what material would mill well enough to make a mold?

annihilator · Aug 20, 2004, 02:34 AM

allright guys, Im exploring the costs involved in finding a block/sheet/anything that can be stacked, glued whatever to CNC mill out a mold. Ive thought of wood, (cheap, but finish wouldnt be great at ALL!), metal is really expensive (find me a cheap place guys please!) and havent found and chunks of plastic!

im looking for enough to make about a 4 foot wing with a 1.5 inch maximum thickness. do you think if i sanded and waxed the wood you think that would work? anyone have experience with this?

thanks

1nk · Aug 20, 2004, 10:27 AM

You can use tooling foam, it machines real easily. I'm not sure how much it cost, probably expensive, not sure?

I've seen a guy machine a block of balsa wood into a wing once and just finished with varnish, man that was a strong wing.

Ward Hagaman · Aug 20, 2004, 12:55 PM

Just curious, but why 1.5 thick? I used 1/2" cast aluminum tooling plate for a 60" RG-15, and it is pretty thin, but works fine. Still not cheap, but considering the machining time the material cost is a small part of the total cost of the mold (in my opinion.)

annihilator · Aug 20, 2004, 05:52 PM

how much would that aluminum block cost? im not worried about machine time, its free for me

gkamysz · Aug 20, 2004, 09:44 PM

If machine time is free go for aluminum. A good price for aluminum is $2US per pound. But that is basically for off-cuts. Plan on spending $3.50-4.00 per pound minimum for anything large enough to make wing mold out of. Aluminum weighs .1Lb per cubic inch so it's easy to figure 55"x2"x8" would weigh 88Lb and cost $308 at $3.50 per Lb. If you need to ship it that could be substantial so check for local suppliers.

Greg

dharban · Aug 21, 2004, 12:19 AM

Try this site for a modeling plastic:

http://www.nfgsales.com/modeling.htm

Don

Aethertek · Aug 21, 2004, 10:08 PM

Acrylic Plexiglass machines like butter.

erazz · Aug 22, 2004, 03:36 AM

If we're on the subject, is there a free 3d toolpath program that you know of?

annihilator · Aug 22, 2004, 11:08 PM

man that modeling plastic sounds perfect. i sent them an email to find out how much it is.....any ideas on the price range? thinking about the 350 or 450 series.

Florrain · Aug 23, 2004, 02:43 AM

If you go for tooling foam, you have to decide if you are ready to do some finishing work including painting after the machining or if you want a material that can be polished coming out of the mill.

Renshape and Cibatool have both kind of tooling foam they are usually color-coded. Of course the price of the polishable material is very high compared to the more porous type.

A good tip if you have to paint the master is to mill a +-2mm deep groove all around the plug to acomodate for paint filets.
If you use the expensive material this is of course not necessary.

@+
Francois

Ward Hagaman · Aug 23, 2004, 10:58 AM

Florrain, you make a good point--milling a plug and pulling a epoxy mold from the male form is an option. I imagine that a cnc router might be happier cutting Renshape than Aluminum. Are there any other applications when it would be better to go that way instead of cutting the mold directly?

annihilator · Aug 23, 2004, 11:12 AM

yea guys i just priced some ren shape and its way out of my price range. for a 2x16x60 piece of the 350 series it would be 261.42!!!!!!!!!!! and thats the cheapest kind

oh well its was worth a shot. im thinking that the male plug might be the way to go. it would still be quicker than making a plug by hand.

Florrain · Aug 23, 2004, 11:17 AM

Hello

The idea behind milling a male plug is that you can pull multiple molds from it.

The way this usually happens in Europe is that some talented model designer creates a successfull design that a friend with CNC machine is willing to mill for a good price and then they pull a few molds from it.

When the model starts to give some good results, interrest quickly develops and it becomes possible to rent the plugs and recover some of the money involved in the designing, milling and moldmaking work.

Typically a plug for an F5D modell can be rented for +-400€ and for an F3B glider it's more around 1500€ wich might seem expensive but is still far less than if you have to have the plugs milled by a professional.

@+
Francois

devmonkey · Aug 23, 2004, 12:04 PM

You can mill molds from MDF, which is very cheap and can be glued to the required thickness using pva.

The molds will need sealing with epoxy and then polishing but this doesn't take anytime.

The molds will not last as long as those made from aluminium but when you consider the cost is around 4% it is well worth it.

Joe

1nk · Aug 23, 2004, 01:15 PM

What about machining 60 PSI Blue DOW refrigeration foam? That stuff is almost like a tooling foam, I just wonder how you can finish it, probably have to glass and vac bag the plug before you can even splash parts off it.

Aug 20, 2004, 02:34 AM	#1
annihilator making it up as i go. Join Date: Jun 2003 Location: Stillwater, Oklahoma, United States Posts: 169	what material would mill well enough to make a mold? allright guys, Im exploring the costs involved in finding a block/sheet/anything that can be stacked, glued whatever to CNC mill out a mold. Ive thought of wood, (cheap, but finish wouldnt be great at ALL!), metal is really expensive (find me a cheap place guys please!) and havent found and chunks of plastic! im looking for enough to make about a 4 foot wing with a 1.5 inch maximum thickness. do you think if i sanded and waxed the wood you think that would work? anyone have experience with this? thanks

Aug 20, 2004, 12:55 PM	#3
Ward Hagaman Registered User Join Date: Mar 2003 Location: San Diego Posts: 1,012	Just curious, but why 1.5 thick? I used 1/2" cast aluminum tooling plate for a 60" RG-15, and it is pretty thin, but works fine. Still not cheap, but considering the machining time the material cost is a small part of the total cost of the mold (in my opinion.) Last edited by Ward Hagaman; Aug 20, 2004 at 12:58 PM.

Aug 22, 2004, 03:36 AM	#8
erazz Registered User Join Date: Jun 2004 Location: Haifa, Israel Posts: 103	3D toolpath program If we're on the subject, is there a free 3d toolpath program that you know of?

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Aug 20, 2004, 10:27 AM	#2
1nk kill your foamie! Join Date: Jul 2004 Location: Ghanzi, Botswana Posts: 125	You can use tooling foam, it machines real easily. I'm not sure how much it cost, probably expensive, not sure? I've seen a guy machine a block of balsa wood into a wing once and just finished with varnish, man that was a strong wing.

Aug 20, 2004, 05:52 PM	#4
annihilator making it up as i go. Join Date: Jun 2003 Location: Stillwater, Oklahoma, United States Posts: 169	how much would that aluminum block cost? im not worried about machine time, its free for me

Aug 20, 2004, 09:44 PM	#5
gkamysz Dieselized User Join Date: Feb 2000 Location: Chicagoland Posts: 4,776	If machine time is free go for aluminum. A good price for aluminum is $2US per pound. But that is basically for off-cuts. Plan on spending $3.50-4.00 per pound minimum for anything large enough to make wing mold out of. Aluminum weighs .1Lb per cubic inch so it's easy to figure 55"x2"x8" would weigh 88Lb and cost $308 at $3.50 per Lb. If you need to ship it that could be substantial so check for local suppliers. Greg

Aug 21, 2004, 12:19 AM	#6
dharban Registered User Join Date: May 2004 Location: Tulsa, OK Posts: 749	Try this site for a modeling plastic: http://www.nfgsales.com/modeling.htm Don

Aug 21, 2004, 10:08 PM	#7
Aethertek Registered User Join Date: Jan 2004 Location: United States Posts: 418	Acrylic Plexiglass machines like butter.

Aug 22, 2004, 11:08 PM	#9
annihilator making it up as i go. Join Date: Jun 2003 Location: Stillwater, Oklahoma, United States Posts: 169	man that modeling plastic sounds perfect. i sent them an email to find out how much it is.....any ideas on the price range? thinking about the 350 or 450 series.

Aug 23, 2004, 02:43 AM	#10
Florrain Registered User Join Date: Dec 2002 Location: Belgium Posts: 623	If you go for tooling foam, you have to decide if you are ready to do some finishing work including painting after the machining or if you want a material that can be polished coming out of the mill. Renshape and Cibatool have both kind of tooling foam they are usually color-coded. Of course the price of the polishable material is very high compared to the more porous type. A good tip if you have to paint the master is to mill a +-2mm deep groove all around the plug to acomodate for paint filets. If you use the expensive material this is of course not necessary. @+ Francois

Aug 23, 2004, 10:58 AM	#11
Ward Hagaman Registered User Join Date: Mar 2003 Location: San Diego Posts: 1,012	Florrain, you make a good point--milling a plug and pulling a epoxy mold from the male form is an option. I imagine that a cnc router might be happier cutting Renshape than Aluminum. Are there any other applications when it would be better to go that way instead of cutting the mold directly?

Aug 23, 2004, 11:12 AM	#12
annihilator making it up as i go. Join Date: Jun 2003 Location: Stillwater, Oklahoma, United States Posts: 169	yea guys i just priced some ren shape and its way out of my price range. for a 2x16x60 piece of the 350 series it would be 261.42!!!!!!!!!!! and thats the cheapest kind oh well its was worth a shot. im thinking that the male plug might be the way to go. it would still be quicker than making a plug by hand.

Aug 23, 2004, 11:17 AM	#13
Florrain Registered User Join Date: Dec 2002 Location: Belgium Posts: 623	Hello The idea behind milling a male plug is that you can pull multiple molds from it. The way this usually happens in Europe is that some talented model designer creates a successfull design that a friend with CNC machine is willing to mill for a good price and then they pull a few molds from it. When the model starts to give some good results, interrest quickly develops and it becomes possible to rent the plugs and recover some of the money involved in the designing, milling and moldmaking work. Typically a plug for an F5D modell can be rented for +-400€ and for an F3B glider it's more around 1500€ wich might seem expensive but is still far less than if you have to have the plugs milled by a professional. @+ Francois

Aug 23, 2004, 12:04 PM	#14
devmonkey Registered User Join Date: Aug 2002 Location: London City, Great Britain (UK) Posts: 769	You can mill molds from MDF, which is very cheap and can be glued to the required thickness using pva. The molds will need sealing with epoxy and then polishing but this doesn't take anytime. The molds will not last as long as those made from aluminium but when you consider the cost is around 4% it is well worth it. Joe

Aug 23, 2004, 01:15 PM	#15
1nk kill your foamie! Join Date: Jul 2004 Location: Ghanzi, Botswana Posts: 125	What about machining 60 PSI Blue DOW refrigeration foam? That stuff is almost like a tooling foam, I just wonder how you can finish it, probably have to glass and vac bag the plug before you can even splash parts off it.