chance to examine the one Honda had on their museum. The "sandcast" cases have a 400 or 600 grid sandpaper type finsh in light gray. Of course regular cases have a smooth metal finish that shines when buffed.

[elisent]

Sandcasts were not true sandcast in purist terms. They were gravity fed molds. Die cast would be under pressure and would not require the finishing of sandcast.  Diecast is much more expensive on the front side but in volume saves money, as it requires less expertise to finish. Ted's explanation is on the money. Sandcast by definition would be parts actually casted in a sand mold. They use a special sand for this process. It requires very special skills to finish. The only reason sandcast , Gravity molds , were used was because Honda had no idea how popular the 750 would be and it is cheaper upfront. Die casting is much cheaper in volume. I really don't think that weak chains destroyed any more sandcast cases than diecast. Cases cracking was not a casting problem as much as it was a chain problem. Everything Honda did was to save money and improve initial quality. Eli  geocities.com/indian440

[Ted Nomura]

The so-called "sandcast" models, all built in early 1969 (There are no 1970 "sandcasts", nor 1969 Candy Gold CB750s), as we know were built under economy conditions to test the market before going full production tooling. Roughly first 1000 units were handbuilt, mostly assembled in California, until it sold well enough to justify continued production in Japan after the labor strike ended. Incredibly, the early units were retail priced at low $1295 but greedy dealers usually tacked extra costs. Most were registered before August 1969 although some of the early unregistered CB750 test vehicles went back to Japan for complete examination.

[mylittleho]

I did sand casting in College as a sculpture major... it was such a pain in the ass.. But honestly is the easiest way to do LARGE castings.. (100-1000lbs) One example of what a waste sand casting is.. is that I did a 65lbs. bronze casting and it required a sand mold that was approximately 450lbs of resin catalyzed sand!!!!! it had to be atleast 2-4 inches thick in every dimension... It was such a waste of time and effort and resources to do a casting and it came out with little to no detail... the mold had to be made around an object and then the mold had to be taken apart and the object (pattern) removed.. when cast the 2 (or more) halves of the mold left tons of flashing (sharp edges where the metal seeped between the partitions of the mold) and caused a lot of finishing work...

Gravity casting is fine depending on the mold type.. the piece pictured below was done by gravity fed Shell casting.. the pattern is made out of wax and has a "cup" attached to the top used to pour the metal into (later cut off)  it is then dipped in a ceramic slurry over several days and then dusted with a fine layer of sand... this ceramic slurry is built up to about 1/4 inch around the piece and then vents are cut into it and it is placed in a 1000* furnace for 2-3 days to allow the wax to melt out and vitrify leaving a void for the metal to be poured into. the ceramic shells are brought out of the kiln at about 400* and are cast on the spot.. the detail is astounding (I got a perfect fingerprint out of one of my castings) and the material knocked off was very little.. so very little waste. problem is that the slurry had to be applied over several days.. whereas the sand mold could be made and cast in the same day..


http://i14.photobucket.com/albums/a324/scottolan/sculp1.jpg

[mylittleho]

I did sand casting in College as a sculpture major... it was such a pain in the ass.. But honestly is the easiest way to do LARGE castings.. (100-1000lbs) One example of what a waste sand casting is.. is that I did a 65lbs. bronze casting and it required a sand mold that was approximately 450lbs of resin catalyzed sand!!!!! it had to be atleast 2-4 inches thick in every dimension... It was such a waste of time and effort and resources to do a casting and it came out with little to no detail... the mold had to be made around an object and then the mold had to be taken apart and the object (pattern) removed.. when cast the 2 (or more) halves of the mold left tons of flashing (sharp edges where the metal seeped between the partitions of the mold) and caused a lot of finishing work...

Gravity casting is fine depending on the mold type.. the piece pictured below was done by gravity fed Shell casting.. the pattern is made out of wax and has a "cup" attached to the top used to pour the metal into (later cut off)  it is then dipped in a ceramic slurry over several days and then dusted with a fine layer of sand... this ceramic slurry is built up to about 1/4 inch around the piece and then vents are cut into it and it is placed in a 1000* furnace for 2-3 days to allow the wax to melt out and vitrify leaving a void for the metal to be poured into. the ceramic shells are brought out of the kiln at about 400* and are cast on the spot.. the detail is astounding (I got a perfect fingerprint out of one of my castings) and the material knocked off was very little.. so very little waste. problem is that the slurry had to be applied over several days.. and required several days to "burn-out" whereas the sand mold could be made and cast immediately..


http://i14.photobucket.com/albums/a324/scottolan/sculp1.jpg