Question for you folks who cast blanks

[bobleibo]

As many of you know, I enjoy making wood travel mugs that use stainless inserts. They make awesome gifts.
Here's my question... is it feasible/possible/practical to cast a "blank" that is approx. 8" x 4" x 4" that will eventually be hollowed out and turned into one of my mugs still using the stainless liner?
I've never done any casting and don't plan to start. I'm very happy buying blanks from folks right here on IAP who have a far better artistic eye than I do and come up with the most amazing color combos, thus it would be something that I would commission from someone.

Thanks for your input~
Bob

 

[Brooks803]

I made a mold about that size to make a guy some pepper mill blanks. It took ALOT of resin to fill it. Not very practicle, but if its what's needed to do the job then its what you do. I don't know what you sell the mugs for but a blank might cost more than the finished product.

 

[Curly]

If I were going to make a mould for a tall cup I would have plug in the middle. That would give the basic shape wanted without using too much resin. Mr. Brooks could advise about feasibility of pouring into the thinner walls without trapping air.

 

[bobleibo]

Jonathon
The majority of mugs I give away as gifts. When I get a request for one, it depends mostly on the detail (segmenting, wood, etc.). I know the resin blank would cost a lot more. I think I'm really interested in making one with all of the colors and swirls that you guys who pour them come up with and seeing how it turns out.

Pete,
That's a great idea, kind of like building a wood blank out of staves. Cuts down on the waste.

Question: Doing it this way, would the blank be stable enough to endure it getting chucked up and turned until it was concentric and balanced? I'm picturing an out of round issue at first. Can resin/alumalite/poly withstand this when there is a fair amount of weight? Is one product a better choice for this than another?

Thanks~
Bob

 

[Brooks803]

Jonathon
The majority of mugs I give away as gifts. When I get a request for one, it depends mostly on the detail (segmenting, wood, etc.). I know the resin blank would cost a lot more. I think I'm really interested in making one with all of the colors and swirls that you guys who pour them come up with and seeing how it turns out.

Pete,
That's a great idea, kind of like building a wood blank out of staves. Cuts down on the waste.

Question: Doing it this way, would the blank be stable enough to endure it getting chucked up and turned until it was concentric and balanced? I'm picturing an out of round issue at first. Can resin/alumalite/poly withstand this when there is a fair amount of weight? Is one product a better choice for this than another?

Thanks~
Bob

For something this size I would definitely recommend alumilite for strength.

Pete had a great idea about using a plug to cut down on resin and less turning.

I went out and measured my mold and it's 3" in diameter and 8 1/2" long. If you think that'll work and you want to give it a try shoot me a PM and we can figure out the details.

 

[BSea]

If I were going to make a mould for a tall cup I would have plug in the middle. That would give the basic shape wanted without using too much resin. Mr. Brooks could advise about feasibility of pouring into the thinner walls without trapping air.

I've considered this a few times for different projects. I've never tried it though. I have done 1 really large pour for a friend that I basically charged him cost. That was 3 years ago, and he's never turned it. I recently did a 2" round blank that was 4" long. I charged $18 for that one. The plug is a good idea, and is something I've considered for a few other ideas. The big problem is to make a mold. You are probably talking about around $100 or more for a mold that large. And still I'll bet the blank would cost over $25 (just a guess at this point). Mainly because the walls would have to be thick enough to true up. And it would have to have a base large enough to put a tenon on to put into a chuck.

All this guessing is based on using PR. I think alumilite would be better because it's much less brittle. But the cost per blank would basically double.

 

[wyone]

Ok... not sure it is even feasible... make a mold the right size, and make a plug for the inside.. but the plug has a 3/4 hole in it. So in escence you get an almost hollow vessel, but a way to put the tailstock against it to true it up. Added bonus is once you get it trued up enough that you do not bed the tailstock to hold it.. you make a parting tool on a 90 degree so you can reach in and cut out the core.. and finish the inside. The core is of course sized to make a matching pen out of.

Now would it work? I have no idea.. but I like the idea

 

[BSea]

I just did a quick calculation. For a solid blank 4" round, and 8" high, it's around 60 fluid ounces, or close to a half gallon of resin. Compare that to a bottle stopper blank That's 1.5" X 2.5". They start at around $5 and go up from there (made from PR). There are about 3.5 ounces of resin in each one of those.

 

[magpens]

Would love to see a couple pictures of your mugs, please, Bob :biggrin::biggrin: ! If you have already posted some, perhaps you could send me the link, please.

 

[bobleibo]

link

Would love to see a couple pictures of your mugs, please, Bob :biggrin::biggrin: ! If you have already posted some, perhaps you could send me the link, please.

Here's a link to some I posted awhile back. Really easy to make - once you screw up a few dozen learning how NOT to make them :biggrin: .

http://www.penturners.org/forum/f45/christmas-coming-116239/

I have a friend who does my laser engraving on some of them with names, company logos, etc. Makes them more personal.

I'm more than happy to pass along any help I can if you decide to make some and help you avoid the dreaded learning curve.

Cheers
Bob

 

[bobleibo]

O.K., if one of you casters wants to take on the challenge, I would love to give this a try. I know it won't be cheap, but my curiosity is winning out over my wallet right now. The house payment can wait a few months~
I think I'd like to try with a solid block poured from various colors the first time around since that is what I'm use to doing with wood. I'll leave it up to those of you with more experience than me as to which material would be the best to use for a big block like this.

Any takers?

 

[wyone]

those mugs are beautiful!

 

[TellicoTurning]

Could you just pour the casting around the stainless steel insert... then you would only have to shape the outside... Never having done any casting - nor planning to - and never made a travel mug, just a thought expanding on the idea of the plug in the mold.

 

[bobleibo]

those mugs are beautiful!

Thank you~

Could you just pour the casting around the stainless steel insert... then you would only have to shape the outside... Never having done any casting - nor planning to - and never made a travel mug, just a thought expanding on the idea of the plug in the mold.

Hmmm, that's not a bad idea - I think. The biggest challenge would be turning the rough form but not hitting the stainless edges, maybe like turning a pen using bushings.
Casters, would this work? Does the material expand and/or contract when you pour it? Would the material stick to the stainless in the end to keep it together?

 

[bobleibo]

[/quote]

For something this size I would definitely recommend alumilite for strength.

Pete had a great idea about using a plug to cut down on resin and less turning.

I went out and measured my mold and it's 3" in diameter and 8 1/2" long. If you think that'll work and you want to give it a try shoot me a PM and we can figure out the details.[/quote]

The length is perfect, but the width is a little short. Here's a pic of a stainless liner. I need about a 1/2" a more than it to give me some wiggle room. Can a bigger mold be made?

 

[BSea]

The length is perfect, but the width is a little short. Here's a pic of a stainless liner. I need about a 1/2" a more than it to give me some wiggle room. Can a bigger mold be made?

Any size pvc can be used as a mold. So 4" PVC would work.

 

[bobleibo]

The length is perfect, but the width is a little short. Here's a pic of a stainless liner. I need about a 1/2" a more than it to give me some wiggle room. Can a bigger mold be made?

Any size pvc can be used as a mold. So 4" PVC would work.

BINGO! That is a great idea. That is exactly why people like me reach out to people like you for direction.
If you're up for the challenge, I'm in~

 

[MarkD]

I would agree that Alumilite would be the resin I would use. It typically doesn't shrink as PR does. It sticks well to wood but I have no idea if it would stick to stainless or not.
I'm not so sure about casting around the stainless steel insert. Seems like it would be alot of work to keep the resin off the finish portioned of the insert and holding and turning without damaging the insert.

Check out Brendan Stemp's "The Easter Light" video at Wood Turning Videos Archives - You Turn. His idea of using PVC pipe with a wood insert that is later used to turn the finished product might work well in your application. I would modify his design to lengthen the wood insert to include the plug to reduce the amount of resin that is required.

Sounds like a very interesting challenge!

 

[wyone]

So I get the difficulty with using the actual liner in the casting, but I am pretty sure Bob has the skills to make a wooden replica of the insert that could be used as a form insert. Then you just remove it, do the turning as usual and fasten the liner the same way

That sounds REALLY SIMPLE.. lol.. but I know it is way easier to type that than actually do that

 

[MarkD]

So I get the difficulty with using the actual liner in the casting, but I am pretty sure Bob has the skills to make a wooden replica of the insert that could be used as a form insert. Then you just remove it, do the turning as usual and fasten the liner the same way

That sounds REALLY SIMPLE.. lol.. but I know it is way easier to type that than actually do that

I have no doubt of Bob's skills but I question the "Then you just remove it" comment. if you cast Allumilte around a wood insert it's not coming out unless it's drilled or turned out. Now if you make a silicone insert...that's a different story.

 

[lwalper]

... or wrap the liner with plastic wrap so it will come out? How about lost wax? Make a plug mold using the SS liner as the original shape (plaster of paris), then pour it full of parafin. Use the parafin for the alumalite mold. Warm the entire thing after plastic casting and melt the wax out for re-use. You'd have an exact shape of the alumalite to just drop your liner into.

 

[Brooks803]

The length is perfect, but the width is a little short. Here's a pic of a stainless liner. I need about a 1/2" a more than it to give me some wiggle room. Can a bigger mold be made?

Any size pvc can be used as a mold. So 4" PVC would work.

As much as I hate casting in PVC this would be the easiest way to go before investing serious $ in a silicone mold.

I'd be willing to give it a try. The biggest hurdle for me would be time. I couldn't do anything for another 2 weeks. I've got tons of custom pen orders to finish up before I can even think about anything else. Plus I don't think I have enough alumilite here to make that large of a blank. I already have a 7gal pressure pot so the mold will fit in there easily.

I also have a good idea on how to make a mold that would be formed to the stainless steel insert...I'd just need to get one to make everything. Where do you get yours? Would you be willing to send me one? This mold would be silicone for consistent repeatability.

The first blank I'd do at cost just to see if it's something you'd be able to use. If that ends up working we can discuss going with that silicone plug insert and costs of blanks.

 

[BSea]

... or wrap the liner with plastic wrap so it will come out? How about lost wax? Make a plug mold using the SS liner as the original shape (plaster of paris), then pour it full of parafin. Use the parafin for the alumalite mold. Warm the entire thing after plastic casting and melt the wax out for re-use. You'd have an exact shape of the alumalite to just drop your liner into.

Lost wax won't work. When the alumilite cures, it's going to melt the wax. Same with PR. And while alumilite doesn't shrink as much as PR, it does shrink. I don't see a way to make a mold that the liner just drops into. I think there are ways to make something that will significantly reduce the amount of resin, but it will still require a lot of resin. I think if I were try this, I'd have to make a few wooden ones of my own, to see exactly what's involved. However, I would be interested in trying. But I have the same basic problem that Jonathon has. I won't be able to do anything till after the 15th of May.

 

[bobleibo]

The length is perfect, but the width is a little short. Here's a pic of a stainless liner. I need about a 1/2" a more than it to give me some wiggle room. Can a bigger mold be made?

Any size pvc can be used as a mold. So 4" PVC would work.

As much as I hate casting in PVC this would be the easiest way to go before investing serious $ in a silicone mold.

I'd be willing to give it a try. The biggest hurdle for me would be time. I couldn't do anything for another 2 weeks. I've got tons of custom pen orders to finish up before I can even think about anything else. Plus I don't think I have enough alumilite here to make that large of a blank. I already have a 7gal pressure pot so the mold will fit in there easily.

I also have a good idea on how to make a mold that would be formed to the stainless steel insert...I'd just need to get one to make everything. Where do you get yours? Would you be willing to send me one? This mold would be silicone for consistent repeatability.

The first blank I'd do at cost just to see if it's something you'd be able to use. If that ends up working we can discuss going with that silicone plug insert and costs of blanks.

... or wrap the liner with plastic wrap so it will come out? How about lost wax? Make a plug mold using the SS liner as the original shape (plaster of paris), then pour it full of parafin. Use the parafin for the alumalite mold. Warm the entire thing after plastic casting and melt the wax out for re-use. You'd have an exact shape of the alumalite to just drop your liner into.

Lost wax won't work. When the alumilite cures, it's going to melt the wax. Same with PR. And while alumilite doesn't shrink as much as PR, it does shrink. I don't see a way to make a mold that the liner just drops into. I think there are ways to make something that will significantly reduce the amount of resin, but it will still require a lot of resin. I think if I were try this, I'd have to make a few wooden ones of my own, to see exactly what's involved. However, I would be interested in trying. But I have the same basic problem that Jonathon has. I won't be able to do anything till after the 15th of May.

PM's sent to both....thank you