Converted CNC mill for mold tooling

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skyfrog
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Converted CNC mill for mold tooling

Post by skyfrog » Sun Jun 05, 2005 2:15 am

Hi guys,

It seems that some members in this forum have experience converting manual mill to a CNC one. I'd like to know if anybody has used this kind of mill for mold tooling. I use commercial CNC mills for making molds, the mills are 100% MIT (Made In Taiwan), while the controllers are mainly FANUC, some of which are Mitsubishi. It is very obvious why are we so interested in converted CNC mill : a commercial CNC mill will cost around US$60K, while for converted one, very little money.

My humble opinion there are two major problems for converted CNC mill :

1. Vibration problem and frame rigidity. These two factors are very vital in accuracy, so the right kind of mill must be selected.
2. Automatic tool changer is a must. We need to change several tools for different machining purposes in s single operation, and machining hour tends to be very long.

It seems that converted CNC mill is suitable for green sand mold (for casting use), ie, machining wood, and the accuracy requirement doesn't have to be very high.

So what's your opinion guys ?
Long live jet engine !
Horace
Jetbeetle

pezman
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re: Converted CNC mill for mold tooling

Post by pezman » Sun Jun 05, 2005 2:57 am

Just about 20 years ago, I worked at Centroid for a brief time ...

It was started by two guys that built stepper motor controllers and they eventually honed in on the CNC retrofit market.

http://www.centroidcnc.com/bridgeportkneemill.htm

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Re: re: Converted CNC mill for mold tooling

Post by skyfrog » Sun Jun 05, 2005 3:51 am

pezman wrote:Just about 20 years ago, I worked at Centroid for a brief time ...

It was started by two guys that built stepper motor controllers and they eventually honed in on the CNC retrofit market.

http://www.centroidcnc.com/bridgeportkneemill.htm
Thanks, Centroid's products look good, and the pricing is very competitive too.

A nice manual mill will cost US$10k, plus Centroid's controller, another US$10k, a total of US$20k for mold tooling, hmm, sounds not bad.
Long live jet engine !
Horace
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re: Converted CNC mill for mold tooling

Post by Freepower » Sun Jun 05, 2005 11:13 am

Home made CNC is a bad idea!

The cost to retrofit with ballsrews and big enough servomotors is not worth it, and the there is the software, usually the cheap ones lack many features of the commersial ones.

So save yourself a lot of grief and bad experience, fork out the money for a good CNC mill!

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Re: re: Converted CNC mill for mold tooling

Post by skyfrog » Sun Jun 05, 2005 2:25 pm

Freepower wrote:Home made CNC is a bad idea!

The cost to retrofit with ballsrews and big enough servomotors is not worth it, and the there is the software, usually the cheap ones lack many features of the commersial ones.

So save yourself a lot of grief and bad experience, fork out the money for a good CNC mill!
I agree. But there are some mold tooling works might be quite suitable for retrofitted CNC mill. For example wood mold used in green sand casting, I always wanted to do that by low cost CNC mill. I think the total cost would be even cheaper, a US$1000 mill, plus a US$2000 controller+servo mtotrs, US$3000 in total. Doing wood milling need no high precision machines.
Long live jet engine !
Horace
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re: Converted CNC mill for mold tooling

Post by marksteamnz » Mon Jun 06, 2005 8:21 pm

The idea is to get a heavy old cnc with obsolete controls and up grade. There is a lot of activity round the world with CNC Bridgeports etc being upgraded. I know at least 3 people here in New Zealand that have imported CNC machines and retrofitted with PC based controls. These machines are 20% of the price of a new machine with 90% of the capability.
Turner tech offer a controller with all the big guy functions, look ahead, interpolation etc
Ajax are the same as Centroid just offer mail order rather than full dealer support so are cheaper
EMC is a FREE machine controller with simlar features to fanuac.
Yahoo groups DIY-CNC, jobshophomeshop and CAD_CAM_EDM_DRO have heaps of help and many many examples of people using updated PC controlled machines to make parts in comercial operations.
There are also good CAM programs now that follow the 90% 20% rule such as Visualmill.
Cheers
Mark Stacey
www.cncprototyping.co.nz

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re: Converted CNC mill for mold tooling

Post by El-Kablooey » Tue Jun 07, 2005 3:14 am

Just out of curiosity, what are you making molds for????
I have a bit of experience in sandcasting myself, as well as machining molds from brass and aluminum, for pouring with lead (fishing lures)

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Re: re: Converted CNC mill for mold tooling

Post by skyfrog » Tue Jun 07, 2005 4:37 am

El-Kablooey wrote:Just out of curiosity, what are you making molds for????
I have a bit of experience in sandcasting myself, as well as machining molds from brass and aluminum, for pouring with lead (fishing lures)
I build mostly wax molds for investment casting, they need to be very precise, I don't think home built CNC mill could be that good having the job done.

However I build sandcasting molds too, for casting casing of my planetary gearbox. I am quite sure home built CNC mill is nice for this purpose.

We are in different business, but we have something in common, that is, sport and leisure. Check my website and you know why I built these molds.
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Re: re: Converted CNC mill for mold tooling

Post by skyfrog » Tue Jun 07, 2005 4:40 am

marksteamnz wrote:The idea is to get a heavy old cnc with obsolete controls and up grade. There is a lot of activity round the world with CNC Bridgeports etc being upgraded. I know at least 3 people here in New Zealand that have imported CNC machines and retrofitted with PC based controls. These machines are 20% of the price of a new machine with 90% of the capability.
Turner tech offer a controller with all the big guy functions, look ahead, interpolation etc
Ajax are the same as Centroid just offer mail order rather than full dealer support so are cheaper
EMC is a FREE machine controller with simlar features to fanuac.
Yahoo groups DIY-CNC, jobshophomeshop and CAD_CAM_EDM_DRO have heaps of help and many many examples of people using updated PC controlled machines to make parts in comercial operations.
There are also good CAM programs now that follow the 90% 20% rule such as Visualmill.
Thanks for the info, I am a member of CAD_CAM_EDM_DRO group, but frankly I spent much more time in this forum than that one.
Long live jet engine !
Horace
Jetbeetle

RG Rhodes
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re: Converted CNC mill for mold tooling

Post by RG Rhodes » Tue Jun 07, 2005 5:28 pm

Acouple of other options are second-hand machines, which can sometimes
be a good deal if you know what your're looking for, and then there professionaly rebuilt machines which can be just as good or better than brand new if done by an experienced top-line machine rebuildiing house.
These can be a real bargain, and you have real capability if needed.
Check 'em out.
RG

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re: Converted CNC mill for mold tooling

Post by resosys » Tue Jun 07, 2005 6:44 pm

Skyfrog,

Homebuilt CNC is not a bad idea, especially for wax cutting. I've built a CNC plasma cutter which was used to cut all of our pulsejet parts as well as many other parts and art pieces.

I am in the middle of converting a small sherline mill to cnc. I've got all the parts on my bench at home and hope to get it completed in the next few weeks. I've also got a Harbor Freight (Taiwan) bench mill and a Jet 12"x48" lathe to be converted as time and cash allow. I found a small robot arm to be used for building a surface mount pick and place machine. We're also in the planning stages of building a new 13' x 6' CNC plasma and router table once we get the shop moved and have some cash.

The hobby industry CNC control software is now at near industrial levels. I use a program called Mach3 from http://www.artofcnc.ca It works very well and the support and user group is wonderful. It does things today that have Fanuc running, and in a few months it will be able to handle hundreds of inputs and outputs via Modbus, so custom stock feeders, tool changers, etc will be easy to implement. This will be handy for my pick and place machine.

The stiffness of your base machine is always going to be important. If you have the space and can find an old Bridgeport BOSS or other CNC mill with a bad controller, the conversion to a new controller will be much easier than starting with a manual mill and converting.

My sherline mill will have a CNC rotary table as well so I hope to be able to machine some nice turbine parts. That will a long while from now though.

I can answer most questions that you have, or point you to some great email lists and web resources.

Chris

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Re: re: Converted CNC mill for mold tooling

Post by skyfrog » Wed Jun 08, 2005 4:05 am

RG Rhodes wrote:Acouple of other options are second-hand machines, which can sometimes
be a good deal if you know what your're looking for, and then there professionaly rebuilt machines which can be just as good or better than brand new if done by an experienced top-line machine rebuildiing house.
These can be a real bargain, and you have real capability if needed.
Check 'em out.
RG
Yeah, thanks, a nice alternative way of getting the CNC mill. However it needs some luck to get a usable second hand machine,
1. There are many CNC mills listed on eBay, but are too far away for me to check the machine's condition in person, and the shipping cost is quite high too.
2. To find a nice used machine here on this island is not so easy, because the source is very limited.
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Horace
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Re: re: Converted CNC mill for mold tooling

Post by skyfrog » Wed Jun 08, 2005 4:14 am

resosys wrote:Skyfrog,

Homebuilt CNC is not a bad idea, especially for wax cutting. I've built a CNC plasma cutter which was used to cut all of our pulsejet parts as well as many other parts and art pieces.

I am in the middle of converting a small sherline mill to cnc. I've got all the parts on my bench at home and hope to get it completed in the next few weeks. I've also got a Harbor Freight (Taiwan) bench mill and a Jet 12"x48" lathe to be converted as time and cash allow. I found a small robot arm to be used for building a surface mount pick and place machine. We're also in the planning stages of building a new 13' x 6' CNC plasma and router table once we get the shop moved and have some cash.

The hobby industry CNC control software is now at near industrial levels. I use a program called Mach3 from http://www.artofcnc.ca It works very well and the support and user group is wonderful. It does things today that have Fanuc running, and in a few months it will be able to handle hundreds of inputs and outputs via Modbus, so custom stock feeders, tool changers, etc will be easy to implement. This will be handy for my pick and place machine.

The stiffness of your base machine is always going to be important. If you have the space and can find an old Bridgeport BOSS or other CNC mill with a bad controller, the conversion to a new controller will be much easier than starting with a manual mill and converting.

My sherline mill will have a CNC rotary table as well so I hope to be able to machine some nice turbine parts. That will a long while from now though.

I can answer most questions that you have, or point you to some great email lists and web resources.

Chris
Wow, gee, you're many steps ahead of me. Please give us a update after your project is completed. If you are milling the diffuser, the rotatry table will be needed. Wish you best luck converting the machine !

Sorry for my bad English, what I meant by "wax mold" was actually metal mold used for wax injection.
Long live jet engine !
Horace
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Re: re: Converted CNC mill for mold tooling

Post by resosys » Wed Jun 08, 2005 6:27 pm

skyfrog wrote:Wow, gee, you're many steps ahead of me. Please give us a update after your project is completed. If you are milling the diffuser, the rotatry table will be needed. Wish you best luck converting the machine !
Certainly. I'll try to snap some photos of the gear all spread out on the table tonight. I'm tearing an old power supply apart to use the box for the new power supply and motor drivers so hopefully I'll get to that this evening.
Sorry for my bad English, what I meant by "wax mold" was actually metal mold used for wax injection.
Ahhh, and your english is very good. You should be able to build a CNC mill that will cut mild steel or aluminum with plenty of accuracy, and harder materials at slow speeds/feeds with the same accuracy. There are several companies that sell ballscrew conversions for the various Taiwan mills and Bridgeports. I've seen these in operations that make very nice parts. I'll try to dig up the URLs for you.

Chris

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re: Converted CNC mill for mold tooling

Post by evildrome » Thu Jun 09, 2005 12:03 am

Thsi guy is so good it just makes me spit

http://www.5bears.com/cnc01.htm

Cheers,

Wilson.

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